基于光纤Michelson干涉仪的钻孔应变传感器

钻孔应变测量是观察地壳应力状态和变化,研究分析应变异常与地质灾害之间关系的主要手段。提出了一种基于光纤Michelson干涉仪的钻孔应变传感器,将钻孔应变转换成测量臂光纤的长度变化,并通过参考臂光纤补偿温度与环境的影响。实验结果表明,其精度为117nm,同时具备有很大的提升空间。该传感器耐高温高压,抗电磁干扰,抗雷击,可应用于野外观测站。     

用光纤迈克耳孙干涉仪测量折射率

对测量群折射率的白光干涉和光纤迈克耳孙(Michelson)干涉仪技术进行了改进.采用样吕夹片和样品与探测纤端面接触的方法,可以使群折射率的测量过程简单化.根据反射峰宽度的变化,可以调整样品反射界面与光纤的准直性,提高测量精度.     

一种结构新颖波长间距可调谐的光纤激光器

提出一种获得波长间距可调谐稳定激光输出的新颖结构,即把非平衡Michelson干涉仪接入光纤激光器谐振腔内,同时利用压电陶瓷调节干涉仪光程差,在1562.24 nm 波段得到小于0.06 nm可调谐波长间距的多波长激光输出.     

光纤传感器在微机电系统振动测量中的应用

本文介绍的光纤传感器根据Michelson干涉仪的原理,通过测量相干光的干涉条纹的移动来测量反射面的位移.同时,利用宽带光源,采用相位跟踪技术测量极微小的位移和位移的方向.从而,既能测量nm级极微小的振动,也能测量mm级的振动.为了适应高频振动的测量,引入DSP充当数据处理系统的核心,提高处理速度.该光纤传感器设计巧妙,精度高,使用方便.     

红外傅里叶变换光谱在化学上的应用

(一)红外傅里叶变换光谱(FT-IR)的特点 1.FT-IR FT-IR是利用干涉谱的傅里叶变换取得红外光谱的技术,被变换的干涉谱是双光束Michelson干涉仪当光束间光程差从零变到一些极大值时的记录。FT-IR系统是由Michelson干涉仪和计算机组成的,它是多路技术、干涉量度技术和变换技术的结合体。这里,光谱是通过数字变换复原的量,而干涉谱才是原始测量的量。当光源的发射为复色辐射时,干涉谱为:     

复合材料分层检测用光纤Mach-Zehnder干涉仪

发展了一种能够有效检测复合材料分层的光纤Mach Zehnder干涉仪。用一只2×2耦合器和一只3×3耦合器构成光纤干涉仪,输出信号经A/D转换后送入计算机,用软件进行信号解调。将此干涉仪的一个臂埋入材料内部或粘贴在复合材料表面,沿光纤逐点下压材料,通过光纤干涉仪测量出传感光纤形变的大小和方向,这样就能够有效的检测出材料内部是否存在分层。     

用三干涉臂马赫-曾德尔干涉仪制成的光纤密集型波分复用器

提出一种新型的光纤干涉仪 ,它是采用二个 3× 3单模光纤耦合器组成三光纤系统的马赫 -曾德尔 (Mach- Zehnder)干涉仪 ,当干涉仪的三条光纤干涉臂两两之间分别存在长度差Δ L和2Δ L时 ,干涉仪形成了一个波分复用间隔相等的三波分复用器 ,波分复用的波长间隔仅仅取决于ΔL的大小。实验样品的使用波段为 1.55μm,波长复用间隔为 1.6 nm,附加损耗为 0 .6 d B。     

光纤Mach-Zehnder干涉仪系统

介绍了光纤Mach-Zehnder(MZ)干涉仪系统的结构.给出了光纤Mach-Zehnder干涉仪系统中信号光与参考光的干涉原理以及影响干涉光强的因素.同时也分析了光纤耦合器的交叉耦合,另外也给出了PZT的作用.阐述了光纤偏振控制器的结构、工作原理及其对光纤Mach-Zehnder干涉仪系统传感臂偏振态的控制,最后给出了光纤Mach-Zehnder干涉仪系统的应用.     

光纤速度干涉仪

本文提出了一种用光纤作为延迟臂的新型速度干涉仪——光纤速度干涉仪,用以测量速度随时间的变化。选取不同长度的光纤,可测不同的速度范围。它扩展了测速范围,提高了测量精度。该系统提供两个相位差为90°的信号,因而提高了分辨率,并可鉴别加速与减速。     

基于匹配干涉仪的光纤环形激光相干坍塌抑制

跳模会导致单波长光纤环形激光器相干性有不同程度的退化,严重影响光学系统的性能。设计一种基于匹配干涉仪的相干坍塌抑制方案,分析抑制机理。并分别搭建臂差可调的空间光匹配干涉仪(SLMI)和全光纤结构匹配干涉仪(AFMI),通过实验对抑制效果进行方案验证。结果表明:当SLMI的等效臂差不断逼近理论值时,可监测到多模匹配干涉现象,该现象等效于单纵模激光干涉,从而实现相干坍塌抑制;AFMI结构紧凑,便于嵌入光纤相干探测系统中,能有效抑制随机跳模引入的相干坍塌和相位噪声谱级的大幅上升,降低系统虚警概率。作为一种被动手段,匹配干涉仪对抑制或规避模式失稳引起的相干坍塌具有指导意义。     

基于洛伦兹线型极光的上层大气风场探测模式研究

从洛伦兹线型极光的干涉强度、调制度与光程差的理论公式出发,用λ/4的步进光程差即“四强度法”获得一个波长范围内的4个干涉强度值,以实现基于洛伦兹线型极光的上层大气的风速、温度、压强等物理量的探测。提出用改形萨尼亚克成像干涉仪替代迈克耳孙干涉仪实现上层大气风场,给出了基准光程差的公式,并用四面角锥棱镜镀膜技术获得4个干涉强度值来同时探测上层大气风场的模式。最后在实验室将Kr灯557.0nm调整光束到一定宽度,对称地从顶角为60°的两面镀膜角锥棱镜的顶点入射,用768pixel×576pixel的CCD照相机接收到两个光斑的成像,这两个光斑的再复制就得到镀膜四面角锥棱镜在一个周期内的4个干涉强度光斑,从而获得上层大气风场。     

基于重采样技术的调频连续波激光绝对测距高精度及快速测量方法研究

调频连续波激光测距方法可以实现高精度的大尺寸绝对距离测量, 且测量过程无需合作目标, 在大空间坐标精密测量领域有很高的研究价值. 而如何提高测量分辨率和实用化一直是近年来调频连续波激光绝对测距研究的热点. 本文研究了调频连续波激光测距的原理, 基于双光路调频连续波激光测距系统, 提出了通过信号拼接提高测量分辨率的信号处理优化方案, 该方案可以提高测距分辨率, 且可以降低对激光器的性能要求; 提出了可实现高速测量的简易测量方法. 设计加工了双光路光纤调频连续波激光测距系统, 利用该系统进行了测距分辨率及测距误差标定实验, 实验结果表明: 优化方案可以有效地提高测量分辨率和测量效率, 在26 m测量范围内, 测距分辨率达到了50 μm, 测距误差不超过100 μm; 快速测量方案有较高实用价值.     

VISAR准零程差调试方法研究

介绍了任意反射面速度干涉仪(VISAR)中马赫-曾德干涉仪必须满足的准零程差条件.根据白光光程差调试精度高但不易相干的特点,提出了先利用激光粗调,再利用白光调试来实现零程差精密调节的方案.详细分析了激光粗调马赫-曾德干涉仪的调试原理、调试精度以及光程差不确定性.针对光程差不确定性,提出了改进的激光粗调方案,将光程差调节精度由毫米量级提高到微米量级,大大减小了白光调试的盲区,使白光精调变得简易可行.干涉仪最终光程差调试精度为1.6 μm.     

迈克尔孙干涉仪组合实验的改进与设计

采用HNL-55700多束光纤He-Ne激光器、钠光、日光灯作为相干光源，利用自光相干长度小的特点对迈克尔孙干涉仅调节优化，并对组合实验提出改进和设计。     

Analysis of a moderate resolution Fourier transform imaging spectrometer

A moderate resolution Fourier transform imaging spectrometer based on a modified Michelson interferometer is presented. The moving part of the interferometer is a moving wedged prism (MWP) instead of a moving mirror. The principle of the interferometer is described and the optical path difference as a function of the displacement of the MWP is calculated. Theoretical calculation and analysis are presented for the two moveable directions (hypotenuse and right angle side) of the MWP. The modified Michelson interferometer is not so sensitive to the non-uniform variation of moving speed and the environmental vibrations compared with the conventional Michelson interferometer. It is compact and has a large numerical aperture. The interferometer facilitated by CCD camera and the accompanying digital hardware and software are becoming the imaging spectrometer with moderate resolution is applicable in ultraviolet-infrared region.     

New Laser Interferometer with OPD Multiplication for Nanometer Measurement

By using coupled differential interferometry a new laser displacement measurement interferometer with nanometric accuracy has been developed. The resolution and the stability of the interferometer are improved by multiplicating the optical path difference (OPD). The new interferometer is simple in concept,symmetric in optical paths,without optical deadpath,easy to set up and align. λ/1600 resolution and nanometric accuracy are achieved within the measurement range of 10 mm.     

New Laser Interferometer with OPD Multiplication for Nanometer Measurement

1lntfortionLaserinterferometersarewidelyadoPtedinthefieldsoflengthmeasurementandtheyaredevtheingveryqulcklyintheseyears.RecentdevefoPment0fnanornetr0lDyhasputincreaseddemandsonthepedrianceofthelaserinterferomters,suchasstability,reS0utionandmeasuretnentaccuray.Bothdomesticandinternatdriallaserinterferometerswithhighaccuracy,esPeciaIlywithnanOInetricaccuracy,arelindtedtobewidelyaPpliedandcomrnerciahaedondifferentdegreebecauseofthesarneproblemi.e.thehighrequlrementformeasurementconditbo.Thea…     

A spectral interferometric method to measure thickness with large range

We present a spectral interferometric method to measure the thickness of an optical plate or a film with a single layer. The system is based on the Michelson interferometer configuration, and the spectral interference signal of a broadband light source is recorded by a spectrometer. The optical path difference (OPD) between two interfering beams can be obtained by Fourier transform from the spectral interferogram. Gaussian fitting is used to find the exact peak of fringe to enhance the precision of the measurements. When the sample is inserted into the sample beam, the film’s thickness can be calculated by comparing the change of OPD, provided that the sample group refractive index is known. Only a single measurement is needed to determine a film’s thickness after the initial OPD of the system is calibrated. As no moving parts are required, the system has good stability. In particular, a large range of thicknesses, from micrometers up to several millimeters, can be measured. Such a large range is valuable for optical measurements. For demonstration, we measured the thicknesses of preservative film, cover glass and carrier glass, which were 9.6 ± 0.55, 156.1 ± 0.75, 1008.44 ± 0.96 μm, respectively.     

Optical refractometer based on an asymmetrical twin-core fiber Michelson interferometer

We report and demonstrate an optical refractometer based on a compact fiber Michelson interferometer. The Michelson interferometer is composed of an asymmetrical twin-core fiber containing a central core and a side core. By chemically etching a segment of the twin-core fiber until the side core is exposed, the effective index of the side core in the etched region is sensitive to the environmental refractive index, which leads to a shift of the transmission spectrum of the Michelson interferometer. The experimental results show that such a device has a refractive index resolution of more than 800 nm/refractive index unit in the range of 1.34-1.37.     

Measurement of angular distributions by use of low-coherence interferometry for light-scattering spectroscopy

We present a novel interferometer for measuring angular distributions of backscattered light. The new system exploits a low-coherence source in a modified Michelson interferometer to provide depth resolution, as in optical coherence tomography, but includes an imaging system that permits the angle of the reference field to be varied in the detector plane by simple translation of an optical element. We employ this system to examine the angular distribution of light scattered by polystyrene microspheres. The measured data indicate that size information can be recovered from angular-scattering distributions and that the coherence length of the source influences the applicability of Mie theory.