Rapid wavefront shaping using an optical gradient acquisition

A promising approach for overcoming tissue scattering is the usage of a computer-controlled modulation element in the optical path of a microscope that can undo the aberration of light inside the tissue. Despite its large potential, wavefront shaping was not yet put into practical utility mostly because estimating the desired shape of the modulation is a time consuming process. The main challenge is that the desired modulation depends on the unknown shape of the tissue; and thus, most optimization approaches rely on coordinate descent optimization schemes, where a single parameter of the modulation is varied at each shot. As the desired modulation has a very large number of freedom degrees, this optimization scheme is time consuming. Here we suggest a new approach, which can capture the gradient of the merit function, with respect to all SLM pixels, in one shot. With this scheme we can update all modulation parameters at once, resulting in a rapid optimization scheme that can find good wavefront-shaping modulations with a very small number of trial shots.