Deep and optically resolved imaging through scattering media by space-reversed propagation.

We propose a novel technique of microscopy to overcome the effects of both scattering and limitation of the accessible depth due to the objective working distance. By combining laser optical feedback imaging with acoustic photon tagging and synthetic aperture refocusing we demonstrate an ultimate shot noise sensitivity at low power (required to preserve the tissues) and a high resolution beyond the microscope working distance. More precisely, with a laser power of 10 mW, we obtain images with a micrometric resolution over approximately eight transport mean free paths, corresponding to 1.3 times the microscope working distance. Various applications such as biomedical diagnosis and research and development of new drugs and therapies can benefit from our imaging setup.