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2022, Volume 66,  Issue 4

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Abstract:
Laser interferometry technique provides an alternative way for measurement of underwater acoustic, which is different from the traditional way using a hydrophone. This paper presents a review of the applications in underwater acoustic measurement using laser interferometry, including hydrophone calibration, acoustic distribution measurement, and measurement of transducer surface velocity. The current research progress are summarized and analyzed. The measurement theories of the above three techniques are introduced and some representative results are given, the constraints of each technique and the key problems to be solved are analyzed, and the future research and development directions are predicted. Although laser interferometry is not yet a complete replacement for traditional underwater acoustic measurement, it is expected that the advantages of laser interferometry will be better utilized and the level of underwater acoustic measurements will be improved after continued research and development.
Abstract:
With the continuous reduction of the critical dimension in integrated circuits, the measurement accuracy is required to reach the atomic level to ensure the effectiveness of devices, which brings new challenges to the precise measurement of the nanowire width. In 2018, the 26th Conférence Générale des poids et Mesures (CGPM) proposed the use of silicon {220} lattice spacing as a realization of the definition of the metre, which provides new ideas and methods for atomic scale nanowire width metrology technology. In China, we have mastered the measurement principle of the line width based on the lattice constant of silicon, developed a series of small-value nanowire width standards, and established intelligent methods for nanowire width estimation. These works are basic for the preliminary establishment of our nation’s atomic traceability system of the line width. In addition, we introduce the next stage of research goals of the line width measurement technology, the future influence in the world, and its supporting role in the development of large-scale integrated circuits with independent intellectual property rights in China.
Abstract:
Magnetic field as a vector field with magnitude and direction information, how to achieve high-precision measurement of the magnetic field vector in the existing atomic magnetometer has become an important research direction of the atomic magnetometer. The simultaneous detection of the magnitude and direction of the magnetic field in a single atomic magnetometer unit not only can obtain more magnetic field information and characterize the magnetic source more comprehensively and accurately but also reduces the size of the magnetic measurement device in the mobile platform. This paper divides the vector atomic magnetometer into two technical routes: configuration of applied magnetic field and all-optical detection, and introduces the basic principles, the current research status at home and abroad, and the future research directions of the vector atomic magnetometer. Several major vector magnetometer technical methods are introduced and summarized, including the applied magnetic field compensation method, bias magnetic field modulation method, external radio frequency field measurement method, electromagnetic induction transparent (EIT) detection method, the Bell-Bloom all-optical measurement method, etc. Finally, the future development direction and measurement application prospects of the high-sensitivity vector atomic magnetometer are prospected.
Abstract:
This paper discussed the performance evaluation of ophthalmic Optical Coherence Tomography (OCT) and the development of metrology technology in terms of the principles, technical classification, commercial development, metrology parameters, and standard production of ophthalmic OCT devices. This paper summarized the domestic and foreign research progress of measurement and evaluation methods such as measurement standard, system resolution, signal-to-noise ratio/contrast, and image quality of ophthalmic OCT equipment in detail, and clarified the ideas for the further improvement of ophthalmic OCT technology standardization.
Abstract:
Optical dead-path is a major error source in the laser interferometer, which, however, is hard to be accurately measured. Joule balance is a mass measurement apparatus traceable to the Planck constant, in which the laser interferometer is used to measure the relative displacement between the suspended coil and the exciting magnet, while the optical dead-path in the interferometer is so large that displacement measurement in the air has been adversely affected. Given this problem, this paper discussed an optical dead-path measurement method based on the optical path difference measurement between the vacuum and non-vacuum environment. This method uses a vacuum system to change the air pressure where the measurement optical path is located, and measures the optical range difference introduced by the change of the refractive index of air, and then calculates the length of the optical dead-path between the excitation interferometric path and the suspension coil interferometric path. The method can reduce the optical dead-path measurement uncertainty from millimeter to micron scale. In addition, by using the dead-path as the absolute distance, this paper discussed the vertical relative position measurement between the suspended coil and the exciting magnet, so that the relative zero position is measured.
Abstract:
Laser gyro can not be used as a metrological standard due to the problems of zero drift and traceability. To give full play to its superior high-precision angle measurement performance, this paper introduces its application in the measurement field in detail, redefines the performance parameters that can characterize the laser gyro goniometer more intuitively, and gives the definitions of “scale factor” and “bias” corresponding to “scale factor” and “zero drift” in the laser gyro. The performance parameters of the laser gyro goniometer, such as scale factor nonlinearity, stability and scale factor temperature sensitivity, scale coefficient temperature sensitivity, bias repeatability, stability and bias temperature sensitivity are tested experimentally, and the calibration method suitable for the laser gyro goniometer is given. Finally, a method to remove the linearity error is proposed to solve the problem of on-line measurement of laser gyro goniometer. The experimental results showed that the angle measurement error introduced by linear fitting error is less than 0.05'', and the zero division error of laser gyro goniometer is ±0.5'', which provides an effective on-line measurement method for measuring angular position error.
Abstract:
A method was developed for the analytical determination of six amphetamine drugs in hair samples by GC-MS and LC-MS/MS. The hair samples were prepared by immersing in the drug-dimethyl sulfoxide solution including target analytes. The sample pretreatment process was optimized using the one-way variable method, and the prepared hair samples were quantified using GC-MS and LC-MS/MS methods. The working curve method was used for quantitative analysis with methamphetamine-D5 as the internal standard. The results showed that the optimal pretreatment methods for the six amphetamine drugs in the prepared hair samples were: 0.01 mol·L−1 HCl, liquid-material ratio 100:1 (mL·g−1), extraction temperature 40 ℃, extraction time 50 min. In GC-MS, the linear range of 6 amphetamine drugs was 0.5 ~ 5.0 ng·mg−1, r2>0.999. The detection limits of the method were 0.04~0.08 ng·mg−1, and the recovery rates were greater than 85.46%, RSDs≤3.6% (n=9). In LC-MS/MS, the 6 amphetamine drugs showed a good linear relationship within the concentration range of 0.06~0.50 ng·mg−1, r2>0.999. The detection limits were 0.05~5.0 pg·mg−1and the recovery of appended contrast in the blank sample ranged from 86.50% to 111.9%, RSDs≤4.2% (n=9). The established methods were used for the detection of amphetamine drugs in human hair, with high sensitivity, good accuracy, and strong specificity. These two methods can be used as the certification method of the reference material of the amphetamine drug in human hair, which could be applied for drug abuse testing and laboratory quality control in the forensic field.
Abstract:
DNA methylation is a common epigenetic modification in eukaryotes and plays a crucial role in the evolution of many physiological and disease processes. Methylated DNA has become a type of key biomarker, and accurate quantification of the methylation levels is of great value for clinical management and basic scientific research. However, current results based on different platforms and different methods often have more significant differences in results, and this uncertainty poses a great potential for its application. In this paper, we summarize some typical detection methods for the locus-specific methylation analysis, especially highlighting the application of digital PCR in DNA methylation detection with high sensitivity and accuracy, and analyze the key factors affecting the result accuracy, and finally prospect the establishment of a standard evaluation system for quantifying methylated DNA.
Abstract:
In this paper, the effects of sample particle size and sample volume on the results of WD-XRF measurement of elemental content in bovine liver powder samples were evaluated. A feasible, accurate, and measurably traceable method for the determination of inorganic elements in biological matrix samples by WD-XRF was established by comparing three different sample preparation additions. In addition, the method was validated for the K, Na, Ca, Mg, Cu, and Zn elements in the NIST standard reference materials 1577c, all elements showed good linearity, and the test results are within the uncertainty range, which proved that the method is accurate and reliable for the determination of inorganic elements in biological samples by the rapid WD-XRF method without matrix-matched standards.
Abstract:
Focusing on the goal of establishing a national primary standard for gear helix calibration, the first hybrid gear helix measurement standard has been developed successfully by independent research, which transforms the complex spatial three-dimensional curve measurement into the simultaneous measurement of laser interferometric length measurement and self-calibration rotary angle, originally realizes the shortest traceability chain for the fundamental quantities of length and angle. The calibration and measurement capability of the gear helix measurement primary standard has reached the international advanced level by verification of international comparison results. The helix values obtained from the standard have been widely used in domestic calibration institutions, universities, and gear manufacturing companies, providing strong technical support for the development of the gear industry.
Abstract:
The UV LED measurement standard was established to satisfy the high demand for UV LED calibration. The measurement apparatus can measure the optical radiometry parameters (including spectral or broadband irradiance, radiant exposure, spectral or broadband radiant flux, average radiant intensity) of UV LED and UV standard lamps, and further derive the values of peak wavelength, center wavelength, bandwidth, relative spectral distribution, photon flux, photon flux density, external quantum efficiency, and ultraviolet hazards. The UV LED measurement standard adopts a spectroradiometer at primary standard level, as well as the self-designed measurement system and control system. The combined standard uncertainty for 200~450 nm spectral irradiance is 3.3%~0.6%, while the combined standard uncertainty for 200~450 nm spectral radiant flux is 3.4%~0.8%. The establishment of UV LED measurement standard fills the gap in UV spectral radiant flux, significantly improves the measurement uncertainty of UV irradiance, and provides accurate traceability for UV curing and UV disinfection.
Abstract:
To better meet the field radiometric calibration requirements of the thermal infrared band satellite remote sensor, and to improve the calibration frequency, timeliness, and measurement accuracy of the field radiometric calibration, a Multi-channel Self-calibration Thermal Infrared Radiometer (MSTIR) with automatic observation capabilities has been developed for measuring the atmospheric downward radiance and ground surface radiance in the field. In this paper, the structure, working principle, and test results of the MSTIR were introduced, and field experiments are carried out on this basis. Taking the observation data of the Golmud calibration field in Qinghai Province as an example, combined with the temperature and emissivity separation algorithm of the multi-channel data of the site, the land surface temperature, and channel emissivity results of the calibration site were obtained, and the uncertainty was evaluated. The data results show that the maximum relative standard deviation of channel emissivity obtained by the four spectral channels of the MSTIR is 0.012 at maximum, and the field temperature deviation is within 0.11 K. The developed MSTIR can meet the application requirements of thermal infrared band field calibration, which lays a foundation for the application of site automatic radiometric calibration of thermal infrared band remote sensor.
Abstract:
Microwave anechoic chamber is one of the most important test sites in the microwave band, which is widely used in antenna measurements, target scattering parameter measurements and radar imaging. The investment construction of the microwave anechoic chamber is relatively high, and the quiet zone performance of the chamber depends on the characteristics and layout of the absorbing materials laid on its inner wall, while the quiet zone parameter of the chamber is closely related to the measurement accuracy of the devices measured in the chamber. Therefore, acquiring the accurate anechoic chamber quiet zone parameter through measurements not only is an essential step for the site validation, but also the basis for estimating the contribution of the anechoic chamber environment to the measurement results. The method to measuring the quiet zone reflectivity level of the chamber, which is the key parameter of the quiet zone, is discussed in this article, and a quiet zone measuring system based on a three-dimensional scanner with a maximum travel of 4 m is established for medium-to-large microwave chamber covering the frequency range of 1 to 40 GHz. An example of reflectivity level measurement for an anechoic chamber is presented, the measured results are shown, and the uncertainties component which effect the results are discussed, and the total uncertainty for the quiet zone reflectivity level is estimated for the first time. The results show that the expanded uncertainty is 1.72 dB (k=2) at 1.1 GHz for reflectivity level of −33dB.
Abstract:
To solve the problem of direct 131I activity measurement in human thyroid for radiological protection and diagnosis and treatment in nuclear medicine, and the problem of traceability of related instruments for 131I activity measurement in human thyroid, a portable on-site radioactivity measurement metrological standard device was developed. In combination with the IAEA/ANSI neck phantom, the detection efficiency calibration and activity determination methods of the standardization were studied. Through experimental measurement and simulation calculation, the efficiency curve at different detection distances was determined, and the traceability method of 131I activity in the human thyroid was established. The minimum detectable activity reached 4.67 Bq when the standard was directly measured close to the neck for 600s; the portable gamma spectrometer used to measure the activity of 131I in the human thyroid was calibrated with the relative expanded uncertainty of 5.5% (k=2). The development of this standard has established a key equipment foundation for the accurate measurement and traceability of 131I activity in occupational health monitoring, nuclear emergency, and diagnosis and treatment of thyroid diseases.
Abstract:
The low-frequency standard shaker is the main component of the low-frequency vibration standard device, and its measurement performance directly affects the measurement uncertainty of low-frequency vibration calibration. By carrying out the design and research on the measurability of the low-frequency standard shaker, the ability of the metrology guarantee can be improved. Based on the functional analysis of low-frequency standard shakers, this paper analyzes three typical measurement scenarios of low-frequency standard shakers, including type test, conventional use, and periodic measurement, and composes and extracts three key measurement parameters and relevant requirements as the measurable requirements, including transverse vibration ratio, acceleration harmonic distortion, and frequency indication error, and then carries out the measurable design and verification. Given the large distortion of the low-frequency accelerometer in low-frequency calibration, a grating-based measurement method is proposed. The measurement interface and method of the grating are designed by using the measurable design method, which effectively improves the convenience and accuracy of distortion measurement. The measurability design method and the process can provide a reference for the measurability design of other verification and calibration devices.
Abstract:
Measurement of sulfur content of solid and liquid fuels is restricted by the lack of certified reference material (CRM) of organic pure substance for sulfur, which can not meet the demand for traceability. In this paper, the CRM of dibenzothiophene for sulfur content labeled as GBW 06204 was developed, and an internationally advanced method for determining the elemental content of organic pure substances was adopted, that is, based on the content of each component and its molecular content of the element to be measured, the elemental content of the standard substance was calculated to obtain the determined value. Among them, the organic impurity content was determined by using gas chromatography-spectrometry and differential scanning calorimetry. The water content was determined by Karl Fischer coulometric titration. The inorganic impurity content was determined by the residue on ignition. The certified value of CRM was traceable to the mass of pure substances, temperature, and atomic weight. The certified sulfur content of CRM was 17.403% with an uncertainty (U) of 0.005%, which has reached the international advanced level. This CRM is suitable for the calibration of elemental analyzers such as the Dumas method, and the preparation of CRM of petroleum for sulfur content, which is helpful for the accuracy and reliability of sulfur content results of fuels.
Abstract:
The time scale performance of different clock ensemble configurations is compared and analyzed concerning the technical specifications of atomic clocks. Simulations of hydrogen maser and cesium clock differential data were performed based on the technical specifications and actual operation of typical atomic clocks. The atomic time scales of the cesium clock ensemble, hydrogen clock ensemble, and combined hydrogen-cesium clock ensemble were calculated by applying the ALGOS algorithm, and the clock ensemble time scale performance was examined in four aspects: time deviation, time stability, frequency deviation, and frequency stability. The results showed that the frequency stability of the clock ensemble of 180 cesium clocks is equivalent to the frequency stability of 1 hydrogen maser. Due to the large difference between the frequency stability of cesium clocks and hydrogen masers, the weight of cesium clocks is much lower than that of hydrogen masers in the atomic time calculation process, and the contribution to the atomic time is limited. The clock ensembles with a high proportion of hydrogen maser have better time scale stability, and the time deviation and frequency deviation in the traceability state are also smaller. The clock ensembles with good time scale stability also have better timekeeping ability in the timekeeping state.
Abstract:
The article aims to realize the remote measurement calibration of the high voltage DC voltage divider. The traditional calibration method is to send the instrument to the higher-level verification organization or the verification personnel to the site for verification, which is time-consuming and has the risk of damage during transportation, while remote calibration can perfectly solve these problems. Based on QT, we developed the console and fieldside software, realized the communication between the software of both sides and the cloud platform through sockets, and then used the cloud platform to forward messages to realize the communication between the two sides. The Ezviz Cloud is applied to realize real-time monitoring of on-site images and voice calls to ensure the legality of calibration. The verification results show that the cloud-based remote calibration system of the high-voltage DC voltage divider can achieve the purpose of remote calibration.