1College of Mathematics and Physics, Beijing University of Chemical Technology, Beijing 100029 2State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments, Tsinghua University, Beijing 100084
Abstract：When light travels in biological tissues, it undergoes multiple scattering and forms speckles, which seriously restricts the penetration depth of optical imaging in biological tissues. With wavefront shaping method, by modulating the wavefront of incident light to compensate for the wavefront aberration, light focusing and scanning imaging through scattering media can be achieved. However, wavefront shaping must be accomplished within the speckle decorrelation time. Considering the short speckle decorrelation time of living tissues, the speed of wavefront shaping is rather essential. We propose a new iterative optimization wavefront shaping method to improve the speed of wavefront shaping in which the existing parallel optimization wavefront shaping method is improved and is combined with the superpixel method. Compared with the traditional multi-frequency parallel optimization method, the modulation rate of our method is doubled. Moreover, we combine the high frame rate amplitude modulator, i.e., the digital micromirror device (DMD), with the superpixel method to replace the traditional phase modulator (i.e., spatial light modulator), which further increases the optimization speed. In our experiment, when the number of the optical modes is 400, light focusing is achieved with only 1000 DMD superpixel masks and the enhancement factor reaches 223. Our approach provides a new path for fast light focusing through wavefront shaping.
2020, Vol. 37 
