Patent ID: 6965482
Filing Date: 2005-11-15
Classification: G02B,G11B

Abstract:
1. A lens for multiple wavelengths condensing plural kinds of monochromatic lights respectively, the lens comprising: a lens surface sectioned into plural aspherical zones having different refractive power in a common use area for all the monochromatic lights, wherein the plural sectioned aspherical zones respectively have one common single focal point corresponding to an inherent wavelength of each of the monochromatic lights, one focal point corresponding to the inherent wavelength of one of the monochromatic lights is arranged in different position with other focal points corresponding to the inherent wavelengths of other monochromatic lights, each of the aspherical zones, with regard to each of the monochromatic lights, differs in optical path length from each other by approximately integral multiple of wavelength λ when a difference between a maximum value and a minimum value of a wavefront aberration of each of the monochromatic lights in each of the aspherical zones is (ΔV a ratio between differences of each of the monochromatic lights is between 0.4 and 2.5 in each of the aspherical zones, and the wavelength λ