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Optical Engineering

Method Of Improving The Performance Of Lenses For Use In Thermal Infrared
Author(s): M. W. McDowell; H. W. Klee
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Paper Abstract

A method is described whereby the field performance of an all-germanium triplet, as used for imaging radiation in the 8 to 13 µm waveband, can be improved. The principle of the method, which could also be used to improve the performance of achromatic triplets or aspherized doublets, involves the use of a field flattener lens which replaces the germanium window of the detector. The curvature of this lens can be optimized to minimize field curvature, which together with chromatic aberration is one of the most serious residuals of thermal imaging systems with relative apertures of around f/0.7. It is also shown that for such relative apertures, and for typical fields of less than 15 degrees, at 100 mm focal length, the location of the aperture stop is not a significant design parameter. This arises as a result of the intrinsic optical properties of germanium.

Paper Details

Date Published: 1 October 1980
PDF: 5 pages
Opt. Eng. 19(5) 195748 doi: 10.1117/12.7972598
Published in: Optical Engineering Volume 19, Issue 5
Show Author Affiliations
M. W. McDowell, National Physical Research Laboratory (South Africa)
H. W. Klee, National Physical Research Laboratory (South Africa)

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