Diamond is an excellent optical material with high transmittance in the whole band from X-ray to microwave. For example, MPCVD single crystal diamond can be made into the energy transmission window of high-power laser devices, but also can be made into the diamond window of space detectors. Diamond has the characteristics of heat shock resistance, chemical corrosion resistance and mechanical wear resistance, and has been studiedand applied in infrared window, microwave window, high power laser window, thermal imaging system window, X-ray window and other aspects.