SMART · Scattering Matrix Approach in Reflection applied to Turbid media

Scattering Matrix Approach in Reflection applied to Turbid media

The general theme of this project is an experimental study of the multiple scattering and distortion of classical waves, with the goal of improving imaging and characterization of complex biological materials. This theme is important for society to improve optical and acoustic medical imaging. In the world of classical wave imaging, multiple scattering and aberrations are often seen as unavoidable obstacles. Technologies such as echography, radar, and optical coherence tomography (OCT) rely on the assumption that detected waves have scattered only once from the target. When there are multiple scattering events between source and detector, the equivalence of time-of-flight and target depth is lost, so conventional imaging techniques no longer work. To achieve deeper imaging, more powerful sources (i.e. lasers for optics) can be used, but for in-vivo medical imaging the source power that can be used safetly is limited. In addition, these setups (such as conventional OCT for light) can be costly. The work proposed here is to develop an alternate approach to classical wave imaging which can go beyond all of these limitations. We approach this theme with two related sub-topics: (a) Deep imaging with classical waves (optics and acoustics) in biological (i.e. inhomogeneous) media. (b) A fundamental study of extreme strong scattering of light. The objectives are to develop superior imaging and characterization approaches based on (i) incoherent (low power) illumination and (ii) the measurement and manipulation of a matrix of responses between multiple inputs and outputs to the medium. The development of these sub-projects in parallel helps to advance the experimental and post-processing techniques of each. We have been able to demonstrate improved optical imaging with a SMART-OCT system in optics (an OCT-like imaging with low-coherence illumination, improved resolution and depth capabilities compared to OCT) and ultrasonic imaging (deeper imaging through strong aberration, and new contrasts for alternate characterization). We have developed post-processing techniques to image through areas of aberration and multiple scattering in biological media. We have also demonstrated that materials which scatter light exceptionally strongly can be investigated using a similar low coherence, multi-input-output imaging approach.

Data: CORDIS, © European Union