THERMALLY STABLE BIREFRINGENT PRISM ASSEMBLY

摘要

A thermally stable polarizing optical component, such as a polarizing beam splitter, which overcomes the effects of thermally induced stress birefringence by using one or more elements constructed of a material with a low optical stress coefficient, typically less than 1x10<-6> mm<2>/N. Such a material reduces the termal stresses resulting from passage of the beam itself, either because of a non-uniform beam cross section, which heats some parts of the element more than other parts, or from a uniform beam cross-section, but with non-uniform heat dissipation from the element's surfaces. The presence of thermal stress within the element results in stress-induced birefringence because of the optical stress coefficient. In addition, thermally induced stress birefringence is reduced by the use of materials which reduce the formation of the thermal gradients themselves, or reduce the level of mechanical stess caused by any thermal gradients nevertheless present.