【作者】 张锐；

【导师】 沈亦兵； 杨甬英；

【作者基本信息】 浙江大学 ， 光学工程， 2020， 博士

【摘要】 光学波前检测技术在工业、天文、生物医学等领域扮演着重要的角色。传统泰曼格林和斐索干涉系统动态范围和灵敏度为固定值,针对不同待测对象不能动态的调节,且系统结构复杂对环境干扰敏感,不适合于现场检测;夏克-哈特曼传感器结构简单,动态范围大,但是横向分辨率很低;点衍射干涉仪、三波前横向剪切干涉仪和交叉光栅横向剪切干涉仪都存在针孔或级次选择窗口对准困难的问题;改进哈特曼模板横向剪切干涉仪存在周期性Talbot效应,只能在特定位置才能得到高对比度干涉图。基于光通量约束的随机编码混合光栅(Randomly Encoded Hybrid Grating,REHG)横向剪切干涉系统无需级次选择窗口,没有周期性Talbot效应,具有抗干扰能力强,动态范围大,结构紧凑,剪切率连续可调,分辨率高等特点,在光学元件面形检测、光学系统像差检测以及定量相位成像等领域具有非常广阔的应用前景。本文在课题组已有工作的基础上,对REHG横向剪切干涉系统设计原理,以及剪切率、动态范围、灵敏度和波前重构精度等关键参数进行了讨论,提出了基于剪切波前特征提取的剪切率标定算法,应用REHG横向剪切干涉技术建立了非球面非零位通用化检测系统和宽带灵敏度增强实时定量相位成像系统。主要研究内容如下:论述了光学波前检测技术的背景及其在航空航天、军事、工业、生物医学成像等领域的重要意义,叙述了目前常用的波前检测技术及应用研究进展,综合分析了各波前检测技术的优缺点,提出REHG横向剪切干涉系统研究的必要性。论述了 REHG横向剪切干涉系统模型,针对传统剪切率计算误差较大的问题,提出了基于剪切波前特征提取的剪切率标定算法。分析了 REHG的数学模型、系统特性以及主要加工误差,并讨论了 REHG横向剪切干涉波前重构算法。明确了决定剪切率的主要因素,对系统相对灵敏度和动态范围等关键参数进行了详细讨论。提出了基于剪切波前特征提取的剪切率高精度标定算法,仿真结果相对于初始设定值误差仅为0.2%,具有很高的标定精度。针对非球面难以实现快速高精度通用化检测的问题,提出了基于REHG横向剪切干涉的非球面非零位通用化检测系统。阐述了系统结构特点和回程误差产生机理,分析了系统的通用化检测能力。讨论了基于实际检测系统建模的迭代逆向优化回程误差校正算法。基于本系统对非球面检测的原理性仿真,理想情况下面形重构残差均方根(Root Mean Square,RMS)值约为5×10-3λ,论证了 REHG横向剪切干涉非球面非零位检测方法的可行性和精确性。分析了系统关键元件位姿误差,并给出了误差控制方法。针对传统光强型显微镜对细胞观测需要染色标记的问题,提出了基于REHG横向剪切干涉的宽带灵敏度增强干涉显微镜(Wideband Sensitivity Enhanced Interferometric Microscope,WSEIM),可用于实时定量相位成像。针对单剪切定量相位成像系统存在频谱周期性缺失的不足,引入双剪切干涉系统对缺失的频谱进行补偿,并给出了灵敏度增强的剪切率选择约束条件。为了满足实时可视化定量相位成像的要求,提出了一种可用于并行计算的完全矢量化路径无关差分整平相位解包裹算法,对于两幅2048×2048像素干涉图的相位重构帧率可达54.91 fps。WSEIM仿真实验相位重构残差的标准差为0.751 nm,论证了系统的相位成像精度。对本文研究内容展开实验验证。首先采用刻蚀有特定图案的熔石英位相板进行剪切率标定实验,并对位相板刻蚀深度和球面镜面形进行表征,与ZYGO干涉仪测量结果RMS值误差均在10-3λ量级,论证了剪切率标定的精确性。搭建了非球面非零位检测实验系统,完成了关键元件位姿误差的控制,测量结果与ZYGO干涉仪无像差点法测量RMS误差为2×10-3λ,论证了系统的可行性和精确性。采用两个不同剪切率的REHG横向剪切干涉仪搭建了 WSEIM系统,对熔石英基板的表征与Wyko NT9100白光轮廓仪标准差为4.164 nm,验证了系统相位重构的高精确性。与传统单光栅四波前横向剪切干涉定量相位成像系统相比,WSEIM可以消除频谱缺失引起的周期性误差,并将时间标准差减小约50%。应用WSEIM实现了红细胞的实时动态定量相位成像,达到了预期研究目标。更多还原

【Abstract】 Optical wavefront testing technology plays an important role in industry,aerospace,biomedicine and other fields.The dynamic range and sensitivity of traditional Twyman-Green and Fizeau interferometric systems are fixed values,which cannot be adjusted dynamically for different requirments.The system structure is complex and sensitive to environmental vibrations,which is not suitable for testing in situ.The Shack-Hartman sensor holds the features of simple structure,large dynamic range,and good stability,but the lateral resolution is extremely low.The point diffraction interferometer,three-wavefront lateral shearing interferometer and cross grating lateral shearing interferometer all involve the problem of pinhole or order selection mask alignment difficulties.The modified Hartmann mask lateral shearing interferometer has periodic Talbot effect,and high-contrast interferograms can only be obtained at specific locations.Randomly encoded hybrid grating(REHG)lateral shearing interferometer based on luminous flux shows features of strong anti-vibration ability,high dynamic range,high resolution,continuous adjustable shear ratio with no order selection mask and Talbol effect.It has a broad application prospect in the testing of optical surface,optical system aberration and quantitative phase imaging.In this dissertation,the design principles of REHG lateral shearing interferometric wavefront testing system,as well as key parameters such as shear ratio,dynamic range,sensitivity and wavefront retrieval accuracy,are discussed.The shear ratio calibration algorithm based on shearing wavefront feature extraction is proposed.An aspheric non-null general testing system and a wideband sensitivity enhanced real-time quantitative phase imaging system using REHG lateral shearing interferometer are established.The main research contents are as follows:The background of optical wavefront detection technology and its important significance in aerospace,military,industrial and biomedical imaging are discussed.The current commonly used wavefront testing technology and application research progress are described and the advantages and disadvantages of each technology are analyzed.The necessity of studying the REHG lateral shearing interferometric system is proposed.The model of REHG lateral shear interference system is discussed and a shear ratio calibration algorithm based on shearing wavefront feature extraction(SWFE)is proposed.The mathematical model,system characteristics and main machining errors of REHG are analyzed,and the wavefront retrieval algorithm of REHG lateral shearing interferometer is discussed.The formula for calculating the shear ratio of the system is given,the main factors that determine the shear rate are clarified,and key parameters such as the relative sensitivity and dynamic range of the system are discussed in detail.A high-precision calibration algorithm for shear ratio based on SWFE is proposed.The error of the simulation result of shear ratio relative to the initial setting value is only 0.2%,which has a very high calibration accuracy.A generalized detection system for aspheric non-zero position based on REHG lateral shearing interferometer is proposed.Firstly,the structural characteristics of the system and the mechanis:m of return error are elaborated,and the universal detection ability of the system is analyzed.The iterative reverse optimization backhaul error correction algorithm based on actual detection system modeling is discussed.Based on the principle simulation of the aspheric surface detection by this system,the root mean square(RMS)value of the surface reconstruction residual is about 5×10-3 λ,under ideal conditions,which demonstrates the feasibility and accuracy of the system.The posture errors of key components of the system are analyzed,and the error control methods are givenA wideband sensitivity enhanced interferometric microscope(WSEIM)based on REHG lateral shearing interferometer is proposed,which can be used for real-time quantitative phase imaging.In view of the shortcomings of the spectral leaking in the single shear quantitative phase imaging system,a novel dual-shear wideband sensitivity enhancement interferometric microscope is introduced,the constraint for the optimal shear ratio selection is obtained.To accelerate the phase retrieval algorithm for real-time visualization,a fully vectorized path-independent differential leveling phase unwrapping algorithm is proposed.The phase retrieval frame rate for each pair of two 4 mega pixel interferograms can reach 54.91 fps.The standard deviation of the phase retrieval residual error in WSEIM simulation experiment is 0.751 nm,which demonstrates the phase imaging accuracy of the systemExperiments are carried out to verify the research content of this dissertation.First,the shear ratio calibration experiment is carried out by using the quartz phase plate fused with a specific pattern,and the etching depth of the phase plate and the spherical surface are characterized.The comparison with the testing results of the ZYGO interferometer demonstrates the accuracy of the shear ratio calibration.Then,an aspheric non-null testing experimental system is built,and the control of the posture and position errors of key components is completed.The RMS error measured by ZYGO interferometer is 2×10-3λ,which demonstrates the feasibility and accuracy of the system.Finally,a wideband sensitivity-enhanced quantitative phase imaging system based on two REHG lateral shearing interferometers with different shear ratios is established.The standard deviation of the characterization of the fused silica substrate by WSEIM and the testing result of the Wyko NT9100 white light profiler is 4.164 nm,which verifies the high accuracy of the phase retrieval of the system.Compared with the traditional quantitative phase imaging system based on single shear quadriwave lateral shearing interferometer,WSEIM can eliminate the periodic error caused by the lack of spectrum and reduce the time standard deviation by about 50%,providing an effective method for label free real-time dynamic quantitative phase imaging of biological cells.更多还原