Scanning a focus through scattering media without using the optical memory effect

TL;DR

This paper introduces Sparse Field Focusing (SFF), a novel method that enables focus scanning behind scattering media without relying on the optical memory effect or measuring the full transmission matrix, thus broadening imaging capabilities.

Contribution

The paper presents a new SFF technique that allows focus scanning at arbitrary positions without full transmission matrix measurement or memory effect limitations.

Findings

SFF accurately focuses and scans behind scattering media.

Experimental results match the theoretical model.

Method extends imaging through media with limited memory effect.

Abstract

Wavefront shaping makes it possible to form a focus through opaque scattering materials. In some cases, this focus may be scanned over a small distance using the optical memory effect. However, in many cases of interest, the optical memory effect has a limited range or is even too small to be measured. In such cases, one often resorts to measuring the full transmission matrix (TM) of the sample to completely control the light transmission. However, this process is time-consuming and may not always be possible. We introduce a new method for focusing and scanning the focus at any arbitrary position behind the medium by measuring only a subset of the transmission matrix, called Sparse Field Focusing (SFF). With SFF, the scan range is not limited to the memory effect and there is no need to measure the full transmission matrix. Our experimental results agree well with our theoretical model. We expect this method will find applications in imaging through scattering media, especially when the optical memory effect range is small.