Abstract

Altair is an acquisition, tracking, and pointing space experiment sponsored by the Strategic Defense Initiative Organization Directed Energy Program Office. The principal optical component is the 80-cm Cassegrain telescope. The primary mirror is an egg crate ULE structure supported by two independent mounting systems. One system supports the mirror during high-g launch conditions and the second during zero-g operation. It is mounted in a graphite–epoxy metering structure that contains a 5-DoF mount for remote adjustment of the secondary mirror. A two-ton test structure was designed and installed in a class 10,000 clean room to support the telescope and a 42-in retroflat. The interferometric tests were performed at two orientations. This technique yielded an independent test of the transmitted wavefront that obviated the need to use a gravity off-load support for the lightweight primary mirror. The preload forces on the flight mounts were determined to be too low on some bipods. The stability of the boresight of the telescope was verified to be within specification. The remote secondary adjustments were tested and discrepancies found in the command module. The protected silver coatings contained many pinholes and scattering centers. All of the observed nonconformances need to be addressed and repaired before launch and space operation. None entail extensive analysis, redesign, or hardware repair.

© 1992 Optical Society of America