基于荧光成像分析的双光子直写离焦主动补偿方法(特邀)  

Proactive Focus-Compensation Method Based on Fluorescence-Image Analysis in Two-Photon Laser Direct-Writing Processing(Invited)

作　　者：徐晨曦 刘一宁 王怡洁 张琛[1,2,3] 赵伟[1,2,3] 陆宝乐[1,2,3] 王凯歌[1,2,3] 白晋涛[1,2,3] Xu Chenxi;Liu Yining;Wang Yijie;Zhang Chen;Zhao Wei;Lu Baole;Wang Kaige;Bai Jintao(Institute of Photonics&Photon-Technology,Northwest University,Xi an 710127,Shaanxi,China;National Key Laboratory of Photon-Technology in Western China Energy,Northwest University,Xi an 710127,Shaanxi,China;Key Laboratory of Optoelectronics Technology in Shaanxi Province,Northwest University,Xi an 710127,Shaanxi,China)

机构地区：[1]西北大学光子学与光子技术研究所,陕西西安710127 [2]西北大学省部共建西部能源光子技术国家重点实验室,陕西西安710127 [3]西北大学陕西省光电子技术重点实验室,陕西西安710127

出　　处：《中国激光》2024年第12期440-449,共10页Chinese Journal of Lasers

基　　金：国家重大科研仪器研制项目(51927804);国家自然科学基金(62275216,62375220);陕西省科技创新团队项目(S2018-ZC-TD-0061,2023-CX-TD-06)。

摘　　要：针对双光子直写大面积微纳结构中的离焦问题,提出一种基于荧光成像分析的焦点主动补偿方法。首先利用光刻胶荧光信号在光刻胶与基底介质界面处快速变化的特点,结合相应的图像处理方法分析相机捕获的荧光图像,高效地判断出物镜焦平面与基底平面间的倾角。随后,通过空间位置旋转变换关系得出加工区域内每一个加工位点的补偿值,以及补偿过程中这些位点与激光焦点在三维空间中的相对运动速度。最后,由纳米压电平移台执行相应的位置与速度即可实现对离焦的主动补偿。进行大范围微纳米线、尺度渐变微纳米结构阵列和尺度渐变复杂几何结构的双光子直写加工实验,结果表明提出的方法能有效地解决双光子直写中的离焦问题,最小补偿倾角达到4.62×10^(-4)rad。在预期300 nm高度的大面积微纳米线阵列加工中,离焦补偿精度标准差达到23 nm。同时,提出的方法能够实现尺度渐变的微纳结构的高精度加工,获得的尺度渐变双针结构的最小特征结构高度为12 nm、半峰全宽为79 nm。提出的方法简单易行、不需要额外引入参考光和复杂的标定,对于降低系统技术难度和控制系统成本具有一定的现实意义。Objective Two-photon polymerization laser direct writing(TPP-LDW)is a key technique in micro/nanofabrication.It offers many advantages,such as high precision,maskless fabrication,three-dimensional lithography,and diverse customization.Since the lateral and axial linewidths of voxels in TPP-LDW are on the order of hundreds of nanometers and 1‒2μm respectively,a slight inclination between the focal plane of the objective lens and the substrate might cause defocusing,thus resulting in the collapse or deformation of fine structures.Therefore,defocusing correction and compensation is extremely important,particularly in large-scale micro/nanostructure processing.However,most compensation methods used for commercial products and research require additional reference beams and precise compensation for defocusing is based on the accurate calibration of the auxiliary detection optical path with respect to the fabrication beam,which significantly increases the cost,complexity,and difficulty of the TPP-LDW system.In this study,we propose a proactive focus-compensation method based on fluorescence-imaging analysis.This methodology does not require additional reference beams or complex calibration;additionally,it is easy to operate and implement,with high compensation accuracy.Methods A femtosecond laser with a wavelength of 800 nm is used as the excitation source for the TPP-LDW setup in this study.The photoresist resin adopted in the current experiment contains 7-diethylamino-3-thenoylcoumarin(DETC)with a mass fraction of 0.5%as the initiator,and the monomer is pentaerythritol triacrylate(PETA).The two-photon-excited fluorescence of DETC is obtained using a high numerical aperture objective and imaged using a complementary metal-oxide-semiconductor transistor(CMOS)camera.A six-axis piezoelectric nanotranslation platform is used to support and actuate the samples.By exploiting the rapid change in the fluorescence signal intensity at the interface between the photoresist and substrate as well as adopting the appropriate ima

关 键 词：双光子聚合 荧光成像分析 焦点主动补偿 微纳加工 

分 类 号：O437[机械工程—光学工程]