利用激光谐振腔测量透明介质薄板的光学均匀性

提出了一种利用激光谐振腔测量透明介质薄板光学均匀性的新方法.该方法将对折射率微差的测量转化为对激光谐振频率的变化进行测量.两种样品的实验对比结果表明,该方法可以实现10－5量级以上灵敏度的光学均匀性测量.最后分析了实验结果的误差及适用的灵敏度测量范围.     

光学玻璃光学均匀性高精度测量技术

高质量的透射光学系统对光学材料的光学均匀性要求非常高 ,材料局部折射率 10 -6 量级的变化就可能破坏整个系统的性能。详细介绍了三种用于测量光学玻璃光学均匀性的干涉法 ,研制了一台高精度光学玻璃材料光学均匀性测量仪。实验结果表明 :40mm左右厚的光学玻璃材料的光学均匀性检测精度可达 1× 10 -6 。     

红外光学材料折射率均匀性的测量不确定度评定

基于多样品多型号仪器的测试信息及其GUM和MCM方法,讨论了四步干涉法测量红外光学材料折射率均匀性的测量范围及其测量不确定度评定。红外干涉测量的绝对灵敏度和准确度虽不及可见激光干涉仪,但采用了四步干涉测量的方法,消除了干涉仪的固有系统误差,有利于实现对红外光学材料折射率均匀性的高准确度测量。实际测试表明,该测量范围覆盖110-5～510-3,测量相对标准不确定度为210-1～210-2。     

Direct measurement on transparent plates by using Fizeau interferometry

It is shown that Fizeau interferometry provides an accurate optical method to measure the refractive index and wedge angle of transparent plates used as optical components in different experiments. A near IR external cavity diode laser having spectral resolution up to 10⁻⁷ has been employed to measure the refractive index of the test plates by introducing amplitude modulation technique in the detection system of our phase shifting Fizeau interferometry. Detection of spatial fringes has been performed to find out the wedge angles of the plates by using a He–Ne laser along with the CCD-image sensor.     

Fizeau型偏振移相干涉仪的实验研究

研究了一种Fizeau型偏振移相干涉仪。以中心波长为650nm的多纵模半导体激光器作为光源,利用光源的短相干特性和一套偏振延迟装置分出一对偏振方向正交的参考光和测试光,采用巴比涅-索列尔补偿器作为偏振移相器。测试了一块平行平板的前表面面形,面形PV值为0.0682λ,RMS值为0.0127λ。该方法的优点是移相精度高,移相时无须推动参考镜,适用于大口径光学系统的干涉测试,可消除多表面干涉杂散条纹的影响。     

Simultaneous measurement of several near-parallel surfaces with wavelength-shifting interferometry and a tunable phase-shifting method

Wavelength-shifting interferometry can distinguish in frequency space interference signals from different surfaces, and therefore allows the measurement of optical thickness variation between several quasi-parallel surfaces of a composite transparent object. Frequency analysis of the signal spectrum with a tunable phase-shifting formula can then detect the phase of the individual signals. We have devised a tunable phase-shifting method which uses a freely adjustable number of intensity samples and can be adapted to any frequency spectrum. To extract the signal reliably, two properties of the phase-shifting method are particularly important: it should suppress cross-talk from unwanted frequencies, and it should allow for some variation in the signal frequency. We show that a carefully designed sampling function envelope will combine these benefits, and demonstrate the technique in measurements of three different composite objects each consisting of three reflecting surfaces. The importance of phase-shift linearisation is discussed, and methods for selecting optimal set-up parameters are given.     

Inspection of axial stress and refractive index distribution in polarization-maintaining fiber with tomographic methods

An experimental method is given for determination of three-dimensional axial stress distribution in polarization-maintaining optical fibers. The method relies on using phase-shifting digital photoelasticity for gathering several integrated retardation maps for multiple angular position of object and using them as input data for tomographic procedure. The experimental data obtained for panda-type fiber show the regions of high stress in the core and stress member areas of the fiber cladding. The obtained results are in good agreement with the theoretical values known from literature. Also measurement of refractive index distribution in the fiber was done by means of microinterferometric tomography. Interesting correlation between the stress and refractive index distributions is shown and explained.     

3-D surface profilometry using simultaneous phase-shifting interferometry

Urgent needs for high-speed, non-contact and on-line measurement with high accuracy and repeatability are of great interest for automatic optical inspection (AOI) industries. Therefore, optical phase-shifting interferometry for precision 3-D surface profilometry has become an important metrological method due to its non-contact and high measurement accuracy. Traditional phase-shifting interferometry is very sensitive to vibrations because image acquisition in various phase-shifting sequences could easily introduce measurement errors from environmental influences, such as air disturbance and system structure vibrations. In this paper, we introduce a new simultaneous phase-shifting interferometer for 3-D surface profilometry which employs a single glass plate to generate simultaneous phase-shifted interferograms. Phase reconstruction is performed by using a developed phase-shifting algorithm which uses a three-step phase-shifting method with phase differences of 90°, 180°, and 270° for three interferograms. To verify measurement accuracy and repeatability, the system was employed to measure surface profiles of surface of a flat mirror and set of Mitutoyo gauge blocks. The experiment result shows that the method is proven to be capable of performing one-shot interferometric measurement and minimizing influences from environmental disturbances with measurement repeatability down to 10 nm or less.     

移相干涉仪的抗振技术研究进展

在对光学元件面形进行检测和光学系统成像质量的评价中,移相干涉测量技术有着广泛地应用。但是,光学干涉仪的测量精度对环境的要求非常苛刻,环境的振动和空气的扰动会对测量结果产生很大影响。提高移相干涉仪的抗振性很有必要,受到广泛重视。国际上移相干涉仪的抗振技术主要包括主动抗振和被动抗振两方面,两种技术具有各自特点。     

A refractive index interferometry method based on the X-ray crystallography

The absorption contrast image is very low for those weakly absorbing materials or weak phase object, such as the soft biological tissues, however, the phase item value of refractive index is a thousand larger than the absorption item, therefore the refractive index interferometry method is expected to be a new imaging tool for them. An interferometry method based on the X-ray crystallography is explored to the measurement of refractive index in this paper. The theoretical foundation, the optical design, the crystal transistor performance are the key parts to this interferometry method based on the X-ray crystallography. We give out a special refractive index detection scheme, using a laboratory hard X-ray source, and four single Si crystals. With this instrument, refractive index profile of those weak phase object can be unfolded accurately using this method. This refractive index interferometry method based on the X-ray crystallography will provide a new research tool for those special material properties or biological tissues study.     

Effect of xylenol orange on the crystalline perfection,optical, piezoelectric and NLO behavior of unidirectionally grown imidazolium L-Tartrate single crystal

Pure and 0.1 mol% Xylenol orange (XO) doped Imidazolium L-tartrate (IMLT) nonlinear optical (NLO) single crystals were grown using Sankaranarayanan–Ramasamy (SR) method of uniaxial solution crystallization technique. The pure IMLT crystal is 100 mm in length and 15 mm in diameter. The doped IMLT crystal is 25 mm in length and 10 mm in diameter. UV–Vis-NIR spectrum shows that the pure and XO doped IMLT crystals' cut off wavelength is 235 nm. High-resolution X-ray diffraction (HRXRD) measurement and birefringence interferometry confirm that the SR method grown crystal has good crystalline perfection and optical homogeneity. The wavelength dependent refractive index and piezoelectric d₃₃ coefficient were measured. The difference refractive index (Δn) of (100) plane in parallel and perpendicular directions shows a strong dependence on wavelength. The dielectric constant, hardness and SHG conversion efficiency were also increased as a result of XO dye doping in IMLT crystal.     

超快激光抽运-探测中探针光时间延迟量的 实时测量原理与光学设计

为了在飞秒激光抽运-探测(pump-probe)的超快测量中对探针光时间延迟量进行实时检测与有效控制,提出了一种四路同步移相干涉的光学测量系统.应用琼斯理论对该光学测量系统进行了优化设计与计算,推导出同步移相干涉系统各帧干涉图相应点的光强表达式,确定了相邻干涉图之间的相移步长,并给出了相位延迟量测量的解析表达式.最后,对光学系统在检测中可能存在的误差进行了计算分析,结果表明,系统的设计不仅能满足超快pump-probe精度的基本要求,而且优于目前同步移相干涉测量的光学设计,对于800 nm中心波长的探针光在理论上可达阿秒级的时间分辨率. 关键词： 超快抽运-探测 时间延迟量 同步移相干涉 琼斯矩阵     

Simultaneous measurement of whole in-plane displacement using phase-shifting ESPI

A novel method for simultaneously measuring whole field in-plane displacements by using optical fiber phase-shifting electronic speckle pattern interferometry (ESPI) is presented in this paper. A 1 × 4 single mode optical fiber beamsplitter is employed to split the laser beam into four beams of equal intensity. One pair of fibers is utilized to illuminate the diffuse target at equal angles in the horizontal plane so it is sensitive only to horizontal in-plane displacement. Another pair of optical fibers is set to be sensitive only to vertical in-plane displacement. The polarization directions of light emitted by fibers are the same for each pair, but are at a right angle between pairs. The optical fibers are equal in length for each pair, but are not equal between two pairs. In this case the speckles are interference between each pair of fibers, thus the horizontal and vertical displacement components can be obtained simultaneously. By means of a fiber phase shift technique we can obtain the quantitative data of whole field displacements. This method has made it possible to study the in-plane displacement of a thin metal plate, and the examples of the results are shown to demonstrate the novel method.     

Measurement of surface figure of plane optical surfaces with polarization phase-shifting Fizeau interferometer

A Fizeau interferometer based set up for measurement of surface forms of plane optical surfaces has been discussed. Phase shifting interferometry has been applied using polarization phase shifter. A linearly polarized (632.8 nm) He–Ne laser has been used as the source. Light reflected from the object and the reference/master surfaces are made circularly polarized in opposite senses by means of two properly oriented quarter wave retardation plates placed at appropriate positions, one inside and other outside the interference cavity of the interferometer, and phase shifts are introduced between the object and the reference/master waves by varying angular orientation of a polarizer/analyzer. Final result is made free from any residual wave-front aberrations introduced by the (intra-cavity) wave plate by subtracting phase values obtained by PSI technique between a high optical quality master surface and the reference surface from that obtained for the test object surface with respect to the same reference surface for each point of the interference field. Results are shown for a plane surface.Advantages of the technique presented are linearity and high accuracy in phase stepping, no perturbation of the interference cavity during the phase shifting and possibility of real time or dynamic interferometry.     

A Method for Measuring the Three-Dimensional Refractive-Index Distribution of Single Cells Using Proximal Two-Beam Optical Tweezers and a Phase-Shifting Mach—Zehnder Interferometer

This paper describes a method for measuring the three-dimensional (3D) refractive-index distribution in a single cell. The method can be used to observe the distribution of cell components without fluorescence staining. The two-dimensional optical path length distributions from multiple directions are obtained by non-contact rotation of the cell. These optical path lengths are converted into the line integrals of the refractive index, and the 3D refractive-index distribution is reconstructed by means of computed tomography. The refractive-index distribution in a breast cancer cell can be measured using a phase-shifting Mach—Zehnder interferometer in conjunction with proximal two-beam optical tweezers.     

光学材料光学均匀性检测方法分析

光学均匀性是光学材料的重要指标,直接影响到透射光学系统的波面质量,改变系统的波相差。惯性约束聚变（Inertial Confine Fusion,ICF）激光驱动器的研制要求对材料的光学均匀性进行高精度的检测,同时兼顾洁净度要求。实验中利用斐索干涉仪实现了大口径光学材料光学均匀性的检测,并与国外检测数据进行了对比,对检测过程中的影响因素主要包括样品的厚度测量偏差及折射系数偏差进行了分析。结果表明,样品的厚度测量偏差及折射系数偏差对结果的影响较小,可以忽略。同时用两种干涉仪专用软件对大量样品测量数据进行处理,对比了不同干涉仪光学均匀性的计算结果,表明这两种情况下对光学均匀性的处理结果相符,解决了大口径光学坯件光学均匀性的检测问题。     

基于白光扫描干涉法的光纤折射率分布的测量

提出了一种光纤折射率分布的测量方法,采用白光扫描干涉技术,并在参考镜上构造与光纤样品相同的结构来克服白光相干长度短的限制,优化了光路,提高了干涉条纹间的对比度.采用与白光干涉信号的包络线呈高斯分布的Morlet小波作为小波变换的母小波进行拟合处理,得到光纤与已知折射率的匹配液之间的相对高度.通过计算获得光纤的折射率分布...     

基于飞秒光梳多路同步锁相的多波长干涉实时绝对测距及其非模糊度量程分析

飞秒光梳被广泛用于时间频率技术和精密光谱测量,由其时频特性所衍生的绝对测距技术以可溯源、大尺寸、高精度等优点有望成为未来长度计量的最重要手段.本文提出了一种基于飞秒光梳多路同步锁相的多波长干涉实时绝对测距方法,使多个连续波激光器通过光学锁相环技术同步锁定到飞秒光梳梳模上,通过多路同步相位测量和小数重合算法最终实现绝对距离测量.所提测量方法不仅能保留传统激光干涉测距的高分辨力和精度,而且可溯源至时间频率基准,对高精度长度测量、尤其是对物理复现“米”的定义具有重要计量意义.测距实验证明,四波长干涉测距的非模糊度量程达到44.6 mm,折射率波动导致非模糊度量程变化为纳米量级;多波长干涉测距的非模糊度量程也受制于空气折射率的测量误差,多波长干涉绝对测距的非模糊度量程在实验室环境下可达数米、甚至几十米,并通过2米线性位移实验证明了多波长绝对测距的大量程和线性测量性能.     

光电极值法结合外差干涉法监控膜厚的研究

光电极值法是光学薄膜厚度监测的常用方法,该方法在镀膜前引用块状材料的折射率设计膜系。而在实际镀制过程中,用于镀制光学薄膜的材料折射率会发生改变,从而给膜厚的监控带来误差。为了避免折射率变化的影响,采用外差干涉法测量折射率,将实际测得的薄膜折射率应用光电极值法监控薄膜的设计,从而减少了因材料折射率的变化引起的误差。以750nm截止滤光片的镀制为被测对象进行了实验,对制备的滤光片透射率光谱曲线进行了比较。结果表明,实际的透射率曲线与设计的透射率曲线吻合较好,两次实验曲线平均吻合度均在98%以上,系统稳定性很好,从而说明结合外差干涉法的光电极值监控法可以很好地克服折射率变化引起的误差。     

测量光纤折射率分布还原算法的研究

用透射式微分干涉法测量光纤内部折射率分布,其原理是利用旋转检偏器对测量光束进行调制,从相位分布和光程分布中计算出折射率分布。其中,从光程分布中解算出折射率分布的算法是关键。讨论了该算法的数学模型,推导了测量公式,并对算法的稳定性和误差进行了分析。利用自行研制的系统对渐变折射率分布光纤进行实测,与在NR 9200光纤测量仪上的结果进行了比较,对主要误差源进行了分析和计算机模拟。实测和模拟计算结果表明,该算法原理正确,系统稳定,测量精度优于10-3,完全可以用来测量光纤折射率分布。