差动临界角法高精度动态检焦技术研究  

Research on high-precision dynamic focus detection technology of differential critical angle method

作　　者：彭玲娜 赵圆圆 张杨 段宣明 Peng Lingna;Zhao Yuanyuan;Zhang Yang;Duan Xuanming(Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications,Institute of Photonics Technology,Jinan University,Guangzhou,Guangdong 511443,China;School of Physics and Optoelectronic Engineering,Jinan University,Guangzhou,Guangdong 510632,China)

机构地区：[1]暨南大学光子技术研究院,广东省光纤传感与通信技术重点实验室,广东广州511443 [2]暨南大学物理与光电工程学院,广东广州510632

出　　处：《光电工程》2024年第7期84-94,共11页Opto-Electronic Engineering

基　　金：广东省珠江人才计划项目(2019CX01Z389);国家自然科学青年基金项目(62005097);广东省基础与应用基础研究项目(2023A1515011404)。

摘　　要：基于临界角检焦技术具有光能量损耗小、组装相对简单、调试相对容易、系统分辨率高等特点,当引入差动信号处理技术,可放大提取的检焦信号,提升检测灵敏度和提高检焦曲线的光滑度,同时可实现更大的焦面检测范围,减少由于基底本身存在不平整影响到的检焦误差。本论文首先从差动临界角法检焦技术的基本原理出发,通过Fresnel公式和牛顿公式得到离焦量与离焦信号的关系。其次搭建差动临界角法检焦验证系统,利用四象限光电探测器采集单个临界角棱镜的离焦信号,并对两个垂直放置的四象限光电探测器接收到的离焦信号进行差动计算,以获得差动K值大小与离焦量z之间的关系。实验结果表明:采用波长532 nm的激光,数值孔径0.3的投影物镜时,检焦线性范围可达22μm;采用数值孔径0.45的投影物镜时,检焦线性范围可达14μm,差动临界角检焦法分辨率可达25 nm。Based on the characteristics of low light energy loss,relatively simple assembly,relatively easy debugging,and high system resolution,the critical angle focusing technology can be introduced to amplify the extracted focusing signal,improve the detection sensitivity and the smoothness of the focusing curve,and at the same time achieve a larger focal plane detection range,reducing the focusing error affected by the unevenness of the substrate itself.This paper first starts from the basic principle of the differential critical angle focusing technology and obtains the relationship between the defocus amount and the defocus signal through the Fresnel formula and the Newton formula.Secondly,a differential critical angle focusing verification system is built,a four-quadrant photodetector collects the defocus signal of a single critical angle prism,and the defocus signals received by two vertically placed four-quadrant photodetectors are differentially calculated to obtain the relationship between the differential K value and the defocus amount z.The experimental results show that when a wavelength of 532 nm laser and a numerical aperture of 0.3 projection objective are used,the focusing linear range can reach 22μm.When a numerical aperture of 0.45 projection objective is used,the focusing linear range can reach 14μm,and the resolution of the differential critical angle focusing method can reach 25 nm.

关 键 词：差动临界角 检焦技术 亚微米级 检焦精度 检焦范围 

分 类 号：O436[机械工程—光学工程]