11 November 1999 Vibration-compensated interferometer for measuring cryogenic mirrors
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An advanced interferometer was built for measuring large mirrors at cryogenic temperatures. This instrument uses active control to compensate the effects of vibration to allow high resolution phase shift interferometry. A digital signal processor and high speed phase control from an electro-optic modulator allow phase measurements at 4000 Hz. These measurements are fed back to a real time servo in the DSP that provides a vibration-corrected phase ramp for the surface measurements taken at video rates. This instrument is planned to be integrated at NASA Marshall Space Flight Center's X-ray Calibration Facility for measuring NGST mirrors at 40 K.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Chunyu Zhao, James H. Burge, "Vibration-compensated interferometer for measuring cryogenic mirrors", Proc. SPIE 3782, Optical Manufacturing and Testing III, (11 November 1999); doi: 10.1117/12.369217; https://doi.org/10.1117/12.369217

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