The Research On Focusing Light Through Strongly Scattering Media

Light transmitting through scattering media leads to wavefront aberrations.Wavefront shaping plays an important role in biological imaging and therapy,such as Photodynamic Therapy,Laser Ablation and Confocal laser scanning microscope and so on.Recently,focusing light through scattering media can be realized by wavefront shaping technique using the liquid crystal spatial light modulator and the digital micromirror device.The digital micromirror device runs faster than the liquid crystal spatial light modulator because of its high refresh rate,which makes rapid wavefront shaping technique come true.Some algorithms used for wavefront shaping can’t meet the requirement of anti-noise ability.Therefore,the main work of this paper lies on realizing the high intensity of focus and a faster optimization speed.What we mainly explore are as follows:1.Based on the previous work,we studied the theory of wavefront shaping and compared the phase conjugation and measuring transmission matrix approach.Our work mainly lies on focusing light through scattering media by genetic algorithm using the digital micromirror device.2.We studied the ideas of genetic algorithm and improved it.The improved genetic algorithm is applied to wavefront shaping technique,which achieves good experimental results.3.The wavefront shaping experiment system based on digital micromirror device is built,and the genetic algorithm is used to realize focusing light through strongly scattering media on the target plane.Two kinds of scattering medium,the nano-ZnO sheet and a scattering film were used in the experiment.The intensity of the focus is close to the theoretical value,and the anti-noise ability and optimization time of the experimental system have been greatly improved.