Phase

Due to the wave-nature of the light, light can be more accurately described using both intensity and phase information. Using the coherence property, the team has demonstrated imaging deep in the scattering medium using transmission matrices.

 
 

Coherent Inverse Scattering via Transmission Matrices

A transmission matrix describes the input-output relationship of a complex wavefront as it passes through/reflects off a multiple-scattering medium. The double phase retrieval method is a recently proposed technique to learn a medium’s transmission matrix that avoids difficult-to-capture interferometric measurements. Unfortunately, to perform high-resolution imaging, existing double phase retrieval methods require (1) a large number of measurements and (2) an unreasonable amount of computation. The team focused on the latter of these two problems and reduced computation times with two distinct methods: firstly we develop a new phase retrieval algorithm that is significantly faster than existing methods, especially when used with an amplitude-only spatial light modulator (SLM). Second, we calibrate the system using a phase-only SLM, rather than an amplitude-only SLM which was used in previous double phase retrieval experiments.

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Inverse scattering algorithms

We combined physics and learning to create efficient and accurate heterogeneous inverse scattering algorithms.

From the traditional auto-encoder architecture to the proposed physics-aware architecture (left); clock-wise from top left: thick smoke cloud and reconstructed density, albedo, and phase function (right).

From the traditional auto-encoder architecture to the proposed physics-aware architecture (left); clock-wise from top left: thick smoke cloud and reconstructed density, albedo, and phase function (right).