Recently, we received a technical inquiry from a customer regarding our large Fresnel lens (CP1300-1100, focal length 1300mm, PMMA, groove pitch ~0.5mm). Below is a summary of the questions and our answers.
Q. What is the minimum achievable focal spot size?
- For the CP1300-1100 lens, under ideal conditions, the minimum focal spot diameter is about 6–7 mm.
- The most critical factor affecting the focal spot size is alignment error.
Q. What are the differences in material types, durability, and the temperature at which deformation or optical degradation occurs?
- Recommendation:
- PMMA: Has low weather resistance, weak against scratches, cannot withstand high temperatures, expected lifespan is only 3–5 years. The temperature at the focal spot can reach nearly 1,000°C.
- SOG: Excellent weather resistance, strong against scratches from wind and sand, high thermal tolerance, usable for over 20 years. The temperature at the focal spot is about 500°C.
- Maximum temperature at which PMMA lens deformation or optical degradation occurs: about 75°C.
Q. What is possible in terms of custom manufacturing, anti-reflective coating, and surface treatment?
- Custom design is available upon request with your preferred specifications.
- The largest manufacturable mold diameter is 2200 mm; actual lens size is 1600 × 1400 mm.
- Due to the large product size, anti-reflective coatings or special surface treatments are not available.