Measuring the transmission matrix of a complex medium : focusing and beyond
Event details
| Date | 05.09.2012 |
| Hour | 14:00 |
| Speaker | Prof. Sylvain Gigan, ESPCI ParisTech |
| Location | |
| Category | Conferences - Seminars |
Scattering of coherent light in disordered media, such as heterogeneous biological tissues, leads to strong scattering and interferences phenomena which seemingly destroy both the spatial amplitude and phase information of any laser illumination. At the spatial level, it gives rise to the well-known “speckle”. At the temporal (or spectral) level, a short pulse entering a scattering medium will be stretched due to the multiplicity of path lengths in the propagating medium. Scattering greatly limits the possibility to image or manipulate with light in a complex medium. Fortunately, multiple scattering is a highly complex but nonetheless deterministic process: it is therefore reversible, in the absence of absorption, and speckle can be coherently controlled. By « shaping » or « adapting » the incident wavefront, it is in principle possible to control the propagation and to overcome the scattering process. Liquid crystal spatial light modulator (SLM) is a tool of choice to shape at will a laser beam over a very large number of modes, in order to match the high complexity of a multiple scattering. I will show how, using an SLM, one can measure the transmission matrix which links the input - output modes of a scattering medium. I will detail our recent experiments with phase-SLMs applied to, spatial focusing, imaging and phase conjugation through a thick opaque multiply scattering media. Beyond the spatial aspects of wave control, I will also review the recent progress on temporal control in complex media.
Practical information
- General public
- Free
Organizer
- Loeffen Berthet Carole <[email protected]>
Contact
- Loeffen Berthet Carole <[email protected]>