The structural aspects of developing a flat laser radar beam
steering mirror for optical discrimination of an array of spaceborne targets
at 10.6 ?m are discussed. Results of trade studies to determine feasible
design concepts capable of meeting the system performance goals during
steering are included. Aperture diameters between 0.5 and 2 m were studied
for three principal structures: (1) a thin glass sandwich coupled to a
deep backup structure, (2) a full-depth beryllium sandwich, and (3) a fulldepth
graphite epoxy sandwich. The results of computer simulations of
the structural performance of each of these concepts are presented, and
fabrication efforts in support of these concepts are described. These studies
demonstrate that lightweight, dimensionally stable flat mirrors can be
fabricated with present technology. Aluminum-clad graphite/epoxy mirrors
were successfully manufactured within 0.5 pm rms of a flat surface,
and initial test results indicate dimensional stability after several thermal
cycles. A low cost, uncomplicated method to manufacture low thermal
expansion aluminum-clad graphite/epoxy tubes as backup structural
members for large space-based optics was also developed. Further investigations
are warranted to determine the dynamic tensile strength of
glass, to develop thermal distortion compensation methods for metal mirrors,
and to improve the dimensional and temporal stability of clad graphite/
epoxy mirrors.
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