为解决双光子荧光显微成像系统轴向扫描问题, 提出一种基于数字微镜(DMD)的快速轴向扫描系统。该系统采用DMD选择光路, 不同光路放置不同焦距的透镜组对光束发散角产生不同的改变, 经物镜聚焦后得到不同深度的轴上扫描点。对该系统的轴向扫描距离、扫描点位置及衍射效率进行了理论计算仿真, 结果表明: 扫描系统采用4个模块以及5个模块时其轴向扫描距离均可达到1 mm, 4模块系统中透镜的焦距为297.3 mm, 5模块系统中透镜焦距为361.47 mm。轴向扫描点除边缘点外线性分布,轴向扫描频率达到几十kHz, 满足脑神经成像的要求。

Aiming at solving axial scanning problem of dual photon fluorescence microscopy imaging system, fast axial scanning system based on digital micromirror device (DMD) is proposed in this paper. DMD is used for selecting optical path in this system, and lens groups with different focal lengths are placed in these optical paths to generate different changes of beam divergence angle. Then axial scanning spots with different depth are obtained after beam focused by objective lens. Axial scanning distance, scanning spot and diffraction efficiency are calculated and simulated. Results show that when scanning system adopts four modules or five modules, axial scanning distance can reach 1mm, focal length of lens in four modules and five modules is 297.3 mm and 361.47 mm respectively. Axial scanning spot varies in good linearity except marginal spot. Axial scanning frequency approaches to dozens of kilohertz. This scanning system can meet requirements of cranial nerve imaging.