Patent ID: 6844973
Filing Date: 2005-01-18
Classification: G01J,G02B

Abstract:
1. A plane diffraction grating with grooves formed on a surface thereof, the plane diffraction grating being rotated about a rotational axis which is normal to the surface, and being characterized in that a profile of the grooves at a radial area is determined depending on an azimuthal position φ of the area about a rotational center defined as a foot of the rotational axis on the surface of the plane diffraction grating for maximizing a diffraction efficiency of the radial area, wherein the plane diffraction grating is a blazed type, and a blaze angle θ where α is an angle of an incident ray from a normal to the surface of the plane diffraction grating in the area, and β is an angle of a diffraction ray from the normal, and a blaze angle θ