Silicon (Si) single crystal is a chemically inert material with high hardness, insoluble in water, and a light transmittance range of 1.5-8 microns. The advantages of silicon mirrors are that they have good durability, thermal stability and relatively low cost. Coated silicon substrates are commonly used as mirrors for CO2 lasers. Silicon mirrors are also used in commercial applications such as lightweight scan mirrors, semiconductor wafer handling, and reflective imaging systems.