Time Holographic Interferometry Research Articles

Opto-Electrochemical Spectroscopy

Opto-electrochemistry is the state of the art and technology of not only imaging surfaces of a condensed matter, i.e., solid metal, submerged in aqueous solutions, but also, the science of measuring electrochemical properties of the condensed matter by solely light. In the present investigation, holographic interferometry was utilized for the first time to determine the rate change of the electrical resistance of aluminium samples during the initial stage of anodisation processes in aqueous solution. In fact, because the resistance values in this investigation were obtained by holographic interferometry, electromagnetic method rather than electronic method, the abrupt rate change of the resistance was called electrical resistance–emission spectroscopy. The anodisation process of the aluminium samples was carried out by electrochemical impedance spectroscopy (EIS) in different sulphuric acid concentrations (1.0–2.5% H2SO4) at room temperature. In the meantime, the real time holographic interferometry was used to determine the difference between the electrical resistance of two subsequent values, dR, as a function of the elapsed time of the EIS experiment for the aluminium samples in 1.0, 1.5, 2.0 and 2.5% H2SO4 solutions. The electrical resistance–emission spectra of the present investigation represent a detailed picture of not only the rate change of the electrical resistance throughout the anodisation processes but also the spectra represent the rate change of the growth of the oxide films on the aluminium samples in different solutions. As a result, a new spectrometer was developed based on the combination of the holographic interferometry and electrochemical impedance spectroscopy for studying in situ the electrochemical behavior of metals in aqueous solutions. Keywords: Holographic interferometry; Electrical resistance; Anodisation process; Electrochemical impedance spectroscopy (EIS); Sulphuric acid; Aluminium.

Opto-electrochemical spectroscopy of metals in aqueous solutions.

In the present investigation, holographic interferometry was utilized for the first time to determine the rate change of the electrical resistance of aluminium samples during the initial stage of anodisation processes in aqueous solution. In fact, because the resistance values in this investigation were obtained by holographic interferometry, electromagnetic method rather than electronic method, the abrupt rate change of the resistance was called electrical resistance-emission spectroscopy. The anodisation process of the aluminium samples was carried out by electrochemical impedance spectroscopy (EIS) in different sulphuric acid concentrations (1.0%-2.5% H2SO4) at room temperature. In the meantime, the real time holographic interferometry was used to determine the difference between the electrical resistance of two subsequent values, dR, as a function of the elapsed time of the EIS experiment for the aluminium samples in 1.0%, 1.5%, 2.0%, and 2.5% H2SO4 solutions. The electrical resistance-emission spectra of the present investigation represent a detailed picture of not only the rate change of the electrical resistance throughout the anodisation processes but also the spectra represent the rate change of the growth of the oxide films on the aluminium samples in different solutions. As a result, a new spectrometer was developed based on the combination of the holographic interferometry and electrochemical impedance spectroscopy for studying in situ the electrochemical behavior of metals in aqueous solutions.

Electrical Resistance-Emission Spectroscopy for Determining the Electrochemical Behavior of Anodized Aluminum in Aqueous Solutions

Holographic interferometry was utilized for the first time to determine the rate change of the electrical resistance of aluminum samples during the initial processes of anodization of the samples in aqueous solution without any physical contact. In fact, because the electrical resistance values in this investigation were obtained by holographic interferometry, electromagnetic method rather than electronic method, the abrupt rate change of the electrical resistance was called the electrical resistance –emission spectroscopy. The anodization process of the aluminum samples was carried out by the electrochemical impedance spectroscopy (EIS) test in different sulfuric acid concentrations (1.0–2.5% H2SO4) at room temperature. In the meantime, the real time holographic interferometry was used to determine the difference in the electrical resistance of two subsequent values, dR, as a function of the elapsed time of the EIS test for the aluminum samples in 1. 0, 1.5, 2.0 and 2.5% H2SO4 solutions. The electrical resistance–emission spectra of the present investigation represent a detailed picture of not only the rate change of the electrical resistance throughout the anodization processes but also the spectra represent the rate change of the growth of the oxide films on the aluminum samples in different solutions. Consequently, holographic interferometry is found to be very useful for surface finish industries, especially for monitoring the early stage of anodization processes of metals, in which the rate change of electrical resistance of the aluminum samples can be determined in situ. Keywords: holographic interferometry; electrochemical impedance spectroscopy (EIS); anodization process; oxide film thickness; sulfuric acid; aluminum.

Thermal Stress Monitoring on Piston Rings by Real Time Holographic Interferometry

In this paper, real time holographic Interferometry (RTHI) technique was used to monitor the thermal stress on the piston rings. The piston rings holograms were recorded and the holographic plate replaced on the holder after development. The piston ring was subjected to thermal stress as it was illuminated by Laser beam acting as the object beam. This process led to generation of interferograms which were captured by a CCD camera at different temperatures. The captured interferograms were analyzed using atmosfringe version 3.3 software. From the analysis, the peak to valley (P-V) aberrations measured for each of the piston ring varied for the same temperature value. The P-V aberrations ranging from 0.0128λ to 1.2989λ were obtained. From this result, it was evident that the three rings on the piston had different unique structural characteristics due to their function.

AC impedance–emission spectroscopy for determining the electrochemical behaviour of anodised aluminium in aqueous solutions

In the present investigation, holographic interferometry was utilised for the first time to determine the rate change of the alternating current (AC) impedance of aluminium samples during the initial stage of anodisation processes in aqueous solution without any physical contact. In fact, because the AC impedance values in this investigation were obtained by holographic interferometry, electromagnetic method rather than electronic method, the abrupt rate change of the AC impedance was called AC impedance–emission spectroscopy. The anodisation process (oxidation) of the aluminium samples was carried out chemically in different sulphuric acid concentrations (0.5–3.125% H2SO4) at room temperature. In the mean time, the real time holographic interferometry was used to determine the difference in the AC impedance of two subsequent values, dZ, as a function of the elapsed time of the experiment for the aluminium samples in 0. 5, 1.0, 1.5 and 3.125% H2SO4 solutions. The AC impedance–emission spectra of the present investigation represent a detailed picture of not only the rate change of the AC impedance throughout the anodisation processes but also the spectra represent the rate change of the growth of the oxide films on the aluminium samples in different solutions. Consequently, holographic interferometry is found to be very useful for surface finish industries, especially for monitoring the early stage of anodisation processes of metals, in which the rate change of AC impedance of the aluminium samples can be determined in situ.

HOLOGRAPHIC INTERFEROMETRY AS A METHOD FOR MEASURING STRAIN CAUSED BY POLYMERIZATION SHRINKAGE OF DENTAL COMPOSITE

Савремени материјали, међународна научна конференција - Contemporary materials, International scientific conference,Савремени материјали 2010 - научна конференција у Бањој Луци

Real-time color holographic interferometry devoted to 2D unsteady wake flows

A new optical technique based on real time holographic interferometry in true colors has been implemented around the transonic wind tunnel of the ONERA-Lille center to analyze 2D unsteady wake flows. Tests realized in color interferometry, real time and double exposure, use simultaneously three wavelengths of a continuous waves laser (argon and krypton mixed) and holograms are recorded on silver-halide single-layer panchromatic Slavich PFG03c plates. The very principle of real-time true color holographic interferometry uses three primary wavelengths (red, green and blue) to record, under no-flow conditions, the interference among the three measurement beams and the three reference beams simultaneously on a single reference hologram. After the holographic plate is developed, it is placed on the test setup again in the position it occupied during exposure and the hologram is illuminated again by the three reference beams and three measurement beams. A flat, uniform color can then be observed behind the hologram. So a horizontal, vertical, or even circular fringe pattern can be formed and the achromatic central fringe can be made out very clearly. The single color is used to determine the path difference zero on the interferograms. The flow studied was the unsteady flow downstream of a cylinder placed crosswise in the test section. A sequence of hundred interferograms was recorded on the flow around the cylinder at Mach 0.37. The vortex formation and dissipation phases can be seen very clearly, along with the fringe beat to either side of the cylinder.

Large-scale geophysical flows on a table top.

Results from two similar experimental systems that attempt to create laboratory geophysical analogs in spherical geometry are presented. In the first system, real time holographic interferometry and shadowgraph visualization are used to study convection in the fluid between two concentric spheres when two distinct buoyancy forces are applied to the fluid. The heated inner sphere has a constant temperature that is greater than the outer sphere's constant temperature by DeltaT. In addition to the usual gravitational buoyancy from temperature induced density differences, another radial buoyancy is imposed by applying an ac voltage difference, DeltaV, between the inner and outer spheres. The resulting electric field gradient in this spherical capacitor produces a central polarization force. The temperature dependence of the dielectric constant results in the second buoyancy force that is especially large near the inner sphere. The normal buoyancy is always present and, within the parameter range explored in our experiment, always results in a large-scale cell that is axisymmetric about the vertical axis. We have found that this flow becomes unstable to toroidal or spiral rolls that form near the inner sphere and travel vertically upward when DeltaT and DeltaV are sufficiently large. These rolls start near the center sphere's equator and travel upward toward its top. In the second experimental system, the central force is applied to a highly compressible near-critical fluid in weightlessness (parabolic flight) and normal gravity. Although a geophysically similar density distribution could not be obtained in the limited time of a parabolic flight, clear influences of the central force on the fluid were observed in both weightlessness and terrestrial experiments.

209 実時間ストロボホログラフィー干渉法による水中超音波音圧分布の測定(GS-10 計測)

209 実時間ストロボホログラフィー干渉法による水中超音波音圧分布の測定(GS-10 計測)

Thickness Variation of a Liquid Sheet Formed by Two Impinging Jets Using Holographic Interferometry

In the work presented in this paper a real time holographic interferometry technique is developed to measure instantaneously and nonintrusively the thickness distribution of a liquid sheet formed by the impingement of two liquid jets. The experimental results are compared with earlier largely unverified analytical predictions. It is shown that the assumption that the sheet thickness is inversely proportional to the radial distance from the impingement point is in principle good. The dependence of the theoretically obtained proportionality constant on the azimuthal angle, however, while exhibiting the same trend it also shows some quantitative differences. Reasons are given in the context of the work. In addition, a weak effect of the jet velocity on the proportionality constant is found to exist. In the theories no such effect was modeled. Finally, comparisons between theoretical and experimental isothickness contours show differences. Overall, there appears to be a justification for improved theoretical studies including effects such as that of gravitation.

Limitations of temperature measurements with holographic interferometry in the presence of pressure variations

Abstract In recent years oscillatory flows have shown to be a promising strategy to enhance heat transfer. However, the mechanisms underlying oscillatory heat transfer enhancement are not yet completely understood. One problem, when investigating heat transfer in oscillatory flows experimentally, is to resolve the temperature distribution as a function of time. This is one reason that most studies reported in the literature so far were restricted to frequencies of a few hertz. As shown in this paper, an appropriate tool to investigate oscillatory heat transfer phenomena at higher frequencies (∼1000 Hz) is real time holographic interferometry (HI) combined with high-speed cinematography. In the present paper HI was applied to study acoustically driven flow. To apply HI to such a physical situation it was necessary to expand its applicability to cases where changes in the refractive index are caused not only by temperature changes but also by pressure variations. For this purpose a new evaluation formula that accounts for pressure variations was derived. On the example of the acoustic field, we discuss the impact of the pressure variations on temperature measurements. Additionally, an image processing algorithm was developed that allows the measurement of time dependent temperature distributions. The uncertainties of the temperature measurements introduced by the image processing algorithm were found to be in the range of thermocouple measurements.

Two interferometric methods for the mechanical characterization of thin films by bulging tests. Application to single crystal of silicon

Two optical methods are presented for the mechanical characterization of thin films, namely real time holographic interferometry and a fringe projection method called “contouring.” These two methods are coupled to the interferometry by the phase measurements, thus allowing the displacement field to be measured at all points on the membrane. We discuss the solutions retained in terms of their precision and sensitivity. These methods are then applied to membrane bulging tests, a type of test that is widely used in micro-mechanical studies. The measurements are performed on silicon single crystal and the results are compared to the solutions calculated by finite element methods. In both cases, the good agreement between theory and experiments allows the experimental apparatus to be validated.

Numerical simulation and laser holographic study on thermal diffusion in counterflow with different temperatures

This paper presents a numerical simulation and a laser holographic interferometric study on thermal diffusion characteristics of combined forced and free heat convection in a counterflow with different temperatures. The purpose of this paper is to make clear the characteristics of a direct mixing heat exchanger for advanced energy conversion. In the numerical study, the flow patterns and isotherms for both adiabatic and non-adiabatic wall conditions are simulated in two-dimensional fields over a wide range of the Reynolds number and Grashof number for steady and unsteady, laminar and turbulent flows. Real time holographic interferometry is applied to visualize the isotherms for the simulated flow fields and to build a new concept of practical heat exchanger design. In evaluating non stationary interferograms, the time averaged heat flow rate is introduced and the thermal diffusion effect is discussed. As the result, thermal diffusion at the mixing interface of counterflows can be well characterized.

Holography and Holographic Interferometry with a near IR Sentitive photopolymer System

0Holographic images of test targets were reconstructed from a new, self-processing photopolymer material. A laser diode operating at 780 nm was used in the experiments. Possible effects of the polarization of the construction beams on the reconstructed image were also studied. The applicability of this material to real time holographic interferometry was demonstrated.

Selected reconstruction methods and applications to real-time tomography

Real-time interferometry described in this paper refers to multidirectional Fourier transform holography using a photorefractive crystal. In real time holographic interferometry, a reconstruction using a few interferometric images is a challenge. For this reason, two established iterative methods and the function specification method of reconstruction are selected, evaluated, and then applied to experimentally obtained holograms. The iterative methods are useful for reconstruction of three-dimensional temperature fields although they are numerically slow. In contrast, the function specification method is significantly faster but requires a knowledge of the physical processes for successful selection of a functional approximation. It was found that a coordinate transformation prior to reconstruction significantly improves the accuracy.

Non-destructive evaluation of metallic electrodes under corrosion fatigue conditions by holographic interferometry

A study on the effect of cyclic deformation on the corrosion behaviour of polarised metallic electrodes in aqueous solution was conducted. The study aimed to determine the initial behavior of a nickel (Ni) electrode in 1 m H 2SO 4 and molybdenum (Mo) electrode in 0.75 m KCl solutions under a condition known as corrosion fatigue (CF) by using methods of real time holographic interferometry. As a result, a relationship between the deformation, obtained by holographic interferometry, and corrosion current density, produced by typical electrochemical methods, are established.

Nondestructive evaluation of an epoxy-based coating by optical interferometry techniques

A study on evaluating an epoxy-based coating was conducted. The study aimed to determine the performance of the coating on a low carbon steel as a result of chemical contaminations. Coated samples were tested in a local tap water by using the method of real time-holographic interferometry. A mathematical model was used along with the obtained experimental data. The model described processes of detecting the early corrosion of the steel under the coatings by holographic interferometry. Consequently, the holographic interferometry technique was found very useful in detecting the early corrosion processes of the coated steel. Also, a relationship between the displacement of the coating, due to metal corrosion under the coating, and corrosion current density of the coated steel was established for the epoxy-based coating with and without an addition of sodium chloride to the coating.

Experimental investigation on convective heat transfer of heated spinning sphere

The average Nusselt number of a heated sphere rotating in quiescent air was measured experimentally over the range 0 < Re < 33 320 from free to forced convection regimes. As well, real time holographic interferometry was applied to the observation of flows structure and evolution, and later employed to analyze the deviations revealed by a comparison of the measured data Nu with previous experimental and theoretical results. Thus, real time holographic visualization provides a physical understanding of the effect of the evoluting flow structure on Nu as rotational speed increases. In addition, a new asymptotic formula for correlating the experimentally measured Nu was established.

Flexion characteristics of four-unit fixed partial denture frameworks using holographic interferometry

Flexion of a metal/ceramic fixed partial denture (FPD) framework under function can cause fracture of the porcelain or deterioration of the cement seal. This study evaluated the iexion under compressive load of a four-unit mandibular FPD replacing the second premolar and the first molar. Testing was accomplished with elapsed time holographic interferometry, using 39 porcelain fused-to-metal frameworks cast with a silver-palladium alloy. The results demonstrated that solder joints at the junction of the premolar and molar pontics flexed under a reduced compressive load and exhibited a higher failure rate than other connector designs.

An Experimental Study of Subcooled Film Boiling on a Vertical Surface—Thermal Aspects

Wall and liquid side heat fluxes near the leading edge of a vertical wall 6.3 cm wide and 10.3 cm high were measured during subcooled film boiling of water at 1 atm pressure. The heat flux from the interface into the liquid and temperature profiles in the liquid thermal layer were measured using real time holographic interferometry. The wall heat flux was measured with thermocouples embedded in a copper block, one face of which served as the heated wall. The role of the leading edge vapor layer, ripples, and large bulges in modifying the liquid side heat transfer is quantified.