Interferometric Determination Research Articles

Interferometric Determination for Cosmological and Stellar Phenomena

The development of experimental methods that distinguish between light from objects with a similar color temperature and polarization presents a significant practical problem. In this paper, we demonstrate that the two-point correlation function (and its resultant correlation length) of a black body with an extended angular spectrum significantly differs from that of a black body with a narrow angular one. Using these results, we discuss an interferometric method as a possible experimental tool for discriminating between objects with the same color temperature but having different angular spectra.

Frequency-domain interferometry for the determination of time delay between two extreme-ultraviolet wave packets generated by a tandem undulator

Synchrotron radiation, emitted by relativistic electrons traveling in a magnetic field, has poor temporal coherence. However, recent research has proved that time-domain interferometry experiments, which were thought to be enabled by only lasers of excellent temporal coherence, can be implemented with synchrotron radiation using a tandem undulator. The radiation generated by the tandem undulator comprises pairs of light wave packets, and the longitudinal coherence within a light wave packet pair is used to achieve time-domain interferometry. The time delay between two light wave packets, formed by a chicane for the electron trajectory, can be adjusted in the femtosecond range by a standard synchrotron technology. In this study, we show that frequency-domain spectra of the tandem undulator radiation exhibit fringe structures from which the time delay between a light wave packet pair can be determined with accuracy on the order of attoseconds. The feasibility and limitations of the frequency-domain interferometric determination of the time delay are examined.

Generation of THz Vortex Beams and Interferometric Determination of Their Topological Charge

In this article, we developed and demonstrated the efficacy of 3-D printed spiral phase plates (SPPs) for the generation of vortex terahertz (THz) beams with angular momenta <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\ell = \pm 1$</tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\ell = \pm 2$</tex-math></inline-formula> . The vortex beam generation was confirmed by means of frequency-domain transmission spectroscopy. The topological charge <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\ell$</tex-math></inline-formula> of the vortex beams was determined via phase-sensitive Mach–Zehnder interferometry, which enabled the superposition of a vortex beam with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\ell$</tex-math></inline-formula> and its conjugate beam with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$-\ell$</tex-math></inline-formula> . The resulting interference patterns were found to be consistent with the expected intensity distributions for a given <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\ell$</tex-math></inline-formula> , which provides strong confirmation of the spatial phase structure of the generated vortex beams in the THz regime.

Interferometric Method for Determination of X–ray Train Length

It is elaborated, made and tested a special interferometer–train metering device. А method for interferometric determination of X–Ray train length is offered. It is proved that the interference pattern disappears, when the path difference between imposing waves is more than the monochromatic X–Ray train length. The limit of disappearance of interference pattern depending on the value of path difference is determined. The X–Ray train length is determined which is close to the meaning determined theoretically.

Interferometric radius of curvature measurements: an environmental error treatment.

Interferometric determination of sphere radii is a well known technique. To keep accuracy high and uncertainties low, a precisely controlled environment is usually necessary. Environmental changes in temperature lead to time dependent drift in important measurement parameters and to disturbed results. We present a method to minimize time dependent drift to the first order. With this method, it is either possible to reduce the uncertainties further, or to relax environmental conditions and still be able to accomplish high precision measurements. We discuss two typical measurement configurations, the associated benefits and drawbacks and some relevant error sources.

Holistic Approach to R&D Products’ Evaluation for Commercialization under Open Innovations

A holistic approach to R&amp;D products’ evaluation for commercialization under open innovations is developed. The approach is tested on the example of the device of the interferometric determination of the refractive index of crystalline materials in the optical range. The proposed approach will allow setting a price that will satisfy all the parties of a transfer agreement with a higher level of accuracy and will meet market requirements. Unlike popular methods of evaluating the R&amp;D product, a holistic approach will, on the one hand, be based on the actual costs and the break-even level of a R&amp;D product and, on the other hand, will determine how much the consumer is receptive to a R&amp;D product, and, then again, will show how the added value of the product will develop under the influence of market effects. It is noted that the application of a holistic approach to R&amp;D products’ evaluation for commercialization should be supplemented by assessing the willingness of potential customers to purchase this R&amp;D product at a specific price. It is proved that the proposed holistic approach to R&amp;D products’ evaluation for commercialization is multifunctional. The approach can be applied to different types of economic activity, R&amp;D products, and types of markets. The obtained prices based on the application of a holistic approach to R&amp;D products’ evaluation for commercialization and the results of marketing research of the interferometry market testified to potential prospects of the commercialization of a R&amp;D product of the interferometric determination of the refractive index of crystalline materials in the optical range and its long-term competitiveness. Based on the results, the key provisions of the concept of providing competitive benefits for the period of implementation of the analyzed R&amp;D product are identified. Taking into account fundamental elements of the open innovation paradigm underpins the authors’ holistic approach.

Interferometry and Simulation of the Thin Liquid Film between a Free-Rising Bubble and a Glass Substrate.

Because of their practical importance and complex underlying physics, the thin liquid films formed between colliding bubbles or droplets have long been the subject of experimental investigations and theoretical modeling. Here, we examine the possibility of accurately predicting the dynamics of the thin liquid film drainage using numerical simulations when compared to an experimental investigation of millimetric bubbles free-rising in pure water and colliding with a flat glass interface. A high-speed camera is used to track the bubble bounce trajectory, and a second high-speed camera together with a pulsed laser is used for interferometric determination of the shape and evolution of the thin liquid film profile during the bounce. The numerical simulations are conducted with the open source Gerris flow solver. The simulation reliability was first confirmed by comparison with the experimental bubble bounce trajectory and bubble shape evolution during the bounce. We further demonstrate that the simulation predicted time evolution for the shape of the thin liquid film profiles is in excellent agreement with the high-speed interferometry measured profiles for the entire experimentally accessible film size range. Finally, we discuss the implications of using numerical simulation together with theoretical modeling for resolving the complex processes of high velocity bubble and droplet collisions.

Correction to: Statistical and interferometric determination of the optical thickness of a multilayer transparent plate

In the original publication Acknowledgements was not included. The Acknowledgements is given in this correction.

Interferometric determination of thermal expansion coefficient of piston/cylinder unit – preliminary investigation

This paper describes laboratory method for experimental determination of the pressure balance piston and cylinder coefficients of thermal expansion (CTE) using interferometric technique with internally developed software. Measurements were carried out on one gas standard piston/cylinder units in the Croatian National Length (HMI/FSB-LPMD) and Pressure Laboratory (HMI/FSB-LPM). Measurement method, equipment, procedure and CTE results are given, as well as an evaluation of the measurement uncertainty. Results were compared with other relevant data from literature.

Statistical and interferometric determination of the optical thickness of a multilayer transparent plate

Wavelength-tuning Fizeau interferometry has been widely used to measure and estimate the optical thickness of optical components. However, in multilayer interferometry, the coupling errors between the higher harmonics and phase-shift error cause systematic errors in the calculated phase distribution. This paper presents the derivation of a 15-sample phase-shifting algorithm that can compensate for the phase-shift miscalibration and up-to-first-order nonlinearity of the coupling errors between the second-order harmonic and phase-shift error. The characteristics of the 15-sample algorithm are estimated with respect to the Fourier representation in the frequency domain. The optical thickness of a highly reflective lithium niobate crystal wafer is measured using a wavelength-tuning Fizeau interferometer and 15-sample algorithm. Finally, the optical thickness is determined from the measured data using the statistical Student’s t test.

A TGAS/GaiaDR1 parallactic distance to the σ Orionis cluster

With the new Tycho‐Gaia Astrometric Solution (TGAS), I derive a new parallactic distance to the young σ Orionis open cluster, which is a cornerstone region for studying the formation and evolution of stars and substellar objects from tens of solar masses to a few Jupiter masses. I started with the list of the 46 brightest cluster stars of Caballero (2007). After identifying the 24 TGAS stars in the 30 arcmin‐radius survey area and accounting for 11 FGKM‐type dwarfs and giants in the foreground and background, I got a list of 13 cluster members and candidates with new parallaxes. Of them, I discarded five cluster member candidates with questionable features of youth and/or discordant parallaxes and proper motions, including a distant Herbig Ae/Be star, and proceeded with the remaining eight stars. The σ Orionis mean heliocentric distance is , which is consistent with a contemporaneous interferometric determination that concludes a two‐decade dispute on the cluster distance. As a by‐product, the reclassification of those five cluster member candidates, now interlopers, shows a manifest deficit of cluster stars between 1.2 and 2.1 M⊙, which leaves the door open to new astrometric membership analyses with the next Gaia data releases.

Non-interferometric determination of Berry phases: Precession reversal in noiseless systems.

It is pointed out that the transition spectra between energy eigen-states of time periodic two level systems manifesting a Berry phase (BP) have two-peaked structures. These are similar to the twin peaks described by the author in Englman [J. Chem. Phys. 144, 024103 (2016)] for the "Molecular Aharonov-Bohm effect," but are now of unequal heights depending on the values of the BP. A rotation-directional reversal protocol of the precessing field allows a novel, spectroscopic (not interferometric or phase-probing) determination of the dynamic and topological phases from the peak-to-peak line shape distances, here worked out for noiseless BP systems.

Morphological changes in Proteus mirabilis O18 biofilm under the influence of a urease inhibitor and a homoserine lactone derivative

Proteus mirabilis is a pathogenic gram-negative bacterium that frequently causes kidney infections, typically established by ascending colonization of the urinary tract. The present study is focused on ureolytic activity and urease inhibition in biofilms generated by P. mirabilis O18 cells. Confocal microscopy revealed morphological alterations in biofilms treated with urea and a urease inhibitor (acetohydroxamic acid, AHA), as some swarmer cells were found to protrude from the biofilm. The presence of a quorum-sensing molecule (N-butanoyl homoserine lactone, BHL) increased biofilm thickness and its ureolytic activity. Laser interferometric determination of diffusion showed that urea easily diffuses through P. mirabilis biofilm, while AHA is blocked. This may suggest that the use of urease inhibitors in CAUTIs may by less effective than in other urease-associated infections. Spectroscopic studies revealed differences between biofilm and planktonic cells indicating that polysaccharides and nucleic acids are involved in extracellular matrix and biofilm formation.

Swelling of a hemi-ellipsoidal ionic hydrogel for determination of material properties of deposited thin polymer films: an inverse finite element approach

Selective deposition of polymers at the surface of an ionic hydrogel is conventionally used to tailor properties of the composite material for application in for instance drug release and cell encapsulation. Here we describe a method for determination of the mechanical properties of a thin polymer film deposited on an ionic hydrogel core. The ionic strength-dependent hydrogel swelling is affected by the cross-link density and thickness of the deposited polymer layer. A hemi-ellipsoidal geometry of the hydrogel, corresponding to that employed in proof-of-concept experiments, is used to enforce biaxial deformation of the deposited layer when the ionic hydrogel core is equilibrated at various ionic strengths. The ionic strength dependent equilibrium swelling ratio of the hydrogel with the deposited polymer film is modeled using a finite element approach. The free energy of the hydrogel core includes contributions accounting for polymer mixing, elastic deformation of the network and the Donnan equilibrium. The latter type of contribution is not included in the neutral thin layer in the present study. Adding the polymer multilayer/shell at the surface reveals that the ionic strength-dependent swelling constraint is more pronounced the thicker and stiffer the film is. Combining thickness measurements of the polymer film with high resolution interferometric determination of reduction in swelling capacity of ionic hydrogels, an equivalent elastic property of the polymer layer is obtained using inverse finite element analysis. In the proof-of-concept experiments, analysis of data obtained for chitosan–alginate multilayers composed of four and eight polymer bilayers deposited on an anionic acrylamide-based hydrogel core suggests that these bilayers show an elastic stiffness one order of magnitude larger than that of the hydrogel core.

Interferometric determination of heat release rate in a pulsated flame

Introducing a new measurand, namely the rate of change of density in line-of-sight, can be of great interest for people working on thermoacoustics and combustion noise. In this work the relationship between the radiated acoustic pressure, the time rate of change of unsteady heat release and of density fluctuations in a laminar pulsated premixed flame is presented. The burner produced a ‘M’-shaped flame which is excited by harmonic modulations of the flow at two forcing frequencies f=51 and 101Hz. Measurements were performed by a microphone to record the sound pressure radiated by the flame in the far field, a photomultiplier to collect the light emission from which the heat release rate was estimated, and a laser vibrometer to detect the rate of change of density fluctuations within the reaction region. As the latter technique is a novel approach in combustion analysis a detailed description of the fundamentals of laser interferometric vibrometry is presented. Laser vibrometry offers the advantage to be low-demanding in terms of instrumentation and settings and to be relatively straightforward to process for a broad frequency range. The different signals recorded are correlated. An interpretation of the measurement data is given and the potential of laser vibrometry to obtain time resolved data on density and heat release rate fluctuations in the flame region is demonstrated.

Interferometric determination of the high-intensity laser-pulse-material interaction site

We developed a method that accurately determines an unknown position of the high-intensity laser-pulse-material interaction site on the front side of a plate. It is based on interferometric measurements of a normal displacement at known positions on the plate’s rear side. The displacement is caused by reflections of various pulsed-laser-induced mechanical waves. We have superseded the long-established time-of-flight approach with the improved, triple-echo method. To accurately locate the origin of the laser-induced ultrasound on the plate with a known thickness, we only need to detect the arrivals of the first three consecutive mode unconverted waves. Our method works without knowing the propagation velocities of various ultrasonic waves and additionally solves some time-related drawbacks of the conventional time-of-flight approach. The relative uncertainty of the measured source-receiver separations obtained with the presented method is less than 0.01.

Interferometric determination of the birefringence of thermo‐tropic polyester fibers and its copolymers of structure (PCPT‐co‐CPO)

AbstractThe aim of this study is to determine the optical anisotropy of three different samples of thermo‐tropic polyester fibers of structure Poly(chloro‐1,4‐phenylene terephthalate‐co‐4,4′‐oxybisbenzoate) and its copolymers (PCPT‐co‐CPO). The molar fraction of disruptor units ([CPO]) ranging from 0.40 to 0.60. The variable wavelength interferometry, VAWI technique, was used to determine the birefringence and spectral dispersion properties of such of these fibers. The Cauchy's dispersion formula and its related constants were determined using the spectral dispersion curves of the birefringence. A mathematical formula was derived for direct measurement of the birefringence profile of highly birefringent polymer fibers using VAWI technique. The effect of varying copolymer molar fractions of the three samples of thermo‐tropic polyester fibers was investigated throughout the spectral dispersion curves, the Cauchy's formula constants and the birefringence profiles. Microinterferograms are given for illustration. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

The diameter of the CoRoT target HD 49933

Context. The interpretation of stellar pulsations in terms of internal structure depends on the knowledge of the fundamental stellar parameters. Long-base interferometers permit us to determine very accurate stellar radii, which are independent constraints for stellar models that help us to locate the star in the HR diagram. Aims: Using a direct interferometric determination of the angular diameter and advanced three-dimensional (3D) modeling, we derive the radius of the CoRoT target HD 49933 and reduce the global stellar parameter space compatible with seismic data. Methods: The VEGA/CHARA spectro-interferometer is used to measure the angular diameter of the star. A 3D radiative hydrodynamical simulation of the surface is performed to compute the limb darkening and derive a reliable diameter from visibility curves. The other fundamental stellar parameters (mass, age, and Teff) are found by fitting the large and small p-mode frequency separations using a stellar evolution model that includes microscopic diffusion. Results: We obtain a limb-darkened angular diameter of {\theta}LD = 0.445 \pm 0.012 mas. With the Hipparcos parallax, we obtain a radius of R = 1.42 \pm 0.04 Rsun. The corresponding stellar evolution model that fits both large and small frequency separations has a mass of 1.20 \pm 0.08 Msun and an age of 2.7 Gy. The atmospheric parameters are Teff = 6640 \pm 100 K, log g = 4.21 \pm 0.14, and [Fe/H] = -0.38.

Thermal expansion, normalized thermo-optic coefficients, and condition for second harmonic generation of a Nd:YAG laser with wide temperature bandwidth in RbTiOPO_4

Interferometric determination of thermal expansion and of normalized thermo-optic coefficients of RbTiOPO4 at four laser wavelengths are performed as a function of temperature. A suitable vectorial formalism applied to obtained data allows the establishment of the temperature dependence of refractive indices, and subsequent theoretical analysis enables one to predict that an extremum in the evolution of the phase-matching direction in the (X,Y) plane should occur near 100 °C for type II second harmonic generation of Nd:YAG lasers, with a temperature bandwidth that can be as large as 117 °C for a crystal of 10 mm in length. Such unusual behavior is observed experimentally by recording the conversion efficiency from 20 °C up to 220 °C for various propagation angles of light in the (X,Y) plane. Slight quadratic temperature dependence of the effective nonlinear coefficient is also observed.

Simplified procedure for interferometric determination of electro-optic properties of low-Tg photorefractive polymer

A simplified procedure is proposed for the interferometric determination of optical dispersions of refractive-index changes in a low-Tg photorefractive (PR) polymer. A two-level model for the optical dispersions is used in order to separately evaluate the index changes occurring due to molecular birefringence and first-order electronic electro-optic effects. This evaluation is done by estimating the contributions of the two effects in the low-frequency limit of a modulating voltage. The evaluated results are compared with those determined by a PR two-beam coupling experiment.