集成化多薄膜消色差变焦液体透镜研究

Tunable membrane liquid lenses have become one of the most interesting research topics in adaptive optics due to their automatic change of focal lengths. Extensive researches have been conducted on the methods of achieving automatic focus, whereas research about how to automatically correct the optical aberration is still in its initial stage. This initial development is limited by several facts, including the establishment of the imaging theoretic model, the property optimization of the optical materials, the precision control of the membrane surfaces, and so on. This project aims to investigate the influences of optical materials properties on the imaging qualities of liquid lenses, to expand the range of optical materials, and to explore an integrated multi-membrane multi-liquid lens with autonomous correction of optic aberration and its application in adaptive optic systems. To achieve these, following major studies will be carried out: ① mechanism of acrylic film, aspheric PDMS film, non-polar/polar optical liquid on the imaging properties of liquid lenses. ② mechanism of the precise control of membrane surface using Peltier controller and environmental effects (gravity, temperature) on liquid lenses and its solution; ③analysis of the imaging theoretic model, design and manufacture of integrated multi-membrane achromatic tunable focal liquid lenses and their optic characterization. The results obtained from the above studies will facilitate the understanding of imaging characteristics of multi-membrane liquid lens in visible light range, and provide theoretical bases and effective realization methods for the application of adaptive optical systems in automatic aberration correction.

薄膜液体透镜因其灵活的自动变焦特性已成为自适应光学研究热点之一。目前的研究关注主要集中在如何实现自动变焦的功能，对如何自动矫正光学像差的研究尚处于起步，主要困于成像理论模型的确立、光学材料性能优化及薄膜面型的精确控制等。本项目旨在通过研究光学材料属性对液体透镜成像特性的影响和扩展光学材料范围，探索集成化多薄膜、多液体、像差可自动矫正的变焦液体透镜及其在自适应光学系统中的应用。主要研究内容包括：①丙烯酸薄膜、聚二甲基硅氧烷非球面薄膜、无极性/极性光学液体对液体透镜成像性能的作用机理；②微型珀耳帖控制器精确调控薄膜面型的方法，及重力、温度作用对液体透镜的影响和解决方案；③集成化多薄膜消色差变焦液体透镜的成像理论模型分析、设计、制备及光学性能表征。研究成果将有助于获得对集成化多薄膜变焦液体透镜在可见光波段成像特性的新认识，为自适应光学系统在自动矫正像差方面的应用提供新的理论支持和有效实现途径。

液体透镜将光学和微流体相结合，通过控制微升液体来实现光学现象。液体透镜与传统固体透镜相比，其具有体积小、重量轻、可精确操作、良好的成像性能等显著优势。本项目采用薄膜液体透镜作为研究内容，主要研究内容包含：（1）制备聚丙烯酸薄膜，测量该薄膜的光学特性; （2）建立多物理场耦合模型，优化液体透镜光学性能和机械结构；（3）通过热—气驱动精确控制薄膜面型，实现自动变焦；（4）采用MEMS加工工艺和3D打印设备制备三维结构的光流体芯片；（5）搭建光学平台测试薄膜液体透镜的光学性能。..基于以上研究内容，我们设计、制备并表征了两种不同类型的薄膜液体透镜。首先完成基于微型热-气驱动的环形气体腔薄膜液体透镜。该透镜由空气腔和液体腔组成，通过内嵌式三维螺旋微通道将这两部分连接起来。整个结构无需使用任何外部压力泵，结构集成紧凑。项目采用多物理场有限元软件模拟施加电压和温度分布的问题，分析了气体腔体体积与光学液体温度梯度的相互关系。当直流电压从1V到6V，焦距变化范围为5mm到23mm。该设计在精确微小距离自动变焦成像方面有显著优势。..其次，基于内置微型半导体加热片的凹/凸自由表面的集成化薄膜液体透镜。该薄膜液体透镜通过改变半导体加热片的电流方向，实现气体腔体内部自动降温和升温的过程，从而改变薄膜凸凹面型。实验结果表明当电压从0.2V增加到1.1V时，液体透镜的焦距从25mm减小到5mm;反之，而当电流向相反方向施加时，焦距在-25mm到-5mm之间连续变化。该设计结构紧凑，没有任何机械运动部件，实现快速自动变焦功能。与传统的电阻丝产生焦耳热的驱动原理相比,该设计具有以下几个特点：高度集成，极低工作电压控制、快速吸/放热的响应时间。以上两种创新设计的光流控自动变焦透镜在未来自适应成像设备中具有巨大的发展潜力。