JPL's Precision Segmented Reflector (PSR) program is developing enabling technologies for large space telescopes employing segmented optics, and in particular, lightweight, thermally stable mirrors for telescopes operating at sub-millimeter wavelengths. This paper will describe JPL's vacuum cryointerferometric optical test facility located at Phillips Laboratory (formerly Air Force Astronautics Laboratory) Edwards Air Force Base, Edwards, California as well as some recent test results. This evolving facility includes a commercial computer-controlled phase shifting interferometer operating at 10.59 microns and laser metrology for measurement of piston and absolute radius of curvature. The optical metrology has been integrated with a large vacuum chamber including a liquid nitrogen shroud capable of radiatively cooling 1.5 meter aperture mirrors down to 150 K. The facility is now being used to characterize prototype mirrors in both their room-temperature 'as-replicated' condition, and under orbital-like temperature conditions. The paper will discuss performance and limitations of the optical metrology hardware and software components. Representative test results on prototype one meter-class composite mirrors being developed for PSR and related ground-based programs will also be presented. A cryointerferometric facility has been established which is providing useful surface figure measurements of prototype mirrors being developed for sub-millimeter space telescopes. Surface errors down to 0.2 microm RMS can be measured with spatial resolution down to 0.5 cm over one meter aperture spherical mirrors. Absolute radius of curvature measurements are included.
Optical figure testing of prototype mirrors for JPL's precision segmented reflector (PSR) program
Ein optischer Mustertest von Spiegelprototypen für das Präzisions-Segmentspiegel-Programm von JPL (Jet Propulsion Laboratory)
1991
12 Seiten, 10 Bilder, 5 Quellen
Conference paper
English
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