The "glass" used in zinc selenide lenses is not traditional silicate glass, but rather a polycrystalline zinc selenide (ZnSe) infrared optical material grown using the chemical vapor deposition (CVD) process. It is commonly referred to in the industry as "ZnSe glass" or "ZnSe crystal glass." Its typical characteristics are as follows:

1. Transmission Band
   0.6 μm (visible orange-red) – 16 μm (far infrared), with particularly low bulk absorption (α<0.0005 cm?1) near the 10.6 μm CO? laser wavelength.

2. Optical Performance
   ? Refractive index n≈2.403 (@10.6 μm)
   ? Low Abbe number, moderate dispersion
   ? High reflection loss (approximately 17% per surface), typically requiring anti-reflection coating (R<0.2%)

3. Mechanical and Thermal Properties
   ? Knoop hardness HK≈120, relatively soft, prone to scratching, requires handling with finger cots