OPTICAL REFLECTION GRATING, SPECTROPHOTOMETER USING THE SAME AND METHOD OF FINDING OPTICAL REFLECTION GRATING WITH HIGH DIFFRACTION EFFICIENCY

摘要

PROBLEM TO BE SOLVED: To provide an optical reflection grating attaining diffraction efficiency of TE(transverse electric) wave and TM(transverse magnetic) wave equal with each other as far as possible and concurrently attaining diffraction efficiency as high as possible, a spectrophotometer using the reflection grating and a method for finding such an optical reflection grating. SOLUTION: In the optical reflection grating with numerous parallel grooves (5), when a ratio of a grating period (g) to a wavelengthλis <0.9 or preferably <0.7, the depth of the grooves is set to a depth which realizes the diffraction efficiency DE of the TE and TM waves at a defined wavelengthλbeing only <10% or preferably <5% different with each other and respectively being >=60%. Thereby the diffraction efficiency DE is practically independent of the polarization direction of incident light and is extremely high.