| 摘要 |
A transmission grating is used to reduce chromatic aberration in an optical system, wherein the system's chromatic dispersion is offset and substantially canceled by the grating's diffraction-induced dispersion. The grating comprises a Fresnel-type pattern of microscopic facets molded directly into one of the system's refractive optical surfaces. The facets would typically have a profile height of around 4.10<-><5> inch and a profile width of at least 10<-><3> inch. In its primary intended application, the invention would function to improve the optical performance of a Fresnel lens used to concentrate direct sunlight into a piped daylight illumination system. For this application, about a ten-fold reduction in chromtic dispersion would be attained with only about a 2% loss in optical efficiency. |
