Diffraction efficiency model for diffractive optical element with antireflection coatings at different incident angles

Abstract

For diffractive optical elements (DOEs) in imaging optical system, oblique incidence is the normal working situation. An additional phase is introduced by antireflection coatings (ARCs) for DOEs, having an effect on diffraction efficiency. In this study, a diffraction efficiency model for DOEs with ARCs at different incident angles is proposed. Based on the relationship between phase function of DOE and incident angle, and the effect of ARCs on incident angle of diffractive microstructure surface at oblique incidence, the diffractive microstructure height is modified, the diffraction efficiency with ARCs at different incident angles are optimized by the proposed model. A theoretical model of the relationship between the comprehensive polychromatic integral diffraction efficiency (PIDE) and the modified microstructure height of DOE working within a certain incident angle range is established. The diffraction efficiency of DOE designed by the traditional method and the optimal method is compared and analyzed with single layer and multilayer ARCs. Results show that with the optimal design method, the diffraction efficiency and PIDE of the DOE working in the visible waveband at different incident angles are improved, as well as the comprehensive PIDE over the whole working incident angle range.