摘要
圆环达曼光栅(CDG)产生的贝塞尔光束照明可以扩展光学相干层析成像(OCT)系统的焦深,使得系统在较大成像深度范围均保持高的横向分辨率。但CDG一级衍射环的分裂效应会导致贝塞尔光束轴向能量分布出现凹陷,削弱了焦深扩展的效果。本研究团队在分析CDG衍射原理的基础上,优化设计了无一级衍射环分裂效应的CDG,并通过仿真证明了该CDG产生的贝塞尔光束不存在轴向能量凹陷,具有更好的焦深扩展效果;然后将优化设计的CDG应用于搭建的OCT系统中,采用该系统对聚苯乙烯微球琼脂凝胶、白胶带等样品进行成像。结果表明,该OCT系统可以在1.8 mm的焦深范围内获得优于3.9μm的横向分辨率,有效扩展了系统焦深。
Objective Optical coherence tomography(OCT)has been widely used in clinical medicine,materials science,tissue engineering,among other fields due to its advantages of non-destructive,non-contact,high speed,and high resolution.In the traditional OCT system,which is based on Gaussian beam illumination,the lateral resolution is determined by the size of the focused spot of the Gaussian beam.However,the smaller the focused spot,the shorter the depth of focus,and the rapid drop of the lateral resolution outside the depth of the focus area.Therefore,improving the depth of the focus,while maintaining a high lateral resolution is one of the important problems to be solved in a high-resolution OCT system.Bessel beam is used to extend the depth of the focus of the OCT system because of its non-diffracting property.Bessel beams can be generated by the optimal solution of the first-order circular Dammann grating(CDG),and the depth of the focus can be extended effectively,while the diffraction efficiency can reach 81%.However,in the existing CDG design,the splitting effect of the first-order diffraction ring will lead to a zero-energy dent in the axial direction of the central spot of the Bessel beam,resulting in a short depth of focus.To solve this problem,this paper proposes a depth of focus extension method,which eliminates the axial energy dent of Bessel beam generated by CDG.Moreover,it can effectively reduce the splitting effect of the first-order diffraction ring,improve the uniformity of axial intensity distribution within the depth of the focus range of Bessel beam,and realize the depth of the focus extension of the OCT system.Methods In this paper,by optimizing the radius of the central circle of the CDG and the ratio of the binary phase in a single period,we design a CDG for generating Bessel beams that eliminate the energy dent,and apply it to the OCT system,which effectively extends the depth of the focus of the system.Based on the principle of the CDG diffraction,the CDG parameters that meet the requirement of el
作者
欧阳君怡
李中梁
刘腾
南楠
阎晓娜
王向朝
Ouyang Junyi;Li Zhongliang;Liu Teng;Nan Nan;Yan Xiaona;Wang Xiangzhao(College of Sciences,Shanghai University,Shanghai 200444,China;Laboratory of Information Optics and Opto-Electronic Technology,Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Shanghai 201800,China;Center of Materials Science and Optoelectronics Engineering,University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《中国激光》
EI
CAS
CSCD
北大核心
2021年第20期123-132,共10页
Chinese Journal of Lasers
基金
国家自然科学基金(61971406,81927801)
上海市科学技术委员会创新行动计划(19441910000)
中国科学院青年创新促进会资助项目。
