Wavefront shaping in complex media with a 350 kHz modulator via a 1D-to-2D transform

Controlling the propagation and interaction of light in complex media has sparked major interest in the past few years. Unfortunately, spatial light modulation devices suffer from limited speed, which precludes real-time applications such as imaging in live tissue. To address this critical problem, we introduce a phase-control technique to characterize complex media based on the use of fast one-dimensional (1D) spatial light modulators and a 1D-to-2D transformation performed by the same medium being analysed. We implement the concept using a microelectromechanical grating light valve with 1,088 degrees of freedom, modulated at 350 kHz, enabling unprecedented high-speed wavefront measurements. We continuously measure the transmission matrix, calculate the optimal wavefront and project a focus through various dynamic scattering samples in real time, all within 2.4 ms per cycle. These results improve the previously achieved wavefront shaping modulation speed by more than an order of magnitude and open new opportunities for optical processing using 1D-to-2D transformations.