声光调制的双滤波能量反馈型三维高光谱成像技术研究

Three-dimensional stereoscopic imaging technology is the most advanced stereoscopic display technology in the world at present. It is a comprehensive detection technology that can accurately reveal the features and changes of objects, and greatly broadens the breadth and depth of target recognition. In this study, a new filtering method was used to conduct exploratory research on 3D stereoscopic imaging technology. The o-light and the e-light whose polarization directions are perpendicular to each other simultaneously satisfy the momentum matching condition by selecting an appropriate equilibration point. The spectral bandwidth of the diffracted light decreases significantly when the incident light is filtered in two channels respectively. Then the frequency interval of the ultrasonic signal appended to the two channels is gradually increased, and it is found that the spectral bandwidth can be further compressed. The method can effectively reduce the system volume, and since the polarization directions of the incident light on the two crystals are exactly perpendicular to each other, the amount of diffracted light drift after the second acoustic-optic interaction is exactly compensated by the first acoustic-optic interaction. Then the image drift caused by chromatic aberration is eliminated perfectly. Most importantly, the proposed energy feedback technique can effectively improve the intensity and signal-to-noise ratio of the diffracted light. This research can provide a new theoretical method and experimental technique for 3D stereoscopic imaging technology based on acousto-optic tunable filter.

三维立体光谱成像技术是目前世界上最先进的立体显示技术，是一种可以准确揭示出物体特征及变化的综合性探测技术，大大拓宽了目标识别的研究广度和深度。本项目以声光调制为基础，采用一种新的滤波方法进行三维立体光谱成像技术研究。通过选取合适的等值平衡点使偏振方向相互垂直的o光和e光同时满足动量匹配条件，入射光在双通道内分别进行双滤波以后的衍射光光谱带宽显著减小，然后逐渐增大附加在两个通道上的超声信号频率间隔，发现光谱带宽可以被进一步压缩。该方法可以使系统体积减小，而且由于两个晶体上入射光的偏振方向恰好相互垂直，第二次声光互作用后的衍射光漂移量恰好反向补偿了由第一次声光互作用引起的衍射光漂移量，进而完美消除了由色差引起的图像漂移。最重要的是，提出的能量反馈技术可以有效提高衍射光强度和信噪比更高。该研究可以为基于声光可调谐滤波器的三维立体光谱成像技术提供一种新的理论方法与实验技术手段。

三维立体成像技术能迅速及时地获取大量准确客观的被测目标信息，是一种通过分析揭示出物体的特征性质及其变化的综合性探测技术，可以形成多层次、多方式、多侧面、全方位的综合信息，大大拓宽了研究广度和深度。而高光谱成像技术具有高光谱分辨率，可以将目标的精细组分以光谱的形式形成具有可视化的数据立方体。将三维立体成像技术与高光谱成像技术相结合，是一种新的概念，可以准确揭示出被测目标的理化特征。本项目通过一种新型分光方式，以声光调制为基础，提出一种等值平衡的声光互作用技术，通过选取合适的等值平衡点使偏振方向相互垂直的o光和e光同时满足动量匹配条件在声光介质内发生互作用。通过补偿衍射光漂移，在双通道内分别进行双滤波得到光谱带宽显著减小的窄带衍射光。为了得到更窄的衍射光光谱带宽，逐渐增大附加在两个声光通道上的超声信号频率间隔，使光谱带宽被进一步压缩，直到得到合适的光谱带宽与衍射效率。然后搭建了实验装置，对外场目标进行了探测，以及采用分离式双通道设计，对目标进行了不同角度的信息采集。该方法由于两个声光晶体上入射光的偏振方向恰好相互垂直，第二次声光互作用后的衍射光漂移量恰好反向补偿了由第一次声光互作用引起的衍射光漂移量，进而消除了由色差引起的图像漂移。通过研究得到了更准确的声光调制设计方案，根据设计加工了大孔径、高衍射效率、高光谱分辨率的声光可调谐滤波器。该技术可以应用于伪装目标识别、生物医学显微光谱成像、弱光环境下的目标识别等领域。