基于双频激光干涉相位检测的高精度波片测量

波片精度对偏振光学系统性能有着重要的影响,故需要对其相位延迟量和快轴方位角进行高精度测量。提出了一种新型基于双频激光干涉相位检测的高精度波片测量方法,采用双频激光外差干涉光路,利用一个可旋转半波片和一个角锥反射棱镜测量待测波片,可实现任意波片的相位延迟量和快轴方位角的高精度同时测量。所提方法不受波片、偏振片等双折射器件的方位角精度的影响,从原理上避免了该类系统误差。所设计的系统具有共光路结构,测量稳定性高,信号处理采用相位检测方式相对于一般的光强检测方式测量精度更高。此外,所设计的测量系统中元件很少,结构简单,测量过程快捷。误差分析表明,在现有实验条件下,测量系统的波片相位延迟量的测量不确定度约为3.9′,快轴方位角的测量不确定度约为5′′。实验比对结果表明,所提方法的测量结果与其他方法测量结果的一致性很好。重复性测量实验表明,测量结果的标准偏差约为2′。     

四分束全Stokes同时偏振成像系统波片快轴装调误差的分析及优化

建立了包含1/2波片(HWP)和1/4波片(QWP)快轴装调误差的Stokes矢量测量误差方程。分析了波片快轴的装调误差对7种典型基态入射光的Stokes矢量测量精度的影响,推导了任意入射光Stokes矢量测量误差的表征方法。仿真结果表明,偏振度越大,偏振测量误差越大,选取入射光偏振度为1时的偏振测量精度评估系统性能。提出了一种波片快轴装调误差的优化方法,当测量矩阵的条件数小于1.84时,选取0.772/0.228的分束比可使波片快轴装调误差对系统偏振测量精度的影响最小。为满足2%的偏振测量精度,HWP的快轴装调误差应在±0.15°内,QWP的快轴装调误差应在±0.52°内。     

四区域法消除偏振棱镜缺陷对波片相位延迟测量的影响

在起偏器-待测波片-检偏器系统基础卜提出一种四区域测量波片相位延迟量的方法.调整待测波片和检偏器的方位角,获得相应的四组光强值,通过线性运算得到待测波片的相位延迟量,完全消除了起偏器和检偏器不完全消光带来的误差.由于测量系统中不存在标准波片或其他相位调制元件,允许测量波长仅受偏振棱镜和探测器的限制,因此四区域法可适用于很大波长范围内的波片测量.以λ/4波片为例,理论分析了测量系统利用四区域测量法后的仪器误差为σφ≤士3.49065×10-3rad(约0.2°),精度比原算法提高约1个数量级.实验验证了四区域法能有效提高系统精度.     

基于计数法测量激光多普勒测速仪的测速精度

为了测量所设计的激光多普勒测速仪(LDV)的测量精度,用均匀转动的斩波片代替高精度的转台作为标准的速度源,并基于单片机AT89S52,采用光计数的方法测量斩波片上某一固定位置的切向运动速度,LDV的测量结果与之相比较。实验结果表明,LDV测速的相对精度不超过8‰,稳定性较好。     

椭偏法测量云母波片相位延迟量及双折射率(英文)

为了得到云母波片的相位延迟量和双折射率随波长的变化关系,利用椭偏光谱仪连续测量了云母波片在400～770nm光谱范围内的延迟量.在对云母波片进行校准后,测量的数据被光电探测器收集并输送到计算机,根据输出的数据可以得到云母波片的相位延迟量随波长的变化.利用测得的延迟量计算出了云母波片在一定光谱范围内的双折射率,得到了云母波片的双折射率色散曲线,并通过拟合得到了双折射率色散公式.该方法能测量任意波片的相位延迟量,并且具有测量方便、周期短、精度高等特点.     

椭偏法测量云母波片相位延迟量及双折射率

为了得到云母波片的相位延迟量和双折射率随波长的变化关系,利用椭偏光谱仪连续测量了云母波片在400~770 nm光谱范围内的延迟量.在对云母波片进行校准后,测量的数据被光电探测器收集并输送到计算机,根据输出的数据可以得到云母波片的相位延迟量随波长的变化.利用测得的延迟量计算出了云母波片在一定光谱范围内的双折射率,得到了云母波片的双折射率色散曲线,并通过拟合得到了双折射率色散公式.该方法能测量任意波片的相位延迟量,并且具有测量方便、周期短、精度高等特点.     

一种提高1/4波片相移量测量精度的方法

提出了一种新颖的，在已知四分之一波片快轴方向的情况下，利用两个偏振片和一个三棱镜来提高波片相位延迟角测量精度的简便方法，给出了对该方法的理论分析与不确定度公式，并给出了应用实例.此方法的主要优点是可以提高测量精度，并且操作简单，容易实现.     

基于激光回馈的波片在盘位相延迟测量系统

 利用激光回馈测量波片相位延迟精度高的优越性,以激光回馈技术为基础,实现光学波片的在盘测量,即在加工过程中,波片光胶于光胶盘的状态下测量波片位相延迟,以提高波片生产效率和成品率。采用凹面镜作为回馈镜以提高回馈信号调制深度,对激光回馈内、外腔长进行稳定,提高了系统可靠性;研究了波片与光胶盘光胶对波片测量的影响,提出并验证了在光胶盘上开孔,在打孔的光胶盘上光胶、加工、测量波片的新工艺,最终实现了波片在盘测量,测量长期重复性优于1°,经过激光频率分裂系统校正后,系统精度优于0.5°。     

分振幅型全Stokes同时偏振成像系统波片相位延迟误差分析

分振幅型全Stokes同时偏振成像仪具有实时性好、空间分辨率高、精度高等优点,有很高的应用价值.分振幅型全Stokes同时偏振成像系统利用偏振分束器、1/2波片和1/4波片将入射光Stokes矢量调制在4幅图像中,可解析入射光Stokes矢量. 1/2波片和1/4波片的相位延迟误差对Stokes矢量测量精度有着不可忽略的影响.建立了包含上述两种误差的Stokes矢量测量误差方程,分析了1/2波片和1/4波片相位延迟耦合误差对自然光、0°/45°线偏光、左旋圆偏光等典型基态入射光的Stokes矢量测量误差的影响,推导了任意偏振态的Stokes矢量测量误差的表征方法.在邦加球球面和球内选取不同偏振度的Stokes矢量作为入射光进行仿真.结果表明, Stokes矢量测量误差和偏振度测量误差均随着入射光偏振度的增大而增大.选取入射光偏振度为1时的偏振测量精度评估系统.为满足2%的偏振测量精度, 1/2波片相位延迟误差应在±1.6°内, 1/4波片相位延迟误差应在±0.5°内.这对提高系统的偏振测量精度具有重要意义,为系统设计和研制提供了重要的理论指导.     

基于共线外差干涉的波片相位延迟的测量系统

通过共线光外差系统对光波所携带相位信息的精密检测,以及对波片光轴在入射面内的不同方位时寻常光(即o光)和非常光(即e光)的传播特性的理解,搭建了共线光外差测量系统对波片的相位延迟进行测量.实验结果表明该测量方法的测量精度达到±0.5°,并通过对光线斜入射时波片相位延迟的检测对该方法进行了验证.     

A high-precision optical metrology system for determining the thickness of birefringent wave plates

This study develops a non-destructive measurement system for determining the thickness and refractive indices of birefringent optical wave plates. Compared to previous methods presented in the literature, the proposed metrology system provides the ability to measure the thickness of the birefringent optical plate in high-precision. The results show that for a commercially available birefringent optical wave plate with refractive indices of n_e=1.5518, n₀=1.5427 and a thickness of 452.1428 μm, the experimentally determined value for the error in the wave plate thickness measurement is just 0.046 μm. The measurement resolution of the proposed system exceeds that of the interferometer hardware itself. The proposed method provides a simple yet highly accurate means of measuring the principal optical parameters of birefringent glass wave plates.     

环形光纤声发射传感器的相位调制特性研究

提出了一种基于光纤Sagnac干涉仪的环形传感器,用于固体表面传播的超声波的检测.这种传感器的特点是能够精确地检测由固体表面传播的超声波产生的微弱振动.当超声波信号通过光纤传感器的两个臂到达探测器时,干涉仪的输出光强度受到了超声信号的调制.通过检测干涉仪的输出光强度并利用Fourier变换,测得了超声信号的振幅和频率.而且对传感系统的位相调制特性进行了仿真,并对实验结果进行了分析,结果表明该系统可用于固体表面传播的超声波频率特征的识别.     

Wavelength dependence of the phase retardation of a quarter-wave plate

We describe an optical heterodyne polarization interferometer that can be efficiently used for the precision measurement of the change in the state of polarization of a light wave induced by polarizing optical devices. This technique is used to measure the change with wavelength of the phase retardation of a quarter-wave plate. A theoretical derivation is presented to permit computation of the wavelength dependence of the phase shift induced by a quarter-wave plate.     

Measurement of vibrational energy flow in a plate with high energy flow boundary crossing using electronic speckle pattern interferometry

The measurement of vibrational energy flow is an important tool in understanding the vibrational behaviour of structures. In the past, because of transducer constraints, the measurement of vibrational energy flow was mostly restricted to single point measurements. However, recent developments in advanced laser measurement techniques, such as electronic speckle pattern interferometry (ESPI), have gained interest in applying two-dimensional, multi-point measurement techniques to the estimation of vibrational energy flow. This paper addresses the measurement of vibrational energy flow in a plate by using an ESPI based vibrational energy flow measurement technique. A radially symmetric bending wave plate vibration model is introduced and theoretical expressions for energy-based quantities are derived. To assess the accuracy of the measurement method, these theoretical quantities are compared to synthetic results derived from the ESPI energy flow measurement technique. The ESPI measurement technique is also applied to an experimental ‘infinite’ plate. Thus, a specially designed experimental apparatus was constructed so as to minimise undesired wave reflections in the plate and, thus, achieve a high energy flow boundary crossing at the edges of the plate. To reduce the effect of optical noise contamination on the ESPI measured out-of-plane plate displacement data, optimal filters were applied prior to the vibrational energy flow computation. To appraise the accuracy of the experimental method, measured vibrational power on the plate is compared with measured vibrational input power. A difference of less than 1 dB between both quantities indicates that vibrational energy flow within a rectangular plate that contains radially symmetric wave propagation can be measured to a good degree of accuracy if appropriate filtering is applied.     

基于电光补偿测量的光相位延迟拓展测量法

在激光电光调制补偿测量光相位延迟量过程中,加入交流调制电压形成倍频接收信号,获得消光的精确定位,能提高测量精确度。通过调制信号形状变化与相关参量之依赖关系,可拓展测量范围,解决在某些点附近无法测量波片相位的"盲区"问题。根据接收到的调制光信号形状变化趋势与待测波片样品方位、延迟量、旋转方向等条件的联系,在待测波片快轴选定后,通过波片旋转影响信号形状变化规律的观测,可敏锐地甄别在半波点或全波长点附近波片的正负偏差特性,从而解决了一般偏振干涉补偿测量相位无法解决的测量盲区问题。不改变测量系统结构也不需添加任何器件,适应于最小延迟偏差≥λ/360的情况。     

光纤Fizeau干涉仪的声发射检测研究

验证了一种基于光纤Fizeau干涉仪的声发射传感器,可用于固体表面传播的超声波的检测.这种传感器的特点是能够精确地检测由固体表面传播的超声波产生的微弱振动.当超声波信号通过光纤传感器到达探测器时,干涉仪的输出光强度受到了超声信号的调制.通过检测干涉仪的输出光强度并利用Fourier变换,测得了超声信号的振幅和频率.对传感系统的相位调制特性进行了仿真,并对实验结果进行了分析.     

激光遥感偏振成像系统光学元件调整及误差分析

改进了利用双旋转波片方法进行偏振成像的实验装置,提出了通过一次测量获得目标偏振度和强度编码图像的方法.运用光强法对激光遥感偏振成像装置的光学元件进行调整,通过斯托克斯和穆勒矩阵在偏振光学元件中的应用,给出了相应光学元件的调整原理、方法及过程.分析了激光器中心波长变动、偏振片的角度误差和波片的相位延迟及角度误差对整个系统的影响.结果表明,由偏振片角度和波片角度误差造成的出射光斯托克斯误差较小,不超过0.001,可以忽略;由波片相位延迟不精确造成的误差在0.02左右,所以应采用延迟精度较高的波片;激光器中心波长变化的影响最大,不能忽略,必须加滤光片使接收光的中心波长控制在808nm;镀有铝膜望远镜对接收到的散射光偏振度影响较小,适于激光遥感偏振成像系统的应用.     

Compensation of strong thermal lensing in high-optical-power cavities

In an experiment to simulate the conditions in high optical power advanced gravitational wave detectors, we show for the first time that the time evolution of strong thermal lenses follows the predicted infinite sum of exponentials (approximated by a double exponential), and that such lenses can be compensated using an intracavity compensation plate heated on its cylindrical surface. We show that high finesse approximately 1400 can be achieved in cavities with internal compensation plates, and that mode matching can be maintained. The experiment achieves a wave front distortion similar to that expected for the input test mass substrate in the Advanced Laser Interferometer Gravitational Wave Observatory, and shows that thermal compensation schemes are viable. It is also shown that the measurements allow a direct measurement of substrate optical absorption in the test mass and the compensation plate.     

Anisotropic optical feedback of single frequency intra-cavity He--Ne laser

This paper presents the anisotropic optical feedback of a single frequency intra-cavity He--Ne laser. A novel phenomenon was discovered that the laser output an elliptical polarized frequency instead of the initial linear polarized one. Two intensities with a phase difference were detected, both of which were modulated in the form of cosine wave and a fringe shift corresponds to a λ/2 movement of the feedback mirror. The phase difference can be continuously modulated by the wave plate in the external cavity. Frequency stabilization was used to stabilize the laser frequency so as to enlarge the measuring range and improve the measurement precision. This anisotropic optical feedback system offers a potential displacement measurement technology with the function of subdivision of λ/2 and in-time direction judgment. The three-mirror Fabry--Perot cavity model is used to present the experimental results. Given the lack of need of lasing adjustment, this full intra-cavity laser can significantly improve the simplicity and stability of the optical feedback system.