点光源劈尖干涉的条纹分布特征

在有限远的点光源照射下,导出了劈尖干涉的明、暗纹条件,通过Matlab软件,用数值分析方法给出了劈尖表面条纹分布特征,讨论了光源距离对表面条纹分布的影响.     

光的干涉法测金属线胀系数

当用两块平板玻璃制作出的空气劈尖顶角发生变化时 ,应用 CCD可观察到劈尖表面移动的干涉条纹。移过某一点的干涉条纹数决定劈尖项角的变化。若劈尖项角的变化是由金属受热膨胀引起的 ,则可导出金属受热膨胀的绝对伸长量与移过的条纹数之间的关系 ,并通过它计算金属的线胀系数。通过对黄铜棒的测量 ,结果表明该方法是可行的     

平行光入射时劈尖干涉误差的定量分析

定量分析了平行光入射空气劈尖和介质劈尖时,干涉条纹严格定域在劈尖上界面处时的条纹间距.数值计算表明对两种劈尖作光线垂直入射垂直反射的近似处理时,空气劈尖的误差较大,但是小于4%.     

劈尖干涉条纹定域的解析研究

得到了劈尖干涉定域中心参量方程和定域深度的解析解,解析地讨论了定域中心和定域深度与入射角、劈尖角、相对折射率、光源位置等物理量的依赖关系.研究的结果对确定清晰的劈尖干涉条纹位置具有指导意义.     

最小二乘法在劈尖干涉实验中的应用

基于空气劈尖干涉实验中,相邻两个级次干涉条纹所在位置处,在竖直方向上的空气层厚度差为二分之一波长,将移动读数显微镜测得的干涉条纹数据作为横坐标,由干涉条纹级次差确定的空气层厚度差作为纵坐标,进而对劈尖干涉仪中空气薄膜上表面与垂直于棱边平面的交线方程应用最小二乘法进行直线拟合,通过拟合得到的直线方程获取劈尖干涉仪所夹细丝的直径值。实验验证表明,新的实验数据处理方法结果可靠。     

用等厚干涉测液体的折射率

在等厚干涉的实验中,加入了用劈尖干涉对比法测液体折射率的内容,在不改变劈尖膜的条件下,同时测得空气膜和液体膜的干涉条纹宽度,从而可方便地求出液体的折射率,也使得等厚干涉的实验内容更加丰富和充实．     

一种激光定向的多窗口设计

在激光侦察告警等应用领域需要精确测定入射激光的方向。通过对平行激光在光学劈尖上产生等厚干涉条纹的分析，得到了激光入射倾角与条纹间距的关系，提出了利用入射激光在相邻3个光学劈尖上产生干涉条纹的间距来确定激光入射方向的探测模型，并详细论证了该模型的探测原理。给出了一种由9个光学劈尖组成的可实现半球空间激光定向的多窗口设计方案。理论计算表明，该方案切实可行，且在探测精度、反应速度和系统组成等方面与现有的激光定向技术方案相比具有一定的优越性。     

薄膜干涉条纹的可见度

在一级近似条件下，导出薄膜干涉条纹的可见度公式，人条纹可见度的角度定量分析干涉定域问题，直观地给出定域中心、定域深度随扩展光源、薄膜的劈尖角和厚度变化的规律．     

空间相干性的演示

当光源的空间相干度下降时，非定域干涉条纹随之变化为定域条纹．本文用Ｈｅ－Ｎｅ激光器、透镜和毛玻璃屏组成一个时间相干性极好而空间相干性连续可调的光源，在迈克尔逊干涉仪上形成干涉条纹，对该干涉条纹进行观察，以便了解光源的空间相干性．     

利用劈尖的等厚干涉测量液体的折射率

利用劈尖的等厚干涉测量了不同液体的折射率。在不改变劈尖夹角前提下,通过读数显微镜,分别得到劈尖在空气和液体中的干涉条纹间距ΔX_空、ΔX_液,从而运用n=ΔX_空/ΔX_液得到各液体的折射率。通过本实验,丰富了折射率测量的方式。     

Multiple beam Fizeau interferometer with filtered frequency comb illumination

Real wedge interferometers of the Fizeau-type do not allow for fringes in case of a spectral broadband source - or in short: for white light fringes. Here, the use of a suitable frequency comb source will help to overcome this limitation on the one hand and on the other will offer the capability for enhanced phase sensitivity in high precision measurements of surface deviations. Frequency combs can be produced either by using a pulse train from a fs-laser or by passive filtering of the light emitted by a broadband source as a superlum-diode or a fs-laser. The frequency comb produced by a common fs-laser is extremely fine, i.e., the frequency difference of consecutive peaks is very small or the distance of consecutive pulses of the pulse train might be of the order of 1 m. Therefore, the pulse train produced by passive filtering of a broadband source is better adapted to the needs of surface testing interferometers. White light fringes are either applied for the profiling of discontinuous surfaces and/or can serve as an indication for the correct choice of multiplication factors in superposition interferometry. During the last decennium it became more and more clear that spatially incoherent sources provide better measuring accuracy in surface measurements due to the reduced influence of dust diffraction patterns. The advantage of laser illumination can nevertheless be maintained if the laser light is made spatially incoherent through moving scatterers in the light path. Here, we will discuss the application of spatially incoherent broadband light frequency filtered through a Fabry-Perot filter. The main applications are in the following fields: (1) surface profiling applications using two-beam Fizeau interferometers, (2) selection of single cavities out of a series of interlaced cavities, and (3) sensitivity enhancement for multi-beam interferometers for planeness or sphericity measurements. Some of the discussed possibilities will be experimentally demonstrated.     

Surface plasmons modulate the spatial coherence of light in Young's interference experiment

It is shown how surface plasmons that travel between the slits in Young's interference experiment can change the state of spatial coherence of the field that is radiated by the two apertures. Surprisingly, the coherence can both be increased and decreased, depending on the slit separation distance. This results in a modulation of the visibility of the interference fringes. Since many properties of a light field-such as its spectrum, polarization, and directionality - may change on propagation and are dependent on the spatial coherence of the source, our results suggest that the use of surface plasmons provides a new way to alter or even tailor the statistical properties of a light field.     

一个新颖的白光干涉实验的开发与研究

开发了一个获得白光条纹的新实验.把劳埃镜干涉和光栅衍射结合起来,有可能使白光源产生的不同颜色的条纹彼此重合,从而能观察到清晰的黑白条纹.讨论了有关的实验原理、装置和方法,介绍了主要的实验关键并提供了相应的测量数据.     

马赫-曾德尔型相移矢量剪切干涉仪

为了实现对激光波面的等光程测试,设计了一个新颖的相移矢量剪切干涉仪。该干涉仪以马赫曾德尔结构为基础,为等光程干涉仪。通过在相干的两路光束中分别插入楔角方向正交放置的楔板实现矢量剪切;其中一块楔板分成两块(平板部分和楔板部分),楔板部分沿平板部分的表面移动,通过改变光程差来实现相移,2π相移所需的移动距离为几毫米的量级,该相移方法在相移精度控制上比较简单。文中还对楔板引入的横向剪切误差和相移误差进行了分析,最后给出了实验所得的一组相移干涉图。     

一种高精度光学位移传感器的设计分析

利用晶体双折射和由散射偏振引起的光学干涉技术,设计出一种高精度光学位移传感器.该传感器采用同轴光学系统,测量精度约为4 μm,测量范围不小于28 mm,且测量时不需要使用相干光源,故结构紧凑、性能稳定.     

迈克耳孙干涉仪非定域干涉条纹分析

针对迈克耳孙干涉仪实验调节过程中经常会出现椭圆、双曲线等非圆形二次曲线条纹的现象,本文基于点光源条件下非定域干涉的原理,推导出了干涉条纹满足的曲线方程,分析了不同条件下干涉条纹的形状,发现观察屏上可呈现圆、椭圆、抛物线、双曲线和直线5种类型的干涉条纹.基于理论结果进行了数值模拟和实验验证,数值模拟结果和实验结果吻合较好.     

Determination of ordinary and extraordinary refractive indices of nematic liquid crystals by using wedge cells

A new accurate and fast interference method for determining ordinary and extraordinary refractive indices of nematic liquid crystals is presented and discussed. The method relies on microscopic measurements of distances between interference fringes appearing in polarised parallel coherent monochromatic light beam transmitted normally to the surfaces through a wedge cell filled with a nematic. Both glass plates confining the cell are coated with a partly transparent thin film of metal which is deposited by evaporation in vacuum. Owing to the multiple reflections between the surfaces and a small edge angle, the interference fringes observed near the wedge apex edge are sharp and equidistant. To apply this method one needs only small amount of an investigated liquid crystal. Basic mathematical formulae and results of an experiment are briefly discussed.