Production Testing of Large Aperture Paraboloidal Mirrors.
ARMY ENGINEER RESEARCH AND DEVELOPMENT LABS FORT BELVOIR VA
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This report describes a photometric technique and apparatus for the rapid production testing of a large aperture paraboloidal mirrors to determine the ability of such a mirror to concentrate incident radiation at its focus. It is not a test to determine faults in the figure of a mirror. Developed for the rapid testing of mirrors used in radiation receivers, it tests a mirror as an objective under optical conditions simulating those encountered in use. In this test, a mirror of astronomical quality is used to collimate and project the light from a pinhole light source onto the mirror under test. The test mirror concentrates this light into an integrating sphere through a pinhole. A certain fraction of the light is bled off from the integrating sphere and measured by a phototube with associated amplifier. By removing the pinhole diaphragm from the integrating sphere, a hole sufficiently large to pass all light into the sphere is exposed. The ratio of the two measurements -- light passing through the pinhole to total light reflected by the test mirror -- gives the over-all performance of the mirror in concentrating incoming radiation.
- Infrared Detection and Detectors