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Uncertainty evaluation of an 171Yb optical lattice clock at NMIJ
摘要： We report an uncertainty evaluation of an 171Yb optical lattice clock with a total fractional uncertainty of 3.6 × 10^{-16}, which is mainly limited by the lattice-induced light shift and the blackbody radiation shift. Our evaluation of the lattice-induced light shift, the density shift, and the second-order Zeeman shift is based on an interleaved measurement where we measure the frequency shift using the alternating stabilization of a clock laser to the 6s2 1S0–6s6p 3P0 clock transition with two different experimental parameters. In the present evaluation, the uncertainties of two sensitivity coefficients for the lattice-induced hyperpolarizability shift d incorporated in a widely used light shift model by RIKEN and the second-order Zeeman shift aZ are improved compared with the uncertainties of previous coefficients. The hyperpolarizability coefficient d is determined by investigating the trap potential depth and the light shifts at the lattice frequencies near the two-photon transitions 6s6p3P0–6s8p3P0, 6s8p3P2, and 6s5f3F2. The obtained values are d = ?1.1(4) μHz and aZ = ?6.6(3) Hz/mT2. These improved coefficients should reduce the total systematic uncertainties of Yb lattice clocks at other institutes.
关键词： precise measurement,optical lattice clock,optical frequency comb,Frequency standards,SI second
更新于2025-09-23 15:23:52
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Multi-step approach for automated scaling of photogrammetric micro-measurements
摘要： Photogrammetry can be used for the measurement of small objects with micro-features, with good results, low costs, and the possible addition of texture information to the 3D models. The performance of this technique is strongly affected by the scaling method, since it retrieves a model that must be scaled after its elaboration. In this paper, a fully automated multi-step scaling system is presented, which is based on machine vision algorithms for retrieving blurred areas. This method allows researchers to find the correct scale factor for a photogrammetric micro model and is experimentally compared to the existing manual method basing on the German guideline VDI/VDE 2634, Part 3. The experimental tests are performed on millimeter-sized certified workpieces, finding micrometric errors, when referred to reference measurements. As a consequence, the method is candidate to be used for measurements of micro-features. The proposed tool improves the performance of the manual method by eliminating operator-dependent procedures. The software tool is available online as supplementary material and represents a powerful tool to face scaling issues of micro-photogrammetric activities.
关键词： Depth from focus,Photogrammetry,Micro-features,Measurement,International standards,Image analysis,Scale
更新于2025-09-23 15:23:52
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Relating Crosstalk to Plane-Wave Field-to-Wire Coupling
摘要： In this work, a novel formulation of crosstalk (XT) is developed, in which the perturbation/loading effect that the generator circuit exerts on the passive part of the receptor circuit is elucidated. Practical conditions (i.e., weak coupling and matching/mismatching of the generator circuit) under which this effect can be neglected are then discussed and exploited to develop an alternative radiated susceptibility (RS) test procedure, which resorts to crosstalk to induce at the terminations of a cable harness the same disturbance that would be induced by an external uniform plane-wave field. The proposed procedure, here developed with reference to typical RS setups foreseen by Standards of the aerospace sector, assures equivalence with field coupling without a priori knowledge and/or specific assumptions on the units connected to the terminations of the cable harness. Accuracy of the proposed scheme of equivalence is assessed by virtual experiments carried out in a full-wave simulation environment.
关键词： crosstalk,field-to-wire coupling,aerospace standards,weak coupling assumption,radiated susceptibility
更新于2025-09-23 15:23:52
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Open-Source Package for PJVS Testing and Calibration
摘要： This paper describes a software package for PJVS automated measurements written in Python, an interpreted programming language widely used in scientific applications. The code is modular and expandable with the support of many libraries allowing easy reconfiguration for different calibration and testing purposes.
关键词： Python,measurement software,programmable Josephson array,Voltage standards,open source
更新于2025-09-23 15:23:52
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Uncertainty analysis for ac–dc difference measurements with the AC Josephson voltage standard
摘要： A detailed analysis of the uncertainties obtained in ac–dc difference measurements with an AC Josephson voltage standard (ACJVS) is presented. For audio frequencies and for voltages less than 200 mV, ac–dc transfers with the ACJVS may reduce the combined uncertainty by factors of 2–10, compared with conventional methods based on thermal converters. Type A uncertainties are predominantly limited by the thermal transfer standard (TTS), or the digital voltmeter used to acquire the output voltage from the TTS. In agreement with earlier work, the transmission line is the primary contributor to Type B errors for frequencies above 10 kHz. A Monte Carlo sensitivity analysis is used to demonstrate how the uncertainties of transmission line impedance and on-chip inductance impact the accuracy of the rms amplitude conveyed to the TTS.
关键词： ac voltage metrology,transmission line analysis,Josephson junction arrays,quantum voltage standards,uncertainty analysis
更新于2025-09-23 15:22:29
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High-gain optical injection locking amplifier in phase-coherent optical frequency transmission
摘要： Optical amplification, which is necessary for extending the distance of optical frequency transfer, has significant impact on the transmission performance. In this paper, we propose a high gain optical injection locking amplifier (OILA) with low phase noise based on optical injection phase-locked loop for the phase-coherent optical frequency transmission. The high gain OILA can provide more than 75 dB gain and ensure that the input carrier frequency fractional stability can reach 8.2 × 10-20 at an averaging time of over 100 s. We then transfer a commercial narrow-linewidth laser over 220 km fiber link with only one amplification step placed at the remote end. After eliminating the noise induced in fiber link, the fractional frequency instability of transferred frequency can reach 9.0 × 10?16 at 1 s and 7.1 × 10?20 at 20000 s.
关键词： Laser injection-locked,Optical standards and testing.,Metrology,Diode lasers
更新于2025-09-23 15:22:29
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Frequency Extension of Atomic Measurement of Microwave Strength Using Zeeman Effect
摘要： Measuring the field strength of an electromagnetic wave based on atomic quantum mechanics is expected to be an innovative method to realize stable and reliable measurements. However, the major issue of atomic measurements is that the measurable frequency is limited to the resonant frequency of atoms. Therefore, in this paper, we demonstrate the measurement at arbitrary frequencies using the Zeeman effect in a static magnetic field. A cesium vapor cell is placed in a static magnetic field of approximately 40 mT, which causes the resonant frequency of the cesium atom to shift from 9.2 to 8.2 GHz. In addition, the Rabi frequency due to the interaction between cesium atoms and microwaves is measured at the frequency of 8.2 GHz in this experiment.
关键词： frequency measurement,microwave measurements,metrology,microwave spectroscopy,electromagnetic measurements,Atom optics,atomic measurements,measurement standards
更新于2025-09-23 15:22:29
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Technological Assessment of MEMS Alkali Vapor Cells for Atomic References
摘要： This paper is a review that surveys work on the fabrication of miniature alkali vapor cells for miniature and chip-scale atomic clocks. Technology on microelectromechanical systems (MEMS) cells from the literature is described in detail. Special attention is paid to alkali atom introduction methods and sealing of the MEMS structure. Characteristics of each technology are collated and compared. The article’s rhetoric is guided by the proposed classification of MEMS cell fabrication methods and contains a historical outline of MEMS cell technology development.
关键词： MEMS cells,atomic references,microfabrication,frequency standards
更新于2025-09-23 15:22:29
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[IEEE 2018 Seventh Balkan Conference on Lighting (BalkanLight) - Varna, Bulgaria (2018.9.20-2018.9.22)] 2018 Seventh Balkan Conference on Lighting (BalkanLight) - Design and Implementation of a Low-Cost Phasor Measurement Unit: A Comprehensive Review
摘要： The complexity of the contemporary electrical power systems imposes challenges in the aspect of monitoring, protection and control. In order to obtain a high speed of response, wide area effect and prices synchronisation, the grid control functions can be benefited by the implementation of Phasor Measurement Units (PMU). The paper is aimed to make a review of the commercial implementation of Phasor Measurement Units source based implementations (open architecture hardware and software). implementations; as a This paper focuses on standard consequence, the concept of virtual PMU is not discussed here. open then and
关键词： low cost,comparison,review,options,standards,Phasor Measurement Units (PMU)
更新于2025-09-23 15:22:29
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Novel color standards for digital color analysis of optochemical sensor arrays
摘要： The indicator-based polymeric color standards for color referencing in digital color analysis (DCA) of optical chemical sensors (optodes) are proposed. In the novel standards, the colors referring to the actual absorption bands of the protonated and deprotonated forms of the indicator are mixed in constant proportions. The standards are based on the lipophilic pH-indicators: ETH5350 and ETH2439, commonly used in optodes, and the lipophilic electrolyte TBATBB. The dependence of the standard color on the TBATBB concentration in the optode is established and found to be linear. The standard colors remain unchanged upon varying the solution pH and the nature and the concentration of the electrolyte. Calibration curves of the indicator pH-optodes obtained in horse serum and referenced to the developed standards demonstrate lower error to span ratio, broader span and higher sensitivity as compared to the same data processed with the conventional gray standard. The colorimetric signal of the pH-optodes array measured in serum sample and referenced to the developed standards allowed accurate determination of the sample pH thus demonstrating practical prospects of the proposed color standards.
关键词： color standards,digital color analysis,optical chemical sensors,polymeric optodes
更新于2025-09-23 15:22:29