Precision Measurement Technology Research Articles

Research on Precise Attitude Measurement Technology for Satellite Extension Booms Based on the Star Tracker

This paper reports the successful application of a self-developed, miniaturized, low-power nano-star tracker for precise attitude measurement of a 5-m-long satellite extension boom. Such extension booms are widely used in space science missions to extend and support payloads like magnetometers. The nano-star tracker, based on a CMOS image sensor, weighs 150 g (including the baffle), has a total power consumption of approximately 0.85 W, and achieves a pointing accuracy of about 5 arcseconds. It is paired with a low-cost, commercial lens and utilizes automated calibration techniques for measurement correction of the collected data. This system has been successfully applied to the precise attitude measurement of the 5-m magnetometer boom on the Chinese Advanced Space Technology Demonstration Satellite (SATech-01). Analysis of the in-orbit measurement data shows that within shadowed regions, the extension boom remains stable relative to the satellite, with a standard deviation of 30′′ (1σ). The average Euler angles for the “X-Y-Z” rotation sequence from the extension boom to the satellite are [−89.49°, 0.08°, 90.11°]. In the transition zone from shadow to sunlight, influenced by vibrations and thermal factors during satellite attitude adjustments, the maximum angular fluctuation of the extension boom relative to the satellite is approximately ±2°. These data and the accuracy of the measurements can effectively correct magnetic field vector measurements.

Ultra‐Stable Phonon Laser Through Closed‐Loop Feedback Control for Optomechanical Sensing

AbstractThe resonant amplification of the optical and mechanical components in cavity optomechanical systems enhances the performance of sensing applications, which rely on precise frequency control and narrowed mechanical linewidth. This study proposes a direct closed‐loop feedback technique for a narrow linewidth phonon laser based on optomechanical self‐oscillation. By continuously pumping a mechanical resonator with a laser, a phonon laser is achieved with an oscillation frequency of 17.58 MHz, exhibiting a narrow linewidth of just 0.44 mHz and an effective mechanical Q of 4 × 1010, while preserving the linear frequency response. The oscillator phase is fed back to the pump laser, yielding a mechanical frequency stability of 7.2 × 10−11 and providing a real‐time output of direct current voltage corresponding to the oscillator frequency changes. The system's real‐time sensing capability is tested using fiber probes and polystyrene particles, demonstrating a performance approach to the theoretical resolution limit. This work opens new avenues for real‐time precision measurement technology and can be extended to different optomechanical systems.

Laser-Tracing Multi-Station Measurements in a Non-Uniform-Temperature Field

Due to the increasing requirements for the improvement of the accuracy of large coordinate-measuring machines (CMMs), the laser-tracing multi-station measurement technology, as one of the advanced precision measurement technologies, is worth studying in depth in terms of its practical application for the compensation of errors in large CMMs. Since it is difficult to maintain a constant temperature of about 20 °C in the actual workshop under the influence of solar radiation and convective heat transfer, there is a gradient in the spatial temperature distribution, and the overall temperature changes with the influence of external factors with synchronous hysteresis, it is difficult for the actual calibration environment to meet the standard environmental requirements. Therefore, the influence of temperature and other environmental factors on the accuracy of laser ranging and large-scale CMM calibration should not be ignored. In this paper, on the basis of analyzing the temperature distribution and change rule of large CMM measurement space under different working conditions, the radial basis function (RBF) neural network algorithm was used to build a non-uniform-temperature field model, and based on this model and the measurement principle of the laser-tracking instrument, the method of laser tracking and interferometric ranging accuracy enhancement was put forward under a non-uniform-temperature field. Finally, based on the multi-station technique of laser tracing, an accurate solution for the volumetric error of large CMMs under the condition of non −20 °C ambient temperature was realized. Simulation results proved that compared with the traditional temperature-compensation method, the proposed method improved the measurement accuracy of the volumetric error of a large-scale CMM using laser-tracing multi-station technology in a non-uniform-temperature field by 33.5%. This study provides a new approach for improving the accuracy of laser-tracer multi-station measurement systems.

Quantum state tracking and control of a single molecular ion in a thermal environment.

Understanding molecular state evolution is central to many disciplines, including molecular dynamics, precision measurement, and molecule-based quantum technology. Details of the evolution are obscured when observing a statistical ensemble of molecules. Here, we report real-time observations of thermal radiation-driven transitions between individual states ("jumps") of a single molecule. We reversed these "jumps" through microwave-driven transitions, resulting in a twentyfold improvement in the time the molecule dwells in a chosen state. The measured transition rates showed anisotropy in the thermal environment, pointing to the possibility of using single molecules as in-situ probes for the strengths of ambient fields. Our approaches for state detection and manipulation could apply to a wide range of species, facilitating their uses in fields including quantum science, molecular physics, and ion-neutral chemistry.

Pt-Cluster-Embedded Metal-Organic Frameworks-Derived Fe@C as Dual-Enzyme Mimics for NADH Detection in Serum.

Dihydro-nicotinamide adenine dinucleotide (NADH) detection is crucial since it is a vital coenzyme in organism metabolism. Compared to the traditional method based on natural NADH oxidase (NOX), nanozymes with multienzyme-like activity can catalyze multistage reactions in a singular setup, simplifying detection processes and enhancing sensitivity. In this study, an innovative NADH detection method was developed using iron-doped carbon (Fe@C) nanozyme synthesized from metal-organic frameworks with in situ reduced Pt clusters. This nanozyme composite (Pt/Fe@C) demonstrated dual NOX and peroxidase-like characteristics, significantly enhancing the catalytic efficiency and enabling NADH conversion to NAD+ and H2O2 with subsequent detection. The collaborative research involving both experimental and theoretical simulations has uncovered the catalytic process and the cooperative effect of Fe and Pt atoms, leading to enhanced oxygen adsorption and activation, as well as a decrease in the energy barrier of the key step in the H2O2 decomposition process. These findings indicate that the catalytic performance of Pt/Fe@C in NOX-like and POD-like reactions can be significantly improved. The colorimetric sensor detects NADH with a limit of detection as low as 0.4 nM, signifying a breakthrough in enzyme-mimicking nanozyme technology for precise NADH measurement.

Fast simulation for interacting four-level Rydberg atoms: electromagnetically induced transparency and Autler-Townes splitting

Quantum sensing using Rydberg atoms is an emerging technology for precise measurement of electric fields. However, most existing computational methods are all based on a single-particle model and neglect Rydberg-Rydberg interaction between atoms. In this study, we introduce the interaction term into the conventional four-level optical Bloch equations. By incorporating fast iterations and solving for the steady-state solution efficiently, we avoid the computation of a massive 4 N × 4 N dimensional matrix. Additionally, we apply the Doppler frequency shift to each atom used in the calculation, eliminating the requirement for an additional Doppler iteration. These schemes allow for the calculation of the interaction between 7000 atoms around one minute. Based on the many-body model, we investigate the Rydberg-Rydberg interaction of Rydberg atoms under different atomic densities. Furthermore, we compare our results with the literature data of a three-level system and the experimental results of our own four-level system. The results demonstrate the validity of our model, with an effective error of 4.59% compared to the experimental data. Finally, we discover that the many-body model better predicts the linear range for measuring electric fields than the single-particle model, making it highly applicable in precise electric field measurements.

Accuracy enhancement and joint calibration method of multi-station triangulation network based on absolute ranging

Precision measurement methods and technologies for large-scale three-dimensional coordinates are in high demand in advanced equipment manufacturing. The multi-station triangulation network represented by the rotary-laser scanning measurement system has the advantages of having high precision, having multitask parallel measurement capability, and having a high degree of automation. It is widely used in the docking of large components, quality control of key points, and collaborative positioning of production equipment. Nevertheless, due to the limitations in the measurement principle, the positioning accuracy along the depth direction is notably lower when compared to other directions. This difference becomes more pronounced with increasing distance. This paper proposes a method to address this issue by integrating a distance measurement station into the network. A novel, to the best of our knowledge, cooperative target, coupled with a high-dynamic beam guidance mechanism, is designed to achieve fast absolute distance measurement to the target. The weighted fusion of the distance and angle observations effectively enhances the measurement accuracy while preserving the advantages of highly automated measurement. Additionally, we introduce a joint calibration method for extrinsic parameters of multi-type stations. High-precision absolute distances are utilized to establish optical scale bars, complemented by the incorporation of physical scale bars, thereby obviating the necessity for using external reference instruments such as laser trackers. Finally, a series of experimental verifications demonstrate the effectiveness of calibration and measurement methods. The root mean square error of all measured points drop to 42.6% of that the triangulation method measures.

Research on the UOSM four-port Calibration algorithm and determination method of the Transmission error term

As one of the key techniques for vector network analyzers to achieve high precision measurement, calibration, and error correction technology has always been the focus of continuous exploration and innovation. UOSM calibration algorithm uses unknown straight-through transmission standards that do not need to be defined and known open-circuit standards, short-circuit standards, and matching standards to calibrate microwave and millimeter wave bands. Based on the study of the mature UOSM calibration algorithm, this paper proposes a method of self-calibration and comparison of the measurement data based on the unknown cut-through standard, which no longer needs the group delay parameters of the unknown straight-through standard and reduces the dependence on the calibrator. The accuracy of the algorithm and error item determination method is verified by ADS simulation and instrument actual test, and a good calibration effect is achieved. It is proved that the algorithm has the ability of accurate calibration. Due to the reduction of parameters, the stability and applicability of the algorithm are improved.

High-throughput development of tough metallic glass films.

Fast development of metallic glass films with high toughness has been a long-sought goal of humankind in view of their superior properties and great potential for application in the field of soft electronics. However, until now, there has been no effective experimental strategy because of the lack of suitable and precise toughness measurement technology. In the present work, we introduced a feasible route for developing tough metallic glass films using combinatorial material library preparation and high-throughput toughness measurement via nanoindentation. Based on this route, tough metallic glass films for the quaternary Zr-Ti-Cu-Al system were successfully screened out. The corresponding electron work function map was detected to uncover the physical mechanism for the composition dependence of toughness. In addition, the preliminary assessments of the screened tough metallic glass films as strain-sensing materials were also conducted. Our current research not only provides a versatile toolbox for high-throughput development of tough metallic glass films, but also exemplifies their potential as strain-sensing materials.

Multi-Parameter Fiber Bragg Grating (FBG)-based Sensor Fabricated using 3D Printing Technology for Precise Measurement of Vertical Earth and Pore Pressure

Multi-Parameter Fiber Bragg Grating (FBG)-based Sensor Fabricated using 3D Printing Technology for Precise Measurement of Vertical Earth and Pore Pressure

Laser coherence linewidth measurement based on deterioration of coherent envelope

The laser linewidth represents a pivotal parameter for assessing laser energy concentration and coherence, thereby exerting a significant influence on aspects such as detection range, measurement resolution, and signal-to-noise ratio in the domain of laser precision measurement technology. Historically, laser linewidth measurement has predominantly relied upon evaluating energy distribution width within the frequency domain. However, this approach does not provide a direct assessment of laser coherence. In the present study, we introduce the novel concept of “coherence linewidth” as a means to directly quantify laser time–frequency coherence. This concept is based on the coherent envelope generated through delayed self-heterodyne detection. In our proof-of-concept experiment, we derive the coherence coefficient via Fourier transform of the partial coherent envelope, subsequently enabling the measurement of the coherence linewidth of the laser. Notably, the measured coherence linewidth falls between the traditional integrated linewidth and the intrinsic Lorentzian linewidth. This observation suggests that the coherence linewidth is less susceptible to the influence of low-frequency 1/f noise. The concept of coherence linewidth presented herein may serve as a promising method for the direct characterization of coherence in narrow linewidth lasers.

Retracted: Image-Based Precision Measurement Technology for the Quality Inspection of Crane Boom Materials

Retracted: Image-Based Precision Measurement Technology for the Quality Inspection of Crane Boom Materials

Time interval measurement with linear optical sampling at the femtosecond level

High-precision time interval measurement is a fundamental technique in many advanced applications, including time and distance metrology, particle physics, and ultra-precision machining. However, many of these applications are confined by the imprecise time interval measurement of electrical signals, restricting the performance of the ultimate system to a few picoseconds, which limits ultrahigh precision applications. Here, we demonstrate an optical means for the time interval measurement of electrical signals that can successfully achieve femtosecond (fs) level precision. The setup is established using the optical frequency comb (OFC) based linear optical sampling (LOS) technique to realize timescale-stretched measurement. We achieve a measurement precision of 82 fs for a single LOS scan measurement and 3.05 fs for the 100-times average with post-processing, which is three orders of magnitude higher than the results of older electrical methods. The high-precision time interval measurement of electrical signals can substantially improve precision measurement technologies.

Quantum Computing Research at the National Metrology Institute

With a wide range of promising applications arising from unprecedented computing performance, quantum computing has recently received great attention. This technology that relies on quantum superposition and quantum entanglement can be realized in various physical platforms such as superconducting quantum devices, optical systems, semiconductor nanostructures and neutral atoms and so on. The Korea Research Institute of Standards and Science (KRISS), the national metrology institute of Korea, is actively carrying out research on quantum computing technologies with its extensive experience and expertise obtained from the development of measurement standards and precision measurement technologies based on diverse physical systems. In this article, we briefly discuss quantum computing research activities at KRISS.

Enhancing measurement precision through noise analysis and fringe optimization in white light interferometry

White light interferometry is a highly precise non-contact measurement technology. However, in practical applications, certain noise sources such as thermal noise, shot noise, and redundant intensity noise, can introduce signal distortion. In this paper, we propose a mathematical formulation for the key metric, Quality Factor, which serves as an evaluation criterion for the quality of interference signals. The influence of different factors on the measurement is quantitatively analyzed using the signal-to-noise ratio, and various filtering methods are employed to address different types of noise. Finally, experimental results highlight the primary factors and optimization techniques that significantly impact the quality of interference signals, thereby verifing the effectiveness of the method on measurement results.

Frequency combs generated from rotational Doppler effect

In frequency domain, power spectrum density with evenly spaced discrete lines forms a frequency comb, which has become a fundamental physical concept for wave. Especially, in optical electromagnetic wavebands, an optical frequency comb plays a crucial role for a variety of precision measurement technologies and has become one of the representative breakthroughs in modern physics. To extend the study of frequency comb to other wave region would be an interesting and important task. One significant challenge is to develop a general method suitable to different waves. Here, by manipulation one of the essence natures of wave, orbital angular momentum (OAM), we demonstrate an general approach to produce a frequency comb based on a rotational Doppler effect with the OAM comb. We experimentally generate and verify frequency comb with teeth up to 10. Our results not only provide a general way for the frequency comb generation suitable to various waves but also may open up possibilities for application of frequency comb in more types of wave.

Key Technologies and Design Methods of Ultra-Precision Aerostatic Bearings

Precision measurement technology and instruments are the basis for high-quality development in modern industry. With the specialization of supporting facilities, ultra-precision motion guidance has become a core technology to achieve ultra-precision measurement. Aerostatic bearings have the advantages of low friction and high precision, and are gradually playing an irreplaceable role in precision measurement and instruments. This paper summarizes and puts forward two contradictions for improving the loading capacity of aerostatic bearings, and investigates how to solve them via structural design. This paper analyzes the characteristics of the engineering calculation method, the gauge pressure ratio method, the gas resistance calculation method, and the AFVM (adaptive finite volume method) proposed. Finally, this paper summarizes the application scope of each method, gives solutions to the core problems, and outlines the developing trends.

Absolute frequency measurements with a robust, transportable 40Ca+ optical clock

We constructed a transportable 40Ca+ optical clock (with an estimated minimum systematic shift uncertainty of and a stability of ) that can operate outside the laboratory. We transported it from the Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan to the National Institute of Metrology, Beijing. The absolute frequency of the 729 nm clock transition was measured for up to 35 d by tracing its frequency to the second of International System of Units. Some improvements were implemented in the measurement process, such as the increased effective up-time of 91.3% of the 40Ca+ optical clock over a 35-day-period, the reduced statistical uncertainty of the comparison between the optical clock and hydrogen maser, and the use of longer measurement times to reduce the uncertainty of the frequency traceability link. The absolute frequency measurement of the 40Ca+ optical clock yielded a value of 411 042 129 776 400.26 (13) Hz with an uncertainty of , which is reduced by a factor of 1.7 compared with our previous results. As a result of the increase in the operating rate of the optical clock, the accuracy of 35 d of absolute frequency measurement can be comparable to the best results of different institutions in the world based on different optical frequency measurements.

A novel method for 3D reconstruction in tight and restricted space based on improved line-structured light

Three-dimensional (3D) reconstruction techniques have been widely employed in many fields. But precise endoscopic 3D measurement inside of objects, especially in tight and restricted spaces, is still a challenge since there is no easy access for measurement tools. Endoscope with 2D-view function has been widely used. However, the precise measurement technology of the inner surface of small hollow objects has not been widely researched. The components of the existing endoscope three-dimensional measuring probe are complex, expensive and not performed well in accuracy. Thus, a novel method and a miniaturized endoscopic 3D sensor is introduced. To be suit in tight and restricted space, the sensor probe prototype has a maximum 6 mm in thickness. The miniatured sensor prototype is mainly based on improved line-structured light, which performs better in robustness and measurement accuracy than coded projection. Especially, the components are inexpensive and easily available, which reduces the manufacturing cost thus making it easily to popularize in industry. Correspondingly, to ensure the sensor measurement accuracy, we also proposed a calibration method for a miniature line-structured light system based on specially designed planar targets. It should be noted that the 3D extension of the line-structured light system relies on the movement of the translation stage. Taking full account of the characteristics of the sensor prototype, a high-precision direction calibration method of the translation stage based on joint multi-calibration position noise estimation is proposed. Finally, the accuracy experiment is carried out on the gauge block to verify that the measurement method proposed can achieve high-precision 3D reconstruction in a restricted space, and that the 3D reconstruction error is less than 10µm.

Main Factors on Effect of Precise Measurement and Precise Tamping Based on BP Neural Network

With the continuous development of precise measurement and precise tamping (PMPT) technology on Chinese railway conventional speed lines, the efficiency of machinery tamping operation and the quality of the track have been effectively improved. A variety of PMPT modes have been tried in the field operation, however there are some differences in the operation effect. The quality of the tamping operation is affected by multiple factors. In order to identify the key factors affecting the operation quality and to further improve the tamping operation effect, this paper establishes both the database of PMPT operation modes and the selection index system for evaluating the operation effect. Based on mega multi-source heterogeneous data and track geometry inspection data, this paper adopts the Back Propagation Neural Network (BPNN) prognosis model to quantify and sort the main factors affecting the effect of PMPT. The research results show that the initial quality of the track before tamping, whether the stabilizing operation or the tamping modes have great influence weights. It can scientifically guide the field operation to control the key factors and put forward some practical suggestions for promoting the field application of PMPT and the optimization of operation modes on the conventional speed lines.