Proceedings PaperVibration Insensitive Laser Unequal Path Interferometer (LUPI) Test
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A 24 inch diameter segment of a 60 inch diameter, 10 meter focal length parabolic mirror was fabricated at Space Optics Research Labs. Due to the long focal length, a standard null test using a 24 inch flat could not be set up on our 12 foot air table. The test was set up in a long room which was subject to vibrations. A modification was made to a LUPI (Laser Unequal Path Interferometer) to allow the collimated reference beam to follow approximately the same path as the test beam. Adjustable flat mirrors for the reference beam were attached to the sides of the mounts for the parabola and flat. This combination allowed the r-,f,erence beam to "follow along" and pick up the same vibrations as the test beam. Good high contrast fringes were produced by this method. This paper will describe the test procedure and equipment. Additional problems of temperature, turbulence, and coherence will be summarized.