Interferometry In Conjunction Research Articles

In‐situ elasticity measurement for the unquenchable high‐pressure clinopyroxene phase: Implication for the upper mantle

Polycrystal elasticity of the unquenchable MgSiO3high‐pressure clinoenstatite has been measured using ultrasonic interferometry in conjunction with in‐situ X‐ray diffraction and imaging techniques within its stability field in a large volume multi‐anvil apparatus for the first time. At 6.5 GPa, we obtained ∂KS/∂P = 5.6(3), ∂G/∂P = 1.5(1), ∂KS/∂T = −0.017(1) GPa K−1and (∂G/∂T) = −0.015(1) GPa K−1. Our results show that the elastic velocities of HP‐CEN are not only higher than those of OEN but also higher than olivine at upper mantle conditions. According to these new data, the elastic velocities for the “depleted” mantle composition, with ∼20 vol% of HP‐CEN, would result in ∼0.8% and ∼1.6% in difference for P and S waves, respectively, when OEN data were used in previous calculations. Newly measured results also suggest that it is possible to distinguish “undepleted” and “depleted” composition models in the upper mantle.

Role of particle size and filler–matrix adhesion on dynamic fracture of glass-filled epoxy. I. Macromeasurements

The roles of particle size and filler–matrix adhesion strength in the dynamic fracture behavior of glass-filled epoxy are studied. Spherical particles of size 7–200 μm are used to reinforce epoxy matrix at a constant volume fraction (10%) and two different filler–matrix strengths, weak and strong. Optical interferometry in conjunction with high-speed photography has provided information regarding instantaneous crack tip positions and deformations when samples are subjected to impact loading. The crack velocity and stress intensity factor histories are extracted from the interferograms. Elastic characteristics remain unaffected by neither the particle size nor filler–matrix adhesion. Both weakly and strongly bonded particles in the matrix show higher values of fracture toughness relative to unfilled matrix material. Filler particle size affects fracture toughness significantly when the particles are used in the uncoated (or, weakly bonded) state. Additionally, a particle size of 35 μm is seen to enhance the fracture toughness the most when compared to both smaller and larger size uncoated particles. An inverse relationship seems to exist between steady state fracture toughness and crack velocity for different particle sizes. Unlike weakly bonded filler particles, the size effect essentially vanishes when the filler–matrix adhesion is enhanced using silane treatment.

Modern techniques in measuring elasticity of Earth materials at high pressure and high temperature using ultrasonic interferometry in conjunction with synchrotron X-radiation in multi-anvil apparatus

Modern techniques in measuring elasticity of Earth materials at high pressure and high temperature using ultrasonic interferometry in conjunction with synchrotron X-radiation in multi-anvil apparatus

Modern techniques in measuring elasticity of Earth materials at high pressure and high temperature using ultrasonic interferometry in conjunction with synchrotron X-radiation in multi-anvil apparatus

In the past 6 years, state-of-the-art techniques have been developed for the studies of elastic properties of polycrystalline and single-crystal materials using simultaneous ultrasonic and X-ray diffraction techniques at high pressures and temperatures in multi-anvil apparatus. The capability of these techniques is illustrated using recent data for mantle phases such as forsterite, wadsleyite, CaSiO 3 perovskite, and (MgFe)O ferripericlase. Adaptation of the X-radiography technique enables direct measurements of sample length at high pressures and temperatures, enabling studies of unquenchable phases, liquids, and multi-phase aggregates. The use of dual-mode transducers produces P and S wave data at the same pressure and temperature conditions in a single acoustic experiment, thereby eliminating the uncertainties caused by the need for interpolating travel-time data to calculate the elastic wave velocities, and bulk and shear moduli at high pressure and temperature. Implementation of the transfer function method for travel-time measurements opens new opportunities for studying time-dependent processes using ultrasonic measurements, such as phase transformations and plastic deformation.

Elasticity of (Mg0.83,Fe0.17)O ferropericlase at high pressure: ultrasonic measurements in conjunction with X-radiation techniques

The elasticity of ferropericlase with a potential mantle composition of (Mg0.83,Fe0.17)O is determined using ultrasonic interferometry in conjunction with in situ X-radiation techniques (X-ray diffraction and X-radiography) in a DIA-type cubic anvil high-pressure apparatus to pressures of 9 GPa (NaCl pressure scale) at room temperature. In this study, we demonstrate that it is possible to directly monitor the specimen length using an X-ray image technique and show that these lengths are consistent with those derived from X-ray diffraction data when no plastic deformation of the specimen occurs during the experiment. By combining the ultrasonic and X-ray diffraction data, the adiabatic elastic bulk (KS) and shear (G) moduli and specimen volume can be measured simultaneously. This enables pressure scale-free measurements of the equation of state of the specimen using a parameterization such as the Birch–Murnaghan equation of state. The elastic moduli determined for (Mg0.83,Fe0.17)O are KS0=165.5(12) GPa, G0=112.4(4) GPa, and their pressure derivatives are KS0′=4.17(20) and G0′=1.89(6). If these results are compared with those for MgO, they demonstrate that KS0 and KS0′ are insensitive to the addition of 17 mol% FeO, but G0 and G0′ are reduced by 14% and 24%, respectively. We calculate that the P and S wave velocities of a perovskite plus ferropericlase phase assemblage with a pyrolite composition at the top of the lower mantle (660 km depth) are lowered by 0.8 and 2.3%, respectively, when compared with those calculated using the elastic properties of end-member MgO. Consequently, the magnitudes of the calculated wave velocity jumps across the 660 km discontinuity are reduced by about 11% for P wave and 20% for S wave, if this discontinuity is considered as a phase transformation boundary only (ringwoodite→perovskite+ferropericlase).

Statistical Angle-of-arrival and Doppler Method for GPS radio interferometry of TIDs

Abstract A Statistical Angle-of-arrival and Doppler Method for GPS radio interferometry (SADM-GPS) is proposed for determining the characteristics of the Travelling Ionospheric Disturbances (TIDs) by measuring variations of GPS phase derivatives with respect to time and spatial coordinates. These data are used to calculate corresponding values of the velocity vector, in view of a correction for satellite motion based on current information available regarding the angular coordinates of the satellites. Through a computer simulation it was shown that multi satellite GPS radio interferometry in conjunction with the SADM-GPS algorithm allows for detecting and measuring the velocity vector of TIDs in virtually the entire azimuthal range of possible TID propagation directions.

GPS radio interferometry of travelling ionospheric disturbances

This paper presents some results investigating the new possibilities of radio interferometry of Travelling Ionospheric Disturbances (TIDs) that are based on exploiting standard measurements of transionospheric radio signal characteristics and coordinate-time measurements using dual-frequency multichannel receivers of the Global Positioning System (GPS). A Statistical Angle-of-arrival and Doppler Method for GPS radio interferometry (SADM-GPS) is proposed for determining the characteristics of the TIDs dynamics by measuring variations of GPS phase derivatives with respect to time and spatial coordinates. These data are used to calculate corresponding values of the velocity vector, in view of a correction for satellite motions based on the current information available regarding the angular coordinates of the satellites. Subsequently, velocity and direction distributions are constructed and analyzed to verify the hypothesis of whether there is a predominant displacement. If it exists, then the pattern can be considered to be travelling, and the mean travel velocity can be determined from the velocity distribution. Through a computer simulation it was shown that multi-satellite GPS radio interferometry in conjunction with the SADM-GPS algorithm allows the detection and measurement of the velocity vector of TIDs in virtually the entire azimuthal range of possible TID propagation directions. The use of the proposed method is exemplified by an investigation of TIDs during the solar eclipse of 9 March 1997, using the GPS-radio interferometer GPSINT at Irkutsk.

Characterization of the polarization state of weak ultrashort coherent signals by dual-channel spectral interferometry

We demonstrate that dual-channel spectral interferometry in conjunction with a well-characterized reference pulse can be used to time resolve the polarization state of extremely weak ultrashort coherent signals from linear-and nonlinear-optical experiments by measuring the intensity and the phase of two orthogonal polarization components. In this way the signal is completely characterized.

Characterization of the Interface between a Rough Metal and Smooth Mica in Contact

We introduce a technique to characterize,in situ,the solid–solid interface formed when a rough metal surface is placed in contact with a smooth mica surface. The technique is based on the use of extended spectral analysis of multiple beam interferometry in conjunction with the surface forces apparatus (SFA). The intensity versus wavelength spectra of light transmitted through the rough metal/mica interface is measured and compared to that transmitted through a smooth metal/mica interface. Interference theory is used to characterize the rough interface based on differences in the measured spectra. Roughness on the order of nanometers can be resolved. The key to our technique is the creation of a perfectly smooth metal/mica interface that is in all respects, except for roughness, identical to the metal/mica interface created in the SFA. We accomplish this by thermal evaporation of a metal film directly onto mica. We demonstrate the effectiveness of the technique by characterizing the structure of silver/mica and gold/mica interfaces. We also show how the technique can be used to investigate the exchange of fluids within the contact region.

Computer Rigid Disk Surface Assessment With Laser Interferometry Using DDS

Laser interferometry in conjunction with the data dependent systems (DDS) methodology is first used in this paper to eliminate errors caused by instrumentation and software, and to recover the surface topography of a computer rigid disk used for illustration. The DDS methodology is then applied once more to decompose the surface height profile into a series of exponential and sinusoidal modes. The significant modes are related to the waviness and surface roughness resulting from different manufacturing processes. Surface reconstruction using only the important modes is presented. This provides a visual as well as mathematical description of the resultant effect of each process. The methodology can characterize very complex surface textures, reducing the reliance on complicated and expensive instruments needed for inspection, and replacing them with relatively inexpensive but reliable computation.

Moiré interferometry determination of residual stresses in the presence of gradients

The full-field technique of high-sensitivity moire interferometry in conjunction with a multiple-hole-drilling procedure is applied to residual-stress measurements in the presence of gradients. The method arrives at residual-stress estimates starting from in-plane displacement components. Successful applications of the method to problems simulating the nonuniform transverse residual stresses of welded joints are reported.

Crack embrittlement displacement fields

When using precracked fracture toughness specimens to study liquid metal embrittlement is has been necessary to estimate the crack length and applied load as a function of time. These parameters are sometimes difficult to obtain and accuracy is often questionable. Further, these data provide the basis for calculating crack growth rate (d a/d t) as a function of applied stress intensity factor K I. This paper presents an approach based on use of moiré interferometry in conjunction with fracture toughness specimens and acoustic emission techniques to study liquid mercury amalgam embrittlement of 6061-T 6 aluminum. Moiré interferometry provides a unique method for obtaining K I, at the crack tip, without requiring knowledge of crack length and load. This paper describes the approach and provides an evaluation based on test results.

Isopachic contouring of opaque plates

Contour maps of change of thickness of opaque plates subjected to external loads are obtained using holographic interferometry in conjunction with the moire effect. A simple holographic-interferometry arrangement is used first to obtain contour maps of the out-of-plane displacements of the two sides of the object. Carrier patterns of equal magnitude but opposite sings are added to these contours. Superposition of the reconstructed holograms of the two sides produces a pattern of additive-moire fringes, which are contours of change of thickness. Effects of midplane warpage of the loaded specimen are cancelled. Sensitivity is λ/2 per fringe order, contrast of the isopachic-fringe pattern is excellent, and the process is compatible with a mechanical-testing-machine environment.

Strains from holographic data

In this paper, reliable derivatives up to second order over a surface are obtained from holographic interferograms. This is done on a large scale, handling an amount of data that would be prohibitive if attempted by hand smoothing. This opens the way for bending and shear-strain determinations in a noncontacting way over large fields of view. The surface need be treated in no special way, in contrast to the preparation required with brittle lacquers and photoelastic coatings. Strains in the microstrain range are readily measured. Holographic interferometry in conjunction with the numerical methods mentioned herein constitutes a noncontacting optical strain gage. Furthermore, it makes possible experimental application of sophisticated modal analysis because the normal modes upon which these techniques are based are directly measured. For example, if the vibratory behavior is known, through a sufficiently large sample of the normal modes, then the static behavior may be calculated. Similarly, if the normal modes of a nonrotating body are known, its behavior in a rotating system can be calculated. Thus, the centrifugal stiffening of a turbine rotor may be predicted from a knowledge of the spectrum of its normal modes.

Measurement of the Stark broadening parameters of several Ar II lines

The profiles of several electron-impact-broadened Ar II lines emitted by a high-density Z-pinch plasma have been recorded using a rapid scanning Fabry-Perot interferometer. The plasma electron density was determined by Fabry-Perot interferometry in conjunction with a laser light source. Measurement of the relative intensity of an Ar III line and a nearby Ar II line enabled the plasma temperature to be estimated. The measured Ar II linewidths are compared with those predicted by the impact approximation using straight-line perturber orbits and neglecting lower-state broadening. In all cases studied the ratio of experimental to theoretical linewidth was at least a factor of 2. The cause of these large discrepancies, and the implications of the results for other emitting species, are to be discussed in a subsequent paper.