Narrow Results

To address the problem of sources and sinks of atmospheric CO₂, measurements are needed on a global scale. Satellite instruments show promise, but typically measure the total column. Since sources and sinks at the surface represent a small perturbation to the total column, a precision of better than 1% is required. No species has ever been measured from space at this level. Over the last three years, we have developed a small instrument based upon a Fabry-Perot interferometer that is highly sensitive to atmospheric CO₂. We have tested this instrument in a ground based configuration and from aircraft platforms simulating operation from a satellite. The instrument is characterized by high signal to noise ratio, fast response and great specificity. We have performed simulations and instrument designs for systems to detect, H₂O, CO, ¹³CO₂, CH₄, CH₂O, NH₃, SO₂, N₂O, NO₂, and O₃. The high resolution and throughput, and small size of this instrument make it adaptable to many other atmospheric species. We present results and discuss ways this instrument can be used for ground, aircraft or space based surveillance and the detection of pollutants, toxics and industrial effluents in a variety of scenarios including battlefields, industrial monitoring, or pollution transport.

The quantum Hall effect (QHE) discovery has revolutionized the ohm metrology: the representation of the unit of resistance is now universal and the ohm can be maintained in each national metrology institute with a relative uncertainty of one part in 10⁹. This breakthrough also results from the development of resistance comparison bridges using cryogenic current comparator (CCC). The fundamental properties of the QHE allow the realization of Quantum Hall Array Resistance Standards (QHARS) by combining a large number of single Hall bars connected in series and/or in parallel. These standards can be as accurate as a single Hall bar. More generally, the multiple connection technique allows metrologists to design useful circuits based on quantum Hall resistors like voltage dividers or Wheatstone bridges. The QHE Wheatstone bridge is particularly suitable for comparing quantum standards. By detecting the unbalance current of this bridge with a CCC, new universality tests of the QHE with a target uncertainty less than 10¹¹ can be realized.

The hardness properties of materials are tracked from early history until the present time. Emphasis is placed on the hardness test being a useful probe for determining the local elastic, plastic and cracking properties of single crystal, polycrystalline, polyphase or amorphous materials. Beginning from connection made between individual hardness pressure measurements and the conventional stress–strain properties of polycrystalline materials, the newer consideration is described of directly specifying a hardness-type stress–strain relationship based on a continuous loading curve, particularly, as obtained with a spherical indenter. Such effort has received impetus from order-of-magnitude improvements in load and displacement measuring capabilities that are demonstrated for nanoindentation testing. Details of metrology assessments involved in various types of hardness tests are reviewed. A compilation of measurements is presented for the separate aspects of Hertzian elastic, dislocation-mechanics-based plasticity and indentation-fracture-mechanics-based cracking behaviors of materials, including elastic and plastic deformation rate effects. A number of test applications are reviewed, most notably involving the hardness of thin film materials and coatings.

In this work, spatially resolved characterization methods are used to identify loss mechanisms for common $p$-type silicon solar cell architectures, including multicrystalline aluminum back surface field (Al-BSF), monocrystalline Al-BSF, monocrystalline passivated emitter and rear cells (PERC), and bifacial monocrystalline PERC. The characterization methods used in this work include suns-$V_{\mathrm{\text{OC}}}$, photoluminescence imaging, and spatially resolved external quantum efficiency and reflectance measurements. The optical and recombination losses are driven by the material properties, cell processing conditions, and device architecture. These losses are quantified and categorized in terms of underlying mechanisms (e.g., front reflectance, escape reflectance, front recombination, and parasitic optical absorption and recombination in the bulk and rear). The ability to create images of these loss parameters can be used to gain more insight into the materials and manufacturing processes used to produce solar cells, and examples are given in this work to illustrate how these images can help reveal the origin of defects.

Roundness and cylindricity evaluations are among the most important problems in computational metrology, and are based on sets of surface measurements (input data points). A recent approach to such evaluations is based on a linear-programming approach yielding a rapidly converging solution. Such a solution is determined by a fixed-size subset of a large input set. With the intent to simplify the main computational task, it appears desirable to cull from the input any point that cannot provably define the solution. In this note we present an analysis and an efficient solution to the problem of culling the input set. For input data points arranged in cross-sections under mild conditions of uniformity, this algorithm runs in linear time.

The constant of gravitation, G, is the least well-known of the physical constants. A new, independent method of measurement, estimated as having a potential uncertainty at least as small as that achieved by existing methods, would be useful for an improvement in G determination. This experiment is based on the measurement of the relative motion of two freely falling test bodies (discs), caused by their gravitational attraction. The uncertainties are analyzed for two parallel tungsten discs with masses of about 30 kg. The use of test bodies with an incorporated optical system of multipass two-beam interferometers, as well as of multibeam interferometers, is proposed to measure their relative displacement. The estimations were made for laboratory experiment with free fall duration of 0.714 s. In this case, the relative displacement to be measured is about 0.1 μm. These estimates show that relative uncertainties lower than 5 × 10^-5 can be obtained in G measurement in a single drop of the test bodies. The proposed experiment can be made in outer space. In space a lower uncertainty can be achieved because the time interval of the measurement of relative motion of the test bodies can be increased.

This paper describes experimental results of thermal diffusivity measurements performed on different concentrations of aqueous Tartrazine solutions. The measurements are performed using the frequency-resolved thermal lensing technique and the results are compared with the thermal diffusivity value of pure water used as a solvent or host liquid. The results show that at low concentrations, the thermal properties of the solution are roughly equal to those of the water. However, when the concentration is increased, the thermal properties of the solutions diverge from that of the host liquid.

A Traceable Atomic Force Microscope (TAFM) to calibrate the pitch standards is presented. The TAFM consists of an atomic force microscope, a three-axis active compensation flexure stage, two laser interferometers, an L-shape mirror, a vibration isolator, and a super-Invar metrology frame. A test specimen is laid on the same plane of laser interferometers to eliminate the Abbe-offset. The displacements of X and Y axes are taken by the laser interferometers, the Z movement is controlled by AFM cantilever and the displacement is taken by a capacitance sensor while the flexure stage moves the specimen in X and Y axes motions. A water circulator is used to control the TAFM at 20°C. Measuring results of a standard pitch sample show that this TAFM can be used for measuring of pitch standards. A pitch standard with nominal value of 292 nm was served as a test sample. The combined standard uncertainty was 1.2 nm.

We propose to utilize the Bose–Einstein condensate (BEC) for precision phase sensitive measurement of position and momentum displacements. The controlled two-soliton dynamics can be turned into a quantum probe to measure these parameters with high precision in an experimentally verified system of bright solitary trains. A careful phase space analysis of the dynamics of the mesoscopic wave packet is carried out through Wigner phase space picture for finding out the parameter domain exhibiting sub-Planck structures, required for precision quantum metrology. We propose two experimentally feasible scenarios, one involving the overall phase and the other through the relative phase between the two-solitons when they are oscillating inside the trap. In both the cases, detailed analytical studies are carried out through the overlap functions which reveal the sensitivity issue. A careful analysis is also performed to find the parametric domain relevant for the use of BEC for weak value estimation.

A new method of surface profiling and dimensional measurement of submicron VLSI structure by scanning tunneling microscope (STM) has been successfully tested. Compared to the scanning electron microscope (SEM), the STM operates in air, provides three-dimensional imaging and yields better resolution; therefore, the STM has a greater potential than the SEM. The measurement error caused by the geometry of the probe, the only outstanding issue affecting STM accuracy, is explored in detail. An improved technique for etching sharp and slender STM probes has been developed, enabling the STM to be applied to high-density, high-rise microelectronic structure and thereby reducing the measurement error caused by the probe geometry. Probes with ideal tip geometry, tip angle less than 3° and radius of 0.03 µm within 1 µm from the tip, can be consistently produced and are believed to be the best state of the art from known reports. Furthermore, the method of side-wall profiling and true profile reconstruction are developed to avoid the probe geometrical effect, making it possible for the STM to obtain an accurate topographical profile without cleaving the sample and viewing it from the edge as needed by the SEM. Self-calibration of the probe geometry by the STM is used for further compensation of the measurement errors. The same techniques developed in this study can also be applied to the atomic force microscope (AFM), a derivative of the STM, for profiling and measuring nonconductive samples.

Optical coherence tomography (OCT) has been widely applied to the diagnosis of eye diseases during the past two decades. However, valid evaluation methods are still not available for the clinical OCT devices. In order to assess the axial resolution of the OCT system, standard model eyes with micro-scale multilayer structure have been designed and manufactured in this study. Mimicking a natural human eye, proper Titanium dioxide (TiO₂) materials of particles with different concentrations were selected by testing the scattering coefficient of PDMS phantoms. The artificial retinas with multilayer films were fabricated with the thicknesses from 9.5 to 30 micrometers using spin coating technology. Subsequently, standard OCT model eyes were accomplished by embedding the retina phantoms into the artificial frames of eyes. For ease of measurement processing, a series of model eyes were prepared, and each contained films with three kinds of thicknesses. Considering the traceability and accuracy of the key parameters of the standard model eyes, the thicknesses of multilayer structures were verified using Thickness Monitoring System. Through the experiment with three different OCT devices, it demonstrated the model eyes fabricated in this study can provide an effective evaluation method for the axial resolution of an ophthalmic OCT device.

The Sydney University Stellar Interferometer (SUSI) now incorporates a new beam combiner, called the Microarc-second University of Sydney Companion Astrometry instrument (MUSCA), for the purpose of high precision differential astrometry of bright binary stars. Operating in the visible wavelength regime where photon-counting and post-processing fringe tracking is possible, MUSCA will be used in tandem with SUSI's primary beam combiner, Precision Astronomical Visible Observations (PAVO), to record high spatial resolution fringes and thereby measure the separation of fringe packets of binary stars. In its current phase of development, the dual beam combiner configuration has successfully demonstrated for the first time a dual-star phase-referencing operation in visible wavelengths. This paper describes the beam combiner optics and hardware, the network of metrology systems employed to measure every non-common path between the two beam combiners and also reports on a recent narrow-angle astrometric observation of δ Orionis A (HR 1852) as the project enters its on-sky testing phase.

We present a new, inexpensive, bench-top method for measuring groove period over large areas with high mapping resolution and high measurement accuracy, dubbed the grating mapper for accurate period (GMAP). The GMAP has the ability to measure large groove period changes and nonparallel grooves, both of which cannot be measured via optical interferometry. In this paper, we detail the calibration and setup of the GMAP, and employ the instrument to measure three distinct gratings. Two of these measured gratings have customized groove patterns that prevent them from being measured via other traditional methods, such as optical interferometry. Our implementation of this tool achieves a spatial resolution of 0.1mm$\times$0.1mm and a period error of 1.7nm for a 3$\mu$m size groove period.

Geometric optical distortion is a significant contributor to the astrometric error budget in large telescopes using adaptive optics. To increase astrometric precision, optical distortion calibration is necessary. We investigate using smartphone Organic Light-Emitting Diode (OLED) screens as astrometric calibrators. Smartphones are low-cost, have stable illumination, and can be quickly reconfigured to probe different spatial frequencies of an optical system’s geometric distortion. In this work, we characterize the astrometric accuracy of a Samsung S20 smartphone, with a view towards providing large format, flexible astrometric calibrators for the next generation of astronomical instruments. We find the placement error of the pixels to be 189nm ± 15nm Root Mean Square (RMS). At this level of error, milliarcsecond astrometric accuracy can be obtained on modern astronomical instruments.

3D scanning technologies are deployed toward developing a digital 3D model for Additive Manufacturing (AM) applications. It collects data, turning it into a 3D model that uses designated 3D printing processes. Many scanners, ranging from low-cost alternatives to professional series that are far more accurate and reliable, are now available to assist in bringing designs to reality. 3D scanning solutions enable the appropriate measurement of 3D physical parts into the virtual world, allowing factory production teams and corporate offices to share critical design information. These techniques are utilized everywhere in the design process, including product design and development, reverse engineering, quality control and quality assurance. The manufacturing sector can decrease costs while accelerating time to market and resolving quality issues. This study investigates the metrological need as per the advancements of 3D scanners. The procedural steps of the 3D scanners, along with specific metrological components and soft tools for 3D scanning, are discussed briefly. Finally, various 3D scanning applications are identified and discussed in detail. Because of the overall relative advantages of these non-contact measurement techniques, 3D metrological tools are crucial for modern production. Almost every sector aims for smaller, more complex components, which are more vulnerable to contamination or injury from even the slightest touch with a probe. The market is driven by global Research and Development (R&D) investment to develop game-changing technologies and solutions. Precision inspection and quality control are significant market drivers for industry progress. Smart factories will have lifetime access to 3D metrological data, allowing them to enhance quality and gain a competitive advantage in the marketplace.

In this paper, we employ the latest developments in 3D semi-supervised learning to create cutting-edge deep learning models for 3D object detection and segmentation of buried structures in high-resolution X-ray semiconductor scans. We illustrate our approach to locating the region of interest of High Bandwidth Memory (HBM) structures and their individual components and identifying various defects. We showcase how semi-supervised learning is utilized to capitalize on the vast amounts of available unlabeled data to enhance both detection and segmentation performance. Additionally, we explore the benefits of contrastive learning in the data pre-selection for our detection model and multi-scale Mean-Teacher training paradigm in 3D semantic segmentation to achieve better performance compared to the state of the art. We also provide an objective comparison for metrology-based defect detection with a 3D classification network. Our extensive experiments have shown that our approach outperforms the state of the art by up to 16% on object detection and 7.8% on semantic segmentation. Our fully-automated custom metrology package shows a mean error of less than 2 $\mu$m for key features such as bond line thickness and provides better defect detection performance than the direct 3D classification approach. Overall, our method achieves state-of-the-art performance and can be used to improve the accuracy and efficiency of a wide range of failure analysis applications in semiconductor manufacturing. Finally, we also increase the segmentation models flexibility and adaptability to new data. We propose a generic training strategy and a new loss function that reduces the training time by 60% and the required amount of data by 48% making the training process more efficient.

To address the problem of sources and sinks of atmospheric CO₂, measurements are needed on a global scale. Satellite instruments show promise, but typically measure the total column. Since sources and sinks at the surface represent a small perturbation to the total column, a precision of better than 1% is required. No species has ever been measured from space at this level. Over the last three years, we have developed a small instrument based upon a Fabry-Perot interferometer that is highly sensitive to atmospheric CO₂. We have tested this instrument in a ground based configuration and from aircraft platforms simulating operation from a satellite. The instrument is characterized by high signal to noise ratio, fast response and great specificity. We have performed simulations and instrument designs for systems to detect, H₂O, CO, ₁₃CO₂, CH₄, CH₂O, NH₃, SO₂, N₂O, NO₂, and O₃. The high resolution and throughput, and small size of this instrument make it adaptable to many other atmospheric species. We present results and discuss ways this instrument can be used for ground, aircraft or space based surveillance and the detection of pollutants, toxics and industrial effluents in a variety of scenarios including battlefields, industrial monitoring, or pollution transport.

We report on the latest determination of the Newtonian gravitational constant G using our atom interferometry gravity gradiometer. After a short introduction on the G measurement issue we will provide a description of the experimental method employed, followed by a discussion of the experimental results in terms of sensitivity and systematic effects. Finally, prospects for future cold atom-based experiments devoted to the measurement of this fundamental constant are reported.

The quantity notions in mathematics and metrology and their relation and interaction are considered. The quantity in mathematics belong to the modelling field and is an ideal object while the quantity in metrology has an experimental character and so is an uncertain object. Every metrological model object including measurement aim, measurand, metrological characteristic of a measuring instrument, are expressed by mathematical quantities. When the model object is evaluated by using measurement, so the experimental quantity is obtained, that is metrological quantity. Because of the principal uncertain character of metrological quantities, measuring data and relating metrological quantities have to be processed using firstly non-classic mathematical means but of special type, taking into account the above-mentioned character. There are approximate linear equations theory, interval arithmetic, fuzzy set, and so on. There is not wide use of these means. The reasons are traditions, and absence of data structure analysis, and special place of stochastic tools. The latter is conditioned by some peculiarities of probabilistic-stochastic models. Main, and wide spread, mistakes or faults in use of these models are discussed. Indirect measurement is considered as the field of most complicated interaction of experimental and mathematical quantities.

When we do usual Computation in Science, especially in Metrology, we assume that we do Mathematics. This is only partly true in spite of the fact that database handling and data processing are most important indeed. The field of Measurement plus Observation is much more entangled with Mathematics. The following survey “Metrology and Mathematics” will focus on selected ideas, concepts, rules, models, and structures, each of which is of a basic mathematical nature. When doing this, it is not surprising at all that most theoretical and applicational requirements in the field can be reduced to just a few basic logical and mathematical structures. This is also true for complex processes in fields like humanity and society. Signal and System Theory (SST) supports this claim. However, such an endeavour asks for an orderly and consistent definition of quantities and processes and of their mathematical models, called signals and systems. These models represent all kinds of issues, items, and phenomena in the real world. The term model indicates the superordinate means of mathematical description, observation, and representation in Science and Technology. The question arises, what the role of Logic and Mathematics looks like in detail. The term structure will be consistently pivotal. And, as is generally known, structures are best visualised by graphical means, here called Signal Relation Graphs (SRG).