【作者】 柯才军；

【导师】 易新建；

【作者基本信息】 华中科技大学 ， 物理电子学， 2005， 博士

【摘要】 随着现代光学的发展,微光学元件的研究和在各个领域中的应用已经引起国内外科研工作者越来越高度的重视。微透镜阵列就是其中一种重要的微光学元件。本文对于微透镜阵列的设计理论、制作工艺、性能测试进行研究,并着重研究了微透镜阵列与CCD 图像传感器的集成技术,达到改善图像传感器光敏性的目的。本文的主要内容如下: (1) 概述了微光学技术的发展以及微光学元件的种类,介绍了微透镜阵列的研究和应用以及微透镜阵列与CCD 图像传感器集成应用现状。(2) 介绍了微透镜阵列的光学设计理论。包括折射微透镜的几何光学设计方法和衍射微透镜的衍射光学设计理论。对折射和衍射透镜的色散效应进行了理论上的分析。基于严格的矢量衍射理论,分析了亚波长结构衍射元件的衍射机理。此外,本文还分析了制作误差等因素对微透镜阵列衍射效率的影响,对系统中的光能损失进行了分析。(3) 对实用情况下出现的小冠高衍射微透镜,提出了表面直接台阶量化的设计方法,并将此方法应用于CCD 图像传感器的微透镜阵列进行了设计。此方法可以避免采用一般的设计方法对小冠高衍射微透镜设计时所出现的有限台阶数的问题,有效地保证了微透镜保持较高的衍射效率。(4) 基于MEMS(微电子机械系统,Micro-Electro-Mechanical-System)工艺,讨论了微透镜的制作方法,包括紫外光刻、图形转移方法。尤其是对三组分气体SF6/O2/CHF3 反应离子刻蚀方法进行了深入的研究,在硅衬底上得到了比较理想的图形转移效果。同时,首次进行了以聚合物为基的微透镜的制作,并制作出了比较理想的微透镜。(5) 建立了针对微透镜的微光学测试系统,介绍了参数的测量方法,可以测量微透镜的点扩散函数、衍射效率、焦长等性能参数,使得可以有效地对制作的微透镜进行评价。文中同时分析了测量中的误差及影响因素。(6) 对场镜形式的微透镜与CCD 集成系统的聚光效率问题进行了光学分析,使得集成器件有最好的光耦合效果。(7) 重点研究了衍射微透镜在256×256 元Pt/Si IRCCD 上的应用。通过将衍射微更多还原

【Abstract】 With the development of modern optics, the researchers of the world in this field are attaching more and more importance to the investigation and applications of micro-optic elements in many fields. The microlens arrays are the important kind of micro-optics elements. This dissertation places emphasis upon the design theory, fabrication technology and optical performance measurement of microlens arrays. And it emphasizes the researches on integration technology between microlens array and CCD (charge coupled device) image sensors, which can improve the detecting performances of image sensor remarkably. The primary content of the dissertation includes: (1) The development of micro-optics and the kind of micro-optics elements have been summarized. And the statuses in quo of fabrication technology and applications of microlens array and present research on the integration between microlens and CCD image sensors have been introduced. (2) Optical design theory of microlens array is introduced. It includes the geometrical optics design theory for refractive microlens and diffraction optics theory for diffractive microlens. The dispersion effect of diffractive and refractive microlenses has been analyzed theoretically. Base on the rigorous vector diffraction theory, the diffractive mechanism of subwavelength structure has been discussed. Furthermore, the effect of fabrication-related errors on the diffractive microlens array and the optical losses in the system are also studied. (3) There are often the microlenses with low sag and long focal length in the applications. With regard to this kind of microlenses, a design method, the surface directly quantized, has been introduced. By this method, the microlens in the CCD applications has been designed effectively. It avoids finite phase steps, which appears when the microlens is designed by conventional design method. So the diffractive microlens array can keep high diffractive efficiency. (4) Based on MEMS(Micro-Electro-Mechanical-System)technology, the fabrication processes, including photolithography and pattern transfer are discussed. Especially the reactive ion etching (RIE)technology with three ingredients SF6/O2/CHF3 has been investigated deeply and the perfect patterns on the silicon substrate are achieved. At the same time, the polymer microlens array is studied and fabricated. High quality microlenses are completed. (5) The measurement system and testing method of microlens array are introduced. With this system, the microlens parameter such as point-spread function (PSF), diffractive efficiency, focal length and so on, can be evaluated effectively. The errors and influencing factors have been analyzed. (6) In the integration system of microlens and CCD, the microlens is used as field lens. The optical analysis of microlens convergent efficiency is carried out so as to optimize the optical coupling. (7) The integration between diffractive microlens array and 256×256 element PtSi IRCCD has been highlighted. With the microlens integrated, the fill factor (FF) of IRCCD increases evidently. And the IRCCD image sensors operating at 77K indicate an approximate 2-fold increase in relative optical responsivity in the spectral range of from 3μm to 5μm. At the same time, the integration technology between microlens array and visible is investigated. The monolithic and hybrid integration method is introduced, respectively. In sum, the innovations included in the dissertation are as follow: (1) As regard the design theory of microlens, the design method of continuous surface quantized by 2N equal phase for the microlens with low sag and high F-number has been put forward. It not only keeps the diffractive efficiency of microlens with low sag high, but also allows the microlenses with low sag to be made by binary optics fabrication technology. (2) The microlens array is made from the polymer with high transmissivity in the visible band, such as polyimide, BCB, SU-8 photoresist and is applied in the integration between microlens and visible CCD image sensors. (3) In order to evaluate the optical quality of microlens effectively, a testing system is set up and the wave band of microlens can cover 190～1100nm。(4) The hybrid integration between quartz microlens and visible 516×516 element CCD image sensor has been explored.更多还原