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10 June 1987 Performance Characteristics Of Phased Array And Thinned Aperture Optical Telescopes
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Proceedings Volume 0751, Reflective Optics; (1987)
Event: OE LASE'87 and EO Imaging Symposium, 1987, Los Angeles, CA, United States
Phased telescope arrays for broad-band imaging applications suffer from substantial sensitivity losses due to the large number of reflections required to phase and combine the images from the individual telescopes making up the array. They also suffer from severe field-of-view limitations (perhaps as small as a few tens of arc seconds) due to both pupil-mapping errors and the field curvature of the individual telescopes making up the array. In addition, thinned aperture optical systems (including phased telescope arrays) pose unique problems in specifying or characterizing image quality. Traditional image quality criteria such as "resolution" and encircled energy are woefully inadequate for many thinned aperture applications. Variations in the subaperture geometry which produce only subtle effects upon the core of the point spread function (PSF) may produce highly undersirable artifacts or spurious images as well as a modulation transfer function (MTF) which exhibits zero (or negligible) values over substantial regions within the cut-off spatial frequency of a filled aperture circumscribing the array. Clearly some minimum value of the MTF exists below which spatial information cannot be retrieved in the presence of noise. An MTF property called the "practical resolution limit" and defined as the reciprical of the maximum spatial frequency within which no zeros occur in the MTF thus becomes the image quality criteria of choice for those applications where fine detail is required from extended objects. This practical resolution limit and its effect upon mirror size and separation (subaperture configuration) will significantly impact the telescope mechanical architecture, stowage and deployment techniques, and perhaps even the booster vehicle selection for future large space telescopes.
© (1987) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
James E. Harvey and Richard A. Rockwell "Performance Characteristics Of Phased Array And Thinned Aperture Optical Telescopes", Proc. SPIE 0751, Reflective Optics, (10 June 1987);


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