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Proceedings Paper

Improving transmission and image contrast in medium and high performance optical systems using weighted average angle of incidence techniques to optimize coatings
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Paper Abstract

Designers of medium and high performance optical systems often overlook a very simple technique that can improve the system transmission and image contrast, as well as reduce scattering within the system. The resulting improvement in the optical collection efficiency can be used to increase performance or be traded off to realize improvements in other areas (i.e. aperture size, weight, etc.). The technique is based on the observation that many (if not most) anti-reflection coatings specified for lens surfaces, are specified at a normal angle of incidence. Since most of the energy incident on a typical lens impinges at angles other than the normal, the efficiency of an anti-reflection coating at any surface might be improved by using an approach based on weighted average angles of the incident radiation. This paper describes one approach to calculate weighted average coating angles for a optical systems. The optical transmissions are estimated, when the respective coatings are specified at the normal angle of incidence and at an angle based on the incident ray geometry. The measured transmission of two (otherwise identical) aspheric lenses, one coated using a standard SLAR coating specified at a normal incidence angle and the other coated using a standard SLAR coating specified at optimized incidence angles are presented.

Paper Details

Date Published: 3 October 2008
PDF: 8 pages
Proc. SPIE 7119, Optics and Photonics for Counterterrorism and Crime Fighting IV, 711903 (3 October 2008); doi: 10.1117/12.797531
Show Author Affiliations
James A. Harder, ESA, Inc. (United States)
Michaelene Sprague, ESA, Inc. (United States)


Published in SPIE Proceedings Vol. 7119:
Optics and Photonics for Counterterrorism and Crime Fighting IV
Gari Owen, Editor(s)

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