用数值模拟方法研究面光源劈尖干涉问题

在面光源照射下,给出了劈尖表面可观察到干涉条纹的条件,通过Matlab软件进行数值计算,分析了劈尖表面的干涉条纹数目对光源距离和尺寸的依赖关系,结果表明,对给定的光源宽度,要在劈尖表面观察到一定级数的条纹,光源距离不能低于一定的值．这种数值模拟方法对设计复杂的非平行光薄膜等厚干涉试验有参考价值．     

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%.     

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。     

利用等厚干涉法测量玻璃弹性模量

提出了一种基于等厚干涉原理测量玻璃弹性模量的方法。在标准平板玻璃上表面和待测平板玻璃下表面形成空气薄膜劈尖,分别测量待测平板玻璃在自然和受力两种状态下等厚干涉条纹的分布情况,从而得出玻璃弹性模量。该方法有效消除了玻璃平板表面不平整、材料内部不均匀和自身重力等因素对测量结果的影响。干涉条纹的分布信息通过CCD图像采集及计算机处理获得。该方法原理简单,设备常见,测量精度高,适用于实验教学,也可用于科研测量。     

利用等厚干涉法测量玻璃弹性模量简

提出了一种基于等厚干涉原理测量玻璃弹性模量的方法。在标准平板玻璃上表面和待测平板玻璃下表面形成空气薄膜劈尖,分别测量待测平板玻璃在自然和受力两种状态下等厚干涉条纹的分布情况,从而得出玻璃弹性模量。该方法有效消除了玻璃平板表面不平整、材料内部不均匀和自身重力等因素对测量结果的影响。干涉条纹的分布信息通过CCD图像采集及计算机处理获得。该方法原理简单,设备常见,测量精度高,适用于实验教学,也可用于科研测量。     

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.     

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。     

基于迈克耳孙干涉仪及劈尖测量透明液体折射率

提出了基于迈克耳孙干涉仪及劈尖组合的测量透明液体折射率的方法,对迈克耳孙干涉仪进行简单改装,将一个注满待测透明液体的劈尖和一个空的玻璃劈尖分别置入2个光路中.通过调节传动装置使注入液体劈尖在光路中的厚度发生缓慢变化,从而记录生出或消失的干涉条纹个数,进而测量液体的折射率.     

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。     

Double-grating interferometer with a one-to-one correspondence with a Michelson interferometer

We describe a double-grating interferometer that has a one-to-one correspondence with a Michelson interferometer. The half spatial periods of the gratings are equivalent to the wavelengths of the interferometer. The widths of the interference fringes can be changed easily. The intensity distribution of the interference pattern is independent of the wavelength of the light source used. The surface profile of an object can be measured because two interference beams can coincide precisely on the image plane of the object. The measuring range is much larger than that of a Michelson interferometer.     

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.     

The measurement of ultraweak liquid surface wave by laser interferometry

We describe a simple experiment on the interference of refraction light by ultraweak liquid surface wave at low frequency. The surface wave profile is generated by electrically driven vertical oscillations exciters. The high visibility and stable laser interference fringes were gathered experimentally. The theoretical light intensity distribution agrees well with the observations. In particular, we show the relation between the light intensity distribution and the characteristic features of the surface wave. In addition, we can measure the amplitude and wavelength of the ultraweak liquid surface wave at low frequency by this means.     

偏光干涉对光纤陀螺性能的影响

从光纤陀螺光学系统缺陷角度,研究了由于光纤陀螺保偏光纤融接误差及光学器件的不完善引起的偏光干涉效应,理论分析并实验研究了偏光干涉效应对传输光谱的影响及其对光纤陀螺性能的影响。研究表明,在当前的技术条件下,偏光干涉效应对光纤陀螺的标度因数影响可以忽略,偏光干涉不影响一般意义下的光源相干长度,但是却导致光源相干特性的变化,反应在相干图上出现了多个干涉衬比度峰值,这会降低宽谱光源的短相干长度特性给光纤陀螺带来的好处,由此也说明不能仅由相干长度这一个参量描述光源的相干特性。     

干涉高斯光诱导的表面等离子激元驻波场的分析

考虑到实际入射光强的空间分布不均匀,基于Kretschmann模型并采用角谱方法分析模拟了两束高斯光干涉诱导表面等离子激元(SPP)驻波场。与理想平面波不同,高斯光诱导的SPP干涉条纹幅值大小不等,分布复杂,这表明光强空间非均匀程度会严重地影响到曝光深度的分布。还分析了金属薄膜的厚度、损耗以及光刻胶的介电常数对SPP驻波场的影响,并得出不恰当的金属板厚和细微损耗都会极大削弱SPP驻波场,而如果光刻胶的介电常数过大则有可能产生不了表面等离子体共振的结论。     

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.