10 - Computer-Generated Holographic Techniques to Control Light Propagating through Scattering Media Using a Digital-Mirror-Device Spatial Light Modulator

Summary

This chapter reviews the advances in light control through complex media using a DMD. Although these devices are known for their amplitude modulation capabilities, the implementation of binary holographic techniques effectively converts them into phase modulation devices. The fast decorrelation time of tissue, in the milliseconds time scale, motivates the research and development of fast focusing and imaging methods. The main advantage of using these MEMS devices, is the high switching speed, up to more than 20 kHz, improving the bandwidth with respect to the widely used LC-SLMs. DMDs have allowed reducing the total focusing time through complex media to tens of milliseconds, close to the speckle decorrelation times of dynamic biological media (tissue). The signal-to-noise ratio (SNR) of the signal detected is critical in this type of high-speed experiment because SNR decreases with the integration time. Therefore, the implementation of algorithms designed for low SNR environments will be required in the future.