Multiple reflections in a wide-angle Michelson interferometer

The effect of multiple reflections from a semireflecting surface such as an interference filter located in front of or behind a wide-angle Michelson interferometer (WAMI) is examined. By considering the instrument as a complex operator on the incident electric field, theoretical results are obtained which describe a large variety of configurations. Experimental results are presented which are consistent with these results. It is concluded that since the presence of these reflections changes the form of the observed fringes and affects measurements of the phase and visibility of the fringes, care must be taken to avoid such reflections in designing WAMIs.     

White-light Fizeau interferometer

A white-light Fizeau interferometer is described. Commonly, white-light fringes can be produced only by using a virtual wedge instrument such as a Michelson interferometer. By use of a series arrangement of a Fabry-Perot interferometer in front of a two-beam Fizeau interferometer, white-light fringes can be produced. For white-light fringes to be obtained, the thickness of the air gap between the Fizeau plates has to be adjusted to the same thickness as the air gap between the Fabry-Perot plates (or in more general terms to a rational multiple of this value). The contrast of the two-beam type of Fizeau fringes depends on the reflectivity of the Fabry-Perot plates.     

Optical vortices generation using the Wollaston prism

A new setup of interferometers is proposed in which the set of specific optical markers--optical vortices--could be generated. The classical Mach-Zender two-beam interferometer has been modernized using the Wollaston prism. In this setup, the optical vortices could be obtained for a wide range of both beam parameters. The numerical analysis and experiments confirm our theoretical predictions.     

Simple interferometric technique for generation of a radially polarized light beam

We present a theoretical and experimental investigation of an interferometric technique for converting a linearly polarized Gaussian beam into a radially polarized doughnut beam. The experimental setup accomplishes the coherent summation of two orthogonally polarized TEM01 and TEM10 beams that are obtained from the transformation of a TEM00 beam by use of a simple binary diffractive optical element. We have shown that the degree of radial polarization is maximum at a given distance from the interferometer output port that depends on the diameter of the incident beam at the interferometer input port.     

Visual fourier-transform spectroscopy with a single crystal plate.

This paper shows how a single Z-cut plate of uniaxial crystal can be used as a two-beam interferometer of Fourier-transform spectrometer. As a visual device, it permits easy identification of a set of achromatic fringes that can be seen in any two-beam interferometer when a white-light source is observed through it. These fringes apparently have not been described previously. They are expected when we understand that the white-light fringe pattern is in fact the Fourier transform of the spectral-sensitivity curve of the eye.     

Test of photonic crystal fiber in broadband interferometry

Photonic crystal fibers (PCFs) are microstructured waveguides that are used in metrology, nonlinear optics, and coherent tomography. PCF studies are focused mainly on the improvement of dispersion properties and wide spectral single-mode operating domains. Consequently, in the astronomical context this kind of fiber is a good candidate for use in the design of a fiber-linked version of a stellar interferometer for aperture synthesis. We discuss the potential of these fibers to take advantage of wide spectral single-mode operation. We propose an experimental setup that acts as a two-beam interferometer that uses PCFs to measure fringe contrast at four wavelengths (670, 980, 1328, and 1543 nm), which correspond to the R, I, J, and H astronomical bands, respectively, with the same couple of PCFs. For this purpose we use, for the first time to our knowledge, a piezoelectric PCF optical path modulator.     

Accurate interferometric retardance measurements

A two-polarization Michelson interferometer with a low-retardance beam splitter and digital signal processing is used to measure the retardance of optical devices. Error analysis of the improved optical system and data processing shows that the measurement has an uncertainty of 0.039 degrees for measurements of nominally 90 degrees retarders. Retardance variations arising from coherent reflections in the retarder used for intercomparison add an uncertainty of from 0.005 degrees to 0.03 degrees , increasing the combined measurement uncertainty to as much as 0.049 degrees .     

Measurements of the small wave tilt using the optical vortex interferometer with the Wollaston compensator

A classical Mach-Zehnder two-beam interferometer was modernized using the Wollaston compensator, which allowed obtaining a stable set of specific optical markers--optical vortices. This new interferometer setup that generated optical vortices was used to measure small angle tilt. The theoretical basis of setups behavior has been described. The value of the described setup was confirmed by practical experiments.     

Multilocalization and the van Cittert-Zernike theorem. 2. Application to the Wollaston prism

The van Cittert-Zernike theorem can be used to evaluate visibility at the exit of an amplitude-division interferometer with two-beam interferences. If the source illuminating the interferometer is a periodic array of slits, at the exit there is a sequence of localization surfaces. The formulas for the position and fringe spacing of the principal localization surfaces are applied to a Wollaston quartz prism, and there is good agreement between theoretical and experimental results. Moreover, the fringe localization depth and the intermediate localization surfaces obtained experimentally coincide with those predicted by theory.     

Scanning white-light interferometer for measurement of the thickness of a transparent oil film on water

The thickness of a transparent layer of oil upon the surface of water is measured as the distance between the surface of oil film and the interface of the oil with the water. Two experimental results have demonstrated that the interface can reflect a white-light beam well enough to form an interferogram, even if the light is subjected to oil-film dispersion. When a beam of white light is incident vertically onto the oil-film surface, a scanning white-light interferometer in the Michelson configuration is employed to locate two serial reflections, surface reflection and interface reflection. The thickness of the transparent oil film on water is calculated based on the separation of these two interferograms. A limitation thickness, approximately 250 microm with 1.25 microm resolution, is achieved under the condition that there is 50 nW of optical power incident onto the oil-film surface with a wavelength centered at 1310 nm.     

Phase-shifting interferometer based on changing the direction of linear polarization orthogonally

We present a new type of phase-shifting interferometer, which utilizes a polarizing prism to form quadrature phase-shifted fringe patterns onto a single imaging sensor. By changing the direction of linear polarization of the incident light orthogonally, four phase-shifted fringe patterns in quadrature are obtained by taking images twice; thus it is possible to reduce phase errors caused by mechanical vibrations and air turbulence that occur in temporal phase-shifting interferometers. We present the principle of this interferometer with its theoretical analysis, using the Jones matrix, along with experimental results.     

晶片干涉中多种光波的叠加问题

光波在晶体表面来回反射形成了多种不同振幅的光波,光波叠加方式的不同会产生完全不同的效果.针对o光与e光非相干叠加和相干叠加两种情况,导出了光强公式.用铌酸锂晶体做了实验,结果与理论十分吻合.这对于分析晶体偏光干涉测量中的干扰以及充分利用干涉图信息改进测量方法与测量精度均具有重要意义.     

Overall comparison of subpicosecond electron beam diagnostics by the polychromator, the interferometer and the femtosecond streak camera

Measurements of longitudinal bunch length of subpicosecond and picosecond electron beams have been performed by three methods with three radiation sources at the 35 MeV S-band twin liner accelerators at Nuclear Engineering Research Laboratory, University of Tokyo. The methods we adopt are the femtosecond streak camera with a nondispersive reflective optics, the coherent transition radiation (CTR) Michelson interferometer and the 10 ch polychromator that detects the spectrum of CTR and coherent diffraction radiation (CDR). The measurements by the two CTR methods were independently done with the streak camera and their results were consistent with one another. As a result, the reliability of the polychromator for the diagnostics of less than picosecond electron bunch and the usefulness of the diagnostics for the single shot measurement were verified. Furthermore, perfect nondestructive diagnostics for subpicosecond bunches was performed utilizing CDR interferometry. Then the good agreement between CDR interferometry and the streak camera was obtained.     

Use of a laser as light source for an interference study of temperature and concentration fields in liquids

The advantages of using a laser as a light source in an IAB-451 shadow instrument, used as a two-beam diffraction interferometer for studying temperature and studying temperature and concentration fields in liquids, are reported.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 16, No. 1.pp. 136–139, January, 1969.     

Basic features of the upgraded S18 neutron interferometer set-up at ILL

The perfect crystal interferometer instrument S18 at the Institute Laue-Langevin (ILL) in Grenoble has been upgraded to allow more advanced neutron optics experiments for fundamental, nuclear and condensed matter physics. The new supermirror guide together with the multipurpose monochromator provides considerably higher intensities in a wide wavelength region. The optimal use of neutrons is obtained by a nondispersive arrangement of the monochromator and the interferometer crystals. This also allows to obtain completely polarised beams using permanent magnetic prism deflection. An additional third analyzer axis permits novel postselection experiments concerning momentum distribution and polarisation analysis of the interfering beams. Several types of large perfect crystal interferometers are available for different applications. The system can be configured as an advanced high-resolution Bonse–Hart small angle scattering camera. The results of various test measurements concerning intensities, interference contrast, long-term stability, the accessible wavelength range and the basic features as a SANS camera will be presented. Various proposals for experiments will be discussed as well.     

Fourier-transform phase-shifting interferometry

Phase-shifting interferometry is a preferred technique for high-precision surface form measurements, but the difficulty in handling the intensity distortions from multiple-surface interference has limited the general use of the technique to interferometer cavities producing strict two-beam interference. I show how the capabilities of phase-shifting interferometry can be extended to address this problem using wavelength tuning techniques. The basic theory behind the technique is reviewed and applied specifically to the measurement of parallel plates, where surfaces, optical and physical thickness, and homogeneity are simultaneously obtained. Basic system requirements are derived, common error sources are discussed, and the results of the measurements are compared with theory and alternative measurement methods.     

A photoexcited switchable perfect metamaterial absorber/reflector with polarization-independent and wide-angle for terahertz waves

We present a photoexcited switchable perfect metamaterial absorber/reflector for terahertz waves. The switchable absorber/reflector is based on a cross-shaped structure (CSS) integrated semiconductor photoconductive silicon (Si). The electric response property of the photoconductive Si can be easily modified through a pump optical beam. The conductivity of Si pads filled in the gap of CSS is tuned efficiently through the incident pump optical beam with different power, resulting in the modulation of absorption magnitude from 0 to 100% at the fixed operation frequency. Thus, the switch ability of the perfect absorber/reflector can be easily realized. Furthermore, the proposed design is polarization insensitive and operated well at wide incidence angles for both TE and TM waves.     

Analysis of coherent symmetrical illumination for electronic speckle pattern shearing interferometry

In an effort to find a non-contact technique capable of providing measurements of in-plane strain, a speckle shearing interferometer was designed using symmetrical coherent illumination. This paper presents an analysis of the sensitivity to displacement and strain of this interferometer, together with an analysis of the phase-stepping of the resultant fringe patterns. New notation is introduced alongside this analysis to define the interference components in speckle shearing interferometers using multiple illumination beams. Experimental results show fringe patterns and phase stepping in support of the theoretical analysis.     

基于两向设计地震动的二维自由场构建

针对在设计地震动基础上构建平面半空间自由场的问题,在综合考虑水平向与竖直向设计地震动基础上获得平面半空间自由场,实现了将设计地震动与以任意角度组合入射的P波、SV波构成的自由场相联系。首先在已有成果的基础上,研究了以任意角度入射情况下P波及其反射波、SV波及其反射波对水平向和竖直向设计地震动的贡献;然后在假设入射P波、SV波与两向设计地震动具有相同频率组成的基础上,获得了以特定角度组合入射条件下P波、SV波的频谱和相位信息;进而通过傅里叶逆变换获得入射P波、SV波的时间序列;最后依据P波、SV波及其反射波在平面半空间的传播情况获得自由场条件下平面半空间内任意点的水平向和竖直向地震动。该文所采用的波场构建方法可实现对包含任意频谱和相位信息的两向设计地震动所对应的平面半空间自由场的构建,所获得的斜入射P波和SV波也具有各自的频谱和相位信息。最终得到的平面半空间自由场任意点水平向和竖直向地震动时间序列具有非一致性;根据入射P波、SV波结合地基边界条件确定的空间点地震动时间序列可用于结构的非一致地震动输入。     

Measuring the refractive indices of liquids with a capillary tube interferometer

A theoretical analysis of the fringe pattern produced by a capillary tube interferometer is presented, which is expected to be two-beam interference, and a computer program to simulate the interference fringe pattern is established. By comparing the simulated fringe pattern and the experimental fringe pattern, the refractive index of the liquid can be given when the two fringes coincide best. The results of this method are close to those of the Abbe refractometer.