Phase retrieval based on intensity-only spatiotemporal wavefront shaping

Abstract

We introduce a phase retrieval method based on harmonic field representations generated by intensity-only spatiotemporal modulation. A periodic amplitude angular modulation encodes phase information into temporal intensity harmonics, enabling wavefront reconstruction without interferometry, reference beams, or a calibrated phase modulator. We consider a disordered system that can be modeled as a phase plate and measure the intensity pattern in the far field for a rotating excitation pattern generated by a digital micromirror device (DMD). We extract the harmonic components of the spatiotemporal speckle and exploit a gradient-based optimization algorithm to retrieve both the optical phase in the plane of the camera corresponding to a plane-wave illumination and the effective phase plate that represents the disordered system. We demonstrate experimentally the accuracy of the approach in quantitatively estimating and compensating for phase distortion ranging from low-spatial-frequency aberrations to high-frequency distortions of a ground-glass diffuser. The proposed approach establishes a new route toward calibration-free phase retrieval using intensity-only measurements.