Controlled Transmission Through Highly Scattering Media Using Semi-Definite Programming as a Phase Retrieval Computation Method

Tailored physical systems were recently exploited to rapidly solve hard computational challenges, such as spin simulators, combinatorial optimization, and focusing through scattering media. Here, we address the phase retrieval problem where an object is reconstructed from its scattered intensity distribution. This is a key problem in many applications, ranging from x-ray imaging to astrophysics, and currently, it lacks efficient direct reconstruction methods: The widely used indirect iterative algorithms are inherently slow. We present an optical approach based on a digital degenerate cavity laser, whose most probable lasing mode rapidly and efficiently reconstructs the object. Our experimental results suggest that the gain competition between the many lasing modes acts as a highly parallel computer that could rapidly solve the phase retrieval problem. Our approach applies to most two-dimensional objects with known compact support, including complex-valued objects, and can be generalized to imaging through scattering media and other hard computational tasks.

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Non-invasive focusing and imaging in scattering media with a fluorescence-based transmission matrix

Nature Communications ◽

10.1038/s41467-020-19696-8 ◽

2020 ◽

Vol 11 (1) ◽

Cited By ~ 1

Author(s):

Antoine Boniface ◽

Jonathan Dong ◽

Sylvain Gigan

Keyword(s):

Phase Retrieval ◽

Low Rank ◽

Disordered Materials ◽

Transmission Matrix ◽

Scattering Media ◽

Non Invasive ◽

All Optical ◽

The Matrix ◽

Wavefront Shaping ◽

Linear Contrast

AbstractIn biological microscopy, light scattering represents the main limitation to image at depth. Recently, a set of wavefront shaping techniques has been developed in order to manipulate coherent light in strongly disordered materials. The Transmission Matrix approach has shown its capability to inverse the effect of scattering and efficiently focus light. In practice, the matrix is usually measured using an invasive detector or low-resolution acoustic guide stars. Here, we introduce a non-invasive and all-optical strategy based on linear fluorescence to reconstruct the transmission matrices, to and from a fluorescent object placed inside a scattering medium. It consists in demixing the incoherent patterns emitted by the object using low-rank factorizations and phase retrieval algorithms. We experimentally demonstrate the efficiency of this method through robust and selective focusing. Additionally, from the same measurements, it is possible to exploit memory effect correlations to image and reconstruct extended objects. This approach opens up a new route towards imaging in scattering media with linear or non-linear contrast mechanisms.

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Imaging Through Random Scatterer with Spatial Coherence Structure Measurement

Frontiers in Physics ◽

10.3389/fphy.2021.828487 ◽

2022 ◽

Vol 9 ◽

Author(s):

Deming Peng ◽

Xuan Zhang ◽

Yonglei Liu ◽

Yimeng Zhu ◽

Yahong Chen ◽

...

Keyword(s):

Phase Retrieval ◽

Spatial Coherence ◽

Three Dimensional ◽

Retrieval Algorithm ◽

Scattering Media ◽

Image Information ◽

Partially Coherent Light ◽

Spatial Shape ◽

Structure Measurement ◽

Coherent Light Beam

Optical coherence is becoming an efficient degree of freedom for light field manipulations and applications. In this work, we show that the image information hidden a distance behind a random scattering medium is encoded in the complex spatial coherence structure of a partially coherent light beam that generates after the random scatterer. We validate in experiment that the image information can be well recovered with the spatial coherence measurement and the aid of the iterative phase retrieval algorithm in the Fresnel domain. We find not only the spatial shape but also the position including the lateral shift and longitudinal distances of the image hidden behind the random scatterer can be reconstructed, which indicates the potential uses in three-dimensional optical imaging through random scattering media.

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Quantitative analysis by reconstruction of HREM focal series

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100171432 ◽

1994 ◽

Vol 52 ◽

pp. 740-741

Author(s):

W. Coene ◽

A. Thust ◽

M. Op de Beeck ◽

D. Van Dyck

Keyword(s):

Phase Retrieval ◽

Image Plane ◽

Initial Guess ◽

Recursive Least Squares ◽

Objective Lens ◽

Electron Wave ◽

Electron Sources ◽

Original Algorithm ◽

Coherent Field ◽

Direct Interpretation

Compared to conventional electron sources, the use of a highly coherent field-emission gun (FEG) in TEM improves the information resolution considerably. A direct interpretation of this extra information, however, is hampered since amplitude and phase of the electron wave are scrambled in a complicated way upon transfer from the specimen exit plane through the objective lens towards the image plane. In order to make the additional high-resolution information interpretable, a phase retrieval procedure is applied, which yields the aberration-corrected electron wave from a focal series of HRTEM images (Coene et al, 1992).Kirkland (1984) tackled non-linear image reconstruction using a recursive least-squares formalism in which the electron wave is modified stepwise towards the solution which optimally matches the contrast features in the experimental through-focus series. The original algorithm suffers from two major drawbacks : first, the result depends strongly on the quality of the initial guess of the first step, second, the processing time is impractically high.

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Limitations to the Spacing Effect

Experimental Psychology (formerly Zeitschrift für Experimentelle Psychologie) ◽

10.1027/1618-3169.52.4.257 ◽

2005 ◽

Vol 52 (4) ◽

pp. 257-263 ◽

Cited By ~ 22

Author(s):

Peter P. J. L. Verkoeijen ◽

Remy M. J. P. Rikers ◽

Henk G. Schmidt

Keyword(s):

Free Recall ◽

Phase Retrieval ◽

Incidental Learning ◽

Factor Model ◽

Recall Performance ◽

Spacing Effect ◽

Word List ◽

Intentional Learning ◽

Study Phase ◽

Learning Condition

Abstract. The spacing effect refers to the finding that memory for repeated items improves when the interrepetition interval increases. To explain the spacing effect in free-recall tasks, a two-factor model has been put forward that combines mechanisms of contextual variability and study-phase retrieval (e.g., Raaijmakers, 2003 ; Verkoeijen, Rikers, & Schmidt, 2004 ). An important, yet untested, implication of this model is that free recall of repetitions should follow an inverted u-shaped relationship with interrepetition spacing. To demonstrate the suggested relationship an experiment was conducted. Participants studied a word list, consisting of items repeated at different interrepetition intervals, either under incidental or under intentional learning instructions. Subsequently, participants received a free-recall test. The results revealed an inverted u-shaped relationship between free recall and interrepetition spacing in both the incidental-learning condition and the intentional-learning condition. Moreover, for intentionally learned repetitions, the maximum free-recall performance was located at a longer interrepetition interval than for incidentally learned repetitions. These findings are interpreted in terms of the two-factor model of spacing effects in free-recall tasks.

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