Stability of optimal-wave-front-sample coupling under sample translation and rotation

TL;DR

This study investigates how translation and rotation of opaque samples affect wavefront shaping coupling stability, revealing parameter influences and proposing an optimization scheme to enhance robustness, supported by experimental and simulated results.

Contribution

It provides a detailed experimental and theoretical analysis of wavefront-sample coupling stability under sample movement, highlighting factors that influence sensitivity and suggesting optimization strategies.

Findings

Sample translation and rotation reduce coupling stability.

SLM bin size, beam-spot size, and nanoparticle concentration affect sensitivity.

Optimization schemes can improve coupling robustness.

Abstract

The method of wavefront shaping to control optical properties of opaque media is a promising technique for authentication applications. One of the main challenges of this technique is the sensitivity of the wavefront-sample coupling to translation and/or rotation. To better understand how translation and rotation affect the wavefront- sample coupling we perform experiments in which we first optimize reflection from an opaque surface--to obtain an optimal wavefront--and then translate or rotate the surface and measure the new reflected intensity pattern. By using the correlation between the optimized and translated or rotated patterns we determine how sensitive the wavefront-sample coupling is. These experiments are performed for different spatial-light-modulator (SLM) bin sizes, beam-spot sizes, and nanoparticle concentrations. We find that all three parameters affect the different positional changes, implying that an optimization scheme can be used to maximize the stability of the wavefront-sample coupling. We also develop a model to simulate sample translation or rotation and its effect on the coupling stability, with the simulation results being qualitatively consistent with experiment.