• ZnSe Substrate
• Broadband AR Coating for the 8-12 µm Range
• Focal Length: -75 mm

Thorlabs' Ø1" Zinc Selenide (ZnSe) Bi-Concave Lens, which offers a high transmission from 0.6-16 µm, is available with a broadband AR coating optimized for the 8-12 µm spectral range deposited on both surfaces. This coating greatly reduces the high surface reflectivity of the substrate, yielding an average transmission in excess of 97% over the entire AR coating range.

The bi-concave lens has a negative focal length, making it useful for a wide range of applications. It is often used to increase the divergence of a converging beam. In optical systems, it is common for researchers to choose their optics carefully so that the aberrations introduced by the positive- and negative-focal-length lenses approximately cancel. Others use these lenses in pairs to increase the effective focal length of a converging lens. In particular, ZnSe lenses are well suited for use with high-power CO2 lasers.

• Material: Laser Grade Zinc Selenide
Wavelength Range: 0.6 - 16.0 µm
• AR Coating Range: 8-12 µm
• Reflectance over Coating Range (Avg.): <1.5%
• Diameter Tolerance: +0.00/-0.10 mm
• Thickness Tolerance: ±0.2 mm
• Focal Length Tolerance: ±1%
• Surface Quality: 60-40 Scratch-Dig
• Spherical Surface Power: 33λ/2
• Spherical Surface Irregularity: 3λ/2
• Centration: ≤3 arcmin
• Clear Aperture: 80% of Diameter
• Design Wavelength: 10.6 µm
• Diameter: Ø 1" (25.40 mm)
• f: -75 mm
• R: -211 mm
• t_c: 2 mm
• t_e: 2.8 mm
• f_b: -75.4 mm
• Suggested Mount: LMR1