ABSTRACT
This chapter discusses the properties of vitreous silica because of its more extensive use in optics for several applications and glasses for mirror substrate optics. Schott has developed multicomponent fluorophosphate glasses that feature good transmission at wavelengths in the ultraviolet range compared with other multicomponent oxide glasses. The vitreous silicas can be distinguished by the source of raw material used and the process of melting or consolidating the raw material into bulk vitreous silica. The most important criterion for choice of a mirror substrate glass is its thermal expansion coefficient. Mirrors must maintain their optical figure precisely during use. An important advance in optical properties provided by these glasses is an extension of optical transmission into the infrared range beyond the 3-μm limit of silicate glasses. The choice of glass will depend on available degree of control of the temperature of the operating environment.
