postponed - new date to be announced
Marc GUILLON, Saints-Pères Paris Institute for Neurosciences (SPPIN), Université Paris-Cité
Amphithéâtre : Amphi POISSON, Ecole Polytechnique
Aberrations and multiple scattering in biological tissues critically distorts light beams into highly complex speckle patterns. Several approaches have been investigated to perform in-depth focusing in these conditions, most of which iteratively optimizing a signal metric. So far, single-shot characterization of complex media could only be achieved using coherent guide stars and interferometric systems. In contrast, digital optical phase conjugation turns out to be especially challenging with fluorescent guide-stars for three main reasons: the absence of reference beam preventing holographic measurement, the weakness of the signal limiting the number of measureable modes and the large spectral bandwidth typically resulting in inextricably blurred speckle through multiply scattering samples.
In my presentation, I will show that it is actually possible to focus a laser beam through multiply scattering samples by measuring speckle fields in a single-shot with a simple reference-less high-resolution wavefront sensor.By taking advantage of the large spectral bandwidth of forward multiple-scattering samples, DOPC is achieved to focus a laser beam at the excitation wavelength while measuring the broadband speckle field arising from a fluorescent micron-sized bead.
Contact : Marie-Claire Schanne-Klein
marie-claire.schanne-klein at polytechnique.edu
A télécharger: Séminaire GUILON