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Proceedings Paper

Chromatic Dispersion Compensation In A Fresnel Lens By Means Of A Diffraction Grating
Author(s): Kenneth C. Johnson
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Paper Abstract

A Fresnel lens's imaging performance can be seriously impaired by chromatic dispersion which typically doubles the diameter of the focused sun image in a solar concentrator. This problem can be alleviated by means of a molded diffraction grating whose diffraction-induced dispersion offsets and substantially cancels the lens's intrinsic refractive index dispersion. The grating lines would comprise a second tier of small-scale, Fresnel-type facets superimposed on the lens facets, with a typical grating facet height of about 40 microinches and a facet width ranging from about 1 milliinch at the edge of the lens to around 5 or 10 milliinches near the center. In its primary intended application the grating would function in a core daylighting system to improve the optical performance of a collector which focuses direct sunlight into fiber optic couplers. For this application chromatic dispersion would be reduced by an order of magnitude with only a 2% loss in optical efficiency.

Paper Details

Date Published: 12 December 1989
PDF: 13 pages
Proc. SPIE 1149, Optical Materials Technology for Energy Efficiency and Solar Energy Conversion VIII, (12 December 1989); doi: 10.1117/12.962179
Show Author Affiliations
Kenneth C. Johnson, Lawrence Berkeley Laboratory (United States)

Published in SPIE Proceedings Vol. 1149:
Optical Materials Technology for Energy Efficiency and Solar Energy Conversion VIII
Claes-Goeran Granqvist; Carl M. Lampert, Editor(s)

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