Precision custom optics from crystals
Modern industry and science can't exist without precision optical technologies. The study of space and the depths of the World Ocean, dynamics of the atmospheric and volcanic processes, the creation of aircrafts, space rockets, submarines and etc. one can't imagine without using precision optical crystalline materials. High temperature furnaces, high pressure systems need to be monitored through precision optical components (precision optical windows and others).
Huge telescopes, optical binoculars and microscopes, different holographic and spectral systems are able to function due to modern precision optical manufacturing only. Also it's hardly possible to imagine gas and solid state lasers and lasers systems without precision optics.
Materials of precision custom optics
The development of the solid state physics, crystallography and crystal growing technology allows to get the different crystal materials for custom crystal manufactures. Rather old semiconducting crystals Ge (Germanium), Crystal Quartz, Calcium Fluoride and Zinc Selenide keep on being the foreground as materials for the precision optical windows, optical lenses and prisms. Of course, newer materials for precision optics are also used.