<title>Design, analysis, and testing of a CCD array mounting structure</title>

A method has been developed for mounting charge-coupled device (CCD) arrays in an optical telescope so as to minimize thermal defocusing errors. The mounting arrangement was developed for a six-inch aperture, visible band, off-axis reimaging telescope attached to an experimental satellite. The mounting arrangement consists of two pieces: a fiberglass frame which holds the actively cooled CCD package and provides thermal isolation from the telescope body; and a titanium flexure, which acts to minimize structural distortions caused by the difference in thermal expansion properties of the CCD array and the telescope body. This paper describes the design, analysis, and testing of this CCD array mounting arrangement. A detailed finite-element model of the CCD array and the mount was developed and used to predict thermally-induced defocus and gravity sag deformations, as well as natural frequencies. Experimental tests to verify the computer model results were performed using holographic interferometry. Vibration tests were also performed to verify the natural frequencies as well as structural integrity during launch. A comparison of the computer model predictions and the holographic interferometric measurements of thermally-induced defocussing indicates agreement to within 15 to 20%. Both the experimental and computer results indicate that the mounting structure provides focus stability over the operational temperature range of the telescope with sufficient structural integrity to survive the anticipated spacecraft launch loads.