Comparative Analysis of Interferometric and Diffraction-Based Phase Calibration for LCoS Spatial Light Modulators

Optical systems that rely on precise phase modulation commonly use LiquidCrystal on Silicon (LCoS) Spatial Light Modulators (SLMs), and the optical fidelity ofapplications such as beam shaping, adaptive optics, and holography depends on precise phasecalibration. In this work, we compare two primary phase calibration techniques for LCoSSLM setups: a Michelson interferometer-based method and a diffraction-based self-referencedinterferometric method. The Michelson interferometric technique measures phase shiftsdirectly via fringe pattern intensity analysis, offering high accuracy in characterizing theglobal phase response, although its practical downside is the requirement for a complicatedand vibration-sensitive setup. In contrast, the diffraction-based interferometric technique,which uses a binary phase grating to generate an interfering beam, provides a faster assessmentvia a simpler and more robust calibration process, albeit with slightly lower accuracy. Whilethe Michelson interferometric technique offers higher precision for mapping the average phaseresponse, the diffraction-based calibration method yields results more quickly and may bea better choice for applications requiring rapid data acquisition or operation in less stableenvironments. The unique value of this study lies in its direct, side-by-side experimentalcomparison of these two foundational calibration techniques using the same device andconsistent methodologies, evaluating them across key performance areas. Therefore, thisstudy helps inform the selection between the two techniques by providing justification beyondabsolute accuracy, considering factors like complexity, robustness, and the experimentalsetting.