Marshall Space Flight Center (MSFC) has been performing optical wavefront testing at cryogenic temperatures since 1999 in the Space Optics Manufacturing Technology Center's (SOMTC's) X-ray / Cryogenic Facility (XRCF). Recently the cryogenic optical testing capability has been extended to a smaller chamber. This smaller horizontal cylindrical vacuum chamber has been outfitted with a heliumcooled liner that can be connected to the existing helium refrigeration system bringing the kilowatt of refrigeration capacity to bear on a 1 x 2 meter test envelope. Cryogenic cycles to 20 Kelvin, including setup and chamber evacuation/backfill, are now possible in only a few days. Since activation and chamber characterization tests in September 2001, the new chamber has been used to perform a number of proprietary cryogenic tests on mirrors, adhesives, and actuators. A vibration survey has also been performed on the test chamber. Chamber specifications and performance data, vibration environment data, and optical test capability will be discussed.

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By utilizing the unique x -ray test facility at NASA's Marshall Space Flight Center, high resolution data have been obtained for the scattering of x rays from smooth optical flats. Using x rays with energies in the range from 2.99 keV to 8.06 keV, the resulting reflected images from five state -of-the -art polished mirror flats with various substrate and coating materials are presented and analyzed. Evidence for large angle scattering is shown to exist for some energies and is discussed in terms of theoretical models for surface defects.

The AXAF Technology Mirror Assembly (TMA) was characterized prior to x -ray testing by properties measured mechanically or with visible light; these include alignment offsets, roundness and global axial slope errors, axial figure errors with characteristic lengths greater than about five mm, and surface roughness with scale lengths between about 0.005 and 0.5 mm.The x -ray data of are compared with predictions based upon the mechanical and visible light measurements.Introduction.

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