Being the diffraction optical element which is used for the diffraction optical element, the spectrum colorimetry device and

摘要

PROBLEM TO BE SOLVED: To provide a spectral color sensor which has little detection color difference in relation to chromaticity of a specimen by decreasing generation of mixed colors by high order diffraction light of short wavelengths and by acquiring precise spectral information in an entire evaluation wavelength band considering the optical efficiency of an entire optical system.;SOLUTION: In a concave reflective spectral element used for a Rowland type spectrometer, when a range of wavelengths detected by the Rowland type spectrometer is above λ1 and below λ2 (λ1λ2), the diffraction efficiency D (λ) at a wavelength λ of a refraction optical element takes a maximum and highest value at a wavelength λa in the range of equation 1, the reference surface of the concave reflective spectral element has an anamorphic shape, and Rr is satisfied, wherein the bus radius of curvature is R and the sagittal radius of curvature is r.;COPYRIGHT: (C)2011,JPO&INPIT