PREFERRED CRYSTAL ORIENTATION OPTICAL ELEMENTS FROM CUBIC MATERIALS

摘要

The invention provides a method of making a <194 nm wavelength calcium fluoride crystal optical lithography element for transmitting wavelengths less than about 194 nm along an optical axis with minimal birefringence by providing an optical element optical calcium fluoride crystal with an input face {100} crystal plane and forming the input face {100} crystal plane into an optical lithography element surface of an optical lithography element having an optical axis, with the optical axis aligned with a <100< crystal direction of the optical calcium fluoride crystal. In a preferred embodiment, the below 194 nm transmitting optical element is a <100> oriented calcium fluoride lens. In a preferred embodiment, the below 194 nm transmitting optical element is a <100> oriented calcium fluoride beam splitter.