High-Fidelity and High-Speed Wavefront Shaping by Leveraging Complex Media

TL;DR

This paper introduces a novel wavefront shaping method leveraging complex media and sparsity constraints to significantly improve fidelity and speed in light manipulation, overcoming limitations of existing spatial light modulators.

Contribution

The authors develop a sparsity-constrained wavefront optimization technique that enhances DMD-based wavefront shaping, enabling high-fidelity, high-speed projection through complex media without hardware changes.

Findings

Achieved up to 89% increase in projection accuracy.

Improved speckle suppression by 126%.

Maintained 22 kHz frame rate with enhanced fidelity.

Abstract

Achieving high-precision light manipulation is crucial for delivering information through complex media with high fidelity. However, existing spatial light modulation devices face a fundamental tradeoff between speed and accuracy. Digital micromirror devices (DMDs) have emerged as a promising candidate as accessible high-speed wavefront shaping devices but at the cost of compromised fidelity, largely due to the limited control degrees of freedom and the challenge of numerically optimizing a binary amplitude mask. Here we leverage the sparse-to-random transformation through complex media to overcome the dimensionality limitation of spatial light modulation devices. We demonstrate that pattern compression in the form of sparsity-constrained wavefront optimization allows sparse and robust wavefront representations of generic patterns in the random basis provided by the complex media, and thus effectively addresses the dimensionality limitation of DMDs, which significantly improves the projection fidelity without sacrificing the full frame rate (22 kHz), hardware complexity, or optimization time (0.5 s for 1000 frames). Since the dimensionality limitation is intrinsic to spatial light modulation devices and sparse-to-random transformation to complex media, our methods can be generalized to different pattern types, complex media, and device settings, supporting consistent superior performance across different types of complex media with up to an 89% increase in projection accuracy and a 126% improvement in speckle suppression. The proposed optimization framework has the potential to enhance existing holographic setups without any change to the hardware, enable high-fidelity and high-speed wavefront shaping through different scattering media and platforms, and directly facilitate a wide range of physics and real-world applications.