摘要
[目的]激光刻蚀高分子薄膜是制备仿生纳米通道的常用方法,刻蚀尺寸的测量对提高制备质量具有重要意义.受到刻蚀尺寸在微纳米级,薄膜反射率低、受成像噪声干扰严重等影响,激光刻蚀薄膜微纳表面形貌高精度测量一直是艰巨的挑战.[方法]基于并行物方差动共聚焦成像与图像抗干扰方法结合,实现激光刻蚀聚对苯二甲酸乙二醇酯(polyethylene terphthalate,PET)膜后的微纳表面形貌的高精度测量.首先,介绍并行物方差动共聚焦三维成像原理,刻度了系统在40倍物镜下的轴向差动曲线,拟合光强差与离焦量的线性关系式.然后,采集激光刻蚀薄膜焦前焦后共聚焦图像,使用图像增强提取刻蚀区域并合成差动共焦图像.并利用非线性空间滤波器,消除图像中的干扰,获取刻蚀形貌的三维结构.[结论]实验结果表明,该方法与白光干涉仪的测量结果相近,在测量线宽3.230μm、深度0.082μm的激光刻蚀PET薄膜沟槽实验上,拟补了白光干涉仪无法准确解析高度信息的不足.本研究为高分子薄膜显微加工形貌测量提供了一种高效率、高精度、无损的可行性测量方法.
[Objective]With the progress of scientific research on polymer materials,an increasing number of polymer materials are widely used in electronic and mechanical fields such as flexible printed circuit boards,computer floppy disks,and membrane switches.Laser-etched bionic nanochannels are funnel-shaped,conical,etc.The morphology and size of nanostructures,such as thin-film trenches and holes after laser etching have a decisive effect on the performance of the material.Because the thickness and horizontal dimension of the film are very small,generally on the micrometer scale,and the reflectivity of the film is low,it is easily disturbed by imaging noise and other difficulties.[Methods]This paper proposes a parallel object-variance dynamic confocal imaging method for the measurement of thin film etched groove topography,which realizes the high precision of the micro-nano topography of the PET(Polyethylene terephthalate,PET)thin film after laser etching 3D topography measurement.First,the parallel object-variance dynamic confocal three-dimensional measurement system is introduced,which consists of a spatial light modulation illumination light source,a microscope imaging optical system,and a camera using a digital micromirror device(DMD)as the illumination pinhole.Then,the axial differential curve under the 40×objective lens of the parallel object-variance dynamic confocal system was calibrated.The system collected the confocal images of the laser-etched PET film sample at 1.5μm before and after the focus,and subtracted the two images to obtain a differential image.Based on the previously fitted linear function relationship,the differential image was converted into a 3D topography image.[Results]The system uses a digital micromirror device DMD as the space for the illumination pinhole Light modulation illumination light source,modulates the illumination beam into a point light source array,realizes multipoint fast parallel measurement,and greatly improves the measurement efficiency;For the burr problem on the topography surface in the 3D topography,starting from the optical properties of the PET film,the surface burr in the three-dimensional topography comes from the uneven illumination of the system and the existence of the surface of the PET film itself.To solve the problem of low image contrast in images collected based on parallel confocal imaging system,gray histogram equalization was used to enhance the contrast between processing traces and background in the image,and through image processing technology.The spatial position information of the laser-etched grooves is obtained by means of morphological processing and removal of small connected domains in the confocal image,and then the area(background)outside the laser-processed area in the pre-focus and post-focus confocal images is set to zero to eliminate the influence of complex background with uneven reflectivity on 3D topography restoration;For impurities with low reflectivity,bubbles with high reflectivity,and columnar burrs caused by uneven reflectivity,the template size for differential images is 25*25 nonlinear spatial filter,that is,median filtering technology,eliminates the influence of isolated points with high or low reflectivity on the surface of the film,realizes smoothing of three-dimensional topography,completes line width 3μm,depth 100 nm,stacking high-precision and fast three-dimensional restoration of the groove morphology of laser-processed thin films with a height of approximately 0.043μm.[Conclusions]Transparent polymer films have excellent mechanical properties,optical properties,chemical resistance and heat resistance properties and are one of the best choices for the preparation of artificial nuclear pore membrane templates and biomimetic nano-channels.The micropore shapes of nuclear pore membranes prepared by using thin films as raw materials include cylindrical,biconical,ellipsoidal,etc.,and the internal morphology and size information of the pore channels have guiding significance for measuring the porosity and retention effect of nuclear pore membranes.Compared with traditional imaging characterization technology,which is complicated in operation and low in measurement efficiency,this method only needs to collect two images of the sample before and after the focus,and it only takes a few seconds to complete a three-dimensional topography measurement of a laser-etched PET film.For narrow trenches that cannot be measured,the method can still accurately restore topographical dimension information such as the line width and depth of the narrow trenches.The research provides a high-efficiency,high-precision and nondestructive measurement method for the measurement of the morphology of polymer thin films by laser microfabrication.
作者
谢佳豪
黄彩虹
易定容
叶一青
黄磊
XIE Jiahao;HUANG Caihong;YI Dingrong;YE Yiqing;HUANG Lei(Optical Imaging Inspection Laboratory,College of Mechanical Engineering and Automation,Huaqiao University,Xiamen 361021,China;School of Information Sciences and Engineering,Huaqiao University,Xiamen 361021,China;School of Life Sciences,Xiamen University,Xiamen 361102,China)
出处
《厦门大学学报（自然科学版）》
CAS
CSCD
北大核心
2024年第4期630-639,共10页
Journal of Xiamen University：Natural Science
基金
福建省自然科学基金面上项目(2021J01293),福建省自然科学基金重点项目(2020J02005)。
关键词
三维测量
PET薄膜
图像对比度
图像平滑
three-dimensional measurement
PET film
image contrast
image smoothing
