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Accueil > Équipes > OPTique et IMAgeries > Instrumentation et Méthodes > Manipulation d’ondes

Wavefront shaping

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A second approach consist in shaping the wave before it enters the complex media, in order to control the patterns at the location of interest. In optics, both Optima and MOTIV team share extensive experience in adaptive optics and complex wavefront shaping. In the context of the endoscopy part of the ERC Coherence project (E. Bossy), we will develop real-time wavefront shaping of pulsed light for hybrid fluorescence-photoacoustic imaging through multi-mode fibers. This will be based on implementing wavefront shaping method currently demonstrated only with relatively slow devices with DMDs (Digital Micromirror Devices) working at frame rates of several tens of kHz. The general approach will be to acquire the transmission matrix of the fiber during a calibration step (within less than a second), and then to raster-scan focused spots at the rate of the DMD to provide imaging with at least one image per second. The team has also extensive experience in ultrasound wavefront shaping and whenever possible, we will adapt wavefront control method from optics to ultrasound or vice versa. For instance, ultrasound and optical propagation through multi-mode waveguide are very similar, despite the different scales involved. We will apply wavefront shaping approaches developed for multi-modal propagation in optical fibers, to perform focusing of monochromatic waves through ultrasound waveguides in the context of ultrasound therapy. In particular, we will investigate the possibility with a multi-element ultrasound matrix array coupled to a relatively thin ultrasound waveguide to control a high-intensity focused ultrasound (HIFU) beam at the output of the waveguide, to demonstrate that is possible to deliver HIFU remotely within a sample otherwise inaccessible with bulky ultrasound transducer. This will be investigated in particular in the context of photoacoustic cavitation, as part of B. Arnal’s project.