1 June 1983 Progress In Absolute Distance Interferometry
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This paper describes the results of recent research undertaken to examine the feasibility of employing laser interferometry to precisely measure absolute distance over extended ranges. Data are presented that show a resolution of 0.03 um (rms) for measurements over distances up to 10 meters. The technology developed for achieving these results is based on two-color, synthetic Michelson interferometry employing a new CO2 laser source. Indeed, the new laser is the key element in this process: it was specifically designed to sequentially switch between four sets of stable R- and P-line pairs and thereby provide a basis for forming simultaneous equations which were employed to greatly reduce the half-wavelength ambiguity typical of single wavelength interferometers. Potential applications to future optical telescopes--particularly the large, multipanel telescopes under consideration for 10-15 years hence--their initial alignment and control, are suggested.
C. W. Gillard, N. E. Buholz, "Progress In Absolute Distance Interferometry," Optical Engineering 22(3), 223348 (1 June 1983). https://doi.org/10.1117/12.7973117 . Submission:

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