Chromatic dispersion compensation in a Fresnel lens by means of a diffraction grating
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. 6 refs., 9 figs.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- DOE/CE
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 5231732
- Report Number(s):
- LBL-27950; CONF-890836-22; ON: DE90004030
- Resource Relation:
- Journal Volume: 1149; Conference: 33. SPIE annual international technical symposium on optical and optoelectronic applied science and engineering, San Diego, CA (USA), 6-11 Aug 1989
- Country of Publication:
- United States
- Language:
- English
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99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
FRESNEL LENS
PERFORMANCE TESTING
CHROMATIC ABERRATIONS
DAYLIGHTING
DIFFRACTION
ENERGY EFFICIENCY
FIBER OPTICS
GEOMETRY
GRATINGS
ILLUMINANCE
LIGHT TRANSMISSION
MATHEMATICAL MODELS
OPTICAL DISPERSION
REFRACTION
SOLAR ENERGY CONVERSION
COHERENT SCATTERING
CONVERSION
EFFICIENCY
ENERGY CONVERSION
LENSES
MATHEMATICS
SCATTERING
TESTING
141000* - Solar Collectors & Concentrators
990200 - Mathematics & Computers
320106 - Energy Conservation
Consumption
& Utilization- Building Equipment- (1987-)