Model Design And Performance Evaluation Method Of Stray-light Testing Equipment For Diffraction Grating

Grating scatter is an important performance index for plane grating, and itsmeasurement is a difficult problem for grating research field. In order to solve theproblem of high precision measurement for grating scatter, Changchun Institute ofOptics, Fine Mechanics and Physics, Chinese Academy of Sciences recentlylaunched independent research about grating scatter testing equipment--Stray-LightTesting Equipment for Diffraction Grating. However, how to eliminate the stray lightof instrument itself to achieve direct measurement of grating scatter, is the mostemphasis and difficulty of the equipment’s development. As a preliminary design ofthe equipment’s development work, the optical mechanical structure and stray lightsuppression technology is in-depth studied in this thesis. The main contents includethe following aspects:First, a comparison about different grating scatter detection method is madeboth at home and abroad. Based on the scalar diffraction theory and classicalFresnel-Kirchhoff diffraction theory, the stray light in diffraction gratingmonochromators has been studied, and an measurement system for non-spatiallayout model of parallel light irradiation conditions is designed.Second, for the grating scatter measurement requirements of wide band(200~1000nm) and different area (15×15mm2~200×200mm2), the optical mechanical structure of the equipment’s measurement system is design. In addition, thescattering model of measurement system is established using ASAP software.Third, main pathway of the instrument’s stray light is calculated and analyzedby the simulation with ASAP software. Accordingly, four stray-light suppressionstructures including Lens hood, vanes, aperture stops and light traps are proposed toreduce instrument’s scattered light and grating’s multiple diffraction. Finally,contrast analysis of the instrument’s stray light is made before and after addingstray-light suppression structures.Fourth, with the study of software modeling, simulation and results analysis,effectively stray-light suppression and ways to improve is put forward, whichprovides guidance for the practical development of "Stray-Light Testing Equipmentfor Diffraction Grating".These studies are conducted for the laboratory high-precision "Stray-LightTesting Equipment for Diffraction Grating". They also provide a theoretical basisand design basis of the practical development.