Time-resolved measurement of the scattered light with an interferometric method based on the use of a camera

We have already demonstrated the potentiality of interferometry to perform timeresolved measurements of the light scattered by a tissue: the fluctuations of the speckle pattern, linked to a wavelength-modulation of the source, are registered, and the time-resolved average intensity can be numerically obtained from these data[1]. The competitive results were obtained with a simple photodiode as detector[2]. Such a method can be cheaper and more accessible for biomedical applications than direct time-resolved methods, but it is not its unique advantage: this method allows to perform Diffusing Wave Spectroscopy (DWS) with selected photon pathlengths[3,4]; for instance, we have shown that we can improve the spatial resolution in transillumination imaging of a dynamic heterogeneity through the selection of short photon transit times[4]. Therefore such a method can offer interesting applications, for example in mammography. A way to improve the signal to noise ratio of this method can consist in multiplying the number of detectors. That's the reason why we decide to consider the use of a high speed camera, that can reach a rate of 1000 frames per second. We will present the first results obtained with this new system. The performance will be discussed, and compared to our previous setup.