Controlling light in scattering media non-invasively using the photoacoustic transmission matrix

Optical wavefront-shaping has emerged as a powerful tool to manipulate light in strongly scattering media. It enables diffraction-limited focusing and imaging at depths where conventional microscopy techniques fail. However, while most wavefront-shaping works to-date exploited direct access to the target or implanted probes, the challenge is to apply it non-invasively inside complex samples. Ultrasonic-tagging techniques have been recently demonstrated but these require a sequential point-by- point acquisition, a major drawback for imaging applications. Here, we introduce a novel approach to non-invasively measure the optical transmission-matrix inside a scattering medium, exploiting the photo-acoustic effect. Our approach allows for the first time to simultaneously discriminate, localize, and selectively focus light on multiple targets inside a scattering sample, as well as to recover and exploit the scattering medium properties. Combining the powerful approach of the transmission-matrix with the advantages of photoacoustic imaging opens the path towards deep-tissue imaging and light-delivery utilizing endogenous optical contrast.