摘要
定量相位成像具有无标记、非入侵及三维观测的特点,在生物医学、工业检测等领域有着显著的优势。本文提出利用二维朗奇相位光栅实现基于四波横向剪切干涉的定量相位成像的方法。理论分析了光栅周期和照明波长对四波剪切干涉的影响,得到了光栅周期与探测器像素尺寸的最佳匹配关系,论证了宽光谱光源照明下定量相位成像的可行性。实验搭建了结构紧凑的四波剪切干涉定量相位显微成像装置,实现了对PMMA微球、微透镜阵列和葡根霉菌切片的定量相位成像和测量。该装置可方便地与普通光学显微镜相结合,具有巨大的应用潜力。
Quantitative Phase Imaging(QPI)is a technique that can measure the phase map of the light field.It has the characteristics of label-free,non-invasive and three-dimensional observation and has been widely used in bioimaging and industrial inspection.A number of techniques have been developed to measure phase information of objects,including the interferometric method such as Digital Holographic Microscopy(DHM),and the non-interferometric method such as the Fourier Ptychography Microscopy(FPM),Transport of Intensity Equation(TIE)method and so on.The interferometric method has high measurement accuracy but a complex experimental setup sensitive to the environmental disturbance.The non-interferometric method recovers phase from the intensity patterns of objects,but requires iterative calculation or multiple images recorded at different positions,which makes the imaging speed slow and unsuitable for real-time observation.The quantitative phase imaging based on Quadriwave Lateral Shearing Interferometry(QLSI)has the advantages of the referenceless beam,simple configuration,high stability and fast imaging speed.In the existing studies,Cross Grating(CG),Modified Hartmann Mask(MHM),Randomly Encoded Hybrid Grating(REHG)and other splitter elements were used for QLSI.The cross grating has low diffraction efficiency and energy utilization rate(~10%)for the four beams of first-order diffraction.The MHM and REHG can concentrate the diffracted light energy on the four firstorder diffraction beams.But the MHM still has a low energy utilization rate(~37%),and the REHG has a complex structure for fabrication.This paper proposes a quantitative phase imaging method based on QLSI using a two-dimensional(2D)Ronchi phase grating.The light incident to the 2D Ronchi phase grating is diffracted mainly with energy concentrated on the four first-order diffraction beams,occupying 65.7% of the total incident energy.The object light carrying the sample′s phase information is imprinted to the 2D Ronchi phase grating and then copied into four beams,which interfere with each other to produce the quadriwave lateral shearing interferogram.The quantitative phase image of the sample is reconstructed by Fourier analysis of the interferogram.The influence of the grating period on the QLSI imaging is analyzed theoretically,and the optimal grating period is determined to be six times of the pixel size of the detector.This match can make the best use of the spatial bandwidth product of detector and achieve high resolution image.The influence of the illumination wavelength on the phase reconstruction is theoretically analyzed,which shows that the proposed method is insensitive to the illumination wavelength.The feasibility of quantitative phase imaging under wide spectral light illumination source is demonstrated.The compact QLSI module is constructed with the pixel size of 9 μm×9 μm of the detector and the period of 54 μm of the 2D Ronchi grating.The grating period is precisely six times of the pixel size,meeting the requirement of the optimal condition.The QLSI module is directly connected to a conventional optical microscope to implement the QPI imaging of e.g.,Polymethyl Methacrylate(PMMA)microspheres,microlens arrays and staphylococcus section.The relative error of phase experimentally measured is about 1.8%,proving that the method has a high precision of phase measurement.The experimental results also show that the method can be used for quantitative phase imaging with a wide-spectrum light source,making it easily combined with conventional optical microscopes to have a great application potential in biomedicine,three-dimensional topography measurement and other related fields.
作者
宋金伟
闵俊伟
袁勋
薛雨阁
姚保利
SONG Jinwei;MIN Junwei;YUAN Xun;XUE Yuge;YAO Baoli(State Key Laboratory of Transient Optics and Photonics,Xi’an Institute of Optics and Precision Mechanics,Chinese Academy of Sciences,Xi'an 710119,China;University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《光子学报》
EI
CAS
CSCD
北大核心
2022年第11期212-221,共10页
Acta Photonica Sinica
基金
国家自然科学基金(No.61975233)
中国科学院青年创新促进会(No.2019393)
国家重点研发计划重点专项(No.2018YFE0128300)。
关键词
干涉术
四波横向剪切干涉
定量相位成像
相位测量
相位光栅
Interferometry
Quadriwave lateral shearing interferometry
Quantitative phase imaging
Phase measurement
Phase grating
