The Design, Construction, and Testing of the Optics for a 147-cm-Aperture Telescope

Abstract

In this report we describe the work carried out under contract F19628-72-C-0047 entitled "Geodetic Optics Research" for the Air Force Cambridge Research Laboratories (AFCRL). The work consisted mainly of the fabrication of the optical components for a telescope with a 152 cm-diam (60-in.) primary mirror masked down to 147-cm diam for use by the AFCRL for a lunar ranging experiment. Among the noteworthy achievements of this contract were the following: (a) Completion of the primary and secondary mirrors for a high -quality 147 -cm- diam telescope system in eight months from the start of edging the primary. (b) Manufacture and testing of a unique center mount for the primary according to an AFCRL design that allowed for a thin-edged and therefore less-massive mirror. (c) Development of a quantitative analysis of the wire test for calculating the departure of the mirror figure from the design figure quickly and accurately after each polishing step. This analysis method in conjunction with a knowledge of polishing rates for given weights and diameters of tools, mirror, and polishing materials should considerably reduce the polishing time required for future large mirrors. The emphasis in this report is on these three items; however, considerable work was also undertaken in telescope design; null lens design and mounting; tracking optics design, fabrication, and mounting; and special thin -film coatings for the laser send and receive optics.