Focusing of light through scattering media

摘要

Convergence of light towards a desired location in optically diffusive and aberrative media is highly relevant to optical methods of biomedical imaging. In this study, we demonstrated the feasibility of employing photoacoustic signals originating from an optically absorptive target as feedback for shaping the incident wavefront to increase optical energy density at the absorptive target. The wavefront of a collimated laser beam was shaped by an array of two-dimensional MEMS deformable mirrors and then transmitted through optically scattering paraffin. The phase of light reflected by each mirror was varied (0-27c) iteratively to maximize the amplitude of the photoacoustic signal. The photoacoustic signal potentially provides a non-invasive and reliable feedback for manipulating spatial phase distribution of light to achieve focusing in diffusive media and may facilitate optical imaging at greater depths.