Chromatic Dispersion Compensation in a Fresnel Lens by Means of a Diffraction Grating
Date Published |
08/1989
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Publication Type | Conference Paper
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Author | |
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LBL Report Number |
LBL-27950
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Abstract |
A Fresnel lens 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 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 micro-inches and a facet width ranging from about 1 milli-inch at the edge of the lens to around 5 or 10 milli-inches 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. |
Conference Name |
SPIE Optical Materials Technology for Energy Efficiency and Solar Conversion Conf. XIII
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Year of Publication |
1989
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Conference Location |
San Diego, CA
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Custom 1 |
<p>Windows and Daylighting Group</p>
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Organizations | |
Research Areas | |
File(s) | |
Download citation |