OPTIMIZED DESIGNING METHOD FOR MAKING FRESNEL GRATING

摘要

Disclosed is an optimized designing method for making a Fresnel grating, comprising the following steps: a) enabling a Fresnel surface profile of the Fresnel grating to be equivalent to a curved surface profile, determining an optical path difference function of the Fresnel grating based on the equivalent curved surface profile of the Fresnel surface profile: Φ(λ) = AP₁P₂B - AOB + Nmλ, wherein a point A represents an object point, a point B represents an image point, a point O represents a reference original point of the grating, P₁ is an incident point of the light ray from the object point on a lens surface, P₂ represents a point at which the light ray falls on the grating, λ represents a wavelength, m represents a diffraction order, N represents a grating distribution function, "" represents an optical path length corresponding to the path; and b) determining a Fresnel grating parameter minimizing a function value of the optical path difference function so as to make the Fresnel grating have the effect of cancelling optical aberration. The Fresnel grating thus made can effectively cancel a part of the optical aberration of the Fresnel grating, thus enhancing the resolution of a spectrometer.