Method for optimum design of planar variable-pitch grating

Abstract

The invention discloses a method for optimum design of a planar variable-pitch grating and relates to the spectrum technical field. By the adoption of the method, the problem that the groove density function of a variable-pitch grating manufactured with existing methods is quite different from an expected groove density function is solved. According to the method, the meridian expected groove density function of the planar variable-pitch grating is obtained by means of a spherical wave exposure system, the deviate focus, meridian coma and spherical aberration of the planar grating are obtained according to the eikonal function of the variable-pitch grating, the variable-pitch grating is made to focus according to a grating equation, the expected groove density function, the value of the deviate focus F20, the value of the meridian coma F30 and the value of the spherical aberration F40, the meridian coma and the spherical aberration are zero, the expected groove density function coefficient optimized spherical wave logging parameters of the planar variable-pitch grating are obtained, the integral function of the square of the difference between expected groove density and designed groove density of each point on the surface of a substrate of the grating serves as an objective function and is optimized, the minimum value is obtained, and then optimum design of the planar variable-pitch grating is achieved. By the adoption of the method, computing time is shortened, and computing efficiency is improved.

Description

technical field [0001] The invention relates to the field of spectrum technology, in particular to an optimal design method of a variable pitch grating. Background technique [0002] The variable pitch grating mainly has the following main features: self-focusing, aberration correction ability and flat focal field, which can reduce the optical components in the optical system, reduce stray light, and improve diffraction efficiency and resolution. The above-mentioned advantages of the planar variable pitch grating can only be realized by strictly designing the grating line density function according to the requirements of the spectroscopic instrument. [0003] There are two methods of making variable pitch gratings, mechanical scribing and holographic exposure. Compared with ruled gratings, holographic gratings are easy to manufacture, easy to change the shape of the ruled lines, more types of substrates can be produced, and have the advantages of no ghost lines and low stra...

AI Technical Summary

Problems solved by technology

[0004] In order to solve the problem that there is a large error between the reticle density function and the expected reticle density function of the variable grating grating produced by the existing method, the present invention provides an optimal design method for a plane variable grating grating

Images