Optical Properties of Insulators—Some Applications

The chapter discusses the applications of the optical properties of insulators. Transparent crystals are an important class of insulating optical materials with their main application in nonlinear optics, while glasses have majority of their applications in linear optics. Glasses are desirable for optical elements because of their high homogeneity, transparency, high hardness to allow good polishing and resist scratching, and an excellent optical window over the visible. Optical plastics are another useful application of insulating optical materials. Under conditions of mass production, plastics are more economical than glass. Plastic optics weigh less and can be made into very complex shapes. Another great potential for plastic optics is in digital and Fresnel optics. However, they have some drawbacks as well. They can never achieve the optical quality of glass, have low scratch resistance, lower thermal stability, and are more difficult to AR-coat than glass.They also exhibit greater stress birefringence and higher temperature dependence in their refractive index.