CE42 - Capteurs, instrumentation

Multiplexed phase sensing for metrology & imaging – MaxPhase

MaxPhase - Multiplexed phase sensing for metrology & imaging

The MaxPhase project will develop phase sensing and imaging systems, based on an original approach that takes advantage of the unique characteristics of speckle patterns from a diffuser, enabling to perform high-resolution, multiplexed phase measurement using low-cost devices, for use in metrology and imaging.

Enabling single-shot, high resolution, spatio-spectral phase sensing and 3D phase imaging

Phase sensing is at the basis of many applications in metrology or imaging, in particular when in-situ, high-sensitivity, non-contact phase measurement is required. Currently, interferometric and wavefront sensing (WFS) techniques provide a combination of resolution, dynamic range & accuracy that fulfills many needs. However, recent technological advances in complex optics manufacturing or in ultrafast lasers require better spatio-spectral WFS performance. Moreover, in biology, Quantitative Phase Imaging still requires compact and fast tomographic instrumentation for high-throughput non-invasive cellular analysis. In order to overcome these limitations, the MaxPhase project will develop new phase sensing and imaging approaches to enable single-shot multiplexed WF measurements, using a simple and versatile design based on the analysis of speckle patterns arising from an optimized diffuser. The project will be a first step towards future cost-efficient commercial devices.

Whenever several wavefronts originating from different sources at different wavelengths are superimposed, current wavefront sensors measure a meaningless wavelength-averaged wavefront, and differentiated reconstruction is impossible. Taking advantage of specific properties of scattering media, we recently proposed a simple, low-cost, and original implementation of high-resolution wavefront sensor based on the memory effect of a thin diffuser. When passing through a diffuser, a wavefront creates on a camera a speckle pattern which carries high-spatial-density information. Moreover, speckles carry a unique spatial and spectral signature, making them a unique solution to perform simultaneous “compressed detection” of several wavefronts at the same time. For these reasons, speckle patterns intrinsically offer spectrally resolved and high-resolution phase imaging capabilities
We specifically propose to implement, demonstrate, and start commercializing diffuser-based high-resolution wavefront sensors and imagers taking advantage of two tunable speckle properties:
- thin diffusers exhibit a memory effect resulting in a simple shift of the speckle pattern when inducing a tilt on the wavefront. Measuring a local speckle shift gives access to the local phase gradient.
- Since speckle patterns result from the interference of many waves with random phases, they strongly depend on the impinging wavelength.
The MaxPhase project aims at exploiting these two properties at the same time in order to dispose of a wavefront sensor yielding both spatial and spectral information.

At the current stage of the project, the MaxPhase project demonstrated:
- optimized multiplexed phase reconstruction algorithms regarding spatial resolution, accuracy and temporal performance, providing phase maps at a frequency of tens of Hz typically using 4 kPixels cameras.
- first multipexed phase measurements both spatially and spectrally resolved from a single acquisition
- a new phase imaging microscope using a wavefront sensor based on a diffuser for high throughput imaging and characterization of cells.

The technological developments of the project offer significant scientific and industrial opportunities:
- in optical metrology: to develop and launch high-resolution, low-cost wavefront sensors for the metrology of modern, complex optics
- in lasers: to develop and validate the capability of the system to characterize spatio-spectral coupling effects in high-power lasers in a single shot
- in biology: to provide biology plateforms an affordable, plug and play and scalable module for label-free imaging of cells with high throughput

To date, there were no scientific publications issued from the project. 6 scientific talks were given at conferences.

Phase sensing is at the basis of many applications in metrology or imaging, in particular when in-situ, high-sensitivity, non-contact phase measurement is required. Currently, interferometric and wavefront sensing (WFS) techniques provide a combination of resolution, dynamic range & accuracy that fulfills many needs. However, recent technological advances in complex optics manufacturing or in ultrafast lasers require better spatio-spectral WFS performance. Moreover, in biology, Quantitative Phase Imaging still requires compact and fast tomographic instrumentation for high-throughput non-invasive cellular analysis. In order to overcome these limitations, the MaxPhase project will develop new phase sensing and imaging approaches to enable single-shot multiplexed WF measurements, using a simple and versatile design based on the analysis of speckle patterns arising from an optimized diffuser. The project will be a first step towards future cost-efficient commercial devices.

Project coordination

Fabrice Harms (IMAGINE OPTIC)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

UParis - SPPIN Saints-Pères Paris Institute for the Neurosciences
IO IMAGINE OPTIC
IdV Institut de la vision
LULI Laboratoire pour l'utilisation des lasers intenses

Help of the ANR 623,929 euros
Beginning and duration of the scientific project: December 2020 - 36 Months

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