Colloquia of the Physics, LiMat, and Frimat departments

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May 2018

Wednesday, 23.

Colloquium Physics

How SLM-based wavefront shaping impacts Biophotonics, from holographic optical micro-manipulation to programmable microscopy

Prof. Dr. Monika Ritsch-Marte - Department for Physiology and Medical Physics

Time: 16:00h

Location: Adolphe Merkle institut - salle de Seminaires - Chemin des Verdiers 4 - 1700 Fribourg - Switzerland


Wavefront shaping with liquid-crystal spatial light modulators (SLMs) has become a powerful tool in Biophotonics. It is well-known that SLM-controlled holographic optical tweezers can be used to steer optical traps in real time. But an SLM can also be integrated into optical imaging systems, to use it as a programmable Fourier-filter which emulates classic microscopy techniques. This only requires sending a pre-calculated voltage pattern to the pixels of the SLM placed in the Fourier plane, which imprints a spatially-varying phase shift to the optical wavefront. Going from dark-field microscopy, to Zernike phase contrast or to spiral phase contrast, and toggling between these modalities, is as easy as replacing the pattern on the SLM. Thus microscopy becomes programmable and customizable with respect to a given sample.  A particular strength of the SLM-approach with programmable phase masks is the possibility to “pack several things into one hologram”, i.e. for multiplexed imaging. It is thus possible to take microscopic images that contain sub-images belonging to different imaging modalities, to different depths inside the sample, or to different parameter settings. This opens a “treasure box” of advanced possibilities in optical imaging and trapping.



Friday, 27.04.2018 - Thursday, 16.08.2018

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