用于红外焦平面的正方形孔径球面微透镜阵列研究

针对目前红外焦平面光敏阵列中存在的占空比小、光能利用率低的实际问题,展开了正方形孔径球面微透镜阵列制作及其与红外焦平面阵列集成应用的研究.本文从红外焦平面光敏阵列特点入手,对比分析了正方形孔径相比于传统圆形孔径微透镜阵列在光能利用上的优势.提出正方形孔径微透镜阵列激光直写变剂量曝光制作技术,建立光刻胶曝光数学模型和正方形球面微透镜面型函数,以此为基础,编制直写设备变剂量曝光控制软件;利用长春理工大的学复合坐标激光直写系统和等离子刻蚀机进行相关工艺实验,制作了阵列256×256、单元尺寸40×40μm2、球面半径60μm、单元间距1μm的红外石英微透镜阵列;并将其与相应阵列的碲-镉-汞红外光敏阵列进行集成.结果表明:微透镜的占空比达到95%,红外焦平面光能利用率从原来的60%提高到90%以上.由此得出结论:变剂量曝光制作微透镜技术是可行的,正方形孔径球面微透镜阵列代替圆形孔径微透镜阵列,对于提高红外探测器的灵敏度、信噪比、分辨率等性能具备明显优势.

Square Aperture Spherical Microlens Array for Infrared Focal Plane

In allusion to the current practical problem of small duty ratio, low light energy utilization in infrared focal plane array, the manufacture of square aperture spherical microlens array and integrated application with infrared focal plane array are studied. Starting with the character of microlens arrayinfrared focal plane array, the advantages of square aperture spherical microlens array and round aperture spherical microlens array are compared. The laser direct writing varying dose exposure making technology of square aperture spherical microlens array is proposed, and the mathematical model of photoresist exposure and the square aperture spherical microlens array surface figure functions are established, based on which the direct writing varying dose exposure software is written. Related process experiments are carried out by the model number of laser direct system and plasma etching machine from Changchun University of Science and Technology. The infrared quartz spherical microlens array is made, of which micro-lens element size is 40×40 μm2, spherical radius is 60 μm and element spacing is 1 μm, and then is integrated with the square aperture spherical microlens array with infrared photosensitive array. The results show that the duty ratio achieves 95%, and the utilization ratio of light energy increases from original 60% to 90%. It can be concluded that the way using square aperture spherical microlens array instead of the round aperture spherical microlens array can significantly improve sensitivity, signal-to-noise ratio and resolution ratio of the infrared detector.