Transmission Measurements Research Articles

Poroelastic Response of a Fractured Rock to Hydrostatic Pressure Oscillations

AbstractPoroelastic coupling between fractures and the surrounding rock is important to numerous applications in geosciences. We measure the in‐situ fluid pressure and local strain response of a fractured carbonate sample to hydrostatic pressure oscillations. A linear poroelastic model that represents the rock sample is parameterized using X‐ray imaging and ultrasonic wave transmission measurements. The numerical solution, based on Biot's quasistatic equations, is consistent with the measured frequency dependent dispersion of the apparent bulk modulus of the background matrix and the in‐situ pore pressure response, which is caused by fluid pressure diffusion from the compliant fractures into the stiffer matrix. The observed fluid pressure diffusion is causally related to the numerically quantified intrinsic attenuation at seismic frequencies, which is a major contributor to the dissipation of seismic waves. Our analysis supports the use of a simple approximation of fractures as compliant and planar inclusions in numerical simulations based on linear poroelasticity.

Synchrotron CT dosimetry for wiggler operation at reduced magnetic field and spatial modulation with bow tie filters.

The Australian Synchrotron Imaging and Medical Beamline (IMBL) uses a superconducting multipole wiggler (SCMPW) source, dual crystal Laue monochromator and 135 m propagation distance to enable imaging and computed tomography (CT) studies of large samples with mono-energetic radiation. This study aimed to quantify two methods for CT dose reduction: wiggler source operation at reduced magnetic field strength, and beam modulation with spatial filters placed upstream from the sample. Transmission measurements with copper were used to indirectly quantify the influence of third harmonic radiation. Operation at lower wiggler magnetic field strength reduces dose rates by an order of magnitude, and suppresses the influence of harmonic radiation, which is of significance near 30 keV. Beam shaping filters modulate the incident beam profile for near constant transmitted signal, and offer protection to radio-sensitive surface organs: the eye lens, thyroid and female breast. Their effect is to reduce the peripheral dose and the dose to the scanned volume by about 10% for biological samples of 35-50 mm diameter and by 20-30% for samples of up to 160 mm diameter. CT dosimetry results are presented as in-air measurements that are specific to the IMBL, and as ratios to in-air measurements that may be applied to other beamlines. As CT dose calculators for small animals are yet to be developed, results presented here and in a previous study may be used to estimate absorbed dose to organs near the surface and the isocentre.

Development of a multi-layer high-efficiency GEM-based neutron detector for spallation sources

Neutron detection is nowadays mostly based on 3He gas detectors, but its shortage and the continuous upgrades of the neutron facilities require new devices to perform experiments with maximum performances. This work presents a new detector based on the Gas Electron Multiplier (GEM) combined with several boron layers. This detector combines the features of GEM technology with the properties of boron as a neutron converter and the device is produced to sustain high neutron fluxes with high detection efficiency. The detector has been characterised at the ISIS Pulsed Neutron and Muon Source (UK). Based on the analysis of our results, the detector has shown a good response to thermal and epithermal neutrons reaching a detection efficiency of 16% at 1.8 Å (25 meV). The good detection efficiency (even increasable with the addition of further boron GEM foils) and the good time resolution, make the detector a unique device for the neutron techniques. In particular, its use can easily be envisaged in techniques involving neutron transmission measurements, that require high fluxes impinging on the detectors, with the added bonus of a 2D-resolved capability due to the padded anode.

Evaluation and analysis of the electro-optic effect and the Stark effect in electro-optic polymers by the simple transmission measurement technique without an aperture

A simple and reliable transmission measurement technique without an aperture was utilized to evaluate both the electro-optic (EO) effect and the Stark effect of EO polymers. For some EO polymers, both the EO effect and the Stark effect were evaluated using laser light sources with various wavelengths of 1550 nm, 1308 nm, 980 nm, and 640 nm and the analysis method was also described. We showed that both the magnitude and the phase of the modulated light signal in lock-in detection at both the π/2 and 3π/2 points are very important for appropriate analysis.

Combined Acoustic Emission and Ultrasonic Measurements in Cross Laminated Timber-Steel Composite Beam

Combined acoustic emission and ultrasonic measurements were carried out before and during a four-point bending test on a composite floor beam made of cross-laminated timber with length of 11.6 m, width of 1.5 m, and thickness of 0.28 m. One key aspect of the composite design is the formation of the shear-resistant connection between the panel and steel girder. For the measurements a 16-channel system with combined acoustic emission and transmission measurements was used. The signals were digitized with a very high frequency of 10 MHz with amplitude resolution of 16 bits. To monitor acoustic emission activity a network of 16 AE sensors were attached to the surface of the specimen in the central part of the specimen where the highest deflection and load were expected. For this purpose, broadband AE sensors with measurement frequency of up to 200 kHz were used. The ultimate failure of the specimen occurred at a maximum test load of approximately 200 kN. The deflection at this force was about 200 mm. During the tests which lasted about 50 minutes approximately 8,500 AE events were detected. More than 2,600 events were recorded by at least six channels which makes them well suited for three-dimensional localization. Because of the inhomogeneous cross-laminated timber conventional localization using an unique velocity model are not possible. Therefore, a velocity model was experimentally determined by measure the velocity of the elastic waves in all directions. The greatest value was measured in the longitudinal direction along the beam axis. The average value is approximately 4000 m/s. While in the transverse direction the velocity drops down to approximately 2800 m/s. The lowest value was measured in thickness direction of about 1800 m/s.

Experimental determination of the sulfur K-shell fundamental parameters employing the holistic approach

Abstract Sulfur and its compounds are both very abundant in the environment and very important for technological applications such as batteries. X-ray spectroscopic characterizations of sulfur compounds for a quantitative determination of the present amount of sulfur often requires a good knowledge on the atomic fundamental parameters involved. These quantitatively describe the processes of photoionization and X-ray fluorescence emission, making them crucial for X-ray spectroscopy-based quantifications. 
By employing the recently demonstrated holistic approach, the atomic fundamental parameters of the sulfur K-shell were experimentally determined using the radiometrically calibrated instrumentation of the Physikalisch-Technische Bundesanstalt (PTB). The transition probabilities of the main K-shell fluorescence lines, the K-shell fluorescence yield, the K-shell Auger yield, the subshell photoionization cross section and fluorescence production cross section were determined by means of photon energy dependent X-ray fluorescence and transmission measurements on a thin InS coated silicon nitride membrane. The results are also downloadable from Zenodo as plain text.

Fabrication of kesterite Cu2ZnSnS4 thin films using sequentially sputtered multilayers of Cu2SnS3 and Zinc.

Radio-frequency sputtered Cu2ZnSnS4 (CZTS) thin films deposited on glass substrates were characterized. The film deposition was carried out in an argon atmosphere with RF powers of 200 W for zinc and 300 W for the CTS films. After the deposition, the films were annealed at temperatures ranging from 350 °C to 500 °C in a nitrogen and sulfur atmosphere. By using X-ray diffraction, the CZTS films were observed to crystallize in a tetragonal structure with some minor secondary phases in some samples. The absorption coefficient and optical band gap are identified by the ultraviolet-visible-near-infrared optical transmission measurements and the calculated band gap was found to range between 1.4 eV and 1.51 eV. This research comprehensively addresses the effects of layer thickness and annealing temperature on our CTS/Zn films. The annealing process was oberved to result in a significant improvement in electrical conductivity, particularly in films without secondary phases.

56 Gbps externally modulated widely tunable lasers with SOA boosters heterogeneously integrated on silicon

We demonstrate externally modulated widely tunable lasers co-integrated with semiconductor optical amplifiers (SOAs) heterogeneously integrated on silicon. The widely tunable laser enables continuous single-mode operation over a tuning range of approximately 40 nm, with a side-mode suppression ratio (SMSR) of at least 50 dB and an average waveguide-coupled optical power of 5 mW. The integrated electro-absorption modulator (EAM) exhibits an extinction ratio (ER) of 16 dB when reversed biased at -2 V. The bit-error-rate (BER) measurements conducted across the available optical bandwidth (15 nm) showcase error-free transmission at 32 Gbps using non-return-to-zero (NRZ) signals for the majority of wavelengths in a back-to-back (B2B) configuration. Additionally, transmission measurements over distances of up to 10 km through a standard single-mode fiber (SSMF) have been successfully demonstrated. Dynamic extinction ratio (DER) values exceeding 4.5 dB are achieved for all wavelengths. Open-eye diagrams were measured up to 56 Gbps. These results demonstrate that this compact mono-epitaxial externally modulated tunable laser with integrated optical amplification can be a cost-effective transmitter solution for dense wavelength division multiplexing (DWDM) metropolitan and access networks.

Interaction of acoustic waves with spin waves using a GHz operating GaN/Si SAW device with a Ni/NiFeSi layer between its IDTs.

A two port surface acoustic wave (SAW) device was developed to be used for the control and excitation via spin waves (SW). The structure was manufactured using advanced nanolithography techniques, on GaN/Si, enabling fundamental Rayleigh interdigitated transducer (IDT) resonances in GHz frequency range. The ferromagnetic resonance of the magnetostrictive Ni/NiFeSi layer placed between the IDTs of the SAW device can be tuned to the SAW resonance frequency by magnetic fields. Using structures with finger and interdigit spacing of 170 nm and 100 nm, fundamental Rayleigh IDT resonance frequencies of 6.4 and 10.4 GHz have been obtained. Coupling of SAW to SW was demonstrated through transmission measurements at the fundamental Rayleigh frequencies in a magnetic field, μ0H from -280 to +280 mT, at different angles (θ) between the SAW propagation direction and the magnetic field direction. For the 6.4 GHz resonator a maximum decrease of about 1.2 dB occurred in |S21|, at μ0H = 30 mT and at θ = 45. Time-gated processing of the frequency domain raw data was used to remove the direct electromagnetic cross talk and triple transit effects. Nonreciprocity associated to the coupling was analyzed for the two SAW structures. The quantitative influence of the magnetic field strength on the phase of the transmission parameters is also presented.

Thin Film TaFe, TaCo, and TaNi as Potential Optical Hydrogen Sensing Materials.

This paper studies the structural and optical properties of tantalum-iron-, tantalum-cobalt-, and tantalum-nickel-sputtered thin films both ex situ and while being exposed to various hydrogen pressures/concentrations, with a focus on optical hydrogen sensing applications. Optical hydrogen sensors require sensing materials that absorb hydrogen when exposed to a hydrogen-containing environment. In turn, the absorption of hydrogen causes a change in the optical properties that can be used to create a sensor. Here, we take tantalum as a starting material and alloy it with Fe, Co, or Ni with the aim to tune the optical hydrogen sensing properties. The rationale is that alloying with a smaller element would compress the unit cell, reduce the amount of hydrogen absorbed, and shift the pressure composition isotherm to higher pressures. X-ray diffraction shows that no lattice compression is realized for the crystalline Ta body-centered cubic phase when Ta is alloyed with Fe, Co, or Ni, but that phase segregation occurs where the crystalline body-centered cubic phase coexists with another phase, as for example an X-ray amorphous one or fine-grained intermetallic compounds. The fraction of this phase increases with increasing alloyant concentration up until the point that no more body-centered cubic phase is observed for 20% alloyant concentration. Neutron reflectometry indicates only a limited reduction of the hydrogen content with alloying. As such, the ability to tune the sensing performance of these materials by alloying with Fe, Co, and/or Ni is relatively small and less effective than substitution with previously studied Pd or Ru, which do allow for a tuning of the size of the unit cell, and consequently tunable hydrogen sensing properties. Despite this, optical transmission measurements show that a reversible, stable, and hysteresis-free optical response to hydrogen is achieved over a wide range of hydrogen pressures/concentrations for Ta-Fe, Ta-Co, or Ta-Ni alloys which would allow them to be used in optical hydrogen sensors.

Controlling Isotropic Reflectivity with Multi‐Oriented Self‐Assembled Hexagonal Arrays in Plasmonic Metasurfaces

AbstractThe fabrication of plasmonic metasurfaces on large surfaces is the next challenge to adapt them to augmented reality systems. The optical properties of a self‐assembled hexagonal plasmonic metasurface, realized with a large‐area compatible approach, are compared at different levels and a correlated‐disorder plasmonic metasurface fabricated by electron‐beam lithography and considered here as the reference: the contribution of plasmonic nanostructure arrangements is studied using the structure factor, physical properties are assessed by optical transmission and reflection measurements, and finally the entire metasurfaces are tested macroscopically in a head‐up display system.

Synthesis and Upconversion Luminescence Fine-tuning of Yb3+/Ho3+-Doped Indium and Gallium Oxide Nanoparticles.

Rare earth (RE) dopants can modulate the bandgap of oxides of indium and gallium and provide extra upconversion luminescence (UCL) abilities. However, relevant UCL fine-tuning strategies and energy mechanisms have been less studied. In this research, InGaO, Ho3+ monodoped and Yb3+/Ho3+ codoped In2O3, and Ho3+ monodoped Yb3Ga5O12 nanoparticles (NPs) were synthesized by a solvothermal method. The effects of Yb3+ and Ho3+ dopants on the crystal structures, UCL properties, and optical bandgaps of the oxides were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UCL spectroscopy, and measurements of decay times, pump power dependence, and transmittance spectra. The crystal structures of oxide products of indium and gallium were significantly modified with RE dopants. In2O3 and Yb3Ga5O12 were selected as the host materials. For Yb3+/Ho3+ codoped In2O3 NPs, there existed energy transfers from the defect states of In2O3 to Ho3+ and from Yb3+ to Ho3+. With a fixed Ho3+ concentration, In2O3:0%Yb3+,2%Ho3+ NPs showed the optimal UCL properties mainly due to In2O3-Ho3+ energy transfer and Ho3+-Yb3+ energy-back-transfer, while with a fixed Yb3+ concentration, In2O3:5%Yb3+,3%Ho3+ NPs with a slight Yb2O3 impurity and Yb3Ga5O12:2%Ho3+ NPs did mainly due to Ho3+-Ho3+ cross-relaxation. Besides, the optical bandgaps of In2O3 and Yb3Ga5O12 were noticeably broadened with RE dopants. These findings can offer feasible directions for the synthesis and UCL fine-tuning of RE-doped oxides of indium and gallium and improve their multifunction application prospects in the fields of semiconductor and UCL nanomaterials.

An Automated pre-Dilution Setup for Von Willebrand Factor Activity Assays.

Accurate quantification of von Willebrand factor ristocetin cofactor activity (VWF:RCo) is critical for the diagnosis and classification of von Willebrand disease, the most common hereditary and acquired bleeding disorder in humans. Moreover, it is important to accurately assess the function of von Willebrand factor (VWF) concentrates within the pharmaceutical industry to provide consistent and high-quality biopharmaceuticals. Although the performance of VWF:RCo assay has been improved by using coagulation analyzers, which are specialized devices for blood and blood plasma samples, scientists still report a high degree of intra- and inter-assay variation in clinical laboratories. Moreover, high, manual sample dilutions are required for VWF:RCo determination of VWF concentrates within the pharmaceutical industry, which are a major source for assay imprecision. For the first time, we present a precise and accurate method to determine VWF:RCo, where all critical pipetting and mixing steps are automated. A pre-dilution setup was established on CyBio FeliX (Analytik-Jena) liquid handling system, and an adapted VWF:RCo method on BCS-XP analyzer (Siemens) is used. The automated pre-dilution method was executed on three different, most frequently used coagulation analyzers and compared to manual pre-dilutions performed by an experienced operator. Comparative sample testing revealed a similar assay precision (coefficient of variation = 5.9% automated, 3.1% manual pre-dilution) and no significant differences between the automated approach and manual dilutions of an expert in this method. While no outliers were generated with the automated procedure, the manual pre-dilution resulted in an error rate of 8.3%. Overall, this operator-independent protocol enables standardization and offers an efficient way of fully automating VWF activity assays, while maintaining the precision and accuracy of an expert analyst. Key features • Automated pre-dilution setup for von Willebrand factor concentrates of various natures. • Combination of a liquid handling system (CyBio FeliX) with a coagulation analyzer (BCS-XP). • Simplifies method transfer to other laboratories. • Basic training for CyBio FeliX and BCS-XP is required. Graphical overview VWF:RCo assay principle and measurement setup. Platelets (yellow ellipsoids) with negative surface charge (- - -) are treated with formaldehyde, which partly denatures the cell surface and thus stabilizes platelets for use as assay reagents. Stabilized platelets (dark-yellow-framed yellow ellipsoids) are then brought in contact with ristocetin A (chemical structure shown; black dots), which binds to the platelet surface and facilitates binding of VWF (green circles). The graphs show an example of quantitative determination of platelet agglutination by measurement of light transmission, where increasing amounts of VWF increase light transmission over time. The photo in the left-bottom corner shows the CyBio FeliX setup for VWF sample dilution and the photo in the right-bottom corner displays the BCS-XP system, which is used for VWF:RCo measurements.

Infrared optical properties of SiGeSn and GeSn layers grown by molecular beam epitaxy

The infrared optical properties of thick GeSn films (>500 nm) having 10% Sn concentration and of SiGeSn layers, utilized for the growth of strain-relieved, direct-gap GeSn films by molecular beam epitaxy, are investigated. Two growth methods are used: a graded-growth structure and a stepped-growth structure that help us to illustrate the properties of the GeSn and SiGeSn layers. Interestingly, there can be strong absorption in SiGeSn films throughout the infrared. We observe an increase in infrared absorption with increasing Sn concentration up to 21% Sn and in films, where the Sn is held constant at 18%, with increasing Si concentration up to 30%. Cavity effects in the infrared transmission measurement of stepped-growth structures are observed and associated with reflections at growth interfaces. Si–Si bond formation is proposed to occur at high Si concentrations in SiGeSn films, and the bandgap in SiGeSn films appears to decrease with increasing Si and Sn concentrations.

A pulse-echo measurement setup to determine viscoelastic material parameters

Abstract Due to their versatility, the application of polymers in research and industry continues to increase. Since the majority of design processes are simulation-aided, precise material parameters are required to obtain realistic results. The quasi-statically and destructively measured material parameters provided by manufacturers for this purpose are usually insufficient. An acoustic method is generally capable of measuring the frequency-dependent viscoelastic material parameters in a non-destructive manner. In particular, an ultrasonic transmission measurement setup for determining these parameters has already been presented in previous publications. However, this approach has several drawbacks, including a low sensitivity to shear parameters. To increase the sensitivity to shear parameters, a measurement setup using a pulse-echo method with a corresponding inverse approach is presented to obtain viscoelastic material parameters of polymers. A brief comparison is made between the transmission and pulse-echo methods.

Acoustic Transmission Measurements for Extracting the Mechanical Properties of Complex 3D MEMS Transducers.

Recent publications on acoustic MEMS transducers present a new three-dimensional folded diaphragm that utilizes buried in-plane vibrating structures to increase the active area from a small chip volume. Characterization of the mechanical properties plays a key role in the development of new MEMS transducers, whereby established measurement methods are usually tailored to structures close to the sample surface. In order to access the lateral vibrations, extensive and destructive sample preparation is required. This work presents a new passive measurement technique that combines acoustic transmission measurements and lumped-element modelling. For diaphragms of different lengths, compliances between 0.08 × 10-15 and 1.04 × 10-15 m3/Pa are determined without using destructive or complex preparations. In particular, for lengths above 1000 µm, the results differ from numerical simulations by only 4% or less.

Determining the thickness of a thin aluminum sheet using the transmission measurement of X-rays with varying energies: A comparative analysis between calibration curve fitting and artificial neural network approaches

This study proposes an innovative configuration for thickness measurement based on X-ray transmission, intending to improve the precision of measuring thin aluminum sheets. In this configuration, an activation sample containing Zr, Sb, and Ba elements is irradiated by 59.54 keV gamma rays emitted from three 241Am radioactive sources with a total activity of 1.78 GBq. Subsequently, the activation sample emits fluorescent X-rays at energy levels of 15.78 keV (Zr-Kα1,2), 17.67 keV (Zr-Kβ1), 26.36 keV (Sb-Kα1,2), 29.73 keV (Sb-Kβ1), 32.2 keV (Ba-Kα1,2), and 36.38 keV (Ba-Kβ1). These X-rays are collimated into a narrow beam, which then penetrates through an absorbing sample, and is ultimately recorded by a Si(Li) detector. Two different approaches are investigated to determine the thickness of absorbing samples including Calibration Curve Fitting (CCF) and Artificial Neural Network (ANN). The CCF approach requires constructing linear calibration curves for establishing the relationship between lnR (R is the ratio of the peak areas in measurements with and without absorbing sample) and the thickness of the absorbing sample at each X-ray energy level. The sample thickness is then determined by calculating a weighted average of the measured thicknesses associated with all analyzed energy levels. This approach requires in-depth understanding of radiation physics and proficiency in X-ray spectrum analysis. Meanwhile, the ANN approach uses raw spectra obtained by the Si(Li) detector to predict the thickness of aluminum sheets, facilitating analysis without requiring human intervention. The reliability of these approaches is evaluated through experimental measurements on aluminum sheets with thicknesses ranging from 0.064 cm to 1.074 cm. The results indicate that using X-rays with many different energies leads to superior accuracy in thickness measurements compared to using X-rays with a single energy. Besides, both the CCF and ANN approaches yield relative deviations of less than 3% between the predicted and reference thicknesses. It is important to emphasize that the ANN approach represents a promising solution for automated analysis without the intervention of experts.

Line-field dispersive interference ellipsometry based on an anisotropic crystal

We propose an anisotropic crystal-based line-field dispersive interference ellipsometry, capable of both transmission and reflection measurements. This technique is adept at characterizing the optical polarization properties of transparent materials and is applicable for real-time film thickness monitoring in industrial line-field configurations. Experimental demonstrations include the dynamic line-field birefringent phase of the quarter-wave plate and the Soleil-Babinet compensator in the near-infrared band. The developed method also accurately measured the thickness distribution of a conveyor-based film specimen with thicknesses of 250 nm and 510 nm. A phase stability of 9.5 × 10−4 rad under 200 Hz update rate was demonstrated.

An Imaging and Spectroscopic Exploration of the Dusty Compact Obscured Nucleus Galaxy Zw 049.057* *Based in part on observations obtained with the Southern African Large Telescope (SALT).

Zw 049.057 is a moderate-mass, dusty, early-type galaxy that hosts a powerful compact obscured nucleus (CON, L FIR,CON ≥ 1011 L ⊙). The resolution of the Hubble Space Telescope enabled measurements of the stellar light distribution and characterization of dust features. Zw 049.057 is inclined with a prominent three-zone disk; the R ≈ 1 kpc star-forming inner dusty disk contains molecular gas, a main disk with less dust and an older stellar population, and a newly detected outer stellar region at R > 6 kpc with circular isophotes. Previously unknown polar dust lanes are signatures of a past minor merger that could have warped the outer disk to near face-on. Dust transmission measurements provide lower limit gas mass estimates for dust features. An extended region with moderate optical depth and M ≥ 2 × 108 M ⊙ obscures the central 2 kpc. Optical spectra show strong interstellar Na D absorption with a constant velocity across the main disk, likely arising in this extraplanar medium. Opacity measurements of the two linear dust features, pillars, give a total mass of ≥106 M ⊙, flow rates of ≥2 M ⊙ yr−1, and few Myr flow times. Dust pillars are associated with the CON and are visible signs of its role in driving large-scale feedback. Our assessments of feedback processes suggest gas recycling sustains the CON. However, radiation pressure driven mass loss and efficient star formation must be avoided for the active galactic nucleus to retain sufficient gas over its lifespan to produce substantial mass growth of the central black hole.

Signatures of top versus bottom illuminations and their predicted implications for infrared transmission microspectroscopy.

Since both top and bottom illuminations are widely used in infrared transmission measurements, in this paper, we study the effects of different illuminations on the signatures in infrared microspectroscopy. By simulating a series of dielectric samples, we show that their extinction efficiency, , remains unchanged when the direction of the incident plane wave is reversed, even though the field distributions both inside and outside of the sample may be dramatically different. We find features in that are correlated with whispering gallery modes for one beam direction and correspond to completely different field distributions for the opposite beam direction. In addition, by linking the optical theorem and the reciprocity relation of far-field scattered field, we rigorously prove the invariance of for arbitrary dielectric targets under opposite plane-wave illuminations. Furthermore, we show the difference in the apparent absorbance spectrum for opposite beam directions when considering numerical apertures.