Diffraction grating of the reflective-type

摘要

Reflection-type diffraction grating (1), the cross-section of which having an asymmetrical triangular shape, wherein if ¸ denotes the blaze angle, i.e. the angle between the short side (6) and the base (7) of the triangular shape, Æ denotes the vertex angle, i.e. the angle between the short side (6) and the long side (9) of the triangular shape, and ± denotes the angle of incident light (5) with respect to a normal to the base (7), the angles ¸ and Æ, in degrees, satisfy the following formulas (6) and (7): (6) Æ + ¸ ‰¤ 90 + ±; and (7) 0.1127291 (Æ - Æ d ) 2 - 19.67453 (Æ - Æ d ) + 938.74 + ¸ d ‰¤ ¸ 0.36631 (Æ - Æ d ) + 48.84 + ¸ d where Æ d = 0.845à and ¸ d = 1.065à represent the shift in vertex angle and the shift in blaze angle, with à = ± - 79.25 denoting the amount of change in the angle of incident light.