Author: Ashton KIM

SWIR vs. FIR: What Is the Difference Between Short-Wave Infrared and PIR Thermal Infrared?

Last Updated: July 24, 2026
Author: Myungjoong Kim, CEO, Fresnel Factory Inc.
Reading Time: Approximately 10 minutes

Quick Answer

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SWIR and the infrared band used by PIR motion sensors are both outside the visible spectrum, but they operate as almost entirely different technologies.

  1. SWIR systems typically operate from approximately 0.9 to 1.7 µm and usually image reflected or transmitted light.
  2. PIR motion sensors typically detect thermal radiation near 8–14 µm, which is more accurately described as LWIR or thermal infrared.
  3. SWIR commonly uses InGaAs detectors, while PIR sensors use pyroelectric elements.
  4. A SWIR system may require sunlight, an LED, or a laser illuminator. PIR sensors detect radiation emitted by people without active illumination.
  5. SWIR and 8–14 µm systems require different detectors, optical materials, lens geometries, manufacturing tolerances, and evaluation methods.

The term “FIR lens” is widely used in the PIR motion-sensor industry, but specifying the actual operating wavelength—usually 8–14 µm—is more technically accurate.

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Why Is the Term “FIR” Confusing in the PIR Industry?

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Infrared wavelength terminology is not completely harmonized across optics, remote sensing, thermal imaging, telecommunications, and sensor manufacturing.

A practical engineering classification is:

Band Common Practical Range Typical Applications
NIR Approximately 0.75–1.0 µm 850 nm and 940 nm illumination, 905 nm LiDAR, ToF, and 3D sensing
SWIR Typically 0.9–1.7 µm InGaAs imaging, inspection, spectroscopy, and 1,550 nm systems
Extended SWIR Up to approximately 2.5–2.6 µm Chemical analysis and extended-InGaAs detection
MWIR Approximately 3–5 µm Cooled thermal imaging and high-temperature measurement
LWIR / thermal IR Approximately 8–14 µm PIR sensing, uncooled thermal cameras, and thermopiles
FIR Definition varies by field Frequently used informally for 8–14 µm PIR lenses

NASA Earth Science refers to 8–15 µm as thermal infrared because this region is useful for observing long-wave thermal energy emitted by the Earth. NASA’s remote-sensing classifications also include SWIR bands near 1.55–1.75 µm and 2.08–2.35 µm, illustrating why SWIR definitions may extend beyond the standard InGaAs range.
Source: NASA Science

For engineering specifications, it is therefore better to write:

  • 8–14 µm PIR Fresnel lens
  • LWIR thermal-imaging lens
  • 0.9–1.7 µm SWIR lens

rather than relying only on the term “FIR.”

At Fresnel Factory, the product terminology can be understood as follows:

  • Poly NIR series: Materials and lenses intended for selected near-infrared wavelengths such as 850, 905, 940, and 1,050 nm.
  • Poly FIR series: Polyethylene-based Fresnel lenses generally intended for human-detection applications near 8–14 µm.

Fresnel Factory provides separate categories for
PIR motion-detector Fresnel lenses
and
NIR and FIR optical components.
These categories should not be treated as interchangeable simply because both involve infrared wavelengths.

A material that performs well at 905 or 940 nm should not automatically be assumed to transmit efficiently at 1,310 or 1,550 nm. Spectral transmission must be verified across the wavelength range of the actual detector and illumination source.

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What Is the Main Difference Between SWIR and PIR Thermal Infrared?

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The most important difference is the origin of the radiation being detected.

Parameter SWIR PIR-Industry “FIR”
Full name Short-Wave Infrared Usually an informal name for LWIR or thermal IR
Typical operating range 0.9–1.7 µm 8–14 µm
Broader definitions May extend from approximately 0.7 to 2.5 µm FIR boundaries vary considerably by field
Main radiation source Reflected or transmitted sunlight, LED, or laser radiation Thermal radiation emitted by people, animals, and objects
Representative detector InGaAs, extended InGaAs, selected HgCdTe detectors Pyroelectric PIR, microbolometer, and thermopile
Typical applications Inspection, spectroscopy, moisture detection, wafer inspection, and laser imaging Motion detection, occupancy sensing, thermal imaging, and temperature measurement
Ordinary glass Some glass types can be used over selected SWIR bands Ordinary window glass is generally opaque at 8–14 µm
Common optical materials Selected optical glass, fused silica, silicon, and chalcogenide Polyethylene, germanium, ZnSe, ZnS, and chalcogenide
Active illumination Frequently used Not required for human thermal-radiation detection
Primary image information Reflectance, transmission, and absorption Surface temperature, emissivity, and thermal contrast

SWIR behaves more like visible-light imaging than conventional thermal imaging. Objects reflect, transmit, or absorb SWIR photons, and these differences create image contrast.

By contrast, PIR sensors and LWIR thermal cameras primarily detect energy emitted by objects because of their temperature.

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Which Wavelengths Are Commonly Used in SWIR Systems?

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A standard InGaAs detector generally covers approximately 0.9–1.7 µm. A representative Hamamatsu InGaAs photodiode specifies a cutoff wavelength of 1.7 µm and a typical peak-sensitivity wavelength of 1.55 µm.
Source: Hamamatsu Photonics

Wavelength Common Classification and Application
850 nm NIR illumination and sensing
905 nm Usually treated as NIR in LiDAR and ToF systems
940 nm NIR illumination, facial sensing, and 3D sensing
1,050–1,064 nm Boundary between NIR and SWIR terminology; industrial lasers
1,310 nm SWIR telecommunications and optical measurement
1,450 nm Strong water-absorption region
1,550 nm Telecommunications, eye-safer LiDAR, and SWIR imaging
Approximately 1,900 nm Strong moisture-sensitive spectral region
2.0–2.5 µm Spectroscopy and chemical identification

The classification boundaries overlap. For example, a 905 nm detector may technically fall within a broad SWIR definition, but most LiDAR engineers refer to 905 nm as NIR. For this reason, the wavelength itself should always be included in the product specification.

Extended-InGaAs detectors can reach longer wavelengths than conventional InGaAs devices. However, the detector material, optical material, coating, and illumination source must all be selected for the same spectral range.

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How Does a SWIR Camera Form an Image?

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Most SWIR cameras form images through a process similar to visible-light cameras:

  1. Sunlight, ambient radiation, a SWIR LED, or a laser illuminates the object.
  2. The object reflects, transmits, or absorbs different portions of the spectrum.
  3. The remaining radiation passes through the optical system.
  4. An InGaAs detector converts photons into electrical signals.
  5. The system produces a grayscale, multispectral, or hyperspectral image

Unlike a PIR sensor, a conventional SWIR camera does not normally detect a room-temperature person primarily from body heat. It usually detects sunlight, ambient nighttime radiation, or active illumination reflected from the person.

Hot metal, flames, furnaces, and molten materials can emit significant radiation in the SWIR band. However, that is a high-temperature application and should not be confused with ordinary human detection at room temperature.

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Why Do PIR Sensors Use Approximately 8–14 µm?

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The thermal-emission peaks of people and ordinary indoor objects therefore fall near 9–10 µm. This is one reason PIR sensors and uncooled thermal-imaging systems commonly operate in or near the 8–14 µm atmospheric window.

NASA describes 8–15 µm as a thermal-infrared region suitable for observing long-wave thermal radiation.
Source: NASA Science

The PIR sensor does not require an infrared LED or laser because the person is already the radiation source. This is the meaning of passive in Passive Infrared.

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How Is a PIR Sensor Different from a Thermal Camera?

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PIR sensors, microbolometer cameras, and thermopiles may all respond to thermal infrared, but they produce different types of information.

How Does a PIR Sensor Work?

A PIR sensor normally uses one or more pyroelectric elements. When the amount of infrared radiation reaching an element changes, the temperature and polarization of the pyroelectric material change, producing an electrical signal.

This expression means that a PIR sensor is primarily sensitive to a change in incident infrared flux, rather than a constant absolute temperature.

Murata explains that a pyroelectric sensor produces an output when the temperature of its pyroelectric ceramic changes. When the ceramic temperature remains stable, it does not continue to produce the same detection output.
Source: Murata Manufacturing

This explains several PIR characteristics:

  • A stationary person can become difficult to detect after the initial signal.
  • Movement across detection zones produces alternating signals.
  • Lens segments determine the direction and spatial distribution of the detection zones.
  • Amplifier bandwidth and digital detection algorithms strongly affect performance.

How Does a Microbolometer Work?

A microbolometer contains a two-dimensional array of pixels. Incident thermal radiation changes the temperature and electrical resistance of each pixel.

The camera can therefore produce a thermal image rather than a simple motion signal. With appropriate calibration, it may also estimate surface temperature.

Commercial LWIR camera lenses and modules are commonly designed for approximately 8–14 µm operation.
Source: Teledyne FLIR OEM

How Does a Thermopile Work?

A thermopile converts the temperature difference created by incident radiation into a thermoelectric voltage.

Thermopiles are commonly used in:

  • Non-contact thermometers
  • Occupancy and presence sensors
  • Low-resolution thermal arrays
  • Gas-analysis instruments
  • Appliance and industrial temperature sensing

Unlike a typical PIR element, a thermopile can respond to relatively steady thermal flux, although its response speed, sensitivity, and spatial resolution depend on the detector structure and signal processing.

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What Information Does SWIR Imaging Reveal?

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SWIR imaging shows differences in spectral reflectance, transmittance, and absorption.

Depending on the wavelength and material, SWIR can reveal:

  • Moisture-content variations
  • Bruising or defects in fruit and agricultural products
  • Contaminants in food-processing lines
  • Features beneath selected inks or coatings
  • Defects in solar cells
  • Structures through silicon wafers
  • Differences between polymers, textiles, minerals, and chemicals
  • Laser spots that are invisible to the human eye

NASA’s remote-sensing systems use SWIR bands to identify differences in leaf water content, minerals, soil characteristics, and other material properties.
Source: NASA Landsat

A SWIR image often resembles a monochrome visible-light image because it can include shadows, reflections, and illumination non-uniformity. However, objects with similar visible colors may appear very different when their SWIR absorption spectra differ.

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What Information Does an 8–14 µm Thermal System Reveal?

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An LWIR thermal image is affected by:

  • Surface temperature
  • Surface emissivity
  • Reflected thermal radiation
  • Thermal conductivity
  • Thermal capacity
  • Heat flow
  • Temperature changes over time
  • Thermal contrast between a target and its background

Two objects with the same visible color can appear very different in a thermal image when their temperatures or emissivities differ.

Conversely, objects with different visible colors may look similar in an LWIR image when their surface temperatures and emissivities are similar.

This distinction is important when selecting a detector. SWIR is usually selected to identify material or spectral differences, while LWIR is selected to identify thermal differences.

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Why Are SWIR and LWIR Lens Materials Different?

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Optical transparency is wavelength-dependent. A material that appears transparent to the human eye may be opaque at another infrared wavelength.

Which Materials Can Be Used for SWIR Optics?

For a conventional 0.9–1.7 µm system, candidate materials may include:

  • Selected optical glasses
  • Fused silica
  • Silicon
  • Sapphire
  • Chalcogenide glass
  • Selected SWIR-transmitting polymers
  • Crystalline infrared materials

SWIR optics generally use optical designs similar to visible-light systems, but the glass selection, anti-reflection coating, and chromatic correction must be optimized for the actual spectral range.

A visible-light lens may physically transmit part of the SWIR spectrum while still producing poor image quality because its focus shift, coating, aberration correction, and material absorption were not designed for that band.

Which Materials Can Be Used at 8–14 µm?

Typical LWIR optical materials include:

  • Germanium
  • ZnSe
  • ZnS
  • Chalcogenide glass
  • Selected infrared crystals
  • Polyethylene-based materials

Ordinary window and camera glass is unsuitable for most 8–14 µm applications. Special infrared-transmitting optical materials are therefore required.

High-resolution thermal cameras usually require precision germanium, chalcogenide, or other engineered infrared optics.

PIR motion detectors have different requirements. They normally prioritize:

  • Low manufacturing cost
  • Wide field of view
  • Detection-zone segmentation
  • Thin-wall construction
  • High-volume production
  • Outdoor durability
  • Suitable transmission near the human thermal-emission band

For these reasons, thin polyethylene-based Fresnel lenses are widely used in PIR motion sensors.

Fresnel Factory develops
wavelength-specific optical polymer materials,
including Poly NIR212, Poly FIR200, and Poly FIR25. The material must be selected according to the operating wavelength, required transmission, mechanical properties, environmental conditions, color, and molding process.

For a more detailed comparison of polyethylene compounds used in human-detection optics, see the
Guide to Material Selection for 8–14 µm FIR Lenses.
The guide discusses factors including infrared transmission, thickness attenuation, UV resistance, and compounded color materials.

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How Does SWIR Fresnel-Lens Design Differ from PIR Fresnel-Lens Design?

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The design objective changes significantly between the two applications.

What Is a SWIR Fresnel Lens Designed to Do?

A SWIR Fresnel lens may be developed for:

  • Concentrating radiation onto an InGaAs detector
  • Collimating a 1,310 or 1,550 nm source
  • Coupling light into a detector array
  • Spectrometer entrance optics
  • Structured illumination
  • Non-imaging collection
  • Compact low-resolution imaging

Important design parameters may include:

  • Spot size
  • Numerical aperture
  • Detector active area
  • Working distance
  • Focal length
  • Chromatic focal shift
  • Wavefront error
  • Modulation transfer function
  • Stray light
  • Fresnel reflection loss
  • Groove profile and surface roughness

Because SWIR wavelengths are relatively short, groove rounding, tool marks, surface roughness, and dimensional errors can introduce scattering and reduce concentration efficiency or image quality.

A Fresnel lens is not automatically suitable for every SWIR camera. A precision refractive lens may be more appropriate when high image resolution and low distortion are required.

What Is a PIR Fresnel Lens Designed to Do?

A PIR Fresnel lens is normally not intended to create a sharp image.

Its primary functions are to:

  • Divide a field of view into multiple detection zones
  • Direct each zone onto a pyroelectric element
  • Generate alternating signals as a target moves
  • Create near, middle, and far detection patterns
  • Establish wall-mount, ceiling-mount, or curtain patterns
  • Control blind spots and overlap
  • Match dual- or quad-element sensor geometry
  • Provide the required horizontal and vertical field of view

The PIR lens therefore behaves more like a field-mapping optic and spatial modulator than a conventional imaging lens.

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Can SWIR Be Used to See Heat?

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SWIR is infrared radiation, so it is not completely unrelated to temperature. However, it is generally unsuitable for observing thermal radiation from room-temperature people or objects.

A person near 310 K has a peak thermal-emission wavelength of approximately 9.35 µm. Thermal emission at 1.55 µm is extremely small by comparison.

A typical SWIR image of a person therefore shows:

  • Reflected sunlight
  • Reflected ambient nighttime radiation
  • Reflected SWIR LED radiation
  • Reflected 1,064 or 1,550 nm laser radiation

An 8–14 µm thermal camera or PIR sensor, by contrast, detects radiation emitted by the person and can operate without active illumination.

SWIR can be used for thermal measurement when the target is sufficiently hot, such as:

  • Molten metal
  • Furnaces
  • Flames
  • Hot glass
  • Semiconductor processes
  • High-temperature industrial components

In those cases, the target temperature shifts a meaningful portion of its thermal emission toward shorter wavelengths.

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When Should an Engineer Select SWIR?

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SWIR is appropriate when the system needs to:

  • Detect moisture-content differences
  • Inspect features beneath selected coatings or inks
  • Examine silicon wafers or photovoltaic cells
  • Detect a 1,310 or 1,550 nm laser
  • Perform food or agricultural sorting
  • Identify chemical or material differences
  • Build a SWIR spectrometer
  • Align an invisible laser
  • Receive a LiDAR signal
  • Improve imaging performance in selected haze, smoke, or low-light conditions
  • Use active illumination in approximately the 0.9–1.7 µm range

Performance through fog or smoke is not universal. It depends on wavelength, particle size, water content, atmospheric path length, and illumination power.

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When Should an Engineer Select PIR or LWIR?

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An 8–14 µm PIR or LWIR system is appropriate when the system needs to:

  • Detect human movement without active illumination
  • Detect occupancy at night
  • Produce a thermal image
  • Measure surface temperature
  • Inspect electrical overheating
  • Detect fires or hot spots
  • Control HVAC or building lighting
  • Detect animals
  • Perform perimeter surveillance
  • Identify thermal leakage or insulation defects

A PIR detector is normally preferred for low-cost motion detection.

A microbolometer is preferred when spatial thermal information or an image is required.

A thermopile is preferred when absolute or slowly changing radiation measurements are more important than motion-zone detection.

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How Can Polymer Fresnel Optics Be Used for Thermal Imaging?

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Polyethylene Fresnel optics can also be considered for compact, low-cost thermal-imaging systems where the required image resolution, field of view, detector format, and environmental conditions allow their use.

Fresnel Factory has developed an
HDPE lens module for 9–14 µm thermal-imaging sensors.
The prototype module uses HDPE and was developed with an 8 mm focal length and a 20° field of view for evaluation with a thermal-imaging sensor.

The company also published an evaluation using a
FLIR Boson 320 sensor with an HDPE Fresnel lens module.
This application demonstrates how molded polymer optics may be evaluated as an alternative to conventional precision infrared lens assemblies in selected compact thermal-camera designs.

Polymer Fresnel lenses are not a direct replacement for germanium or chalcogenide optics in every thermal camera. The acceptable solution depends on:

  • Detector resolution and pixel pitch
  • Required MTF and image quality
  • Focal length and field of view
  • Environmental temperature range
  • Lens thickness and transmission
  • Stray radiation and internal reflections
  • Mechanical packaging
  • Target manufacturing cost

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How Should a SWIR Detector Company Evaluate a Fresnel-Lens Supplier?

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A SWIR detector company should not evaluate a potential supplier only by asking whether it already manufactures “infrared lenses.”

The supplier should be able to define and verify:

  1. The exact wavelength or spectral band
  2. The detector material and active-area dimensions
  3. Whether the system is imaging or non-imaging
  4. The illumination source and beam characteristics
  5. The required field of view or numerical aperture
  6. The focal length and working distance
  7. The target spot size or energy distribution
  8. Material transmission across the complete operating band
  9. Surface-roughness and groove-profile requirements
  10. Environmental and production-volume requirements

Experience with 8–14 µm PIR optics does not automatically prove capability at 1,550 nm. Conversely, a material developed for 940 nm NIR sensing may not be suitable for a broadband 0.9–1.7 µm SWIR camera.

The wavelength-dependent refractive index, absorption, molding characteristics, coating requirements, detector architecture, and required image quality must all be reviewed.

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How Can Fresnel Factory Support SWIR and PIR Optical Development?

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Fresnel Factory’s established PIR capabilities include:

  • 8–14 µm polyethylene Fresnel-lens design
  • Human thermal-radiation collection
  • Wide-field detection-zone mapping
  • Dual- and quad-element pyroelectric sensor optics
  • Wall-mount, ceiling-mount, and curtain detection patterns
  • Injection-molded thermal-infrared optical components
  • Optical simulation and sensor performance testing

For a SWIR project, the development process should begin with the wavelength and system architecture rather than by reusing an existing PIR design.

Potential development support includes:

  • Material-transmission review for the target wavelength
  • Detector-coupling optical design
  • Fresnel concentrator design
  • Laser collimation or beam shaping
  • Detector-array coupling
  • Moldability and tolerance review
  • Prototype tooling
  • Injection-molding process development
  • Optical and system-level performance testing

Fresnel Factory’s
lens simulation and system design consultancy
supports the definition of the field of view, sensing distance, detector geometry, material, mechanical integration, and expected system performance. Optical design should begin before the external product design is finalized because the lens size, shape, and exposed optical area can affect both performance and industrial design.

Once the optical concept has been validated, the design can be transferred to
mold tooling, prototyping, and volume manufacturing.
This process includes converting the optical surface into a manufacturable mold design, reviewing post-molding shrinkage, selecting a suitable material, and controlling the mechanical tolerances between the lens, housing, and detector.

Manufactured optics and completed sensor assemblies can also be evaluated through
optical performance testing for infrared sensing devices.
The test service is intended for motion, presence, and LiDAR applications and can be used to compare simulation results with the performance of the manufactured device.

A Fresnel optical element can be effective when the objective is compact light collection, beam shaping, collimation, field mapping, or non-imaging concentration. For high-resolution SWIR imaging, the benefits and limitations of Fresnel optics should be evaluated against conventional multi-element refractive optics.

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Frequently Asked Questions

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Is SWIR the Same as Thermal Imaging?

No. SWIR normally forms an image from reflected or transmitted radiation, while thermal imaging normally detects radiation emitted by an object because of its temperature.

Is 905 nm Considered SWIR?

It falls within some broad SWIR definitions, but most LiDAR and sensing engineers classify 905 nm as NIR. Specifying the wavelength is more reliable than relying only on the band name.

Is 1,550 nm Considered SWIR?

Yes. A wavelength of 1,550 nm is within the conventional 0.9–1.7 µm SWIR range and is commonly detected using InGaAs devices.

Why Is an 8–14 µm PIR Lens Called an FIR Lens?

The term developed as an industry convention. More precise descriptions are “8–14 µm PIR lens,” “LWIR PIR lens,” or “thermal-infrared PIR lens.”

Can an Ordinary Glass Lens Be Used for SWIR?

Selected glass types can be used over portions of the SWIR spectrum. However, transmission, coating, focus shift, and aberration performance must be verified over the actual operating band.

Can Ordinary Glass Be Used for an 8–14 µm Thermal Camera?

Generally, no. Ordinary window and camera glass is largely opaque in this band, so infrared materials such as germanium, chalcogenide glass, or selected polymers are required.

Why Does a PIR Sensor Have Multiple Fresnel Segments?

Each segment maps a different region of space onto the pyroelectric elements. A moving target crosses these regions and creates the changing or alternating infrared signal required for motion detection.

Can One Fresnel-Lens Material Support Both 940 nm and 1,550 nm?

Possibly, but it should not be assumed. Transmission, refractive index, absorption, surface quality, and molding performance must be verified at both wavelengths.

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Conclusion

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SWIR and PIR thermal infrared should not be treated as interchangeable simply because both are called infrared.

A SWIR system near 0.9–1.7 µm generally observes reflected, transmitted, or actively illuminated radiation. A PIR or LWIR system near 8–14 µm detects thermal radiation emitted by people and objects.

This difference determines:

  • Detector technology
  • Illumination requirements
  • Optical materials
  • Lens geometry
  • Manufacturing tolerances
  • Test methods
  • The information contained in the resulting signal or image

When discussing a new infrared optical project, the most useful first question is therefore not:

“Is this an IR lens?”

It is:

“What is the exact operating wavelength, detector type, and optical function?”

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Discuss Your Infrared Optical Requirements

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Engineers can review Fresnel Factory’s standard components through the
Fresnel Factory supplier page on DigiKey.

For custom SWIR, NIR, PIR, thermopile, or thermal-imaging optics,
contact Fresnel Factory
with the following initial requirements:

  • Operating wavelength or spectral range
  • Detector model and active-area dimensions
  • Imaging or non-imaging application
  • Required field of view
  • Detection or working distance
  • Available lens dimensions
  • Target material and environmental conditions
  • Prototype and expected production quantities

Fresnel Factory operates from its head office in Suwon, South Korea, with a U.S. branch in Silicon Valley.

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About the Author

Ashton Kim is the CEO of Fresnel Factory Inc. His work focuses on Fresnel optical design, PIR and thermal-infrared sensor optics, injection-molded optical components, custom tooling, and sensor performance evaluation.

Related Articles

  • How to Design a 120° PIR Motion Sensor for Lighting Control
  • How PIR Fresnel Lenses Create Detection Zones
  • HDPE vs. Silicon vs. Germanium for Infrared Optical Systems

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How to Design a 120° PIR Motion Sensor for Lighting Control: Why Mechanical Design Matters as Much as Optical Performance

Last Updated: July 16, 2026
Author: Ashton Kim, CEO, Fresnel Factory Inc.
Target Readers: Hardware Engineers and R&D Managers
Application: PIR-Based Lighting Automation

Quick Answer

Achieving a reliable 120° horizontal detection area with a PIR sensor is difficult when the Fresnel lens must remain flat and flush with the product surface. In this lighting-control project, the central target was approximately 6 m, while the outer detection zones were expected to retain at least 50% of the central performance.

  1. A nominal 120° lens FoV is not the same as a guaranteed 120° human-detection area.
  2. The PIR sensor, lens, PCB position, focal distance, and enclosure must be designed as one optical system.
  3. Increasing the sensor-to-lens distance from approximately 8 mm toward 9.5 mm can provide more optical design flexibility.
  4. A lens width of approximately 40 mm may support a wide horizontal detection pattern, but the available vertical area must also be reviewed.
  5. Adding a second PIR sensor does not automatically create a significantly wider FoV unless its position or installation angle is changed.
  6. The Fresnel lens supplier should participate before the mechanical design and PCB position are frozen.

What Was the Customer Trying to Develop?

A global building-automation company approached Fresnel Factory during the early development stage of a new PIR-based lighting-control product. The device was intended to detect human movement across a wide area and use that information to control lighting automatically.

The customer had already selected a compact, low-profile SMD PIR sensor from Murata. The baseline concept used one PIR sensor mounted on a PCB parallel to the wall. The Fresnel lens also needed to remain flat and aligned with the exterior surface of the product.

The primary development targets were:

  • Approximately 120° horizontal field of view
  • Approximately 6 m detection range in the central zone
  • At least 50% of the central performance in the outer zones
  • A flat Fresnel lens flush with the product surface
  • A clean exterior without excessive molding or shrink marks
  • One PIR sensor as the baseline architecture
  • Approximately 30° vertical FoV under review
  • Target production by the end of 2027

The main question was not simply whether the selected sensor could detect a person at 6 m. The more difficult question was whether the system could create a reliable 120° horizontal detection area while remaining within the mechanical and cosmetic limitations of the product.

Why Is a 120° FoV Difficult With a Flat PIR Fresnel Lens?

A PIR Fresnel lens divides the monitored space into multiple optical zones and directs far-infrared energy from a moving person toward the pyroelectric sensing elements. The geometry of these zones depends on the sensor element arrangement, focal distance, lens dimensions, Fresnel segment geometry, and the position of the sensor relative to the lens.

Wide-angle detection becomes more difficult when the optical surface must remain completely flat. A curved or angled lens surface can provide more favorable geometry for collecting infrared energy from the far-left and far-right detection zones. A flat lens provides less freedom for redirecting these steep peripheral rays toward a small PIR sensing element.

To compensate for this limitation, the optical designer may need to use a larger lens area, increase the focal distance, adjust the sensor position, or use more aggressive Fresnel segment geometry. Each option affects other parts of the product.

  • A larger lens requires more exterior and internal space.
  • A longer focal distance increases the required housing depth.
  • A tilted sensor may require a separate PCB or mechanical bracket.
  • Aggressive segment geometry can make injection molding and cosmetic control more difficult.
  • A wider horizontal FoV may reduce the optical area available for vertical coverage.

For this reason, a 120° requirement should not be treated as a lens specification alone. It is a system-level requirement involving the PIR sensor, optics, electronics, mechanical structure, and performance-test criteria.

How Should a 120° PIR Detection Requirement Be Defined?

PIR field of view can be defined differently by different sensor and lens suppliers. A nominal optical angle, a simulated detection zone, and a guaranteed human-detection area are not necessarily the same.

For this project, the 120° target was interpreted as an effective horizontal detection area. The central zone was expected to detect a person at approximately 6 m. The outer zones did not need to provide exactly the same distance, but they were expected to retain at least 50% of the central detection performance.

This is more useful than stating only “120° FoV,” because it defines how the product should perform across the monitored area.

A practical PIR requirement should specify:

  • The guaranteed horizontal detection angle
  • The guaranteed vertical detection angle
  • The central detection distance
  • The minimum peripheral detection distance or performance ratio
  • The installation height
  • The direction and speed of human movement
  • The target size and clothing conditions
  • The ambient and target temperature difference
  • The PIR signal threshold and pass/fail criteria

Without a common test definition, one supplier may describe a lens as 110°, while another may describe a similar detection pattern as 120°. Fresnel Factory therefore recommends reviewing the actual detection map rather than comparing only the FoV number printed on a datasheet.

What Design Changes Were Evaluated During the Consultation?

1. Increasing the Sensor-to-Lens Distance

The preliminary mechanical drawing provided approximately 8 mm between the PIR element and the lens surface. Increasing this distance toward approximately 9.5 mm was discussed.

A longer focal distance can provide more design freedom when assigning the outer Fresnel zones. It does not guarantee 120° performance by itself, but it can make the target more feasible within a flat-lens structure.

2. Using the Available Horizontal Lens Area

The proposed lens width was approximately 40 mm. Fresnel Factory had experience with a similar wide-angle design using an optical surface of approximately 37 mm and a focal distance of about 9.5 mm.

This suggested that the available horizontal width could be sufficient for continued development, provided that the sensor position and focal distance were adjusted appropriately.

3. Increasing the Vertical Optical Area

The preliminary vertical lens area was only about 7 mm. If the customer retains an approximately 30° vertical FoV requirement, the vertical optical area may need to be increased.

A wide horizontal FoV and a wide vertical FoV compete for the limited lens surface. The final window dimensions should therefore be determined after both requirements are confirmed.

4. Evaluating Sensor Tilt

The baseline design positioned the PIR sensor parallel to the wall without horizontal or vertical tilt. A controlled sensor angle could improve coverage in a selected direction, but it would require mechanical or PCB changes.

Because the product was still in an early design phase, the customer agreed to review whether the internal structure could accommodate these changes.

5. Evaluating a Dual-Sensor Architecture

A second PIR sensor was considered as an optional way to increase coverage. However, placing two sensors on the same plane and at the same angle does not automatically double the field of view.

In the discussed geometry, the increase could be limited to approximately 10° unless the sensors were separated, tilted, or assigned different optical zones. A dual-sensor design must therefore be evaluated together with the PCB layout, signal-processing method, cost target, and enclosure space.

6. Using the Sensitivity of the Selected PIR Sensor

Based on Fresnel Factory’s previous design experience, the selected Murata PIR sensor was expected to provide strong signal sensitivity compared with several conventional alternatives.

This made the 6 m central detection target relatively manageable. The more significant design challenge remained the wide peripheral coverage created by the flat optical surface.

How Did the Engineering Direction Change After the Consultation?

Design Item Initial Development Target Engineering Direction After Consultation
Horizontal FoV 120° Retain 120° as the effective detection-zone target
Central Detection Range Approximately 6 m Maintain approximately 6 m
Peripheral Detection Not fully defined Define as at least 50% of central performance
Sensor-to-Lens Distance Approximately 8 mm Evaluate an increase toward approximately 9.5 mm
Lens Width Approximately 40 mm Retain and optimize the available width
Lens Height Approximately 7 mm Increase if an approximately 30° vertical FoV is mandatory
Lens Exterior Flat and flush Retain while recognizing wide-angle optical limitations
Number of PIR Sensors One sensor One sensor as baseline; two sensors as an optional study
Sensor Installation Angle Parallel to the wall Evaluate horizontal or vertical tilt if mechanically possible
Cosmetic Requirement Clean exterior surface Balance optical geometry with molding and shrink-mark control
Target Production End of 2027 Allow sufficient time for simulation, tooling, testing, and iteration

Why Should the Fresnel Lens Supplier Join the Project Early?

In many PIR projects, the enclosure, PCB, and optical window are designed first, and the lens supplier is contacted only after the mechanical structure has been frozen. This sequence creates unnecessary design risk.

The following parameters are directly connected:

  • PIR sensor element size and arrangement
  • Sensor package height
  • PCB position and installation angle
  • Sensor-to-lens distance
  • Lens width and height
  • Horizontal and vertical detection zones
  • Housing depth and exterior curvature
  • Lens material and injection-molding conditions
  • Cosmetic surface requirements

If the PCB position is fixed too close to the lens, the optical designer may not have enough focal distance to create the required peripheral zones. If the optical window is too narrow vertically, the target vertical FoV may not be achievable. If the enclosure must remain completely flat, a wider lens area or different sensor position may be necessary.

Early collaboration allows these trade-offs to be evaluated before tooling begins. In this project, the customer’s mechanical team could still review the additional 1.5 mm of sensor-to-lens distance, lens-window height, and possible sensor tilt before the internal structure was finalized.

What Information Should Engineers Prepare for a Custom PIR Lens Project?

Providing the following information allows an optical supplier to evaluate feasibility more accurately:

  1. PIR sensor manufacturer and exact part number
  2. Pyroelectric element dimensions and arrangement
  3. Required horizontal and vertical FoV
  4. Central and peripheral detection-distance targets
  5. Product installation height and orientation
  6. Expected human movement direction
  7. Available sensor-to-lens distance
  8. Maximum optical-window width and height
  9. Flat, curved, tilted, or recessed exterior requirements
  10. PCB position and allowable sensor angle
  11. Cosmetic and injection-molding restrictions
  12. Target development schedule and production volume

A 3D mechanical drawing is useful, but it should be considered a starting point rather than a fixed constraint during the first optical feasibility review.

How Can Fresnel Factory Support a New PIR Product?

Fresnel Factory supports PIR projects from initial feasibility review through optical design, tooling, manufacturing, and performance verification.

  • Review of PIR sensor geometry and package dimensions
  • Recommended sensor-to-lens distance
  • Horizontal and vertical detection-zone design
  • Custom Fresnel segment layout
  • Mechanical integration guidance
  • Evaluation of single- and dual-sensor architectures
  • Optical simulation and design iteration
  • Prototype tooling and injection molding
  • PIR signal and detection-pattern testing
  • Collaboration with customer mechanical and electronics teams

The objective is not simply to manufacture a lens that fits an existing opening. It is to define a sensor, lens, and mechanical arrangement that can be tested against a measurable detection requirement.

What Was the Main Engineering Lesson From This Project?

The primary challenge was not whether the selected PIR sensor could detect a person at 6 m. The greater challenge was achieving a reliable 120° horizontal detection area while keeping the lens flat, preserving a clean exterior, and fitting the optical system within the available mechanical space.

The practical solution was therefore not a lens-only modification. It required coordinated optimization of the lens area, focal distance, sensor position, vertical coverage, PCB structure, and enclosure design.

For hardware engineers and R&D managers beginning a PIR project, the most important step is to involve the optical supplier before the mechanical design is frozen. A few millimeters of additional focal distance or lens-window area during the concept stage can prevent major performance compromises and costly redesign later.

Frequently Asked Questions

Can a flat PIR Fresnel lens achieve a 120° field of view?

It may be possible, but feasibility depends on the PIR element size, focal distance, lens dimensions, required detection range, and test criteria. A flat surface makes peripheral-zone design more difficult than a curved or angled lens.

Does a 120° lens FoV guarantee 6 m detection across the entire angle?

No. A nominal lens FoV does not guarantee equal detection distance at every angle. The central and peripheral detection targets should be defined separately.

What sensor-to-lens distance is required for a wide-angle PIR design?

There is no universal distance. In this project, increasing the distance from approximately 8 mm toward 9.5 mm was considered to provide more optical design flexibility.

Does using two PIR sensors double the field of view?

No. If two sensors are installed on the same plane and at the same angle, the improvement may be limited. Their positions, angles, optical zones, and signal-processing method must be designed together.

Why can two suppliers state different FoV values for similar PIR lenses?

Suppliers may use different signal thresholds, walking paths, target conditions, and definitions of guaranteed versus non-guaranteed detection. Detection maps and test conditions should be compared instead of the angle alone.

Why does the vertical size of the PIR lens matter?

The vertical lens area determines how much optical space is available for vertical detection zones. A very narrow lens may restrict the achievable vertical FoV even when sufficient horizontal width is available.

When should a Fresnel lens supplier become involved?

The supplier should be involved before the PCB position, housing depth, optical-window dimensions, and sensor installation angle are finalized.

Start a PIR Optical Feasibility Review

To evaluate a new PIR project, prepare the sensor part number, target detection map, installation height, PCB position, lens-window dimensions, and preliminary 3D mechanical data.

Request a custom PIR lens feasibility review from Fresnel Factory

Engineers looking for standard Fresnel Factory components can also review available products through
Fresnel Factory’s DigiKey Supplier Center.

About the Author
Ashton Kim is the CEO of Fresnel Factory Inc. His work focuses on Fresnel optical design, PIR and TMOS sensor optics, infrared lens manufacturing, injection molding, and custom sensor-system development. He also work for IEC building international standards for sensors.

Technical Note: The dimensions and performance targets in this article describe an engineering consultation at the concept-development stage. Final performance must be verified through optical simulation, prototype production, and physical detection testing.


PF25-09015A PIR Fresnel Lens for Wall-Mounted Pet-Immune Burglar Alarm Sensors

Last Updated: 2026-06-23
Author: Myung Joong Kim, CEO, Fresnel Factory

Quick Answer

PF25-09015A is an off-the-shelf PIR Fresnel lens designed for wall-mounted burglar alarm detectors,
PIR camera modules, and indoor surveillance motion sensors. It is specified for a 100° detectable angle,
12 m detectable distance, and 25 mm sensor-to-lens distance.

  • Designed for wall-mounted, pet-immune PIR detector applications.
  • Uses a multi-zone field-of-view structure shown as detection regions A through P.
  • Can support cross-zone confirmation and movement-pattern filtering in PIR detector logic.
  • Helps create broad room coverage compared with a narrow curtain-style detection approach.
  • Suitable for burglar alarm sensors, security cameras, and indoor surveillance motion detectors.

Why is PF25-09015A suitable for wall-mounted burglar alarm sensors?

“`

A burglar alarm motion detector must identify meaningful human movement while avoiding unnecessary alarms
caused by pets, airflow, temperature changes, sunlight, electrical noise, or short environmental disturbances.
The PIR sensor, signal-processing circuit, installation condition, and Fresnel lens must work together as one system.

PF25-09015A is designed for wall-mounted PIR detector configurations. Its datasheet specifies a
100° detectable angle, 12 m detectable distance, and
wall-mounted, pet-immune installation. These characteristics make it a practical starting point
for indoor burglar alarms, PIR photo cameras, and room-monitoring surveillance devices.

The lens has an overall size of 57.7 × 36 mm and a nominal
sensor-to-lens distance of 25 mm. This gives enclosure and PCB designers a defined optical
reference when developing a detector housing.

How does the multi-zone field-of-view structure help reduce blind areas?

“`

Many conventional wall-mounted PIR detectors use a limited number of broad zones or narrow curtain-style
detection patterns. Curtain-type optics can be useful for corridors, doorways, or perimeter-crossing detection,
but they may leave coverage transitions when the objective is broad room monitoring.

The PF25-09015A field-of-view drawing shows multiple optical detection regions identified from
A through P. Rather than relying on a single narrow sensing curtain, the lens distributes
detection coverage across a wider monitored area.

This multi-zone optical structure can help a detector designer create a more continuous room-monitoring pattern.
In a properly designed system, it can reduce large coverage transitions that may occur with simplified curtain
layouts and provide more information about how a moving target crosses the field of view.

Actual blind-area performance must be verified with the final mounting height, detector tilt angle, PIR sensor
alignment, room geometry, furniture layout, and enclosure design.

How can multiple PIR detection zones support lower false-alarm risk?

“`

A Fresnel lens alone does not guarantee false-alarm reduction. False-alarm performance depends on the complete
detector system, including the PIR sensor, analog front end, firmware, threshold settings, installation condition,
and environmental test results.

However, a multi-zone lens structure gives the product designer more options for configuring motion-event logic.
When a target moves through several optical zones, the PIR detector can evaluate the sequence, duration, and
consistency of the signal rather than reacting to one short disturbance.

Detector Logic Concept How a Multi-Zone Pattern Can Help
Cross-zone confirmation Require movement across more than one detection region before making an alarm decision.
Directional movement analysis Evaluate the signal sequence as a target moves from one zone to an adjacent zone.
Time-based filtering Reject very short or isolated disturbances that do not continue through the expected field of view.
Signal consistency check Compare expected signal behavior across multiple optical regions.
Pet-filtering strategy Combine the pet-immune lens configuration with thresholds, timing rules, and movement-pattern filtering.

This approach is especially relevant for burglar alarm and surveillance systems where the detector must respond
to meaningful intrusion events while minimizing nuisance triggers.

“`

What are the key specifications of PF25-09015A?

“`

Specification PF25-09015A
Product Type PIR Fresnel Lens
Installation Wall-mounted, Pet Immune
Detectable Angle 100°
Detectable Distance 12 m
Sensor-to-Lens Distance 25 mm
Overall Size 57.7 × 36 mm
Material Poly FIR200
General Tolerance ±0.2 mm

How does PF25-09015A compare with a basic curtain-type PIR lens?

“`

Design Consideration PF25-09015A Basic Curtain-Type Lens
Primary Application Broad wall-mounted room monitoring Corridor, doorway, or perimeter crossing
Detection Pattern Multiple field-of-view regions shown from A to P Often focused on narrow crossing zones
Coverage Approach Distributed coverage for general room monitoring Focused coverage along a selected path
Motion Analysis Supports cross-zone and directional logic concepts Provides fewer optical regions for movement sequence analysis
Pet-Immune Configuration Specified as pet immune in the datasheet Depends on the specific lens and detector design

A curtain lens remains a suitable solution for narrow-path applications. PF25-09015A is more appropriate when
the goal is broad wall-mounted coverage for a room, burglar alarm detector, or surveillance motion sensor.

“`

What should be validated before releasing a PIR detector to production?

“`

  1. Sensor alignment: Maintain the intended 25 mm sensor-to-lens distance and optical-axis alignment.
  2. Installation height and tilt angle: Confirm coverage using the actual wall-mounted installation position.
  3. Pet-immunity testing: Test with the intended pet size, movement speed, detector height, and alarm settings.
  4. Human detection testing: Verify the required coverage and detection behavior across the final room layout.
  5. Nuisance-alarm testing: Evaluate HVAC airflow, sunlight, thermal reflections, insects, electrical noise, and rapid temperature changes.
  6. Final enclosure validation: Confirm that the housing aperture, decorative cover, adhesive, gasket, and mechanical tolerances do not influence the optical pattern.

“`

Why use an off-the-shelf PIR Fresnel lens before developing a custom lens?

“`

PF25-09015A can be used as an initial optical platform before committing to a custom Fresnel lens project.
An off-the-shelf lens helps engineering teams evaluate PIR sensor selection, optical depth, field-of-view coverage,
pet-filtering algorithms, and detector electronics before finalizing the mechanical enclosure.

A custom Fresnel lens may be required when the product needs a different mounting height, enclosure shape,
sensor arrangement, field-of-view pattern, detection distance, or installation angle.

“`

Frequently Asked Questions

“`

Is PF25-09015A designed for wall-mounted PIR detectors?

Yes. The PF25-09015A datasheet specifies wall-mounted installation.

What is the detectable angle of PF25-09015A?

The datasheet specifies a detectable angle of 100°.

What is the detectable distance of PF25-09015A?

The datasheet specifies a detectable distance of 12 m.

Is PF25-09015A a pet-immune PIR lens?

The datasheet identifies PF25-09015A as a wall-mounted, pet-immune lens. Final pet-immunity performance
must be validated with the complete detector system.

Can PF25-09015A independently eliminate false alarms?

No. False-alarm performance depends on the PIR sensor, electronics, signal-processing algorithm,
mounting condition, and environmental test results. The multi-zone pattern can support filtering logic
such as cross-zone confirmation.

Does PF25-09015A remove every blind spot?

No PIR lens removes every blind spot in all installations. Its multi-zone field-of-view pattern can help reduce
coverage transitions compared with a simplified curtain-type layout when used for broad room monitoring.

What is the required sensor-to-lens distance?

The datasheet specifies a 25 mm sensor-to-lens distance.

What are the overall dimensions of PF25-09015A?

The overall size is 57.7 × 36 mm with a general tolerance of ±0.2 mm.

“`

Evaluate PF25-09015A for Your PIR Security Sensor

“`

PF25-09015A is suitable for engineers developing wall-mounted burglar alarm sensors, PIR cameras,
and indoor surveillance motion detectors that require broad coverage, pet-immune configuration,
and multi-zone motion analysis.


Request PF25-09015A evaluation samples


Request a technical review or custom PIR lens consultation

“`

About the Author
Myung Joong Kim is CEO of Fresnel Factory and works on PIR Fresnel lenses,
optical design, tooling, and volume manufacturing for sensing applications.

What Sensor Can Replace STMicroelectronics STHS34PF80 While Keeping the TMOS10-12030 Lens?

Last Updated: 2026-05-19
Author: Ashton Myung Kim, CEO, Fresnel Factory Inc.
Reading Time: 7 minutes

Quick Answer

If a product was originally designed around the STMicroelectronics STHS34PF80 and the TMOS10-12030 Fresnel lens, the replacement strategy depends on whether the product must keep stationary presence detection or only needs motion detection.

  1. For motion detection with minimal mechanical change: Murata IRS-D200ST00R1 is a practical candidate because it is a low-profile SMD digital PIR sensor.
  2. For comparison: Excelitas PYD 2592 / 7765 can also be evaluated as an SMD PIR option, but Fresnel Factory’s simulation showed less distinct projected-image separation than Murata in this lens condition.
  3. For stationary presence detection: Excelitas TPiS 1S 1385 / 5029 CaliPile is a strong candidate, and Fresnel Factory confirmed through simulation that CaliPile can be a good option when presence detection is required.
  4. For minimum enclosure impact: the first design goal should be to keep the TMOS10-12030 outer lens shape, mounting footprint, and sensor-to-lens distance as close as possible to the original design.
  5. Before changing sensors: engineers should verify optical signal distribution, threshold setting, PCB height, firmware behavior, and real detection performance with the final enclosure.

Why does STHS34PF80 replacement planning matter for TMOS-based products?

The STMicroelectronics STHS34PF80 is an infrared motion and presence detection sensor based on TMOS technology. ST describes the device as an uncooled, factory-calibrated infrared sensor operating in the 5 µm to 20 µm wavelength range. It is designed to detect motion, presence, or an overtemperature condition by measuring IR radiation from objects within its field of view.

In many real projects, the sensor is not the only fixed part of the design. The optical lens, mechanical opening, adhesive structure, PCB location, and enclosure tooling may already be completed before production. This was the situation in a project with a global building-control company, where the TMOS10-12030 lens and mechanical structure had already been designed around the original sensor.

In that case, the engineering question is not simply “which sensor has the best specification?” The more practical question is:

Which sensor can be evaluated while keeping the existing TMOS10-12030 lens and minimizing changes to the mechanical enclosure?

Can the TMOS10-12030 lens be reused with another sensor?

Yes, but only after optical simulation and signal validation. The TMOS10-12030 lens was originally designed for the STHS34PF80 sensor geometry. When another sensor is placed behind the same Fresnel lens, the projected IR image, signal distribution, and sensing-element geometry change.

Fresnel Factory evaluated replacement candidates by keeping the original lens condition as much as possible. The key design constraint was to maintain the existing sensor-to-lens distance of approximately 3.23 mm and avoid changes to the lens mounting footprint. This approach is useful when enclosure tooling is already close to release or when the customer wants to avoid a full mechanical redesign.

However, “lens reuse” does not mean the replacement sensor will behave exactly like STHS34PF80. PIR sensors, thermopile sensors, and TMOS sensors have different sensing principles and different signal-processing behavior.
The lens may be physically reusable, but the firmware threshold, signal interpretation, and final detection map must be revalidated.

What are the main sensor candidates for replacing STHS34PF80?

The following candidates are practical starting points for engineering evaluation when a product originally used STHS34PF80 with the TMOS10-12030 lens.

Sensor model Manufacturer Sensor type Best use case Presence detection Lens reuse potential
STHS34PF80 / STHS34PF80TR STMicroelectronics TMOS infrared sensor Original motion and presence detection design Yes Original design condition
Murata IRS-D200ST00R1 Murata SMD digital PIR sensor Short-term motion-detection replacement with low-profile package No, motion detection only High, based on Fresnel Factory simulation
Excelitas PYD 2592 / 7765 Excelitas Low-power dual-element SMD DigiPyro PIR sensor Alternative SMD PIR comparison candidate No, motion detection only Possible, but simulation showed less distinct projected-image separation than Murata
Excelitas TPiS 1S 1385 / 5029 CaliPile Excelitas Thermopile-based CaliPile sensor Presence, motion, and temperature-related sensing Yes Good candidate when stationary presence detection is required; simulation validation recommended
Fresnel Factory optical simulation comparing projected IR distribution and signal behavior
for STHS34PF80, Murata IRS-D200ST00R1, Excelitas PYD 2592 / 7765, and Excelitas TPiS 1S 1385 / 5029 CaliPile
using the TMOS10-12030 lens condition.

Fresnel Factory optical simulation comparing projected IR distribution and signal behavior
for STHS34PF80, Murata IRS-D200ST00R1, Excelitas PYD 2592 / 7765, and Excelitas TPiS 1S 1385 / 5029 CaliPile
using the TMOS10-12030 lens condition.

Why is Murata IRS-D200ST00R1 a practical motion-detection candidate?

Murata IRS-D200ST00R1 is a small, low-profile, reflowable SMD digital PIR sensor. Murata lists the IRS-D series as a 6 mm × 6 mm × 2.6 mm SMD digital PIR sensor with I²C output. This makes it attractive when the design must avoid a tall through-hole PIR package and preserve the existing mechanical stack-up.

In Fresnel Factory’s simulation using the TMOS10-12030 lens condition, Murata’s SMD PIR sensor produced a clearer projected image and more usable signal separation than the Excelitas PYD 2592 / 7765 comparison case. This does not mean it is a drop-in equivalent to STHS34PF80. It means it is a practical candidate when the product can accept motion detection only.

The key limitation is important: a PIR sensor detects changes in IR energy caused by movement. It does not provide the same stationary presence behavior as the original TMOS-based design.

How does Excelitas PYD 2592 / 7765 compare with Murata IRS-D200ST00R1?

Excelitas PYD 2592 / 7765 is a low-power dual-element SMD DigiPyro PIR sensor. It is a useful comparison candidate because it is also an SMD PIR device and can be considered when the design team wants a digital PIR alternative.

In Fresnel Factory’s lens simulation, however, the projected image from PYD 2592 / 7765 appeared more merged and less distinct than the Murata case under the same TMOS10-12030 lens condition. This matters because the Fresnel lens forms zones of IR energy on the sensing element. If the projected zones become less distinct, the firmware may need more careful threshold tuning and the final detection pattern may differ from the original design.

PYD 2592 / 7765 should therefore be treated as an evaluation candidate, not as the first-choice recommendation when minimum optical change is the main priority.

What if stationary presence detection is required?

If the product must detect stationary presence, a PIR-only replacement is usually not sufficient. This is where Excelitas TPiS 1S 1385 / 5029 CaliPile becomes important.

CaliPile is a thermopile-based intelligent IR sensor family. Excelitas describes the TPiS 1S 1385 CaliPile sensor as capable of motion detection, presence monitoring, and temperature measurement from a compact sensor package. This makes it a stronger candidate when the original design used STHS34PF80 not only for motion, but also for stationary presence detection.

Fresnel Factory’s simulation confirmed that CaliPile can be a good choice when stationary presence detection is required. The final decision should still be made after validating the optical distribution, real detection distance, ambient-temperature behavior, firmware threshold, and product-level detection map with the
final enclosure.

Can the same mechanical enclosure be kept?

In many replacement projects, the most expensive change is not the sensor itself. It is the enclosure tooling, lens opening, mounting structure, adhesive design, and production validation.

For this reason, Fresnel Factory’s recommended approach is:

  1. Keep the TMOS10-12030 outer lens shape if the enclosure opening is already fixed.
  2. Keep the sensor-to-lens distance close to the original value whenever possible.
  3. Change the PCB and sensor footprint first before changing the enclosure.
  4. Use simulation to compare projected IR distribution across candidate sensors.
  5. Validate the final design with motion and presence test scenarios, not only with component datasheets.

If a new optical pattern is required, Fresnel Factory can usually redesign the internal Fresnel pattern while keeping the outer lens footprint. This allows the customer to reduce enclosure impact while still adapting the lens to a different sensor geometry.

Which sensor should engineers choose?

Engineering priority Recommended candidate Reason
Keep the existing TMOS10-12030 lens and minimize mechanical changes Murata IRS-D200ST00R1 Low-profile SMD PIR package; simulation showed clear projected-image behavior under the existing lens condition
Evaluate another SMD PIR option Excelitas PYD 2592 / 7765 Digital SMD PIR candidate, but projected-image separation should be checked carefully
Maintain stationary presence detection Excelitas TPiS 1S 1385 / 5029 CaliPile Thermopile-based sensor capable of presence monitoring; confirmed as a good candidate by Fresnel Factory simulation
Preserve original behavior as closely as possible STHS34PF80 / STHS34PF80TR Original TMOS sensor condition; verify supply continuity and procurement strategy separately

What should be validated before changing the sensor?

Before releasing a replacement sensor design, engineers should validate the following items:

  • Optical projection: Does the Fresnel lens focus IR energy onto the active sensing area?
  • Sensor-to-lens distance: Is the original distance, approximately 3.23 mm in this project condition, still usable?
  • Signal strength by angle: Does the signal remain strong enough at the target field of view?
  • Presence behavior: Is stationary human presence required, or is motion detection sufficient?
  • Firmware threshold: Does the new sensor require different filtering or threshold logic?
  • Mechanical height: Does the package height affect PCB location, enclosure clearance, or lens distance?
  • Environmental behavior: Does the sensor remain stable under expected temperature and sunlight conditions?
  • Product-level detection map: Does the final device meet the required 5 m, 10 m, or other target detection distance?

How can Fresnel Factory support sensor replacement projects?

Fresnel Factory supports IR sensor projects from optical simulation to lens manufacturing and performance testing.
For projects using STHS34PF80, Murata IRS-D200ST00R1, Excelitas PYD 2592 / 7765, or Excelitas TPiS 1S 1385 / 5029 CaliPile, the recommended workflow is:

  1. Review the existing sensor, PCB, lens, and enclosure constraints.
  2. Simulate candidate sensors with the existing lens geometry.
  3. Compare projected IR image, signal strength, and blind-zone risk.
  4. Decide whether the current TMOS10-12030 lens can be reused.
  5. If needed, redesign only the internal Fresnel pattern while keeping the same outer footprint.
  6. Validate the final product with real detection tests using the customer’s target motion and presence scenarios.

FAQ

Can Murata IRS-D200ST00R1 replace STHS34PF80 directly?

Not directly. Murata IRS-D200ST00R1 is a PIR motion sensor, while STHS34PF80 is a TMOS-based infrared motion and presence sensor. Murata can be a practical candidate when motion detection is acceptable and mechanical change must be minimized.

Can the TMOS10-12030 lens be reused with Murata IRS-D200ST00R1?

Fresnel Factory’s simulation showed that Murata IRS-D200ST00R1 can be evaluated with the existing TMOS10-12030 lens condition. The final design should still be verified with real product-level detection testing.

Does Murata IRS-D200ST00R1 support stationary presence detection?

No. Murata IRS-D200ST00R1 is a PIR motion sensor. It is suitable for detecting changes caused by movement, but it should not be treated as an equivalent replacement for stationary presence detection.

Is Excelitas PYD 2592 / 7765 a possible replacement?

Yes, it is a possible SMD PIR evaluation candidate. However, Fresnel Factory’s simulation showed less distinct projected-image separation than the Murata case under the same lens condition.

Which sensor is better if stationary presence detection is required?

Excelitas TPiS 1S 1385 / 5029 CaliPile is a strong candidate when stationary presence detection is required.
Fresnel Factory confirmed through simulation that CaliPile can be a good option for this requirement.

Will changing the sensor require changing the lens?

Not always. If the outer lens footprint and sensor-to-lens distance can be maintained, the same lens may be reused or the internal Fresnel pattern may be redesigned while keeping the same outer shape.

What is the most important validation step?

The most important step is product-level validation. Component datasheets are not enough because the final detection performance depends on the lens, enclosure, sensor position, firmware threshold, and real use case.

Next step: optical simulation and lens validation

If your product uses STMicroelectronics STHS34PF80 or was designed around the TMOS10-12030 lens, the safest next step is to evaluate replacement sensors through optical simulation before changing the enclosure.

Fresnel Factory can help compare Murata IRS-D200ST00R1, Excelitas PYD 2592 / 7765, and Excelitas TPiS 1S 1385 / 5029 CaliPile under your existing lens and mechanical constraints.


Submit a custom IR lens design request

References

About the author: Ashton Myung Kim is CEO of Fresnel Factory Inc., an optical lens manufacturer specializing in Fresnel lenses for PIR, TMOS, thermopile, LiDAR, and infrared sensing applications. Fresnel Factory provides optical simulation, custom lens design, tooling, injection molding, and IR sensing performance validation.

How to Choose a PIR Fresnel Lens for Doorbells and Home Security Cameras

Last Updated: 2026-04-27
Author: Ashton Myung Kim, CEO, Fresnel Factory Inc.
Reading Time: 8–10 minutes
Target Readers: Mechanical engineers, circuit designers, optical engineers, and product engineers developing doorbells, home security cameras, and smart home motion sensors.

Quick Answer

For a consumer doorbell or home security camera, the PIR Fresnel lens should not be selected only by appearance. The lens defines where the device can detect people, how often it may trigger falsely, and how well the PIR sensor works with a camera, radar, or low-power wake-up circuit.

  • For wall-mounted cameras and doorbells, a directional PIR Fresnel lens is usually more practical than a fully omni-directional lens.
  • Omni-directional “golf-ball” type PIR lenses can detect broadly, but they may increase false triggers from the sky, lighting, wind-driven objects, or unnecessary upper and lower zones.
  • A PIR lens for home cameras should define detection distance, horizontal angle, vertical angle, mounting height, and blind-zone tolerance before tooling starts.
  • For battery-powered products, PIR is often used as the first wake-up sensor, while radar or camera sensing may be activated afterward.
  • Mechanical design should consider lens appearance, snap-fit structure, adhesive sealing, waterproofing, and lens-to-sensor alignment together.
  • If the product requires a flat or hidden lens appearance, detection performance may be lower than a more visible but optically optimized Fresnel lens.

Why does the PIR lens matter in doorbells and home cameras?

In many smart home products, the PIR sensor is not just a small component added to the PCB. It is part of the product’s user experience. A doorbell or home security camera has to detect a person approaching the entrance, but it should not trigger every time a tree moves, sunlight changes, or a warm object passes outside the useful field of view.

This is where the PIR Fresnel lens becomes important. The pyroelectric sensor reacts to changes in infrared radiation, mainly from human body heat in the long-wave infrared region. However, the sensor itself does not know whether the signal came from a person, a pet, a lamp, or a moving warm object. The lens creates detection zones and decides which areas are optically emphasized or ignored.

For this reason, PIR lens design is closely related to both mechanical design and circuit design. The housing, PCB position, sensor window, lens material, adhesive structure, waterproofing method, and firmware trigger logic all affect the final sensing performance.

What is the main difference between an omni-directional PIR lens and a directional PIR lens?

An omni-directional PIR lens is designed to detect in many directions. It is often used in ceiling-mounted occupancy sensors or room sensors where detection in all directions is useful.

However, a wall-mounted doorbell or home camera usually has a different requirement. It normally needs to detect people coming from the front or side, not from the ceiling, sky, or unnecessary upper zones.

Lens Type Typical Use Advantage Risk in Doorbell / Home Camera
Omni-directional PIR lens Ceiling sensor, room occupancy sensor Broad detection area Higher risk of false triggers from unnecessary directions
Directional PIR lens Wall-mounted camera, doorbell, switch-height sensor Better control of detection area Lens orientation and mounting position must be controlled
Flat appearance PIR lens Consumer product with design priority Cleaner exterior design Detection distance and zone separation may be reduced
Custom PIR Fresnel lens Product-specific detection area Optimized for product requirement Requires tooling cost and development schedule

For a wall-mounted device, detecting too much area can be worse than detecting less area. A lens that looks powerful on paper may create unwanted detection zones above, below, or outside the camera’s useful view.

Why can omni-directional PIR lenses cause false triggers?

In a doorbell or home camera, the useful detection area is usually limited. The device is looking at a porch, entrance, hallway, garage, or garden path. If the PIR lens detects too broadly, it may react to areas that the product does not actually need to monitor.

Typical false-trigger sources include:

  1. Sunlight or reflected light from outside.
  2. Warm air movement near the housing.
  3. Moving tree branches or curtains.
  4. Cars, pets, or people outside the intended detection zone.
  5. Ceiling lights or sky-facing detection zones.
  6. Thermal changes caused by wind, rain, or outdoor temperature changes.

This is why a PIR lens for a doorbell or home camera should be designed around the actual mounting position and target human path, not just the widest possible angle.

What detection specifications should be fixed before selecting a PIR lens?

Before choosing an existing lens or starting a custom lens design, the engineering team should define the detection specification clearly.

Item Recommended Definition
Mounting type Wall-mounted, ceiling-mounted, corner-mounted, or device-integrated
Mounting height Example: 1.2 m, 1.6 m, 2.4 m, or product-specific height
Detection distance Example: 3 m, 5 m, 8 m, 13 m, or product-specific distance
Horizontal detection angle Example: 90°, 110°, 120°, or product-specific angle
Vertical detection angle Important for reducing sky, ceiling, and floor false triggers
Target object Adult human, child, pet exclusion, vehicle exclusion, or other condition
Sensor model PIR sensor part number and sensor window size
Lens material Usually HDPE or PIR-transmissive PE-based material
Lens position tolerance Distance from sensor, X/Y alignment, and tilt tolerance
Exterior design limit Visible dome, flat window, hidden lens, black appearance, or white appearance
Waterproof level Indoor only, IP65, IP67, or product-specific requirement

The most important point is that detection distance and detection angle must be defined before tooling. If these values are not fixed, the lens design can be delayed even if the mechanical housing is already complete.

How should mechanical engineers design the PIR lens area?

Mechanical engineers often want the PIR lens to look like a clean window rather than a visible sensor dome. This is understandable, especially for consumer products such as doorbells and home cameras.

However, the PIR lens is not a simple cosmetic window. Its internal Fresnel pattern forms optical zones. If the lens is made too flat, too small, or placed too far from the sensor, the detection performance can drop.

Mechanical Item Design Consideration
Lens shape Dome, curved rectangle, flat-looking window, or custom shape
Assembly method Snap-fit, hook structure, ultrasonic welding, adhesive, or insert assembly
Waterproofing Adhesive sealing, gasket, O-ring, or compressible foam tape
Sensor alignment PIR sensor center must match the optical center of the lens
Wall thickness Housing walls should not block the lens viewing angle
Cosmetic surface Black, white, translucent, or hidden appearance
Tooling risk Custom lens shape requires optical pattern and mold design together

For indoor devices, snap-fit or hook structures may be acceptable. For outdoor doorbells and cameras, adhesive sealing becomes more important. Fresnel Factory often recommends DSA150 for many indoor and outdoor applications. For higher waterproof requirements, DSA300 can also be considered because the adhesive layer may act partly like a compressible sealing structure.

DSA150 reference:
View DSA150 adhesive information

DSA300 reference:
View DSA300 adhesive information

How should circuit designers think about PIR, radar, and camera wake-up logic?

In low-power doorbells and home cameras, PIR is often used as the first trigger. The PIR sensor detects possible human movement, then wakes up a higher-power sensing block such as a camera, radar, or AI processor.

A typical wake-up logic can be:

  1. The PIR lens defines the useful detection zone.
  2. The PIR sensor detects a thermal motion event.
  3. The MCU wakes from low-power mode.
  4. The camera, radar, or wireless module activates.
  5. Software checks whether the event is a person, pet, vehicle, or false trigger.
  6. The device records video, sends a notification, or returns to sleep.

This means the PIR field of view should normally be equal to or slightly wider than the radar or camera confirmation zone. If the PIR lens detects too narrow an area, the device may miss an approaching person before the camera wakes up. If it detects too wide an area, the product may wake up too often and waste battery.

For this reason, the PIR lens, radar FOV, camera FOV, and firmware wake-up threshold should be discussed together.

Is a flat PIR lens always better for consumer product design?

Not always. A flat-looking PIR lens may improve the exterior design, but it can reduce detection performance if the optical pattern, sensor distance, or lens aperture becomes too limited.

For doorbells and home cameras, there is usually a trade-off:

Priority Better Lens Direction
Maximum detection distance More optically optimized Fresnel shape
Clean exterior design Flat or hidden lens structure
Lower false-trigger rate Directional lens with controlled vertical FOV
Lower tooling risk Existing mass-production lens
Best product-specific performance Custom lens design
Fastest development Existing lens plus housing adjustment

If the product is still in the concept stage, it is usually safer to test with an existing PIR lens first. After detection distance, angle, and false-trigger behavior are confirmed, the team can decide whether a custom lens is necessary.

When is a custom PIR Fresnel lens worth the development cost?

A custom lens is worth considering when the product cannot meet its requirement with an existing lens.

Typical cases include:

  1. The housing requires a special rectangular or curved lens shape.
  2. The PIR lens must be hidden behind a cosmetic window.
  3. The detection zone must match the camera FOV precisely.
  4. The product must reduce false triggers from the upper or lower field.
  5. The mounting height is unusual.
  6. The customer requires a specific detection pattern.
  7. Existing lens options do not meet both design and performance targets.

However, custom development requires clear specifications. Both product specification and product shape should be fixed before lens development proceeds. As a practical reference, a custom PIR lens project may require several weeks before the first injection sample, depending on optical design, mechanical review, mold fabrication, and sample molding schedule.

Existing lens vs custom lens: which should be selected first?

Selection Path Best For Advantage Limitation
Existing PIR lens Early prototype and cost-sensitive project Faster test and lower development risk Shape may not fit final design
Modified mechanical housing When lens performance is acceptable but fit is not ideal Avoids new optical tooling Housing design may be constrained
Custom PIR lens Mass-production product with specific design or performance target Best fit for product requirement Tooling cost and schedule required
PIR + radar/camera co-design Battery-powered smart camera or doorbell Better balance between wake-up and confirmation Requires cross-team design between optical, mechanical, circuit, and firmware teams

For many doorbell and home camera projects, the practical approach is:

  1. Start with an existing directional PIR lens.
  2. Test actual detection distance and false triggers.
  3. Confirm PIR sensor model and PCB position.
  4. Match PIR FOV with camera or radar FOV.
  5. Decide whether the final product needs a custom lens.

What should engineers check before freezing the PIR lens design?

Before freezing the product design, engineers should confirm the following items:

  • PIR sensor part number and sensor window size.
  • Lens-to-sensor distance.
  • Lens center alignment tolerance.
  • Horizontal and vertical detection angle.
  • Target detection distance.
  • Mounting height and installation angle.
  • Outdoor or indoor use.
  • IP rating requirement.
  • Lens color and exterior appearance.
  • Adhesive, snap-fit, or gasket structure.
  • Camera FOV and radar FOV.
  • Firmware trigger threshold.
  • False-trigger test conditions.
  • Tooling schedule and first sample timing.

A PIR lens should not be treated as a late-stage cosmetic part. It should be reviewed together with the PCB, housing, firmware, and product use case.

How does Fresnel Factory support PIR lens development for smart home devices?

Fresnel Factory provides PIR Fresnel lenses, optical design support, ODM/OEM manufacturing, and performance testing for IR sensing devices. The company supports PIR Fresnel lens development for motion detection, human sensing, smart home sensors, doorbells, and home security cameras.

For smart home camera and doorbell projects, Fresnel Factory can support:

  1. Existing PIR lens selection.
  2. Lens-to-sensor matching review.
  3. Custom PIR Fresnel lens design.
  4. Mechanical structure review for snap-fit or adhesive assembly.
  5. Material and color review.
  6. Detection angle and distance test support.
  7. Mass-production tooling and injection molding.

For early evaluation, engineers can first check available Fresnel Factory PIR lens options through DigiKey or request a custom sensor lens design review through Fresnel Factory.

Fresnel Factory Supplier Center on DigiKey:
View Fresnel Factory products on DigiKey

Request a PIR lens design review:
Request a Custom Sensor Lens Design Review

FAQ

Can a doorbell use an omni-directional PIR lens?

Yes, but it is not always recommended. A doorbell is usually wall-mounted and does not need to detect equally in every direction. A directional lens can help reduce unnecessary detection zones and false triggers.

Is a flat PIR lens possible for a home camera?

Yes, but a flat appearance can reduce optical performance depending on lens size, sensor distance, and Fresnel pattern design. It should be validated with actual detection testing.

Should PIR FOV be wider than camera FOV?

In many low-power products, yes. PIR often works as the first wake-up sensor, so it should detect a person before the camera or radar confirmation stage starts. However, too wide a PIR FOV can increase false wake-ups.

What is the most important specification before custom PIR lens tooling?

Detection distance, horizontal angle, vertical angle, mounting height, sensor model, and final lens shape should be fixed first. Without these, tooling and optical design can be delayed.

Can PIR and radar be used together?

Yes. PIR can be used for low-power thermal motion detection, while radar can help confirm movement or presence. The two sensors should be designed with coordinated FOV and trigger logic.

What material is commonly used for PIR Fresnel lenses?

PIR Fresnel lenses are commonly made from IR-transmissive PE-based materials such as HDPE. The exact material should be selected based on wavelength transmission, molding stability, color, UV exposure, and product environment.

Is adhesive better than snap-fit for outdoor cameras?

For outdoor products, adhesive or gasket-based sealing is often more suitable than snap-fit alone. Snap-fit can position the lens, but adhesive or compressible sealing material is usually needed for waterproofing.

Author

Ashton Myung Kim is the CEO of Fresnel Factory Inc. He works on Fresnel lens design, PIR and IR sensor optics, optical tooling, injection molding, and international standardization activities for sensing technologies.

Related Pages

How to Design and Mass-Produce PIR Sensor Lenses for Outdoor Cameras

Last Updated: 2026-04-27
Author: Myung Joong Kim, CEO, Fresnel Factory
Reading Time: 8 min

Quick Answer

Designing a PIR lens for outdoor cameras requires balancing optical performance, adhesive sealing, mechanical structure, and manufacturability.

  • Use glossy lens surfaces for higher infrared transmission.
  • For waterproofing, adhesive selection and proper mechanical structure are the most important design factors.
  • DSA150 is the recommended adhesive and is widely selected by customers for both indoor and outdoor products.
  • For higher waterproof requirements such as IP67 or above, DSA300 may be used because it can also function like an O-ring.
  • Design detection zones carefully to avoid blind spots.
  • Use PIR lens materials such as Poly FIR200, SBK150, or HGW335 depending on optical and outdoor durability requirements.
  • Validate detection performance using IEC 63180-based radial, boundary, and tangential tests.

Why does PIR lens design matter for outdoor cameras?

PIR (Passive Infrared) sensors are widely used in outdoor cameras, smart home devices, and motion detection systems. The Fresnel lens placed in front of the sensor determines how infrared energy from a moving person is divided into detection zones and delivered to the sensor element.

For outdoor cameras, PIR lens development is not only an optical design task. Engineers must also consider waterproof sealing, adhesive selection, housing structure, material aging, UV exposure, injection molding quality, and mass-production repeatability. A lens that works in a prototype may still fail in mass production if the housing fit, adhesive method, sealing structure, or mold surface quality is not controlled properly.

Should PIR lens surfaces be matte or glossy?

The surface finish of a PIR lens affects both appearance and infrared transmission. A glossy lens surface generally provides stronger infrared transmission and therefore a stronger sensor signal. A matte surface can reduce visible glare and help the lens blend into the product’s industrial design.

In practical PIR lens design, the optical lens area is often polished to a glossy finish, while the surrounding non-optical area may be matte or glossy depending on the product appearance requirement.

Surface Type Benefit Possible Trade-off
Glossy optical surface Higher infrared transmission and stronger PIR signal May be more visually noticeable
Matte non-optical surface Better visual integration with the product housing Not suitable for the main optical transmission area if signal strength is critical

How are PIR lenses attached to the housing?

For PIR lens assembly, the most practical and widely used joining method is double-sided adhesive tape. However, for outdoor products, waterproof performance is not determined by adhesive alone. In most successful designs, waterproofing depends on two factors working together: the adhesive and the mechanical structure of the housing.

Fresnel Factory recommends DSA150 as the primary adhesive option for PIR lens attachment. DSA150 has been selected by many customers not only for indoor products but also for outdoor products where stable bonding and sealing performance are required.

For higher waterproof requirements, such as IP67 or above, some designs may require a thicker or more compressible adhesive structure. In these cases, DSA300 can be considered because it can perform both as an adhesive and as a sealing element similar to an O-ring.

  • Indoor product: DSA150 is commonly suitable for lens attachment.
  • Outdoor product: DSA150 is often selected together with a proper housing structure.
  • IP67 or above: DSA300 may be considered when the adhesive also needs to act like an O-ring.
  • Important design point: waterproofing should be designed as a combination of adhesive, compression, housing groove, and mechanical support.

Reference adhesive information:

Why are adhesive and mechanical structure critical for waterproofing?

In outdoor camera design, waterproof performance should not be treated as a material-only issue. Even if a good adhesive is selected, water can still enter the product if the housing does not provide enough compression, contact area, or mechanical support.

A reliable waterproof design usually includes:

  • Proper adhesive thickness
  • Controlled compression after assembly
  • Enough bonding area around the lens
  • A housing groove or seating structure
  • Stable lens positioning during assembly
  • Mechanical support to prevent peeling or lifting over time

This is why adhesive selection and mechanical design must be reviewed together from the beginning of the PIR lens project. If the adhesive is selected after the housing is already fixed, the design may not have enough space for proper compression or sealing.

How does mold design affect PIR lens performance?

Mold design affects not only the shape of the lens but also the durability and sealing performance of the finished product. Adding ribs around the lens edge can improve structural strength and bonding reliability. It can also help the lens maintain its position during assembly and long-term use.

The trade-off is mold complexity. Ribs, hook holes, and sealing structures increase tooling difficulty and cost. Therefore, the decision should be made based on the required waterproof rating, expected production volume, and target product cost.

Design Option Advantage Trade-off
Lens with ribs Better strength and sealing reliability Higher mold cost and more complex tooling
Lens without ribs Lower tooling cost and simpler mold structure Lower mechanical strength and weaker sealing margin
Groove or compression structure Improved waterproof design when used with the right adhesive Requires early housing and mold coordination

How should IP rating requirements be reflected in the design?

IP rating requirements must be considered from the early design stage. For indoor use, a simple adhesive attachment may be enough. For outdoor cameras, however, the lens and housing interface must be designed so that the adhesive can seal properly under controlled compression.

For many indoor and outdoor products, DSA150 is a practical starting point. When the target requirement is more demanding, such as IP67 or above, DSA300 may be considered because its thicker structure can help it act as both adhesive and sealing material.

A common mistake is to design the lens first and consider waterproofing later. This often causes redesign because the housing may not have enough space for the required adhesive thickness, compression structure, groove, or sealing area. Early coordination between optical design, mechanical design, adhesive selection, and tooling design helps reduce this risk.

What tools are used for PIR lens design?

PIR lens design normally requires both mechanical and optical design tools. Mechanical CAD software such as SolidWorks is used to check the lens size, housing interface, assembly space, adhesive area, compression structure, and sealing geometry.

Optical design tools and internal calculation methods are then used to predict the infrared field, detection zones, field of view, and energy distribution. This combined workflow helps engineers reduce design errors before mold fabrication.

  • Mechanical layout: SolidWorks or equivalent CAD tools
  • Optical prediction: ray-tracing simulation and internal optical calculation tools
  • Waterproof review: adhesive area, compression, housing groove, and sealing structure
  • Verification: prototype testing and IEC 63180-based performance testing

What standards apply to PIR-based motion detector testing?

IEC 63180 is commonly used for testing detection performance of PIR-based motion detectors. It includes three important test concepts: radial movement, boundary detection, and tangential movement.

Test Type Movement Direction Purpose
Radial test Movement toward the sensor Checks detection response as the target approaches the device
Boundary test Movement at maximum distance and angle Checks the outer detection limit
Tangential test Side-to-side movement Checks lateral motion detection performance

Automated test equipment improves repeatability compared with manual walking tests. For engineering validation, this is especially important because small differences in walking speed, path, and body position can affect the measured result.

How much does PIR lens performance testing cost and how long does it take?

A full set of IEC 63180-based tests, including radial, boundary, and tangential measurements, typically costs around USD 2,000. If additional test conditions are requested, such as a higher mounting height or a special detection scenario, the cost may be quoted separately.

From sample receipt to final report, the typical testing and reporting timeline is about three weeks. This includes measurement setup, test execution, data review, and report preparation.

Why are 3D files required before PIR lens development?

A 3D model is required to check how the PIR lens fits into the housing. STEP or IGES files are typically used because they provide the exterior geometry needed for lens design, mold planning, adhesive area review, sealing structure review, and assembly verification.

Even a basic exterior 3D file is enough to begin early design work. Sharing 3D files early can prevent weeks of rework by identifying interference, sealing, compression, and alignment problems before the mold is made.

What materials are used for PIR lenses?

Most PIR lenses are made from infrared-transmitting polymer materials. The material must transmit infrared energy in the human body detection wavelength range, typically around 8–14 μm, while also supporting stable injection molding.

Material Main Characteristic Typical Use
Poly FIR200 Good infrared transmission in the 8–14 μm range General PIR Fresnel lenses
SBK150 Outdoor durability and UV resistance Outdoor cameras and long-life products
HGW335 White appearance with PIR lens application suitability Design-sensitive consumer products

For outdoor cameras, UV stability is especially important. In accelerated weathering evaluation, SBK150 maintained more than 93% of its original transmission level after a five-year equivalent test, while cheaper alternatives may drop below 50%.

How are PIR lens detection zones designed?

A PIR Fresnel lens divides the detection area into multiple zones. Each zone focuses infrared energy from a specific direction onto the PIR sensor element. The number, angle, and size of these zones determine how well the sensor detects motion at different distances and heights.

For example, one lens design may include zones covering 35°, 15°, and 7°. Wider zones may support near or broad-area detection, while narrower zones can support longer-distance detection. If the zone layout is poorly planned, blind spots may appear and the sensor may miss motion in important areas.

What is the typical service life of a PIR lens mold?

A well-maintained PIR lens mold can last around four years and produce approximately 150,000 units per year. Actual lifetime depends on the material, injection conditions, mold maintenance, and polishing frequency.

Because PIR Fresnel lenses include fine optical patterns, mold wear may first appear as reduced optical performance rather than obvious cosmetic damage. Regular inspection and light re-polishing are important for maintaining stable lens quality.

How are final shipment tests carried out?

Before shipment, customers may request full IEC-based performance testing or rely on factory quality checks. Typical final inspection items include detection distance, detection angle, noise resistance, appearance, bonding condition, sealing structure, and waterproofing.

For large-volume production, even a small increase in defect rate can create serious quality and cost issues. Therefore, suppliers and customers should agree on test scope, inspection method, and acceptance criteria before mass production shipment begins.

FAQ

What is the most important factor for waterproof PIR lens design?

The most important factor is the combination of adhesive and mechanical structure. The adhesive must be supported by proper compression, bonding area, housing geometry, and mechanical support.

Which adhesive does Fresnel Factory recommend for PIR lens attachment?

Fresnel Factory recommends DSA150 as the primary adhesive option. Many customers select DSA150 for both indoor and outdoor products.

When should DSA300 be considered?

DSA300 may be considered when the product requires higher waterproof performance, such as IP67 or above. Its structure can allow it to function both as an adhesive and as a sealing element similar to an O-ring.

How long does PIR lens testing take?

PIR lens testing and reporting usually take about three weeks after the sample is received.

How much does full IEC 63180-based performance testing cost?

A full set of radial, boundary, and tangential tests costs around USD 2,000. Additional test scenarios may be quoted separately.

Why are 3D files required for PIR lens development?

3D files allow engineers to check the lens and housing fit, review adhesive area and waterproof structures, design the mold, and prevent assembly problems before tooling.

What materials are commonly used for PIR lenses?

Common materials include Poly FIR200, SBK150, and HGW335. The selection depends on infrared transmission, outdoor durability, color, and molding requirements.

What causes long-term PIR lens performance degradation?

Long-term degradation can be caused by UV exposure, material aging, mold surface wear, and reduced infrared transmission over time.

Next Step

If you are developing a PIR sensor, smart home motion detector, or outdoor camera, early-stage optical design, adhesive selection, and mechanical sealing review are essential. Fresnel Factory supports custom PIR lens design, optical simulation, mold tooling, adhesive structure review, performance testing, and mass production.

For adhesive reference materials:

For available Fresnel Factory products, visit the Fresnel Factory supplier page on DigiKey:
View Fresnel Factory products on DigiKey

About the Author
Myung Joong Kim is the CEO of Fresnel Factory and an expert in optical design, PIR sensor lens development, and sensor-related international standardization.

How Fresnel Factory Built an AI-Driven Automated Production Line for Optical Sensors

Last Updated: 2026-04-25

Author: Ashton Myung Kim, CEO of Fresnel Factory Inc.

Quick Answer

Fresnel Factory’s automated production line is designed to deliver high-consistency optical components with full traceability through AI-based vision inspection, barcode-based tracking, and multi-stage quality control.

  • AI-based vision inspection covering 100% of parts
  • Barcode-based tracking from injection molding to shipment
  • Multi-stage QC: injection, assembly, and final inspection
  • Cycle time of approximately 3 seconds per part
  • Real-time detection of scratches, bubbles, misalignment, and missing components
  • Data-driven quality control for defect reduction and process stability

Why Automated Optical Production Matters in 2026

Optical components for sensors, especially PIR motion detectors, TMOS sensors, and infrared modules, are highly sensitive to surface defects, alignment errors, adhesive placement, and production variation.

A small scratch, bubble, or misalignment can affect optical performance, customer assembly yield, and final sensor reliability. Traditional manual inspection depends heavily on operator skill and fatigue, making it difficult to maintain consistent quality at high production volume.

Fresnel Factory developed its automated production line to reduce manual variation, inspect every part, and create traceable production records from molding to shipment.

How Does the Automated Production Line Work?

1. Injection Molding, Gate Cutting, and Barcode Traceability

The process starts immediately after injection molding. A robot picks the molded optical parts, performs gate cutting, places the parts into trays, and links each tray to a barcode.

Each tray contains 100 pieces, and each shipping box contains 3,000 lenses. By assigning barcodes at tray and box level, Fresnel Factory can trace production date, packing date, packing number, shipment history, and related inspection records.

If a customer reports a defect, Fresnel Factory can use the tray barcode or box barcode to review the production history and inspection images for that lot.

2. Multi-Stage AI Vision Inspection

The automated line is divided into three major quality control stages:

  • Injected Part QC: surface inspection, scratch detection, and dimensional consistency check
  • Assembly QC: protective film position, film angle, adhesive size, and adhesive placement
  • Finished Product QC: bubble detection, missing film, misalignment, and final dimensional confirmation

This is not sampling inspection. The system is designed for 100% inspection of the produced parts.

3. Protective Film and Adhesive Assembly

In the assembly section, robots pick the protective film and adhesive, measure their size and position, adjust alignment, and apply them to the optical part.

The system checks whether the protective film and double-sided adhesive are correctly positioned. It also measures the distance between the injected part edge and the adhesive film edge to confirm assembly consistency.

What Does the AI Vision System Inspect?

Fresnel Factory’s AI-assisted inspection system is designed to detect both appearance defects and assembly defects.

Inspection Area Detected Items Purpose
Injected optical part Scratch, contamination, dimensional variation Prevent defective molded parts from entering assembly
Protective film Missing film, position error, angle error Protect optical surface and maintain assembly accuracy
Double-sided adhesive Size variation, position error, edge offset Maintain stable bonding and customer assembly yield
Finished product Air bubbles, missing components, misalignment Prevent defective parts from being shipped

What Is the Production Speed and Efficiency?

The automated line can process approximately four parts every 12 seconds, which is about 3 seconds per part. This enables Fresnel Factory to combine high-throughput production with full inspection coverage.

Metric Value
Cycle time Approximately 12 seconds per 4 parts
Per-unit time Approximately 3 seconds per part
Inspection method 100% inspection
Traceability level Tray barcode and box barcode
Box quantity 3,000 lenses per box
Tray quantity 100 pieces per tray

Why Does AI-Based Inspection Improve Quality?

1. It Reduces Human Variation

Manual inspection quality can change depending on operator experience, concentration, and fatigue. AI-based vision inspection applies consistent inspection logic to every part.

2. It Enables Real-Time Filtering

Defective parts can be detected during the production flow instead of being found after shipment or during customer assembly.

3. It Creates a Data Feedback Loop

Inspection images and measurement data can be used for process analysis, Cpk review, yield monitoring, and continuous improvement.

4. It Supports Cost Optimization

When the process is stable and traceable, redundant manual inspection can be reduced, rework can be minimized, and the total cost of quality can be improved.

How Does Barcode Traceability Help Customer Quality Communication?

Barcode traceability is important because reported quality issues do not always originate from the same supplier, production date, or process condition.

When a customer or contract manufacturer reports a defect using a tray barcode or box barcode, Fresnel Factory can check:

  • Injection date
  • Production lot
  • Packing date
  • Shipment record
  • Inspection image history
  • Whether the part belongs to Fresnel Factory’s production lot

This helps separate actual production defects from reporting errors, supplier mix-up, or customer-side classification issues.

How Is This Different from Traditional Optical Component Manufacturing?

Item Traditional Manufacturing Fresnel Factory Automated Line
Inspection method Manual or sampling inspection AI-assisted 100% inspection
Traceability Lot-level or limited tracking Tray and box barcode tracking
Defect detection Operator-dependent Vision system and AI-based detection
Data collection Limited Inspection images and measurement records
Root-cause analysis Slow and subjective Data-based and traceable
Production consistency Depends on operator and shift System-controlled process

What Optical Sensor Applications Can Use This Production Model?

Fresnel Factory’s automated production model is suitable for optical components that require stable mass production, tight assembly control, and traceable quality records.

  • PIR Fresnel lenses for motion detection
  • TMOS sensor optical covers
  • IR sensor windows
  • Optical parts with protective film
  • Optical parts with double-sided adhesive
  • Custom sensor optics requiring mass production quality control

What This Means for Engineers and Buyers

For hardware engineers, the main value is process consistency. A stable optical component helps reduce variation in final sensor performance.

For sourcing and quality teams, the main value is traceability. When a defect is reported, the barcode system allows production records and inspection images to be reviewed quickly.

For program managers, the automated line supports scalable production while keeping quality communication data-based and objective.

Key Takeaway

Fresnel Factory’s AI-driven automated production line combines injection molding, robotic assembly, AI-based inspection, and barcode traceability into a single production flow.

This system is designed to reduce manual variation, improve defect detection, support high-volume optical component production, and provide reliable quality records for customers developing PIR, TMOS, and infrared sensor products.

FAQ

Q1. Is AI inspection better than manual inspection?

Yes. AI inspection provides consistent criteria and reduces operator-to-operator variation, especially for small surface or assembly defects.

Q2. Does 100% inspection slow down production?

No. The automated line processes approximately four parts every 12 seconds, or about 3 seconds per part, while maintaining 100% inspection coverage.

Q3. Can defects still escape detection?

A small possibility always exists in any manufacturing process, but multi-stage AI vision inspection and barcode traceability significantly reduce the risk and make root-cause analysis faster.

Q4. How is traceability handled?

Traceability is managed through tray barcodes and box barcodes. Each tray contains 100 pieces, and each box contains 3,000 lenses.

Q5. Can this system reduce cost?

Yes. By improving yield, reducing rework, and minimizing redundant manual inspection, the automated line can support total cost optimization.

Q6. What products can be produced on this automated line?

The system can be applied to PIR Fresnel lenses, TMOS optical parts, infrared sensor windows, and optical components requiring adhesive or protective film assembly.

Next Step

If you are developing PIR motion sensors, TMOS-based sensing modules, or infrared optical assemblies, Fresnel Factory can support optical design, prototyping, performance evaluation, and scalable production.

Contact Fresnel Factory for custom optical component development or mass production support.

Author

Ashton Myung Kim
CEO, Fresnel Factory Inc.
IEC and ISO Sensor Standard Expert
LinkedIn: Ashton Myung Kim

Related Articles

  • AI-Based Optical Inspection Systems in Sensor Manufacturing
  • How to Reduce Defect Rates in Injection-Molded Optical Parts
  • PIR Fresnel Lens Design Guide for Smart Sensors