ECE Seminar: Anat Levin

Title: Seeing Deep Inside Scattering Tissue Using Efficient, Noise-Robust Wavefront Shaping

Abstract: Scattering limits our ability to see inside biological tissue, as light penetration is severely distorted by tissue components with varying refractive indices. One promising method to overcome scattering aberration is wavefront shaping. This technique involves placing a spatial light modulator (SLM) in the microscope's optical path to correct the wavefront emitted from a point deep within the tissue. The goal is to bring light photons from a single target point to a single sensor point, despite tissue aberrations. This technique has the potential to revolutionize tissue imaging by enabling high-SNR imaging deep within scattering biological targets. However, estimating wavefront-shaping modulations in practice is challenging, since the modulations must be estimated in real time, using non-invasive feedback, and under a low photon budget.

In the first part of this talk, I will discuss efforts to derive noise-robust score functions that can identify effective modulation corrections using non-invasive feedback. I will review previous approaches and introduce a new, simple, noise-robust method that uses confocal correction of both incoming and outgoing light with linear single-photon fluorescent excitation. We show that despite the fact that we are only measuring light outside the tissue and have no direct way to measure how well light has focused inside the tissue, maximizing the single-photon confocal intensity guarantees that we also focus all light into a spot inside the tissue.

Given a score function, estimating the desired modulation becomes an optimization problem. However, since the desired modulation depends on the unknown tissue structure, typical optimization strategies involve slow sequential scanning, where each modulation parameter is queried independently. In the second part of this talk, I will present a novel approach for rapid modulation optimization. This method leverages optical computing ideas and uses the optical system to directly measure the gradient of the score function, allowing simultaneous updates of all modulation parameters from a single measurement.

Bio: Anat Levin is a Professor at the department of Electrical and Computer Engineering, Technion, Israel, doing research in the field of computational imaging. She received a Ph.D. in computer science from the Hebrew University in 2006. During the years 2007- 2009 she was a postdoc at MIT CSAIL, and during 2009-2016 she was an Assistant and Associate Prof. at the department of Computer Science and Applied Math, the Weizmann Inst. of Science.

Prof. Levin has received numerous awards for her research, including the CVRP PAMI young researcher award in 2013; the eurographics young researcher award in 2010; the eurographics outstanding technical contributions award in 2024; the Blavatnik award in 2018; and 3 ERC grants.