Field Of Metrology Research Articles

Transport-of-intensity differential phase contrast imaging: defying weak object approximation and matched-illumination condition

Quantitative phase imaging (QPI) has emerged as a promising label-free imaging technique with growing importance in biomedical research, optical metrology, materials science, and other fields. Partially coherent illumination provides resolution twice that of the coherent diffraction limit, along with improved robustness and signal-to-noise ratio, making it an increasingly significant area of study in QPI. Partially coherent QPI, represented by differential phase contrast (DPC), linearizes the phase-to-intensity transfer process under the weak object approximation (WOA). However, the nonlinear errors caused by WOA in DPC can lead to phase underestimation. Additionally, DPC requires strict matching of the illumination numerical aperture (NA) to ensure the complete transmission of low-frequency information. This necessitates precise alignment of the optical system and limits the flexible use of objective and illumination. In this study, the applicability of the WOA under different coherence parameters is explored, and a method to defy WOA by reducing the illumination NA is proposed. The proposed method uses the transport-of-intensity equation through an additional defocused intensity image to recover the lost low-frequency information due to illumination mismatch, without requiring any iterative procedure. This method overcomes the limitations of DPC being unable to recover large phase objects and does not require the strict illumination matching conditions. The accurate quantitative morphological characterization of customized artifact and microlens arrays that do not satisfy WOA under non-matched-illumination conditions demonstrated the precise quantitative capability of the proposed method and its excellent performance in the field of measurement. Meanwhile, the phase retrieval of tongue slices and oral epithelial cells demonstrated its application potential in the biomedical field. The ability to accurately recover phase under a concise and implementable optical setup makes it a promising solution for widespread application in various label-free imaging domains.

Design and Implementation of Digital Calibration Certificate for RFID Tag Storage.

The digital transformation of metrology is one of the most active activities in the field of metrology at present, where the digital calibration certificate (DCC) being developed is the topic receiving the most concern in the current digital transformation. In practical industrial applications, the issue of storage carrier for the DCC plays a crucial role in its promotion and implementation. To address this issue, a DCC meta-model called DCC-Lite schema has been designed along with a corresponding processing method. This solution involves compressing and segmenting the DCC to make it suitable for storage using RFID tags. These RFID tags are affixed to the instruments and accompany them throughout their usage. Additionally, the DCC-RFID processing system has been developed to validate the effectiveness of the DCC meta-model and its corresponding processing method within a wireless temperature acquisition system. Experimental results demonstrate that the system successfully reads and writes the DCC stored within the RFID tag group. Furthermore, it enables automated parsing of the DCC calibration data by the machine and real-time compensation of measurement data to reduce measurement errors.

Analysis of the List of Risks Affecting the Verification of Measuring Instruments

The purpose of this study is to identify and analyze the risks accompanying the process of verification of measuring instruments in metrological services. Risks are analyzed within the framework of a holistic risk and opportunity management system aimed at identifying and managing potential threats and opportunities affecting the achievement of the ultimate goals of the organization. Risk is defined as a possible negative event that could affect project performance and is evaluated by probability of occurrence and possible consequences. The objectives of risk and opportunity management are aimed at ensuring the achievement of the capabilities of the metrology service under conditions of uncertainty. Effective risk assessment of the process of verification of measuring instruments requires a comprehensive approach. In this regard, in the course of the study the regulatory framework was considered, regulating activities in the field of ensuring the uniformity of measurements, identified internal and external environmental factors affecting the process of verification of measuring instruments, identified stakeholders in the field of metrology services. Procedures for risk identification, analysis, assessment and management have been developed within the system. The list of typical risks and opportunities in the process of verification of measuring instruments in the relationship with environmental factors and possible consequences for the organization is compiled. The developed list of potential risks and opportunities is typical for the process of verification of measuring instruments and therefore can be recommended to employees of metrological services of enterprises. With its help it is possible to assess in advance the potential risks and opportunities in the metrological field and to achieve a more effective result by minimizing the negative consequences.

Generation and control of circular Airy solitons in fractional nonlinear optical systems under different modes

In this paper, the dynamics of the circular Airy beam (CAB) in the spatial fractional nonlinear Schrödinger equation (FNLSE) optical system are investigated. The propagation characteristics of CABs modulated by the quadratic phase modulation (QPM) in a Kerr (cubic) nonlinear medium under power function diffractive modulation modes and parabolic potentials are numerically simulated by using a step-by-step Fourier method. Specifically, the threshold for CABs to form solitons in the Kerr medium is controlled by the Lévy index and the QPM coefficient. Secondly, the parabolic potential has the ability to stabilize the FNLSE optical system, making it easier for the formation of CAB solitons. The addition of QPM allows the refocusing of the split beam caused by the Lévy index, and it can change the position and intensity of solitons. Finally, we also study the transmission evolution of QPM-modulated CABs in the Kerr medium under the power function diffraction modulation mode. We can obtain different types of solitons by varying the power function modulation coefficients. A dark soliton with high stability is formed, and we can control its size. Results show that it is possible to optimize the parameter settings (parabolic potential coefficients, power function modulation coefficients, QPM coefficients, Lévy indices, and nonlinear Kerr intensity coefficients) to obtain different types of solitons as well as to modulate the soliton transport. It provides more degrees of freedom for the study of CAB soliton propagation in the Kerr media, which is of great significance and application in fields of nonlinear optical transport, particle manipulation, and optical metrology.

Evaluation of the measurement uncertainty during the calibration of metal reference gauges of the 2nd category

The paper considers problematic issues related to ensuring the uniformity of measurements in the field of legal metrology, namely, during the calibration of working measurement standards used for verification of legally regulated measuring instruments. One of the conditions for ensuring the uniformity of measurements is the compliance of any measuring instrument with the requirements that are prescribed in its technical specification, where standardized metrological characteristics are indicated, which allows us to conclude about the suitability of the instrument for measurements in a known range and with a known accuracy. The procedure for verification of legally regulated measuring instruments establishes a ratio between the expanded measurement uncertainty provided for by the measurement standard and the maximum permissible error of the measuring instruments of no more than one to three. Determining such a ratio is an example of indirect accounting for the measurement uncertainty. The reliability of the assessment of the compliance of a working measurement standard with metrological requirements, which are regulated by the technical specification, depends on the correctness of the procedures for evaluating the measurement uncertainty during calibrations. The paper indicates the problems of updating the existing regulatory framework for the calibration of measuring instruments using reference gauges as an example and ensuring metrological traceability of the results of the calibration of the liquid volume measuring equipment. Attention was drawn to the need to apply in Ukraine the international practice of the standardization of calibration techniques and methods of uncertainty evaluation to ensure the uniformity of measurements. A procedure for evaluating the measurement uncertainty during the calibration of the reference 2nd-grade gauge by the volumetric method, which is used as a working measurement standard when verifying legally regulated measuring instruments – fuel dispensers for refuelling cars – is proposed.

Development of state information systems in the field of metrology: main tasks

Development of state information systems in the field of metrology: main tasks

Coherent population trapping for reservoir engineering and spin squeezing

Spin squeezing has important applications in the field of quantum metrology and quantum information processing. Here we propose that coherent population trapping is well suitable for establishing cavity dissipation mechanism and generating a spin-squeezed state. An ensemble of N double Λ-type atoms is placed inside the two-mode optical cavity, where one Λ subsystem is driven resonantly by two strong control fields to form a dark resonance and the other Λ subsystem is coupled by two cavity vacuum fields and two external fields with large detunings. Due to the dark resonance, the atoms are trapped in a dark state and one has the maximal coherence between the two ground states. Two double off-resonance stimulated Raman scattering interactions are induced between fields and dressed atoms to establish a dissipative quantum dynamical process based on a collective cavity reservoir. As a result, strong stable spin squeezing is generated, which is verified by our numerical and analytical results. Published by the American Physical Society 2024

Diameter-dependent whispering gallery mode lasing effects in quantum dot micropillar cavities

Whispering gallery mode (WGM) based microlasers have gained significant interest across various fields of nanophotonics, including biosensing, metrology, and on-chip excitation of single quantum dots in integrated quantum photonic structures. In this study, we report a comprehensive diameter-dependent study of whispering gallery mode lasing in quantum dot micropillar cavities. The lasing threshold, mode energy, quality factor, light-matter interaction in terms of the Purcell factor, and the free spectral range, are studied systematically for diameters ranging from 1 to 20 µm at cryogenic temperatures. To describe the experimental data, we use rate equation fitting and numerical simulations based on the finite element method, including realistic loss channels. Our results show a strong and systematic dependence of all lasing properties on the diameter of the micropillars. We also observe significant variations in the lasing properties of nominally identical micropillars, indicating a significant influence of the growth and fabrication imperfections on the output of the devices. The study provides important information on the optical properties of micropillar-based WGM lasing, which can aid in the advancement of optoelectronic applications using these nanophotonic structures.

Sustainability-aware measurement design: How to select the right measuring system

Environmental sustainability assessment has been establishing itself as a requirement when selecting any good or service. This approach also applies to the Information and Communication Technology (ICT) infrastructure, and to Measurements, which represent integral components of ICT. This means that, in the measurement design, the traditional parameters of target uncertainty and costs should be accompanied by environmental sustainability ones.To address this aspect, among the steps of the measurement design process, this paper focuses on the selection, for a given measurand, of the most suitable measuring system from a sustainability perspective. Specifically, to guarantee also consistency of the approach, the proposed methodology is developed within a framework that takes into account the pillars of measurement uncertainty (i.e. the Guide to the Expression of Uncertainty in Measurement, GUM) and those of sustainability assessment (i.e. the ISO14000 family of standards).As a case study, three resistance measuring systems are compared under different simulated and experimental scenarios. The obtained results demonstrate how, through the incorporation of sustainability considerations alongside metrological performance criteria, this methodology facilitates a holistic approach to the selection of measuring systems, promoting environmentally conscious practices within the field of Metrology.

Wavefront sensing with a gradient phase filter

Wavefront sensors have now become core components in the fields of metrology of optical systems, biomedical optics, and adaptive optics systems for astronomy. However, none of the designs used or proposed so far achieve simultaneously a high spatial resolution at the pupil of the tested optics and absolute measurement accuracy comparable to those of modern laser-interferometers. This paper presents an improved wavefront sensor concept that reaches both previous goals. This device named Crossed-sine phase sensor (CSPS) is based on a fully transparent gradient phase filter (GPF) placed at an intermediate location between the virtual pupil and image planes of the tested optics. The theoretical principle of the sensor is described in Fourier optics formalism. Numerical simulations confirm that a measurement accuracy of λ/100 RMS is achievable. The CSPS also offers the advantages of being quasi-achromatic and working on spatially or spectrally extended, natural or artificial light sources.

A new method for evaluating roundness error based on improved bat algorithm

Roundness error is one of the core indicators for evaluating the geometric accuracy of round parts mechanical products, directly affecting product performance and service life. In the field of metrology, the accurate, rapid and standardized assessment of roundness error has always been a hot topic. This paper proposed a new method for evaluating roundness error based on improved bat algorithm. This method was based on the new geometric product specification for extraction, filtering and fitting. Based on the advantages of solving optimization problems using the bat algorithm, transformed the roundness error evaluation problem using the minimum zone method into a problem of using the bat algorithm to find the center of the minimum zone circle, then further solved for the roundness error value. Also, this algorithm effectively avoided falling into local optimal solutions by introducing chaotic inertia weights during the velocity update phase, it improved the accuracy and speed of the evaluation. Introduced adaptive parameters during the loudness and emission rate update phases to enhance the algorithm’s global search capability, it enhanced the stability of the algorithm. The experimental results indicated, the efficiency of roundness error evaluation in the new method was significantly better than that of the genetic algorithm, the simplex algorithm and the emperor penguin algorithm. There was a significant improvement in evaluation accuracy and stability. The feasibility of this method in roundness error evaluation using the minimal zone method was validated.

COAT Project: Intercomparison of Thermometer Radiation Shields in the Arctic

A metrological field intercomparison of thermometer radiation shields in the Arctic was conducted with the aim of obtaining information to increase the worldwide comparability of air temperature measurements. Air temperature measurements are performed by different combinations of thermometers and shields. The response of each system (thermometer + shield) to local meteorological conditions depends on the system itself, limiting the comparability of air temperature measurements. Ten different models of radiation shields were included in the intercomparison, involving two campaigns: (1) the laboratory campaign, where all the instrumentation was calibrated just before and just after the field campaign, and (2) the field campaign that lasted 14 months where 41 thermometers were sampled every 2 min. All the delivered data were subjected to quality control to assure the robustness of the conclusions. A reference shield was defined, and the other shields were compared to the reference one for the conditions where maximum divergences were expected, solar irradiance being the highest impact factor. A maximum divergence value of 1.29 °C was derived for one of the shields and, for all the shields, the difference from the reference one decreases with wind speed. Finally, the uncertainties associated with the shields intercomparison were calculated.

Improving Accuracy and Reliability of Hearing Tests: Measurement Standards for Audiometric Devices.

Pure-tone audiometry, using an audiometer, is the fundamental hearing test for diagnosing hearing loss. The requirements of the devices and the detailed process for calibrating the related equipment are described in international standards. However, traceable calibration and uncertainty evaluation processes are not widely accepted or applied to the qualification and maintenance of audiometric equipment. Here, we briefly review standard measurement systems for audiometric devices and introduce their calibration procedures. The uncertainty of each calibration process was investigated, and its impact on hearing test results was considered. Our findings show that the traceability of each procedure can be secured, satisfying the uncertainty requirement and being sufficiently smaller than the permissible deviation from the audiometer requirement. To guarantee the objectivity and reliability of hearing tests and maintain low uncertainty, close cooperation and mutual understanding between the metrology field and the medical community are necessary.

JCGM Guides in Metrology—IUPAC working in the field of metrology with others broadly-based international organizations

JCGM Guides in Metrology—IUPAC working in the field of metrology with others broadly-based international organizations

Metrological support of end-to-end technologies of the sixth technological set-up: directions of development

The issues of metrological support for measurements performed using end-to-end technologies, namely the formation of a metrological infrastructure corresponding to the needs of technologies of the sixth technological set-up, are considered. As a result of the research, mechanisms for determining the directions of development of the metrological infrastructure for the introduction and use of innovative technologies that determine the future of the economy of the Russian Federation are proposed. It is noted that the concept of end-to-end technologies appeared in official documents in the Russian Federation in 2017, however, the topic of infrastructure provision of end-to-end technologies has not been widely discussed. This fact, as well as the importance of timely and effective infrastructural support for the new technological policy of the Russian Federation, became one of the reasons for the completed study. The issues of increasing the importance of end-to-end technologies in the development of the economy of the Russian Federation, the use of patterns of development of metrological infrastructure for the timely modernization of the reference base that meets the requirements of innovative technologies of the sixth technological set-up, the issues of directions for the development of metrological infrastructure taking into account the measuring needs of end-to-end technologies were discussed. The positive results of the verification of the patterns of development of the reference base of the measurement uniformity system identified in 2019 by the author of this article are presented and the directions of application of these patterns for metrological support of measurements of end-to-end technologies are shown. As a result of processing official statistical data in the field of metrology for the period 2005–2023 (the period of the origin of the sixth technological set-up), taking into account the patterns of development of the fourth and fifth technological setups, the importance of metrological support for measurements performed using end-to-end technologies is justified. The analysis of the development of the most important components of the metrological infrastructure within the framework of technological structures made it possible to identify the main directions of development of the reference base, the base of measuring equipment, as well as organizations, institutions and enterprises of the metrological infrastructure. The expediency of using the reference base necessary for metrological support of measurements of end-to-end technologies, patterns of development of metrological infrastructure within technological structures as a mechanism for determining the directions of development is substantiated. The results of the performed research can be used in the formation of the next Strategy for ensuring the uniformity of measurements for the period coinciding with the beginning of the dominance of the sixth technological set-up, in the training of personnel in the field of metrology, who will work in the conditions of the new sixth technological set-up, and at enterprises developing innovative products using end-to-end technologies.

Strategy for Ensuring the Metrological Traceability of Nanoparticle Size Measurements by SEM.

The concept of measurement traceability is crucial for ensuring the data reliability and the comparability of measurement results provided by different instruments and operators. In the field of nanoparticle metrology, determining the size of nanoparticles using electron microscopy-based techniques remains a real challenge. In laboratory settings, the establishment of traceability regarding the instrument calibration procedures, the assessment of uncertainties associated with instruments/operators/samples/environments, as well as the complexities related to electron-sample interactions, are often neglected. In this article, we describe the calibration procedure set up at the LNE (Laboratoire National de métrologie et d'Essais) and propose an evaluation method for determining the uncertainties in measuring nanoparticle size by SEM (Scanning Electron Microscopy). This study investigates the impact of the energy of the primary electrons (PEs) generated by the electron beam and accelerating voltage on the reliability of size measurements. The convolution between the signals coming from a nanoparticle and the substrate on which the particle is deposited induces edge effects that can have a negative impact on the measurement results. Finally, a diagram describing the various stages involved in establishing traceability for SEM measurements of nanoparticle size is proposed to facilitate the work of future operators.

Experimental installation of a reference source of low currents for calibration of electrometers

Today, there is great scientific interest in the possibility of implementing reference sources of low currents based on single-electron pumps using the single-electron tunneling effect and the modern definition of the SI system. However, the practical use of this effect in everyday metrological practice has not yet reached the stage of widespread use. Typically, for routine calibration work in laboratories, either mass-produced instruments (low current sources and meters, electrometers) are used, which are calibrated against higher standards, or specially designed precision current sources. The article describes a reference installation developed on the basis of the VNIIFTRI, where in the mode of generating ultralow currents the principle of forming a linearly increasing voltage on a reference capacitor is used. A simplified block diagram of the reference setup is shown. Issues of practical adjustment of modern electrometers are considered. The generalized results of participation in international comparisons on low currents EURAMET.EM-S44 “Comparison of ultra-low DC current sources” conducted by national metrological institutes in 2018–2020 are presented. The results of a metrological study of the calibration factor Q and an example of calculating the uncertainty budget of measurements carried out at the VNIIFTRI as part of these international comparisons are presented. The research described in the article to increase the accuracy of measurements of small and ultra-low currents of this level has valuable practical significance in the field of electrical measurements, in aeroionometry and metrology of ionizing radiation.

Modulations of superradiance and quantum entanglement of quantum emitters in terahertz frequency

We study the superradiance and entanglement phenomena between two quantum emitters (QEs) operating at terahertz frequencies, facilitated by the presence of a topological insulator bismuth selenide (Bi2Se3). Controlled by the hyperbolic phonon polaritons and electron surface state in the terahertz frequency range, the interaction between QEs is significantly enhanced both within and outside the hyperbolic bands. Moreover, the entanglement between two QEs through Bi2Se3 is studied in detail. Certain initial entanglement states undergo sudden death of entanglement when the system is in non-interaction. However, in the cases of moderate or strong interaction, the entanglement can be revive after experiencing the sudden death phenomenon. These findings hold significant implications for controlling the interaction of QEs and their potential applications in the fields of quantum metrology and quantum imaging in the terahertz frequency region.

Efficient and robust phase unwrapping method based on SFNet

Phase unwrapping is a crucial step in obtaining the final physical information in the field of optical metrology. Although good at dealing with phase with discontinuity and noise, most deep learning-based spatial phase unwrapping methods suffer from the complex model and unsatisfactory performance, partially due to simple noise type for training datasets and limited interpretability. This paper proposes a highly efficient and robust spatial phase unwrapping method based on an improved SegFormer network, SFNet. The SFNet structure uses a hierarchical encoder without positional encoding and a decoder based on a lightweight fully connected multilayer perceptron. The proposed method utilizes the self-attention mechanism of the Transformer to better capture the global relationship of phase changes and reduce errors in the phase unwrapping process. It has a lower parameter count, speeding up the phase unwrapping. The network is trained on a simulated dataset containing various types of noise and phase discontinuity. This paper compares the proposed method with several state-of-the-art deep learning-based and traditional methods in terms of important evaluation indices, such as RMSE and PFS, highlighting its structural stability, robustness to noise, and generalization.

REFORMS IN THE FIELD OF METROLOGY AND ITS IMPORTANCE TODAY

The meteorological service of the state administration bodies of the republic will be introduced (it used to consist of the state meteorological service and the metrological services of legal entities). They are organized in necessary cases to ensure the uniformity of measurements and to carry out metrological control. This article describes the work and reforms carried out in the system for the further development and improvement of work in the field of metrology in our country.