a method and system for localization of fluorescence in a scattering medium such as a biological tissue are provided . in comparison to other optical imaging techniques , this disclosure provides for improved spatial resolution , decreased computational time for reconstructions , and allows anatomical and functional imaging simultaneously . the method including the steps of illuminating the scattering medium with an excitation light to excite the fluorescence ; modulating a portion of the emitted light from the fluorescence within the scattering medium using an ultrasonically induced variation of material properties of the scattering medium such as the refractive index ; detecting the modulated optical signal at a surface of the scattering medium ; and reconstructing a spatial distribution of the fluorescence in the scattering medium from the detected signal .