摘要
透过散射介质传递光学信息在生物医学、航空航天等领域具有广阔的应用前景.但是,当光通过散射介质后会引起波前畸变,导致光学信息失真.基于波前振幅调制技术是利用优化算法不断对入射光波前振幅进行调整,找到可使目标区域光强最大对应的波前振幅分布.实验主要研究通过波前振幅调制使透过散射介质的空间光实现光聚焦,讨论在不同持续时间的散射光场中控球后卫算法与遗传算法对散射光场的调控能力.实验结果表明,在散射介质持续时间相同的情况下,控球后卫算法可以实现比遗传算法更高增强因子的聚焦点以及更均匀的多点聚焦.
Transmitting optical information through scattering medium has broad application prospects in biomedical,aerospace and other fields.However,the light passing through the scattering medium will cause wavefront distortion and optical information blurring.Wavefront shaping technology uses a mathematical matrix to characterize the characteristics of scattering medium,which can achieve refocusing and imaging after light propagation through the scattering medium.It mainly includes optical phase conjugation,optical transmission matrix and wavefront shaping based on iterative optimization.However,the iterative wavefront shaping is considered to be a cost-effective method.Based on the wavefront amplitude modulation technology,the wavefront amplitude of the incident light is continuously adjusted by using the optimization algorithm to find the corresponding wavefront amplitude distribution that can maximize the light intensity in the target area.The system generates binary patterns implemented with digital-micromirror device(DMD)based on on-off state of micromirror,where“on”represents 1 and“off”refers to 0.The DMD has a high refresh rate and can achieve high speed wavefront amplitude modulation by using the iteration algorithm.In the experiment,the scattering medium is prepared with TiO_(2),water and gelatin,whose persistence times are controlled with the water-gelatin ratio(WGR).In addition,the Pearson correlation coefficient(Cor)curve obtained through 300-s-measurement under different WGR conditions,which shows that the greater WGR,the shorter the persistence time is.The experiment mainly studies the focusing of the spatial light through scattering media by wavefront amplitude modulation,and discusses the ability of point guard algorithm(PGA)and genetic algorithm(GA)to control the scattered light field with different persistence times in 64×64 segments.The experimental results show that the PGA can achieve higher enhancement factor and more uniform multi-point focusing than the GA after 1000 iterations in the scattering medium with the same persistence time.The relative standard deviation value is inversely proportional to the WGR value when multi-point focusing can be completed.We also demonstrate that GA can only achieve single-point focusing when WGR=40,and it cannot accomplish multi-point focusing in self-made scattering medium.This study not only verifies a method to achieve focusing scattering light field,but also provides a new scheme for testing the performance of the iterative wavefront shaping.
作者
段美刚
赵映
左浩毅
Duan Mei-Gang;Zhao Ying;Zuo Hao-Yi(School of Applied Sciences,Taiyuan University of Science and Technology,Taiyuan 030024,China;College of Physics,Sichuan University,Chengdu 610065,China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2024年第12期190-197,共8页
Acta Physica Sinica
基金
国家自然科学基金青年科学基金(批准号:12204439)
太原科技大学博士科研启动基金(批准号:20232104)资助的课题。
关键词
散射介质
波前整形
聚焦
振幅调制
scattering medium
wavefront shaping
focusing
amplitude modulation
