26 August 2009 Low dispersion ghost-controlled optical window/combiner component
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A key consideration in designing optical systems, instruments, or test setups requiring windows or beam combiners is the potential for ghost images to be produced from reflections off the window/combiner surfaces. These ghost images will affect the optical system performance and the level to which that performance can be demonstrated during verification testing. Two common solutions for this are to use anti-reflection coatings and to use wedged substrates. Each has performance implications when used in spectrally broadband systems. The use of coatings alone on windows/combiners results in modest reduction (<100X) of ghost image intensity that can be inadequate when using or testing systems designed to find weak targets near bright objects. Using wedged substrates to shift ghost images outside an image region of interest will introduce chromatic aberrations that limit the fundamental broadband system imaging performance. In this paper we present design parameters for window/combiner assemblies that shift ghost images from a region of interest while controlling the chromatic aberrations to a level whereby the system imaging performance is not adversely affected even for broadband imaging systems with high angular resolution. We then present an example demonstrating the performance of a typical low dispersion, ghost-controlled window/combiner assembly.
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Paul Atcheson, Paul Atcheson, "Low dispersion ghost-controlled optical window/combiner component", Proc. SPIE 7436, UV/Optical/IR Space Telescopes: Innovative Technologies and Concepts IV, 74360P (26 August 2009); doi: 10.1117/12.824448; https://doi.org/10.1117/12.824448


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