High-resolution imaging with scattered light

Summary form only given. Random scattering of light that one can observe in paper, paint and biological tissue is an obstacle to imaging and focusing of light and thus hampers many applications. At the same time scattering is a phenomenon of basic physical interest as it allows the study of interference effects such as Anderson localization [1-3], open transport channels [2,4], and speckle correlations [5].Recently the realization has dawned that propagation of laser light in scattering media can be controlled by shaping the incident wavefront [6]. This control relies on the fact that scattering by stationary randomness performs a random linear transformation on the incident light modes. Wavefront shaping methods effectively invert this transform and have given rise to a surge of fundamental studies of light propagation, new modalities of imaging, and focusing of scattered light [6-12]. The resolution of this focusing can exceed that of conventional focusing optics [13,14]. Many of these methods rely on the measurement of a transmission matrix to characterize the scattering medium [15,16], using a probe or detector at the position of the intended focus. Very recently we demonstrated that speckle correlations enable non-invasive fluorescence imaging through strongly scattering layers, without the need of prior calibration [17]. This high-resolution imaging method uses only randomly scattered light. I will discuss the recent rapid advances in methods that exploit scattered light for high-resolution imaging.