Wavefront Shaping; Developing a demonstration setup

Abstract

Wavefront shaping is a promising technique invented circa ten years ago which enables us for example to focus light inside or behind a scattering material. To make this technique well-known we want to make a demonstration setup which can be used in presentations. The principle of our setup is that it reflects a laser beam off a Spatial Light Modulator (SLM), which modulates the spatial phase pattern of the light. We send the light through a scattering sample behind which we want to focus. By modulating the light with the SLM, we can change how the light comes out of the sample and in this way we can for example focus it in a certain spot. The setup we built is compact and portable, reproducable for an affordable price, and very safe to use, which are important assets for using it during a presentation. With our setup we can increase the intensity in the spot where we focused on with a factor of 6. This is an enhancement, but you can't see it by eye, which would be nice for a presentation. The main limitation for increasing the enhancement appears to be the signal-to-noise ratio.