Metrology Methods Research Articles

Real-time detection and discrimination of radioactive gas mixtures using nanoporous inorganic scintillators

The nuclear industry’s expansion to encompass carbon-free electricity generation from small modular reactors and nuclear fuel reprocessing necessitates enhanced detection and monitoring of pure beta-emitting radioactive elements such as 3H and 85Kr; this endeavour is crucial for nuclear safety authorities tasked with environmental monitoring. However, the short range of electrons emitted by these gases makes detection challenging. Current methods, such as ionization chambers and liquid scintillation, do not offer at the same time good sensitivity, real-time analysis and ease of implementation. We demonstrate an approach using a gas–solid mixture to overcome these limitations. We synthetized a transparent and scintillating nanoporous material, an aerogel of Y3Al5O12:Ce4+, and achieved real-time detection with an efficiency of 96% for 85Kr and 18% for 3H. The method reaches a sensitivity below 100 mBq per cm3 over 100 s measurement time. We are able to measure simultaneously as mixtures containing both 3H and 85Kr a capability not possible previously. Our results demonstrate a compact and robust detection system for inline measurement of strategic radioactive gases. This combination of concept and method enhances nuclear power plant management and contributes to environmental safeguarding. Beyond the detection issues, this concept opens a wide field of new methods for radionuclide metrology.

Research on metrology method of surface magnetic field based on the nitrogen-vacancy center (NV) in diamonds

Research on metrology method of surface magnetic field based on the nitrogen-vacancy center (NV) in diamonds

Interactive CAD Layout of Reflection-Based Mirror Metrology Systems

Concentrating solar mirrors need to accurately focus sunlight onto a receiver. Since mirror surface normal determines reflected light direction, reflection-based metrology methods that measure surface normal have the advantage of directly measuring the mirror’s intended functional performance characteristic. Several methods have been reported that produce high-resolution measurements of mirror surface normal of concentrating solar mirrors [1-8]; these systems typically employ an optical target, a camera, and sometimes an external light source. These elements must be placed in a configuration that satisfies multiple feasibility constraints, including mechanical and optical visibility and reflection constraints. For complex problems or installations in cluttered environments, it can be difficult to analyze all of these constraints manually. We have created a computer automated design (CAD) tool that aids in visualization of reflection-based metrology systems, making it possible to determine layouts for complex metrology design problems. The tool is implemented SolidWorks, a commercial CAD system [9]. By exploiting the SoidWorks constraint satisfaction mechanism, the tool is able to present interactive visualization of reflection and field of view constraints in real time without any additional code or macros. The tool supports ease of use and multiple design configurations through an ordinary spreadsheet interface. The tool can be used to address a variety of reflection-based metrology design problems, and is available to the public as open source.

Separation of microplastics from deep-sea sediment using an affordable, simple to use, and easily accessible density separation device

Microplastics accumulate in the environment but methods to extract particles from sediment for quantification and identification often lack accuracy and reproducibility. Existing methods vary greatly and many do not achieve adequate microplastic separation. During method development for extraction procedures, spike-recovery experiments (positive controls) are essential to ensure accurate and reproducible results from each sample matrix. Furthermore, the large variability in grain size and organic matter can affect the extraction of microplastics from the matrix. Scientists have used density separation to separate microplastics from matrices for decades, but apparatuses are often made of plastic, need to be custom made, and require multiple sample transfers from one apparatus to another. This study presents an affordable, easily accessible, and simple to use Density Separation Device (DSD) to remove plastics from deep-sea sediments. Eight polymers were spiked into replicates of environmental sediment, including six fragments: high density polyethylene (HDPE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), nylon (PA6), and crumb rubber (CR) and two fibers: cellulose acetate (CA) and polyester (PEST). Two size classes of polymers were used: 100 μm to 300 μm and > 300 μm. Using a sodium polytungstate solution at a density of 1.9 g/mL and reflectance FTIR microscopy for particle identification, mean recoveries of all fragments exceeded 78% (CR: 92.7% ± 30.8%, PP: 78.4% ± 34.0%, HDPE: 93.8% ± 13.5%, PS: 86.9% ± 25.7%, PA6: 98.4% ± 63.2%, PVC: 100.0% ± 12.4%). Fiber recovery was much lower (PEST: 28.1% ± 28.1% and CA: 25.9% ± 17.3%) because they aggregated, passed through sieves vertically, or were obscured under other particles. The fragment recovery success, accessibility (available online, all parts under $200) and ease of use of this DSD should facilitate widespread use, thus helping to standardize sample preparation methods for microplastic metrology.

The linear Paul Trap's Confined Stability Area for 40Ca+ Ions

تقدم تكنولوجيا الكم طرقًا حسابية واتصالات ومحاكاة وقياسًا جديدة. تحتاج أجهزة الكمبيوتر التقليدية إلى المساعدة في حل المشكلات المهمة مثل التحليل بسبب الزيادات الهائلة في وقت الحساب. ومع ذلك، تستخدم أجهزة الكمبيوتر الكمومية ميكانيكا الكم لحجم المشكلة الأسي الفرعي ويمكنها محاكاة الطبيعة على المستوى الكمي. يهتم العلماء بشكل متزايد بتطوير أجهزة الكمبيوتر الكمومية باستخدام ذرات متأينة مفردة في مصائد باولي. تمثل الحالة الأساسية لكل أيون أقل قيمة ممكنة للبت الكمي. تم استخدام الأيونات المحتجزة 40Ca+ في إحدى الدراسات كمثال على الكيوبت الكمومي. تم استخدام برنامج MATLAB على العوامل النموذجية التي تؤثر على الحالة المقيدة وتأثيراتها. يجب أن تكون الحلول مستقرة في كلا الاتجاهين، مما يتطلب حصرًا ثلاثي الأبعاد لمعادلة ماثيو. تؤثر المتغيرات على المسافة من مركز المصيدة لنهاية القطب، وجهد UDC، وكتلة الأيون، والترددات الراديوية. تم استخدام جهد متغير للتحكم وإظهار تأثيره على سلسلة محددة من الأيونات المحاصرة. يهدف هذا البحث إلى فهم أفضل للظروف المثلى للحجز وحركة الأيونات من الحالة (4S1/2) إلى الحالة (4P1/2) بالرنين. تخضع الحالة الكمومية للتعديل والتغيير، مما يجعلها أداة واعدة لحل المشكلات المعقدة.

Multi-functional photonic spin Hall effect sensor controlled by phase transition

Abstract Photonic spin Hall effect (PSHE), as a novel physical effect in light–matter interaction, provides an effective metrological method for characterizing the tiny variation in refractive index (RI). In this work, we propose a multi-functional PSHE sensor based on VO2, a material that can reveal the phase transition behavior. By applying thermal control, the mutual transformation into different phase states of VO2 can be realized, which contributes to the flexible switching between multiple RI sensing tasks. When VO2 is insulating, the ultrasensitive detection of glucose concentrations in human blood is achieved. When VO2 is in a mixed phase, the structure can be designed to distinguish between the normal cells and cancer cells through no-label and real-time monitoring. When VO2 is metallic, the proposed PSHE sensor can act as an RI indicator for gas analytes. Compared with other multi-functional sensing devices with the complex structures, our design consists of only one analyte and two VO2 layers, which is very simple and elegant. Therefore, the proposed VO2-based PSHE sensor has outstanding advantages such as small size, high sensitivity, no-label, and real-time detection, providing a new approach for investigating tunable multi-functional sensors.

Microsphere-assisted hyperspectral imaging: super-resolution, non-destructive metrology for semiconductor devices

As semiconductor devices shrink and their manufacturing processes advance, accurately measuring in-cell critical dimensions (CD) becomes increasingly crucial. Traditional test element group (TEG) measurements are becoming inadequate for representing the fine, repetitive patterns in cell blocks. Conventional non-destructive metrology technologies like optical critical dimension (OCD) are limited due to their large spot diameter of approximately 25 μm, which impedes their efficacy for detailed in-cell structural analysis. Consequently, there is a pressing need for small-spot and non-destructive metrology methods. To address this limitation, we demonstrate a microsphere-assisted hyperspectral imaging (MAHSI) system, specifically designed for small spot optical metrology with super-resolution. Utilizing microsphere-assisted super-resolution imaging, this system achieves an optical resolution of 66 nm within a field of view of 5.6 μm × 5.6 μm. This approach effectively breaks the diffraction limit, significantly enhancing the magnification of the system. The MAHSI system incorporating hyperspectral imaging with a wavelength range of 400–790 nm, enables the capture of the reflection spectrum at each camera pixel. The achieved pixel resolution, which is equivalent to the measuring spot size, is 14.4 nm/pixel and the magnification is 450X. The MAHSI system enables measurement of local uniformity in critical areas like corners and edges of DRAM cell blocks, areas previously challenging to inspect with conventional OCD methods. To our knowledge, this approach represents the first global implementation of microsphere-assisted hyperspectral imaging to address the metrology challenges in complex 3D structures of semiconductor devices.

The Application of a Non-Intrusive Methodology to Estimate Particle Egress Rate and Advective Heat Losses of a Falling Particle Receiver During On-Sun Tests

Abstract The direct measurement of particle temperatures and advective losses from solid particle receiver has been a topic of necessary interest to de-risk the technology and improve its performance. Due to the flow's transient and stochastic nature, it has presented a challenge to traditional thermometry and metrology methods. In this work, a simplified quantitative non-intrusive imaging methodology previously developed is applied to Sandia's falling particle receiver during on-sun tests to collect image sets, which could help estimate the average particle temperature and particle egress rate from the system. Further additions to the technique are presented to permit the estimation of the plume (air and particles) egress rate and total advective heat losses during on-sun operation. The falling particle receiver testing campaign in 2020 and 2021 allowed the team to capture multiple flow configurations and environmental conditions used to build a large database of data captures with different characteristics. Finally, the results captured were used to complete a regression study to gain further insight into the factors which impact the particle egress and the receiver's efficiency. Particle temperature, receiver flow configuration, and wind speed were found to be the most impactful factors in the study.

Comprehensive Study and Design of Graphene Transistor.

Graphene, renowned for its exceptional electrical, optical, and mechanical properties, takes center stage in the realm of next-generation electronics. In this paper, we provide a thorough investigation into the comprehensive fabrication process of graphene field-effect transistors. Recognizing the pivotal role graphene quality plays in determining device performance, we explore many techniques and metrological methods to assess and ensure the superior quality of graphene layers. In addition, we delve into the intricate nuances of doping graphene and examine its effects on electronic properties. We uncover the transformative impact these dopants have on the charge carrier concentration, bandgap, and overall device performance. By amalgamating these critical facets of graphene field-effect transistors fabrication and analysis, this study offers a holistic understanding for researchers and engineers aiming to optimize the performance of graphene-based electronic devices.

Systematic Radio Telescope Alignment Using Portable Fringe Projection Profilometry

In 2019, the Event Horizon Telescope (EHT) released the first-ever image of a black hole event horizon. Astronomers are now aiming for higher angular resolutions of distant targets, like black holes, to understand more about the fundamental laws of gravity that govern our universe. To achieve this higher resolution and increased sensitivity, larger radio telescopes are needed to operate at higher frequencies and in larger quantities. Projects like the next-generation Very Large Array (ngVLA) and the Square-Kilometer Array (SKA) require building hundreds of telescopes with diameters greater than 10 ms over the next decade. This has a twofold effect. Radio telescope surfaces need to be more accurate to operate at higher frequencies, and the logistics involved in maintaining a radio telescope need to be simplified to support them properly in large quantities. Both of these problems can be solved with improved methods for surface metrology that are faster and more accurate with a higher resolution. This leads to faster and more accurate panel alignment and, therefore, a more productive observatory. In this paper, we present the use of binocular fringe projection profilometry as a solution to this problem and demonstrate it by aligning two panels on a 3-m radio telescope dish. The measurement takes only 10 min and directly delivers feedback on the tip, tilt, and piston of each panel to create the ideal reflector shape.

Effect of Diabetes on Wound Healing: A Bibliometrics and Visual Analysis.

The quality of life of diabetic patients is seriously affected by wound healing difficulty, which can lead to increased infection, skin deep tissue injury and continuous pain. By analyzing the research trends and hot spots in this field, the visualization analysis map is constructed. The contents of the selected articles were sorted out and analyzed by bibliometrics. We use CiteSpace, Vosviewer and HistCite to visualize literature information, including national publication statistics, institutions, authors, journal partnerships, and citations of published articles. Among the 2942 articles, the United States and China ranked first in both article circulation and TGCS, and many countries also cooperated. The collaboration between schools and research institutions is a core part of dissertation research institution collaboration, with most authors coming from the same institution. Most of the literature studies on the mechanisms and methods of promoting diabetic wound healing. Improving cell function or making innovative attempts in local treatment are the fruits of researchers' efforts to promote diabetic wound healing in recent years. Through the metrology method, the time distribution, author institution, cooperation network, research status, research hotspot and development trend of the literature on the influence of diabetes on wound healing were intuitively displayed, which provided a reference for further research and development direction.

Multi-source AdaBoost with cross-weight method for virtual metrology in semiconductor manufacturing

In the context of Industry 4.0, many production scenarios utilise sensors to monitor manufacturing processes, resulting in massive data that can be leveraged to build machine-learning models to improve production efficiency and quality. In semiconductor manufacturing, where many sensors are employed to monitor the production process, the resulting multi-sensor data poses challenges for constructing a virtual metrology (VM) model to assess wafer quality. Furthermore, building separate prediction models for each sensor can result in a loss of redundancy present in the multi-sensor data. Therefore, this paper proposes a multi-source AdaBoost with a cross-weight sampling method for predicting the critical dimension required in VM. Compared with the existing AdaBoost algorithm in regression, the proposed method adapts well to multi-source data by incorporating a cross-weight sampling distribution. Thus, when updating the sampling weight distribution, the impact of both individual and multi-source data is considered to re-sample high-quality observations. Based on the numerical results from the synthetic datasets and case study in semiconductor manufacturing, the proposed method outperforms benchmark methods. Additionally, owing to the redundancy of multi-sensor data, the proposed method demonstrates robust performance regardless of the noise level in the semiconductor VM data.

Features of quantum measurement standards and special status of the second in the SI-2019

The implementation of the New SI in 2019 and the definition of base units in terms of “defining constants” has significantly changed the metrology methods and led to the introduction of a quantum approach to the reproduction of units. The paper highlights a number of features of quantum methods and measurement standards, the ultimate accuracy of which is limited only by the “quantum structure of nature”. For electrical measurements, the implementation of the New SI means the end of the dualism that has existed since 1990. The dualism was that the SI defined the ampere – base unit of electricity – by mechanical measurements and quantities, and for reference measurements in practice, it was recommended to use the quantum effects of Josephson and Hall.
 A number of features of quantum methods and measurement standards are considered, which made it possible to increase the accuracy of reproduction of electrical units (and even earlier – units of time and length) by several orders of magnitude compared to the “pre-quantum” era.
 Another feature of the SI-2019 was the fact that it linked the units of all base quantities to the second and thus paved the way for the reproduction of units in terms of defining constants (which are fixed without uncertainty in the SI-2019) and the second, which is measured with the highest accuracy. Thus, the main task of metrology is to establish the relationship between the measured value and the second. In electrical measurements and some other types of measurements, this function is performed by quantum methods, which are described in this paper.
 The extremely high accuracy of time measurements, the availability of its transfer via communication lines, and the system-forming nature of the second determine its special status in SI-2019.
 The paper presents that the success in creating frequency measurement standards in the optical range promises further improvement of the accuracy of the second, which only raises its status and may lead to official revision of its definition in terms of the frequency of another quantum transition already existing in the optical range.
 It is suggested that the development of quantum measurement methods, the counting nature of these methods, and the features of the second mentioned in the paper bring us closer to the creation of a new metrology that will be a logical continuation of quantum metrology and which can be conventionally called “digital”.

High-SNR mid-infrared dual-comb spectroscopy using active phase control cooperating with CWs-dependent phase correction.

Mid-infrared (MIR) dual-comb spectroscopy (DCS) is a highly effective method for molecular metrology of rovibrational transition spectra in a quick accurate manner. However, due to limited comb frequency instability, manipulating coherence between two frequency combs to accomplish high-quality spectral analysis in the MIR region is a huge challenge. Here, we developed a comb-teeth resolved MIR DCS based on active phase control cooperating with a CWs-dependent (CWD) interferogram timing correction. Firstly, four meticulously engineered actuators were individually integrated into two near-infrared (NIR) seed combs to facilitate active coherence maintenance. Subsequently, two PPLN waveguides were adopted to achieve parallel difference frequency generations (DFG), directly achieving a coherent MIR dual-comb spectrometer. To improve coherence and signal-to-noise ratio (SNR), a CWD resampled interferogram timing correction was used to optimize the merit of DCS from 7.5 × 105 to 2.5 × 106. Meanwhile, we carried out the measurement of MIR DCS on the methane hot-band absorption spectra (v3 band), which exhibited a good agreement with HITRAN by a standard deviation on recording residual of 0.76%. These experimental results confirm that this MIR DCS with CWD interferogram timing correction has significant potential to characterize the rovibrational transitions of MIR molecules.

METHODS OF MACHINE LEARNING IN MODERN METROLOGY

In the modern world of scientific and technological progress, the requirements for the accuracy and reliability of measurements are becoming increasingly stringent. The rapid development of machine learning (ML) methods opens up perspectives for improving metrological processes and enhancing the quality of measurements. This article explores the potential application of ML methods in metrology, outlining the main types of ML models in automatic instrument calibration, analysis, and prediction of data. Attention is paid to the development of hybrid approaches that combine ML methods with traditional metrological methods for the optimal solution of complex measurement tasks.

CCQM-K91.2022 key comparison on pH of an unknown phthalate buffer

Main textKey comparison CCQM-K91.2022, a repetition of the previous comparison CCQM-K91 from 2011, was performed to evaluate the degree of equivalence between pH measurement results of an unknown phthalate buffer reported by participating National Metrology Institutes (NMIs) and Designated Institutes (DIs). The participants used the highest-level metrological method existing at their institution. The nominal pH value of the buffer was 4.0 at 25 °C and the suggested measurement temperatures were 5 °C, 15 °C, 25 °C, 37 °C, and 50 °C. There was a good agreement among the results from most participants at 15 °C, 25 °C, and 37 °C. Due to the lack of results, no evaluation was possible of results at 5 °C and 50 °C.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

A study on metrological cross-validation of hydrogen refueling stations using a hybrid metrology evaluation system

Hydrogen refueling stations play a pivotal role in advancing hydrogen fuel cell vehicles. Ensuring the accuracy and reliability of these stations is crucial for their safe and efficient operation. This study proposes a hybrid metrology evaluation system for the comprehensive cross-validation of hydrogen refueling stations. The system combines experimental measurements with computational models to thoroughly assess the stations' performance. The main objectives of this study are to evaluate the precision, accuracy, and reliability of hydrogen refueling stations and to identify potential uncertainties or sources of error in measurements. Six refueling experiments were conducted, varying the refueling pressure from 476 bar to 735 bar and the refueling rate from 0.601486 kg/min to 0.702694 kg/min. The maximum refueling capacity was determined to be approximately 6.3 kg, based on the specifications of the NEXO vehicle.Throughout the experiments, data on critical parameters such as pressure, weight, and flow rate were collected. These data were meticulously analyzed and compared with expected values derived from computational models. The results convincingly demonstrate that the hybrid metrology evaluation system offers a robust and precise evaluation of hydrogen refueling stations. The system adeptly identifies discrepancies between experimental measurements and computational models, facilitating the correction of potential measurement errors.This study contributes significantly to the enhancement of metrological cross-validation techniques for hydrogen refueling stations, ensuring their precision and dependability. The study findings can inform the development of standardized metrological protocols and guidelines for the certification and calibration of hydrogen refueling stations. By establishing accurate and dependable metrological validation methods, the adoption of hydrogen fuel cell vehicles can be expedited, promoting a sustainable and environmentally friendly transportation system.

Optimization and fabrication of chromium grating in self-traceable interferometer

Metrological methods rooted in natural constants present a robust strategy for ensuring traceability in nanometric measurements. A Chromium (Cr) grating, meticulously constructed through atom lithography and possessing a pitch of d = 212.7705 ± 0.0049 nm intrinsically traceable to the Cr transition frequency 7S3→7P40, exhibits promising potential as a self-traceable length standard in nano-length metrology via a grating interferometer. The objective of this research is to elucidate and optimize the diffraction characteristics that augment the Cr grating's functionality as a self-traceable length standard within the length traceability chain predicated on the Cr transition frequency. To this end, we explore the geometric morphology and diffraction characteristics of the Cr grating. This investigation also dissects the influence of the grating's polarization-sensitive traits on the Littrow configuration grating interferometer and establishes the criteria for Cr grating fabrication. Empirically, we fabricate an enlarged Cr grating through scanning atom lithography, delineate its diffraction performance, and perform an initial verification of length measurement in a self-traceable grating interferometer. This investigation aligns with the global progression towards a more streamlined metrology development, offering a valuable benchmark for propelling future advancements in metrological technologies within the new traceability chain.

R3-DICnet: an end-to-end recursive residual refinement DIC network for larger deformation measurement.

Digital image correlation (DIC) is an optical metrology method for measuring object deformation and has been widely used in many fields. Recently, the deep learning based DIC methods have achieved good performance, especially for small and complex deformation measurements. However, the existing deep learning based DIC methods with limited measurement range cannot satisfy the needs of real-world scenarios. To tackle this problem, a recursive iterative residual refinement DIC network (R3-DICnet) is proposed in this paper, which mimics the idea of the traditional method of two-step method, where initial value estimation is performed on deep features and then iterative refinement is performed on shallow features based on the initial value, so that both small and large deformations can be accurately measured. R3-DICnet not only has high accuracy and efficiency, but also strong generalization ability. Synthetic image experiments show that the proposed R3-DICnet is suitable for both small and large deformation measurements, and it has absolute advantages in complex deformation measurement. The accuracy and generalization ability of the R3-DICnet for practical measurement experiments were also verified by uniaxial tensile and wedge splitting tests.

3D CT scan metrology for solder void formation analysis in ball grid array electronic chips

The miniaturization of silicon chips and the complexity of device functionality has driven the electronic packaging industry to find new methods to enhance the reliability of chips at a smaller size. Solutions such as Ball Grid Array (BGA) packages have contributed to the miniaturization of integrated circuits (ICs) and the reduction in their overall size. However, void formation in the solder joint is a weakness that can affect the robustness of the solder joint integrity, both mechanically and electrically. To detect these voids, metrology methods such as 3D Computed tomography (CT)-scan are used. 3D CT-scans can identify submicron-sized void defects in real-time during thermal tests, which can be utilized to help improve the quality control lines in the electronic chip manufacturing industries. In this paper, two types of BGA packages will be evaluated for solder joint properties. The prepared samples will be subject to high temperature stress conditions to assess the mechanism of void formation in solder joint. The prepared samples will be heated at 260 °C four times where the heating lasts 0, 5, 10, and 15 min, respectively. The prepared samples will be mounted on a PCB board and the results of the thermal stress tests will be analyzed using 3D X-ray CT scans. These 3D-CT scans used in tandem with a reconstruction and visualization software suite, will be utilized to observe changes such as void formation in the solder joint after each heating time. Unexpectedly, void size reduced between the first and second heat cycles on both samples but increased for the third and fourth heat cycles then.