光纤白光干涉仪等臂长技术研究

介绍了几种光纤干涉仪等臂长技术,比较了各自的优缺点和适用范围,对光纤干涉仪的平衡有较大的参考价值。     

适合于内窥成像的共路型光学相干层析成像系统

提出了一种采用光纤型迈克耳孙干涉仪进行光程补偿的菲佐型光学相干层析成像(OCT)系统.该系统的传感探头为共路干涉结构,以解决现有内窥光学相干层析成像系统中存在的探头运动导致图像失真、以及更换使用不同探头时需进行色散和偏振态调节等问题.光程补偿和振动干扰实验结果表明,光程补偿方法正确可行,系统对环境干扰不敏感.利用研制的系统对反射镜和近红外卡进行了成像实验,验证了系统的有效性.提出的方法非常适合于内窥成像,并给出了把系统扩展为内窥光学相干层析成像系统的具体实现过程.     

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.     

An enhanced common path interference optic measurement system for refractive indices and thickness

This study proposes a common path interference optical system for the measurement of refractive indices and thickness of uniaxial crystal material. The measurement system comprises an accurate Mach–Zehnder laser interferometer, a single-axis rotary stepping motor, and a computer. The laser interferometer is composed of a single-frequency He–Ne laser, two-beam splitters and two reflectors. The Mach–Zehnder laser interferometer measures the optical length difference by using its linear measurement accuracy. The proposed solution procedure enables both the refractive indices and the thickness of the optical waveplate to be obtained. The proposed design differs from conventional designs in that it does not use a heterodyne modulator with a lock-in technique. It is shown that the refractive indices and thickness of the tested optical elements can be measured rapidly and accurately.     

基于双边倾斜傅里叶干涉具的激光光谱探测技术研究

为了在不改变静态傅里叶干涉具尺寸的基础上提高光谱分辨率,设计了双边倾斜傅里叶干涉具及等光程条纹展宽的方法。通过计算分析双边倾斜傅里叶干涉具空间产生光程差与传统干涉具光程差的关系,得到在整个干涉具尺寸不变的条件下,光谱分辨率提高到9.1 cm-1,比同尺寸静态傅里叶干涉具提高了近8倍,并且不会因干涉条纹混叠而造成无法采集。采用BK7材料加工制成双边倾斜傅里叶干涉具,用6种不同波长的激光照射分析干涉条纹,实验结果显示干涉条纹会因反射位置增大而导致探测波长较长的激光时中心波长偏大,根据其满足线性变化的规律,拟合可知每1nm的激光波长变化造成0.021 1 nm的增大误差,经过标定后平均误差与传统干涉具接近,同时可以有效地提高静态干涉系统的光谱分辨率。     

光纤干涉仪臂差的测量

用白光干涉和Michelson干涉仪技术测量光纤Michelson干涉仪和Mach-Zehnder干涉仪的臂差.这种方法能在线测量任意长度的光纤干涉仪臂差,包括零臂差,测量的精度由光源的相干长度确定,为微米数量级.     

共光路移相单频激光干涉测长系统

单频激光干涉系统采用偏振光移相方法,用来解决常规单频激光干涉仪中的光强"零漂"问题。共光路设计提高了干涉系统的测量稳定性和重复性。采用光程差放大技术提高了干涉系统的分辨力。在构造了一套实验布局的基础上,分析了影响系统测长精度的主要因素,并对干涉系统的测量误差分量做了定量的分析,完成了系统的精度测试。     

Simple method for measurement of surface roughness using spectral interferometry

The phenomenon that correlation between two beams, in a two-beam interferometer, modifies the spectral characteristics of the light field, is used to estimate the average of the roughness of the surfaces. In the case of intensity interferometer, the path difference between the two arms of the interferometer should be less than the coherence length of the light and the light should be quasi-monochromatic. However, the advantage of spectral interferometer is that the light need not be quasi-monochromatic and the path difference could be much more than the coherence length of light. It is found that more the path difference between the two arms of the interferometer, accurate are the measurements of the roughness of the surfaces. This study shows that spectral interferometry enables one to measure average roughness of the surfaces in the subscales of optical wavelengths.     

Influence of acoustic leakage at fluid–solid interface on interferometric detection of surface acoustic wave

When using laser interferometer to detect surface acoustic wave at fluid–solid interface, there are two factors which will cause the optical path length variation of the probe laser beam: interface deformation, and refractive index changes in fluid induced by acoustic leakage. Influence of acoustic leakage on laser interferometric detection for surface acoustic wave is researched here. A metal plate immersed in an infinite fluid is used as a physical model. Interface deformation due to laser-induced acoustic wave and pressure in fluid due to acoustic leakage are computed for select cases by finite element method. The optical path length variation caused by the two factors are calculated respectively and compared. The results show that the influence of acoustic leakage increases with the increasing acoustic impedance matching of fluid and solid, the peak-to-peak of influence degree increases linearly with the increasing acoustic impedance of fluid, and that decreasing the distance between the interferometer and interface can effectively reduce the influence of acoustic leakage.     

一种提高静态傅里叶干涉仪光谱分辨率的方法

为了在不改变静态傅里叶变换干涉具尺寸的前提下提高光谱分辨率,设计了正交斜楔型静态傅里叶变换干涉具,采用两个正交的等效斜楔形成连续的光程差变化.通过推导传统干涉具与正交斜楔型干涉具的光程差函数,设计了采用正交斜楔型干涉具增加有效探测长度,从而提高光谱分辨率的方法.经仿真计算,正交斜楔型干涉具的最大光程差为0.323 4 mm,比传统干涉具的0.080 8 mm大4倍左右,即光谱分辨率提高了4倍.实验证明,由于正交斜楔的探测原理使干涉具边缘的干涉条纹产生畸变,故要对干涉条纹进行边缘切除及滤波,给出了切除大小的计算公式.采用WQF520型光谱仪进行对比实验,检测800 nm的激光,该干涉具误差小于1 nm.该方法可有效地提高静态傅里叶变换干涉具的光谱分辨率.     

高速转镜干涉成像光谱仪的光程差分析

针对一种新的高速转镜干涉成像光谱仪的工作原理,给出其光程差的计算方法及结果.通过设定相关参量,重新构建光程差方程,并给出光程差在不同参量情况下的计算结果图,比较不同参量的影响.给出的光程差方程,为高速转镜干涉成像光谱仪的设计及获得的光谱图复原提供参量依据.     

Interferometric scanning of laser beams

A new beam deflection technique is based on modulating the optical transmission characteristics of a modified Fabry-Perot interferometer. Electro-optically changing the interferometer length leads to fast high resolution scanning of the transmission fringe. Experiments have been conducted using the 4880 Å argon laser line with an interferometer containing a LiNbO₃ crystal.     

First step toward a benchtop model of the Laser Interferometer Space Antenna

A technique for simulating large optical path lengths by use of digital delay buffers is presented. This technique is used to generate a synthetic interferometer with one arm having an arbitrary length. The response of the interferometer to phase and frequency modulation is measured and found to be in agreement with predictions. This technique could be used to simulate long-baseline interferometric space missions such as the Laser Interferometer Space Antenna.     

双剪切波面干涉测量法

用于星间通信的激光器具有接近衍射极限的激光波面,已有的波面测量方法,在这一具体测量问题中,都存在一定限制。双剪切波面干涉测量法在雅满横向剪切干涉仪的基础上,采用四块楔形平板,将干涉图分为上下两个部分,具有不同的条纹间距,由此求出波面高度和符号,同得到单幅干涉图的其它干涉测量方法相比,它的最小可测量波高减小一倍以上。在介绍干涉仪的基本结构和原理的基础上,模拟了像差存在时的干涉图,并在实验上得到了波高为0．3A的初步结果。双剪切波面干涉测量法,可以目视判断波差的符号和估计量值,为等光程相干,适用于半导体等相干长度小的光源。     

Polarization phase-shifting interferometer by rotating azo-polymer film with photo-induced optical anisotropy

A new type of phase-shifting interferometer was presented by rotating an azo-polymer film with photo-induced optical anisotropy in the light path of orthogonal polarization interferometry. By changing the angle of the optical axis of the azo-polymer film, four phase-shifted fringe patterns were obtained, from which phase difference between orthogonal polarized light could be calculated. The polarization states and the formation of the interferograms were analyzed theoretically using Jones matrix calculations and the experimental verification of the proposed method was also given. This method has a simple optical configuration which utilizes commercially available polarization devices and anisotropic azo-polymer film of low cost. The phase-shifting interferometer also demonstrates a new application of azo-polymer film.     

四种典型旋转型干涉仪的光程差分析和仿真

从经典迈克尔逊干涉仪结构出发,主要分析了四种旋转型干涉仪的结构特点,以及干涉仪的光程差与旋转角度之间的关系。通过设定参数,使用干涉仪光程差表达式对这四种旋转型干涉仪的光程差作了模拟仿真。在干涉仪光程差表达式基础上,对这四种旋转型干涉仪的旋转速度与旋转角度之间关系也作了模拟仿真。通过对干涉仪光程差的模拟仿真和比较,能够直观地反映出干涉仪光程差与旋转角度之间的关系。在要求运动速度误差控制在3%以内情况下,讨论了四种旋转型干涉仪的旋转角度范围。通过对干涉仪的光程差分析和仿真,这对于研究干涉仪的结构和性能分析具有很好的借鉴意义。     

A new lateral shearing interferometer for precision surface measurement

A new lateral shearing interferometer is proposed for precision surface measurement. In this shearing interferometer, a novel shear generator made of a single birefringence crystal plate is utilized. The shear adjustment is realized through the change of angle at which tested wavefront is incident into the crystal plate. By changing the orientation of the principal section of the plate, the generator can adjust the shearing direction. With the incident beam being circularly polarized, the generator can equalize the intensities of two shearing beams to make a good contrast interference pattern. The interferometer is simple and compact in terms of mechanism and has a complete common optical path structure. Phase shifting can be realized conveniently. The interferometer is insensitive to external vibrations and environmental disturbances, and hence has good stability and reliability with high measurement accuracy. To examine the performance of the proposed interferometer, experimental testing was conducted. High accuracy and repeatability are demonstrated.     

A displacement measurement system, utilizing a Wollaston interferometer

A dual interferometric displacement measurement system is presented where a Wollaston prism interferometer is employed in conjunction with a normal Michelson interferometer. The system operates without the use of external polarizers, apart from those associated with the Wollaston prism interferometer itself. It is shown that an optical path difference induced in the Michelson interferometer can be detected using the Wollaston prism in a normal interferometer arrangement. Further, the interference pattern produced by the Wollaston prism interferometer changes in a measurable, linear fashion as the optical path difference from the Michelson interferometer alters. A simple theoretical analysis of the system is presented and used to derive a computer model of the optical arrangement. Results from an experimental implementation of the system, using a Wollaston prism with a beam separation of 0.5 degrees and a superluminescent diode, of wavelength 825 nm, as a light source, are included and compared to the results from the computer model.     

基于莫尔干涉的激光中心波长精确检测的研究

为了提高激光中心波长检测的精确度,提出了基于正交干涉原理的静态干涉系统,由两个相互垂直的棱镜组成产生二维平面上的光程差分布,以面阵CCD取代线阵CCD,对平面上的正交干涉条纹数据进行采集.在计算分析莫尔干涉仪的光程差分布的基础上,计算干涉图像中干涉条纹的拼接及傅氏变换等,最终得到光谱分辨率.由MATLAB仿真软件分析结果可知,静态莫尔干涉系统可以产生的光程差最大为234μm,比等尺寸的傅里叶干涉体高约一个数量级.实验标定用的光谱仪选用LAB SPAKR 750A型光谱仪,针对中心波长为635 nm的半导体激光器进行测量,结果显示中心波长位置基本一致,但在中心波长附近的光谱细节上莫尔干涉优于传统干涉具.     

Wavelength modulation in a two-window common path interferometer for phase-shifting

A novel and simple method for phase-shifting under the scheme of a two-window 4f common path interferometer configuration with a binary grating at the Fourier plane is proposed. The proposal is based on periodicity variations of the grating grooves in the frequency space, which is emulated in an experimental implementation by changing the wavelength of a tunable laser diode used as the light source. Because of the common path configuration, it is expected to diminish errors due to undesired vibrations and optical aberrations. The viability of the proposal will be sustained with simulated and experimental, which include phase-shifted interferograms and reconstructed wavefronts. Due to the characteristics of the proposed experimental setup, it can be easily replicated and automated.