Research on light focusing through scattering media based on super-pixel modulation

When light passes through a scattering medium, the inhomogeneity of the refractive index within the scattering medium causes the incident light to undergo multiple scattering inside the medium, losing the original information of the light wavefront and forming random speckles behind the scattering medium. Although various wavefront shaping methods have been proposed to overcome these image distortions and form focal points through scattering media, common traditional wavefront shaping methods have problems such as long time to obtain the optimal mask, harsh experimental conditions that are difficult to achieve, and low enhancement factors during focusing. These methods all have certain limitations. Aiming at the current problems of slow speed and low enhancement factors in the wavefront field, this paper proposes a super pixel-based method to realize complex amplitude modulation. This method can achieve complex amplitude modulation while retaining the advantage of the extremely fast refresh rate of the digital micromirror device (DMD), enabling fast focusing through scattering media, with a higher enhancement factor compared to the case of using only binary amplitude modulation. In the experiment, efficient optical focusing and scanning at the back end of the scattering medium were demonstrated without an iterative process. Furthermore, we demonstrate that by modifying the input wavefront accordingly, the proposed method can also be extended to focus and scan light along the prediction that the high-speed focusing method through scattering media may have potential applications for rapid point scanning imaging.