Jitter Sensing and Control for Multi-Plane Phase Retrieval

TL;DR

This paper demonstrates a method to sense and correct image jitter in multi-plane phase retrieval sensors using a nonlinear curvature wavefront sensor and fast centroiding algorithms, improving stability and reconstruction quality.

Contribution

It introduces a novel closed-loop tip/tilt correction technique using the WFS without additional peripheral components, validated through laboratory experiments.

Findings

Achieved tip/tilt accuracy of +/-0.1 lambda/D in ideal conditions.

Improved phase retrieval stability and quality with closed-loop correction.

Validated the method with experimental results matching numerical simulations.

Abstract

The family of multi-plane phase retrieval sensors, such as the curvature and nonlinear curvature wavefront sensors (WFS), contain tip/tilt information embedded in their signals. We have built a nonlinear curvature WFS to study different wavefront reconstruction methods and test the ability to extract tip/tilt information. Using reliable and fast centroiding algorithms, combined with knowledge of the measured $z$-distance to each measurement plane, we demonstrate that image jitter may be sensed and compensated for using a fast steering mirror and the WFS in closed loop. This approach obviates the need for peripheral components such as quad-cells or access to a separate scientific imaging channel. Our laboratory experiments validate tip/tilt estimation and correction using nlCWFS data, achieving tip/tilt accuracy of +/-0.1, lambda/D for an unaberrated beam and better than ~+/-0.5, lambda/D in the presence of aberrations, consistent with prior numerical simulations. We further demonstrate a closed-loop tip/tilt control implementation and show a qualitative improvement in the stability and overall quality of multi-plane phase retrieval reconstructions.