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.