大数值孔径生物显微物镜杂散光分析及测量

	大数值孔径生物显微物镜杂散光分析及测量
其他题名	The study of stray light analysis and measurementin large numerical aperture biological microscope objectives
	胡慧杰
学位类型	硕士
导师	武晓东
	2015-10
学位授予单位	中国科学院大学
学位专业	光学工程
关键词	杂散光分析显微物镜 Brdf 表面粗糙度表面颗粒污染水平
摘要	显微镜是现代医学领域的重要检测工具之一，显微镜的性能主要由显微物镜决定。一款优秀的生物显微物镜不仅体现在最优的光学像差控制、精良的加工和装配，更体现在优异的杂散光抑制方面。杂散光会使显微镜像面图像对比度下降，从而导致调制传递函数MTF 下降，层次减少，清晰度变坏。因此良好的杂散光抑制是光学系统能够获得高性能成像质量的前提和基础，这就要求光学系统设计成型前必须进行杂散光分析，光学加工装调成型后必须进行杂散光测试。随着计算机光学辅助设计的发展，显微物镜杂散光仿真分析成为可能，本论文根据显微物镜杂散光测试仪的设计需求立题，研究不同测试条件及不同光机表面散射对显微物镜杂散光系数的影响，内容包括以下几个方面：（1）显微物镜杂散光测试仪方案设计：根据黑斑法测量杂散光系数的理论基础以及国家标准，设计了测量显微物镜杂散光系数的测试仪，从照明系统到黑斑基板、从被测物镜到像面测试积分球光电倍增管，均进行了详细的光能传播分析，并以此为依据对杂散光测试仪进行元器件选型，最后对各关键部分的连接进行结构设计，完成了显微物镜杂散光测试仪总体设计；（2）基于黑斑法测量显微物镜杂散光物理模型的建立：根据杂散光理论基础分析显微物镜的散射表面和杂散光路径，结合现有物镜的光学、机械设计方案，建立基于黑斑法显微物镜杂散光测试仪的模型，并采用TracePro 光学仿真软件进行边界条件设置，包括光源发散角和光强、机械零件和光学表面的BRDF参数、带黑斑（不带黑斑）的基板透过率、像面探测器的位置和尺寸大小，对 98 倍、NA=1.28 的显微物镜分别更换带黑斑基板和不带黑斑基板来测量，得出其杂散光系数为13.07%，验证了显微物镜杂散光测试仪仿真模型的可行性；（3）不同测试条件下显微物镜杂散光系数分析：通过更改仿真模型中的实验参数，如照明数值孔径、照明视场、离焦量、黑斑在视场中位置等，分别探究了他们对杂散光系数的影响，并得出以下结论：杂散光系数随照明数值孔径和照明视场范围的增大而增大；对98 倍、NA=1.28 的显微物镜，四倍离焦量为小值，易于通过手动调焦至视场清晰，所以离焦量对杂散光系数的影响可以不计考虑；显微物镜的杂散光系数随黑斑与中心视场偏移量的增大逐渐减小（除边缘视场外），即最大杂散光系数来源于中心视场，表明中心视场的杂散光特性具有代表性，体现了显微物镜光学系统最大杂散光水平；（4）光机表面散射参数对显微物镜杂散光系数影响分析：通过对不同NA 显微物镜光学表面散射BRDF 参数的设定，深入探究光学表面不同粗糙度（2nm、 5nm、10nm、20nm）、不同镜面颗粒污染水平（100、230、500、750）和机械结构表面是否消光染黑对杂散光系数测量的影响。提出有效减小显微物镜系统像面杂散光系数的途径有--光学精加工中严格控制表面粗糙度的大小、保证镜面洁净程度在基本洁净水平以下以及采用类似Avian Black-S 的消光材料对机械结构表面进行染黑。
其他摘要	Microscope is one of the important detection tools in the field of modern medicine, the function of microscope is mainly decided by the micro-objective. An excellent biological micro-objective is not only reflects in the optimal optical aberration control, excellent processing and assembling, but also in the aspect of excellent stray light suppression. The stray light reduces the imaging contrast of microscope that then lead to the deviation of MTF, gradation and even definition. So well control of stray light is indispensable premise of obtaining the high-performance image quality. Thus, it requires that the stray light analysis must be conducted before the forming of optical system design, and must be tested after adjustment of optical processing. The development of computer-aided optical design makes it possible to do stray light simulation analysis. This paper based on the demand of the design of micro-objective stray light tester, through simulating different conditions and different surface scattering, studies the influence of the stray light as the following several aspects: (1) The design of micro-objective stray light tester. According to the theoretical basis of black spot method and the national standard, design the measuring tester to test the coefficient of micro-objective stray light. From lighting system to black-spot substrate, from objective system to image test of integrating sphere photomultiplier tubes, all have the detailed analysis of the light transmission. And on its basis to select main components and design the key parts of the connection structure, finish the overall design of micro-objective stray light tester; (2) The establishment of the physical model of measuring micro-objectives stray light based on the black spot method: According to the theory basis of stray light to analyze scattering surfaces of micro-objective and stray light path, combine with the existing objectives of optical structure and mechanical structure, establish the model of the micro-objective stray light tester which based on black spot method, and use the TracePro optical simulation software to set up the boundary conditions, including the divergence angle and intensity of light source, the BRDF of mechanical and optical surface, the transmittance of substrate with black spot (without black spot), the position and size of detector. By using NA=1.28, 98× micro-objective，respectively replaced with dark spot substrate and substrate without black spot, it can be concluded that the VGI is 13.07% and verified the feasibility of the simulation model of stray light tester; (3) The analysis of micro-objective stray light under different measurement condition. In the simulation model, exploring the influence on the VGI under different experimental parameters, such as numerical aperture of illumination, field size, defocus and black spot positions in the field. It is concluded that the VGI increases as numerical aperture and illumination field increase; For the micro-objective with 98×, NA = 1.28, four times of defocus is small value, and it’s easy to neglect the influence of defocus through focusing exactly using manual adjustment wheel; Moreover, put the edge field aside, the VGI of micro-objective decreases with the offset of black spot off center position of field, and the largest VGI is derived from the center of filed, In other words, the VGI characteristics of center field represents and reflects the maximum level of micro-objective optical system; (4) The analysis of stray light under different surfaces scattering of micro-objective. Through setting the surfaces scattering of BRDF parameters of different NA, delve into the influence of different parameters, such as optical surface roughness (2 nm, 5 nm, 10 nm, 20 nm), cleanliness levels (100, 230, 500, 230) and the mechanical structure surface black-dyeing or not, on of VGI measurement. So, the methods to reduce the VGI of micro-objective system are strictly controlling the surface roughness, guaranteeing the surface cleanliness under basic level and appropriately using similar Avian Black-S extinction materials for mechanical structure black-dyeing.
语种	中文
文献类型	学位论文
条目标识符	http://ir.ciomp.ac.cn/handle/181722/49266
专题	中科院长春光机所知识产出
推荐引用方式 GB/T 7714	胡慧杰. 大数值孔径生物显微物镜杂散光分析及测量[D]. 中国科学院大学,2015.

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