Two-step phase-shifting interferometry for phase-resolved imaging from a spatial light modulator

TL;DR

This paper presents a two-step phase-shifting interferometry method using a spatial light modulator to directly measure complex laser modes with improved accuracy and noise resistance, without extra optics.

Contribution

The novel approach enables direct amplitude and phase measurement of laser modes via a single hologram on an SLM, simplifying setup and enhancing measurement precision.

Findings

Successful measurement of Laguerre-Gaussian modes

Reduced noise and increased accuracy in phase measurements

No additional optics required for phase control

Abstract

We demonstrate two-step phase-shifting interferometry (holography) of complex laser modes generated by a spatial light modulator (SLM), in which the amplitude and phase of the signal are determined directly from measurements of phase-shifted interferograms. The reference and signal beams are generated and phase-controlled with a single composite hologram on the SLM and propagated collinearly. This requires no additional optics and leads to measurements that are more accurate and less prone to noise, which we demonstrate with collinearly-referenced measurements of various Laguerre-Gaussian modes and structured images.