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 .     

Generation of amplitude squeezed states of light from phase squeezed coherent states

Abstract

We propose a scheme to generate a displaced macroscopic superposition of phase squeezed coherent states by incorporating an optical parametric oscillator (OPO) and a nonlinear Kerr medium in a Mach-Zhender interferometer configuration. We show that the phase squeezed coherent state generated by the OPO evolves into a macroscopic superposition of phase squeezed coherent states on spending a specific amount of time inside a Kerr medium. The phase space displacement is achieved by the interference of the intense reference beam with the signal in the final beam splitter of the interferometer. The noise of the reference beam contaminating the signal is prevented by making this beam splitter highly reflective. We have calculated the photon number uncertainty of the outcoming beam and have shown that it is smaller than the usual amplitude squeezed coherent state's value.     

Determining small angles of beam splitter rotation in optical vortex shearing interferometer

It is suggested to use a singular beam of unit topological charge in a scheme of vortex shearing interferometer intended for the observation of isoclinic fringes. In the interference pattern, the regions of fringe splitting determine the localization of wavefront dislocations and exhibit a shift that depends on the beam splitter rotation angel. Using the proposed method, it is possible to evaluate small angles of beam splitter rotation with an accuracy determined by the interference fringe width.     

Generation of inhomogeneously polarized laser beams by use of a Sagnac interferometer

A principal scheme for an external cavity technique for changing the polarization of a laser beam based on a modified Sagnac interferometer is proposed. The modified Sagnac interferometer includes standard optical components: a displacement polarizing beam splitter, an angle reflector, and a Dove prism. The radially polarized beams, obtained with the help of the developed scheme, allow the generation of a longitudinally polarized electric field by sharp focusing. The phase correction of radially polarized modes of higher orders leads to increasing the longitudinal field in the focus of the beam.     

Application of a Shack cube as a beam splitter in interferometers with a local reference beam

A different setup of the Mach-Zehnder interferometer for testing the convergent wave front is described. A Shack cube is used to replace a traditional recollimator and a parallel-plate beam splitter. An equivalent pupil model has been suggested that describes the point diffraction mechanism. The calibration procedures for the Mach-Zehnder interferometer are described. The Shack-cube beam splitter has the advantages of compactness and better reference-beam quality compared with the recollimator and the parallel-plate beam splitter.     

Creation of NOON States from Double Fock-State/Bose-Einstein Condensates

NOON states (states of the form |N〉 _a |0〉 _b +|0〉 _a |N〉 _b where a and b are single particle states) have been used for predicting violations of hidden-variable theories (Greenberger-Horne-Zeilinger violations) and are valuable in metrology for precision measurements of phase at the Heisenberg limit. We show theoretically how the use of two Fock state/Bose-Einstein condensates as sources in a modified Mach Zender interferometer can lead to the creation of the NOON state in which a and b refer to arms of the interferometer and N is the total number of particles in the two condensates. The modification of the interferometer involves making conditional “side” measurements of a few particles near the sources. These measurements put the remaining particles in a superposition of two phase states, which are converted into NOON states by a beam splitter. The result is equivalent to the quantum experiment in which a large molecule passes through two slits. The NOON states are combined in a final beam splitter and show interference. Attempts to detect through which “slit” the condensates passed destroys the interference.     

Testing Aspherics in Reflected Light Using Blazed Synthetic Holograms

It is shown that blazed computer generated holograms having a rotational symmetry (RSH) are especially suitable for interferometers working in reflected light which can be used in testing aspherics. The RSH acts either as a null lens of a very complex kind or it is used not only as beam splitter but also as beam combiner. From a more technical point of view, the latter version is especially interesting although in this case parasitic light caused by the double passage of all beams through the RSH may spoil the interference pattern. The two versions were tested experimentally. So, a Twyman-Green interferometer, on the basis of a blazed RSH, was built and tested. The interference pattern was free from severe disturbances because of the double passage through the RSH. Also a Fizeau interferometer was tested where the RSH acts as beam splitter and reunifer. Here the disturbances were more severe owing to the fact that the zero order as well as one first order of diffraction must be used. Possibilities for the suppression of stray light in this type of interferometer are discussed.     

一种新型单频激光干涉系统的研究

这种单频激光干涉系统采用共光路设计布局,通过偏振分束器以及1/4波长片等光学器件对干涉条纹进行空间移相,提取相位依次相差90°的三路干涉输出信号,进行比较放大,解决了常规单频激光干涉仪中的光强“零漂”问题。利用共模抑制技术,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。     

Absorbing beam splitter in a Michelson interferometer

The equality of the reflected and the transmitted irradiances by a beam splitter that consists of a thin absorbing coating (typically a metallic film) on a transparent plate is considered. The absorption and the phase difference between the reflected and transmitted fields are also studied. The lack of reversibility of this beam splitter introduces an asymmetry that is discussed for a Michelson interferometer.     

Multipass Michelson interferometer with the use of a wavelength-modulated laser diode

An improved multipass Michelson interferometer is implemented. This technique uses the fact that the wavelength of a laser diode varies in proportion to the diode's injection current. With this method the sensitivity augmentation is accomplished by inserting a beam splitter into one arm of the interferometer, resulting in multiple reflections between the end mirror and the beam splitter. In addition, the interference of laser beams reflected from two arms can be accomplished with unequal arms in the condition of a short coherence length. The sensitivity increase of interference fringes and the compensation of the short coherence length have been demonstrated in experiments.     

Tunneling selection of optical vortices

We have studied the process of separation of the dominant mode and guided vortices in a Y-shaped directional fiber beam splitter. It is shown that, under certain conditions, the dominant mode field is completely pumped to the second channel, leaving the optical vortex field in this channel unchanged. Based on such a splitter, a vortex fiber interferometer has been created and characterized with respect to linearity and temperature sensitivity.     

波片和偏振片对外差干涉仪非线性的影响

为了减小外差干涉仪的非线性误差,必须明确波片和偏振片对非线性误差的影响机理。通过理论分析和试验发现,波片和偏振片位于偏振分光镜之前和之后对非线性的影响是不同的。如果把有误差的波片和偏振片放置在偏振分光镜前面,其误差将100%地引入非线性。如果将相同的这些光学元件安装在干涉仪里面,有可能影响非线性,但通常在高阶误差范围内。     

干涉成象光谱技术

介绍典型的干涉成象光谱仪，包括基于Ｍｉｃｈｅｌｓｏｎ干涉仪的动镜扫描型，基于横切分束器的无动镜型和基于Ｆａｂｒｙ－Ｐｅｒｏｔ干涉仪的多光束干涉型等，给出基基本公式并分析其主要特点。     

Modeling the responsivity and self-emission of a double-beam Fourier-transform infrared interferometer

A modeling study aimed at characterizing the radiometric properties of a double-beam Fourier-transform infrared interferometer is presented. Measurements showed that the two responsivities associated with each interferometer channel are different in certain spectral regions. This anomaly was attributed to a dissymmetry between the optical transmissions of the two plates that form the beam splitter. This dissymmetry is primarily responsible for the instrument residual emission. A secondary cause of residual emission is attributed to the relative alignment of the two input optics. Both effects were taken into account in a model that gives the instrument residual emission in terms of the beam splitter temperature. Actual results indicate that in the 7-14-mum window the instrument residual emission can be modeled with an absolute radiometric error smaller than 0.5 K (blackbody at 290 K). The model was used to develop an automatic calibration procedure that yields radiance errors smaller than 0.05 muW/cm(2) sr cm(-1) in the 7-14-mum band. The radiometric stability of the interferometer was analyzed.     

Interferometric sensor for detection of surface-bound bioreactions

An integrated optical interferometer for direct detection of affinity reactions is presented. A modern version of a Young's interferometer is built with a waveguide structure as beam splitter and as sensing element. Resistive waveguides were produced by plasma-enhanced chemical vapor deposition of silicon oxinitride. At the output of this device a fringe pattern is detected by a CCD line camera. The adsorption of molecules on top of the waveguides is observed with a detection limit of 750 fg/mm(2). The resolvable variation of effective refractive index is 9 x 10(-8).     

Polarization phase-shifting interferometric technique for complete evaluation of birefringence

A full-field technique for simultaneous measurement of the magnitude of birefringence and its orientation is presented. This is achieved using a monolithic birefringence sensitive interferometer where the interference fringes carry the information of both the birefringence phase and the orientation of the fast axis of an optically transmissive anisotropic material placed at the output of the interferometer. The interferometer consists of a suitably polarization-masked cube beam splitter, orientated as in the Gates interferometer, which serves to generate a pair of orthogonally polarized and collinearly propagating light beams. Experimental results are obtained through an algorithm incorporating eight polarization phase-shifted interferograms.     

Inspection of commercial optical devices for data storage using a three Gaussian beam microscope interferometer

Recently, an interferometric profilometer based on the heterodyning of three Gaussian beams has been reported. This microscope interferometer, called a three Gaussian beam interferometer, has been used to profile high quality optical surfaces that exhibit constant reflectivity with high vertical resolution and lateral resolution near lambda. We report the use of this interferometer to measure the profiles of two commercially available optical surfaces for data storage, namely, the compact disk (CD-R) and the digital versatile disk (DVD-R). We include experimental results from a one-dimensional radial scan of these devices without data marks. The measurements are taken by placing the devices with the polycarbonate surface facing the probe beam of the interferometer. This microscope interferometer is unique when compared with other optical measuring instruments because it uses narrowband detection, filters out undesirable noisy signals, and because the amplitude of the output voltage signal is basically proportional to the local vertical height of the surface under test, thus detecting with high sensitivity. We show that the resulting profiles, measured with this interferometer across the polycarbonate layer, provide valuable information about the track profiles, making this interferometer a suitable tool for quality control of surface storage devices.     

X-ray-ultraviolet beam splitters for the Michelson interferometer

With the aim of realizing a Michelson interferometer working at 13.9 nm, we have developed a symmetrical beam splitter with multilayers deposited on the front and back sides of a silicon nitride membrane. On the basis of the experimental optical properties of the membrane, simulations have been performed to define the multilayer structure that provides the highest reflectivity-transmission product. Optimized Mo-Si multilayers have been successfully deposited on both sides of t he membrane by use of the ion-beam sputtering technique, with a thickness-period reproducibility of 0.1 nm. Measurements by means of synchrotron radiation at 13.9 nm and at an angle of 45 degrees provide a reflectivity of 14.2% and a transmission of 15.2% for a 60% s-polarized light, close to the simulated values. Such a beam splitter has been used for x-ray laser Michelson interferometry at 13.9 nm. The first interferogram is discussed.     

Biaxial thin-film coated-plate polarizing beam splitters

We present a design for a biaxial thin-film coated-plate polarizing beam splitter that transmits the p-polarized component of a beam of light without change of direction and reflects the s-polarized component. The beam splitter has a periodic structure and is planned for fabrication by serial bideposition in mutually orthogonal planes. Recent experimental data for form-birefringent silicon is used to establish the feasibility of the design for a beam splitter to be used at 1310 nm and at an angle of 45 degrees in air.