Patent ID: 6678044
Filing Date: 2004-01-13
Classification: G01J

Abstract:
A monochromator comprising:a diffraction grating for diffracting incident light; a selection unit for selecting a desired wavelength of the light diffracted by the diffraction grating; and a substrate that fixes the diffraction grating and the selection unit; wherein the diffraction grating is made of a material selected such that a variation in the wavelength of the selected light due to thermal expansion or shrinkage of members other than the diffraction grating is cancelled out or reduced by a variation in the wavelength of the selected light due to thermal expansion or shrinkage of the diffraction grating; and the diffraction grating is made of a material selected such that a variation in the wavelength of the selected light due to a change in layout of individual members due to thermal expansion or shrinkage of the substrate is cancelled out or reduced by a variation in the wavelength of the selected light due to thermal expansion or shrinkage of the diffraction grating.