Abstract

Evaporative deposition using a mask to produce a spatially varying thickness profile is investigated. Using dielectric evaporants with a carefully designed mask and a rotating substrate, it is possible to produce highly accurate, rotationally symmetric aspheres. The problems of surface roughness, mask misalignment, and mask form error are discussed. The use of this technique for the production of "keystone-distorted" aspheres is also investigated. By this it is meant the family of aspheres having their contour lines distorted to account for the keystone, or trapezoidal distortion which occurs when a converging or diverging beam strikes a surface obliquely. These aspheric types are useful in the design of tilted mirror systems.

© 1987 Optical Society of America