Preparation of optical surfaces on beryllium.

The high strength-to-weight ratio and thermal diffusivity of beryllium are very attractive to the optical system designer for many critical applications. In order to realize the potential advantages of beryllium, it is necessary to have mirror blanks figured to optical tolerances which are also dimensionally stable over the life of the system. As part of a program to improve the dimensional stability of beryllium, we have cataloged the properties of both Kanigen-coated and bare beryllium mirrors. The results presented in this report indicate the bare beryllium is to be preferred over Kanigen-coated beryllium for precision optical surfaces.