Subaperture Optical Testing: Experimental Verification

Tilman W. Stuhlinger

doi:10.1117/12.938467

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20 October 1986 Subaperture Optical Testing: Experimental Verification

Tilman W. Stuhlinger

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Proceedings Volume 0656, Contemporary Optical Instrument Design, Fabrication, and Testing; (1986) https://doi.org/10.1117/12.938467
Event: 1986 International Symposium/Innsbruck, 1986, Innsbruck, Austria

Abstract

The results of an experiment designed to test the feasibility of optical testing using subaperture test flats are presented in this paper. This testing technique involves the replacement of the monolithic optical flat used in conventional double-pass optical system testing by an array of small flats, or subapertures. Subaperture testing was conceived previously by other authors as a low-cost means of testing future telescope systems with large apertures (ca. 10 meters). Previous work by these authors involved the development of analytical techniques for combining subaperture testing data such that the wavefront over the full aperture may be obtained; the present work provides experimental verification of these analytical techniques. A brief description of the algorithms used to analyze the data is given along with a description of the experimental procedure. An array of seven subapertures was used. The subapertures contained random tilts and phase shifts relative to each other; thus the possibility of performing subaperture testing with such an unphased array was specifically tested. Control data were obtained with a monolithic flat. Experimental results are presented. Agreement among the subaperture data and the control data is good; thus it is found that subaperture testing is feasible. Knowledge of subaperture phases and tilts results in significantly increased accuracy. However, a lack of such knowledge may be compensated by increasing the amount of data collected. It is found that the dia-meters of the subapertures affect the accuracy more strongly than the knowledge of subaperture tilts. Data obtained with atmospheric turbulence deliberately introduced show that, in the presence of turbulence, subaperture testing is significantly less accurate than conventional testing.

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Tilman W. Stuhlinger "Subaperture Optical Testing: Experimental Verification", Proc. SPIE 0656, Contemporary Optical Instrument Design, Fabrication, and Testing, (20 October 1986); https://doi.org/10.1117/12.938467

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