A Zinc Selenide (ZnSe) Double Concave Lens features two symmetrical inner-curved surfaces designed to diverge incident infrared light, increase focal lengths, and expand laser beams with exceptional wavefront clarity. Engineered from premium CVD laser-grade Zinc Selenide and optimized for a 10.6 µm design wavelength, these negative lenses come standard with our high-efficiency IR2 broadband anti-reflection (BBAR) coating, yielding an average reflectance (R_avg) of less than 1.5% across the 8–12 µm long-wave infrared (LWIR) spectrum.
ZnSe Double Concave Lens
ZnSe Double Concave Lens with IR2 Coating
ZnSe Double-Concave Lens (IR2 Coating)
| Part no | Dia. (mm) | F (mm) | Tc (mm) | Te (mm) | R | BFL (mm) | Coating |
| LEN3254-M25R4-20-IR2 | 25.4 | -25.4 | 2 | 4.3 | -71.8 | -25.8 | IR2 Coating Ravg < 1.5% @ 8~12µm |
| LEN3254-M50-20-IR2 | 25.4 | -50 | 2 | 3.2 | -140.8 | -50.4 | IR2 Coating Ravg < 1.5% @ 8~12µm |
| LEN3254-M75-20-IR2 | 25.4 | -75 | 2 | 2.8 | -211 | -75.4 | IR2 Coating Ravg < 1.5% @ 8~12µm |
| LEN3254-M100-20-IR2 | 25.4 | -100 | 2 | 2.6 | -281.1 | -100.4 | IR2 Coating Ravg < 1.5% @ 8~12µm |
| LEN3254-M200-20-IR2 | 25.4 | -200 | 2 | 2.3 | -561.6 | -200.4 | IR2 Coating Ravg < 1.5% @ 8~12µm |
ZnSe Double Concave Lens Uncoated
ZnSe Double-Concave Lens (Uncoated)
| Part no | Dia. (mm) | F (mm) | Tc (mm) | Te (mm) | R | BFL (mm) | Coating |
| LEN3254-M25R4-20 | 25.4 | -25.4 | 2 | 4.3 | -71.8 | -25.8 | Uncoated |
| LEN3254-M50-20 | 25.4 | -50 | 2 | 3.2 | -140.8 | -50.4 | Uncoated |
| LEN3254-M75-20 | 25.4 | -75 | 2 | 2.8 | -211 | -75.4 | Uncoated |
| LEN3254-M100-20 | 25.4 | -100 | 2 | 2.6 | -281.1 | -100.4 | Uncoated |
| LEN3254-M200-20 | 25.4 | -200 | 2 | 2.3 | -561.6 | -200.4 | Uncoated |
specifications
- Material: CVD Laser-Grade Zinc Selenide (ZnSe)
- Design Wavelength: 10.6 µm
- Diameter Tolerance: +0.0 / -0.1 mm
- Center Thickness Tolerance: ±0.2 mm
- Focal Length Tolerance (EFL): ±1%
- Lens Centration Tolerance: < 3 arcmin
- Surface Quality: 60-40
- Chamfer: 0.2 mm × 45°







