【作者】 王猛；

【导师】 张新宇；

【作者基本信息】 华中科技大学 ， 模式识别与智能系统， 2011， 硕士

【摘要】 本论文基于衍射微光学原理,设计并制作了红光高清衍射物镜原理性样片及红外、THz波段的衍射波前结构,分别实现了输出面上的光强控制和相位控制。红光高清衍射物镜用于下一代红光高清光电存储系统,要求能将红光激光在3mm焦距处聚焦为0.5μm直径的焦斑。衍射波前结构要求能够产生可控的红外及THz波前,用于模拟自适应光学系统中的大气湍流。采用基于标量衍射理论的平面波角谱衍射理论设计衍射光学元件(Diffractive Optical Element,DOE),与使用基于严格电磁波理论的矢量衍射理论设计结果相近。但设计过程更简单,数据处理量也较少。借鉴传统的衍射光学元件设计方法——盖师贝格-撒克斯通算法(Gerchberg-Saxton Algorithm,GS算法)的思想,将角谱衍射理论与GS算法相结合,设计了迭代角谱算法。用该算法设计了用于光强控制的红光高清衍射物镜,及用于相位控制的衍射波前结构。数值仿真结果显示,设计所得结果满足预期需要。本论文中采用的衍射微光学元件的制作方法,摈弃了传统的多步套刻的方式,而采用了单步光刻的方法,可最大限度的提高精度。在光刻时,根据所制衍射微光学元件特征尺寸的大小,合理选择光刻的方式。对红光高清衍射物镜,采用了单步电子束光刻的方法,以适应其表面处的精细图形结构。对衍射波前结构,由于其面特征尺寸较大,选用了单步掩模光刻的方法。后期腐蚀中,皆采用了相对廉价的湿法腐蚀工艺,节省了器件制作费用。对所制衍射微光学元件进行表面形貌及光学性能测试显示,红光高清衍射物镜和衍射波前结构的表面均存在极精细结构,表面粗糙度都达到了光学镜面水平,初步实现了预期目的。为下一步的实用化,提供了可借鉴的理论与实验基础。更多还原

【Abstract】 In this thesis, the principle diffractive objective lenses for Red-Laser-High-Definition storage system and the diffractive micro-optics structures for controlling wavefront transmission in infrared and THz wavelength range, are designed and fabricated based on the complex diffractive micro-optics theory. Both the intensity or amplitude and the phase of light wave out from the devices mentioned above, can be processed efficiently. The fabricated diffractive objective lens will be used in the next generation of Red-Laser-High-Definition storage system. The basic requirements for diffractive objective lens include: having 3mm focal length and then focusing red incident beam into a very small focal spot of 0.5μm diameter. The diffractive micro-optics structures can be used to generate several wavefronts for simulation the light field in atmospheric turbulence so as to valuate the imaging efficiency of adaptive optical system.Based on the planar wave scalar angular spectrum diffraction theory, several diffractive optical elements, which are similar to that designed by the strict electromagnetic wave theory, are designed. Compared to common method, the current design processes are easier and then the processed data is fairly small. The iterative angular algorithm is constructed through combining the angular spectrum diffraction theory with the Gerchberg-Saxton (GS) algorithm, which is one of the traditional methods for designing diffractive optical elements. The new algorithm has been used to design the diffractive objective lens and then the diffractive wavefront structures by controlling both the light intensity and phase, simultaneously. Numerical simulation shows that the designed results already meet the requirements to diffractive elements.The method for fabrication diffractive elements in this thesis is only consist of single mask photolithography, so as to completely eliminate the traditional multistep photolithography processes and therefore improve the fabrication precision, remarkably. The rational mask layouts are selected according to the feature size and the phase map of diffractive elements. For diffractive objective lens, a single step electron beam photolithography has been used so as to meet the fineness requirements of micro-nano-structures formed over the surface of silicon wafer. The same single step photolithography has also been used to fabricate the diffractive micro-optics structures with large feather size. In the etching process, the low cost wet KOH etching is employed to achieve the fabrication of devices. Surface morphology and optical performance test of the fabricated diffractive elements show that desired fine microstructure patterns are formed efficiently over the surface of silicon wafer, and then their surface roughness has reached the optical mirror level. The constructed theory and obtained experiments will highlight further applications.更多还原