基于液体透镜自动聚焦显微成像系统设计

Auto-Focus Technique of Microimaging System Based on Liquid Lens

设计一种新型自动聚焦显微成像系统,该设计在不移动显微镜或像面情况下,利用液体透镜调节显微成像系统筒镜焦距,对物距离焦进行补偿。本文介绍了微流体透镜调焦方法,理论推导出物距与筒镜焦距的关系曲线。通过ZEMAX优化,设计出一套自动聚焦显微成像系统。该系统以数值孔径为0.25的10×无穷远平常消色差显微为物镜,以液体透镜和4片球面透镜为筒镜,空间分辨率达到1.22微米,物距可离焦范围为±0.5 mm。在不同物距离焦情况下,系统光学传递函数在72 lp/mm处均大于0.2。该设计具有结构紧凑、无机械运动部件、反应速度快等特点,大幅降低了光机系统复杂性。

A new auto focusing micro imaging system was designed. The liquid lens was used to adjust the focal length of the system’s tube lens to compensate the defocus of the objective distance without moving the microscope or the image plane. This paper introduced the focusing method of the micro fluid lens. The relationship between the objective length and the focal length of the tube lens was deduced. And the auto focusing micro imaging system was designed by ZEMAX optimization. The numerical aperture of the 10× objective lens is equal to 0.25. And the tube lens includes one liquid lens and four lenses. The spatial resolution of the optical system is less than 1.22 μm within the scope of the object distance ±0.5 mm. The system’s modulation transfer function (MTF) of all fields at Nyquist frequency (72 lp/mm) is larger than 0.2. This optical system not only could compensate the distance of the object, but also has the advantages of compact structure, no mechanical moving parts, fast reaction speed etc.