Zinc selenide (ZnSe) crystal is a chemically inert material with strong environmental adaptability and easy processing. ZnSe crystal exhibits high transparency in a broad wavelength range from 500 nm to infrared 7.5μm. ZnSe is one of the most important optical materials for high-power CO₂ laser optical elements. It is also an ideal material for protecting windows and optical elements in infrared thermal imaging systems. This material is also widely used as windows and lenses in medical and industrial thermal radiation measuring instruments and infrared spectrometers.