ABSTRACT
The development of novel chemical vapor deposition (CVD) methods for producing diamond has led to an increased interest in using diamond as an optical material. Work dating back to the 1950s also showed that diamond could be produced from the gas phase at low pressures. Work in the Soviet Union in the late 1970s and in Japan in the early 1980s showed that gas-phase processes could be used to produce polycrystalline diamond films over large areas at high-deposition rates. The theory of the solid state indicates that diamond with no defects should be transparent from the wavelength of the electronic band edge at about 225 nm, through wavelengths in the visible and most of the infrared. CVD diamond is predominantly polycrystalline so that some of the properties listed, such as the elastic constants, may not apply directly to this material but must be averaged in an appropriate manner.
