光学精密工程2025，Vol.33Issue(23)：3630-3638,9.DOI:10.37188/OPE.20253323.3630
利用双光栅实现液晶空间光调制器绝对干涉校准
Absolute interferometric calibration of liquid crystal spatial light modulators using dual gratings
摘要
Abstract
Liquid-crystal spatial light modulators(LC-SLMs)hold great promise for applications such as light-field modulation.However,the phase of uncalibrated SLM outputs is typically irregular,and the ac-curacy of phase modulation is difficult to control due to experimental and environmental perturbations.Ac-curate testing and calibration of LC-SLMs is therefore essential to ensure stable and precise performance in practical applications.In this study,a diffractive optical element(DOE)combining a grating and a diffrac-tive lens is designed based on Fermat's principle and the Huygens-Fresnel principle.A pair of gratings is employed to generate three pairs of focal points;interference fringes are produced by the overlapping cen-tral foci,while the remaining beams form an absolute spatial coordinate system that determines the refer-ence point for fringe motion.A U-Net neural network is applied to preprocess the interference fringe imag-es,after which the key centroid positions are extracted using contour detection and a center-of-mass algo-rithm.The phase delay is then obtained by calculating the fringe displacement and period.A phase calibra-tion system comprising a high-coherence light source,beam splitter,LC-SLM,beam-splitting grating,and CCD camera is constructed to perform the experiments.During the loading of different grayscale mod-ulation sequences,the interference fringes exhibit clearly observable displacements as the grayscale values vary,enabling the successful extraction of the phase-grayscale response curve.The fitted results show high consistency with theoretical predictions,with a coefficient of determination R² of 0.985 1 and a root mean square error(RMSE)of 0.241 1 rad.Under fan-induced perturbations,the method still maintains R²>0.95,and the RMSE increases by only 0.14 rad,demonstrating strong robustness and resistance to interference.A high-precision phase calibration method for LC-SLMs is thus proposed,in which a double-grating structure is used to construct an absolute spatial coordinate system.This approach overcomes the limitations of traditional SLM calibration methods,including stringent stability requirements,susceptibili-ty to environmental disturbances,and limited accuracy,and provides a reliable scheme for accurate phase calibration of LC-SLMs.关键词
液晶空间光调制器/绝对干涉校准/光栅衍射/抗振性/U-Net神经网络Key words
liquid-crystal spatial light modulator/absolute interferometric calibration/grating diffraction/vibration resistance/U-Net neural network分类
数理科学引用本文复制引用
ZHANG Guofeng,ZHANG Junyong,WANG Chi..利用双光栅实现液晶空间光调制器绝对干涉校准[J].光学精密工程,2025,33(23):3630-3638,9.基金项目
国家重点研发计划资助项目(No.2023YFF0722902) （No.2023YFF0722902）
国家自然科学基金资助项目(No.62175245) （No.62175245）
中国科学院战略性先导科技专项(A类)资助项目(No.XDA25020302,No.XDA25020101) （A类）
