摘要
白光显微干涉术在平面阶跃型结构的形貌测量中具有显著优势。但在测量斜率变化的曲面样品时,由于物镜数值孔径的限制,样品表面反射光随着斜率的增大而减弱,干涉信号对比度降低,导致形貌测量结果的误差增大。基于表面传递函数(surface transfer function, STF)计算得到的逆滤波器可用于校正曲面样品的形貌测量误差,但现有方法的逆滤波器增益受限,无法有效提升频谱中的高频信号,对最大可测量斜率的提升有限。针对该问题,提取由白光干涉仪特性参数计算获得的虚拟STF的模作为振幅增益函数,由干涉图傅里叶变换得到的实测STF的相位作为相位补偿函数,形成虚实融合型逆滤波器,据此实现白光干涉仪曲面形貌测量误差的校正。应用该方法校正微球的形貌测量结果,校正后最大可测量斜率从8.09°提升到21.20°,均方根误差从0.545 5μm降低至0.175 9μm,实现了提升曲面样品的最大可测量斜率和减小测量误差的目的,有效提升了仪器针对曲面样品的测量范围。
White light microinterferometry has obvious advantages in measuring the topography of planar step structures.However,due to the limitation of the numerical aperture of the objective lens,the reflected light on the surface of the sample is weakened with the increase of the slope when measuring the curved surface sample,and the contrast of the interference signal decreases,which leads to the increase of the error of topography measurement.Based on the theory of surface transfer function(STF),the inverse filter can be calculated to correct the topography measurement error of curved surface samples.However,the gain of the inverse filter of the existing method is limited,which is unable to elevate the high-frequency signal in the spectrum,and the improvement of the maximum measurable slope is limited.To address this issue,the modulus of the virtual STF calculated by the characteristic parameters of the white light interferometer was used as the amplitude gain function,and the phase of the measured STF obtained by the Fourier transform of the measured interferogram was used as the phase compensation function.A virtual-measured fusion inverse filter was formed,which realized the correction of the curved surface topography measurement error of white light interferometer.Using this method to correct the topography measurement results of the microsphere,the maximum measurable slope after correction is increased from 8.09°to 21.20°,and the root mean square error is reduced from 0.5455μm to 0.1759μm,which achieves the purpose of improving the maximum measurable slope of curved surface sample and reducing the measurement error,and effectively improves the measurement range of the instrument for the curved surface sample.
作者
李赫然
袁群
范筱昕
张佳乐
马剑秋
乔文佑
高志山
郭珍艳
雷李华
傅云霞
LI Heran;YUAN Qun;FAN Xiaoxin;ZHANG Jiale;MA Jianqiu;QIAO Wenyou;GAO Zhishan;GUO Zhenyan;LEI Lihua;FU Yunxia(School of Electronic and Optical Engineering,Nanjing University of Science and Technology,Nanjing 210094,China;Jiangsu Institute of Measurement and Testing Technology,Nanjing 210023,China)
出处
《应用光学》
CAS
北大核心
2024年第2期422-429,共8页
Journal of Applied Optics
基金
国家自然科学基金(62175107,62205148)
国家重点研发计划(2022YFF0706302)
上海市自然科学基金(21ZR1483100)
上海市优秀学术/技术带头人计划(21XD1425000)。
关键词
白光显微干涉仪
表面传递函数
表面形貌测量
误差校正
逆滤波算法
white light microinterferometer
surface transfer function
surface topography measurement
error correction
inverse filtering algorithm
