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