Wavefront-sensing with a thin diffuser

TL;DR

This paper introduces a simple, broadband, and low-cost wavefront sensing method using a thin diffuser and speckle pattern translation, enabling high-resolution phase imaging and wavefront measurement.

Contribution

It presents a novel wavefront sensing technique based on speckle translation via a thin diffuser, with a theoretical resolution limit and experimental validation.

Findings

Effective wavefront measurement of Zernike polynomials

High-resolution phase imaging demonstrated

Theoretical resolution limit supported by experiments

Abstract

We propose and implement a broadband, compact, and low-cost wavefront sensing scheme by simply placing a thin diffuser in the close vicinity of a camera. The local wavefront gradient is determined from the local translation of the speckle pattern. The translation vector map is computed thanks to a fast diffeomorphic image registration algorithm and integrated to reconstruct the wavefront profile. The simple translation of speckle grains under local wavefront tip/tilt is ensured by the so-called "memory effect" of the diffuser. Quantitative wavefront measurements are experimentally demonstrated both for the few first Zernike polynomials and for phase-imaging applications requiring high resolution. We finally provided a theoretical description of the resolution limit that is supported experimentally.