Two-dimension trapezoidal grating raytracing based on the scalar diffraction and scattering theory

Diffraction grating is a fundamental optical element in spectral measurement or source monochromation. A newly designed grating named as two-dimension trapezoidal grating (TG), which not only has non-harmonic diffraction, non-background contaminations, but also has high absolute diffraction efficiency and easy fabrication, was proposed, recently. However, its applications in spectral measurement or source monochromation are limited as its diffraction pattern is more complex than ordinary grating and there is no raytracing simulation tool to effectively analyze and evaluate the property of an optical system with TG. A raytracing model for TG based on the scalar diffraction and scattering theory is proposed to solve the above problem. Diffraction direction and absolute efficiency of each diffraction order are obtained by using mathematical derivation with scattering theory and scalar diffraction theory, respectively, which are the key parts of TG’s raytracing model. Once TG’s raytracing module is added into the optical simulation tool, X-LAB, it offers a new opportunity for design and numerical simulation of optical systems with a TG.