Created by sebastien.popoff on 13/11/2013

Talks Wavefront shaping

Imaging through opaque layers

 TedxTwenteu - Simon Huisman

Friday, 11 October, 2013

Simon Huisman, a recent doctoral graduate with both the COPS and OS group at the University of Twente, talks about an interesting phenomenon which earned the COPS group a picture on the cover of Nature: imaging through opaque layers. With a live setup Simon shows us that with the aid of lasers it is possible to look through opaque objects (e.g. milk or paper) and will he talk about the consequences of this new technology.

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Created by sebastien.popoff on 10/10/2013

Tutorials Digital holography

Off-axis holography

Off-axis holography is a popular technique to reconstruct a hologram. It allows retrieving the amplitude and the phase of a field pattern by measuring only one image with a digital camera. It relies on an intereferometric setup with a non-zero angle between the reference beam and the signal beam and requires to numerically filter the spatial frequencies. I provida Matlab and Python example codes.

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Created by sebastien.popoff on 09/09/2013


Imaging with nature: Using a scattering medium as a universal scrambler for imaging by compressed sensing

[A. Liutkus et al., Sci. Rep. 5, (2014)]

The idea of compressive sensing is to acquire an image with fewer measurements than dictated by the Shannon-Nyquist theorem. In other words, an image divided into "pixels" can usually be reconstructed using fewer measurements than the total number of pixels. To do so, one needs a way to mix the information, so that any measurement contains at least a bit of information on any input element. Previous implementations of compressive sensing consisted of artificially designing hardware and a sampling procedure to generate randomness. In the present paper, the authors show that one can use a random scattering medium as a universal image scrambler. The light reflected from an image propagates through a layer of white paint and the field is measured on different receptors on the other side of the sample. By previously measuring the transmission matrix, the authors show that sparse images can be successfully reconstructed using compressed sensing techniques taking advantage of the randomness generated by multiple scattering.

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Created by sebastien.popoff on 20/07/2013

Talks Wavefront shaping


Wavefront shaping: Controlling light in disordered materials

ANP2010 - Elbert van Putten

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