High-precision Measurement Method Research Articles

Application of laser tracker in the industrial measurement field

In recent years, with the rapid development of modern three-dimensional space technology, laser tracker has become a mature technology, high efficiency, stable and reliable performance of high-precision large-size measurement instruments in the industrial measurement system. In some major industries, the 3d high-precision measurement method represented by laser tracker has gradually replaced the traditional measurement method and is widely used in the installation and detection of large precision equipment. This paper mainly introduces the structure, working principle, advantage, and laser tracker applications in main industries.

High-precision GPS measurement method without geographical restrictions using crowd-sensing technology

In order to improve the flexibility of GPS measurement, a high-precision GPS measurement method that is not restricted by the geographical location under crowd-sensing technology was proposed. The performance of the crowdsensing network was improved through a regular hexagon-based crowd-smart big data sensing network deployment mechanism. The GPS /SINS/DR fast and high-precision combined measurement methods were used to achieve high-precision measurement without geographical restrictions. It has been verified that the proposed method in this paper has much better stability in the deployment strategy of a regular hexagon than that of the square. The proposed method can achieve fast acquisition of satellite signals and high-precision positioning, and its measurement accuracy in the low-latitude city and high-latitude city is higher than the online measurement method based on Google Earth, indicating that it has significant application value.

Two-dimensional high-precision non-contact automatic measurement method based on image corner coordinates

Aiming at some shortcomings of the existing non-contact two-dimensional high-precision measurement methods, this paper proposes a two-dimensional high-precision non-contact automatic measurement method based on the corner coordinates of the image. Firstly, this paper designs a set of simple image acquisition device and explains the advantages of the Canny operator used in the image contour detection algorithm. Subsequently, this paper proposes a dimension calibration algorithm based on image corner coordinates, which can convert the pixel size to the actual size, and achieves the function of the algorithm by hierarchical, multi-step processing of the image. Finally, in order to realize the intelligent positioning and selection of the standard size workpiece position, an automatic measurement and positioning system is designed, which can convert the actual size signal into the pulse time control signal. The experimental results show that the measurement method proposed in this paper has the advantages of fast measurement speed, high robustness, low cost and high degree of automation. When using a black-and-white checkerboard paper with an accuracy of 0.1 mm, the measurement accuracy can reach the micron level.

Method for high precision measurement of decaying dynamics using attosecond wave-mixing spectroscopy.

Ultrafast wave-mixing spectroscopies involving extreme ultraviolet (EUV) attosecond pulses provide unprecedented insight into electronic dynamics. Here, we proposed a versatile lifetime-detection method for doubly excited states with odd or even parities by mixing an attosecond EUV pulse with two few-cycle near infrared (NIR) pulses in atomic helium under a noncollinear geometry. By properly choosing the time order of the pulse sequence, the spatially resolved nonlinear signals carry significant information of the decaying dynamics of excited states, which can be utilized to retrieve the lifetimes of states with different parities in a single measurement. The validity and robustness of the method has been verified by numerical simulations based on a few-level model of helium including the spatial distribution of atoms. The accuracy of the lifetime measurement method is better than a few hundred attoseconds. It provides a powerful tool for probing decaying dynamics of the electronic wave packet with superb resolution.

An optimal method for magnesium purification and magnesium isotopic composition obtained by MC-ICP-MS

An optimal method for magnesium purification and high-precision magnesium isotope measurements by MC-ICP-MS.

High precision measurement method for dynamic transient signal based on compressed sensing and spline polynomial interpolation.

During the measurement of dynamic transient signals, a high sampling frequency brings great challenges to the analog-to-digital converter (ADC) and testing system. To address these issues, a high precision measurement method for dynamic transient signals is first proposed in this paper. The characteristics of dynamic transient signals are analyzed first. On the basis of this, a random sampling method combining compressed sensing (CS) with spline polynomial interpolation (SPI) is put forward. The fusion of the two algorithms can effectively reduce the quantity of sampling and observation points to reduce the requirement of the ADC and testing system for transient signal measurement and to improve the observation efficiency of the existing uniform sampling. Finally, a Machete hammer test platform for dynamic transient signals is established. A series of simulation and experimental results validate that the error of data reconstruction using the random sampling method combining CS with SPI is not greater than 5.1%.

Research Status of High-Precision Measurement Methods Based on Weak-Value Amplification

Research Status of High-Precision Measurement Methods Based on Weak-Value Amplification

Research on high-precision error measurement system of angular displacements based on reciprocal roll angles

A high-precision error measurement method of angular displacements based on the biaxial of the reciprocal roll angles (RRA) is presented. The resolution and precision of the angular displacement measurement systems are guaranteed using the principle of small-angle measurements, along with a photoelectric autocollimator and reflector. Based on the method of the biaxial RRA and the principle of full-circle closure, a displacement measurement system covering the full circumferential range is built. The displacement measurement system can recognize the reference angle error elimination, the calibration angle error, and mutual compensation. The total error model of the angular displacement error measurement and the biaxial turntable is established, and the main error terms are analyzed using the total error model of the turntable and the components. The traditional “Fourier harmonic analysis” and sparse decomposition methods are used to correct the system error components. The simulation accuracy of the corrected turntable is similar to that of the error-free term, and the analysis results are used in the system-optimized configuration, including precision distribution. The experiment verifies the feasibility and effectiveness of the proposed high precision, angular displacement, and error measurement method.

High-precision width measurement method of laser profile sensor

Purpose Although a laser profile sensor (LPS) can be used to measure dimensions, the “shadow region” generally degrades the accuracy and precision of width measurements. The accuracy and precision of such measurements should be improved. Design/methodology/approach In this paper, the authors propose herein a technique that combines high dynamic range (HDR) imaging with logistic fitting. First, a HDR image is composed of several images acquired with different exposure times, which augments the grayscale of the object profile and significantly reduces overexposure. Next, the profile is fit to a logistic function, which provides accurate and precise edge coordinates. Finally, given the edge coordinates, the object width is calculated. Findings To verify the stability of this logistic algorithm, the authors simulate different noise conditions and different degrees of incomplete edge data. In addition, the progressiveness of the algorithm is demonstrated by comparing the results with those of other algorithms and with the height measurement. Furthermore, the suitability of the system is verified experimentally. Research limitations/implications Because of the limitation of the condition of laboratory, in the experimental section, this paper cannot represent perfectly the industrial situation. It makes this section limited in demonstration. Originality/value In this paper, the results show that the measurement accuracy and precision of the width is improved and exceeds that of the height measurement. The proposed HDR imaging method with logistic fitting may be applied to LPS width measurements, which should significantly aid the development of LPSs.

Angular stability measurement of a cryocooled double-crystal monochromator at SSRF

Precisely measuring the angular stability is essential to evaluate and improve the performance of the double-crystal monochromator (DCM). Herein, we apply a non-contact high-precision angular measurement method by utilization of the interferometers instead of conventional capacitive sensors, realizing a high resolution of picometer scale; particularly, a large working range of tens of millimeters can be simultaneously achieved, superior to previous method. By this means, we systematically investigate a homemade cryo-cooled DCM at Shanghai Synchrotron Radiation Facility (SSRF). The temporal stability as well as main eigen-frequencies of the DCM mechanics are measured at ambient temperature (25°C) and under liquid nitrogen (LN2) cooling condition, respectively. Fast Fourier Transform (FFT) analysis of these data hints possible vibration sources. Accordingly, flexible tube with an alumina fiber textile inner is adopted and the support of the cooling lines is optimized. Furthermore, relative vibrations with different cryo-cooler settings are compared, revealing a slightly enhanced amplitude with increasing flow rate. Through these optimizations, the DCM achieves a vertical stability of 125 nrad RMS in 1∼100 Hz and 180 nrad RMS in 1∼1000 Hz over the full photon energy, which meets the requirement of the Fast X-ray Imaging beamline at SSRF.

High-accuracy measurement of radius using frequency-modulated technique for laser diode

This paper proposes a method for high-precision radius measurements. The proposed system uses a frequency-modulation technique to improve the accuracy of detecting cat’s eye and the confocal position of a lens. The distance between two points defined as the radius of a lens was measured by using a frequency-modulated Michelson interferometer. In the confocal part, when the tested lens was moved along the optical axis, the intensity at the detector reaches a maximum at the confocal and cat’s eye positions of the sphere. Synchronous detection technique is used to turn the intensity signal from the detector into an odd-symmetry signal through a zero point. These symmetry points coincide with cat’s eye and confocal positions and thus enhance the accuracy with which these two points are detected. A frequency-modulated Michelson interferometer is used to accurately measure the displacement when moving the test sphere between the confocal and cat’s eye points.

Chemical procedure for Zn purification and double spike method for high precision measurement of Zn isotopes by MC-ICPMS

We have developed a new technique for Zn separation and high precision isotope measurement of geological and cosmochemical samples. The protocol includes sample digestion, chemical separation and purification with ion-exchange chromatography and a double spike isotopic measurement using a MC-ICPMS. An analytical precision of 0.02‰ (2SD) for 66Zn/64Zn was obtained by multiple measurements of a secondary standard (JMC-Lyon). In order to test the accuracy of our method, we analyzed the Zn isotopic composition of the geological reference materials BHVO-2, AGV-2, BIR-1, BCR-2 and JB-2, which are consistent with previous measurements from the literature. The measurements of geological reference standards show an external reproducibility ranging between 0.02 and 0.05‰ (2SD). This study provides a high precision and accuracy Zn isotope double spike technique for geological and cosmochemical rock samples, while requiring only 28 ng Zn per analysis, and is therefore suitable for the study of high temperature igneous or cosmochemical processes.

Wear measurement based on the length variation of a sacrificial FBG.

A high-precision wear measurement method with temperature stability achieved by measuring the length variation of a fiber Bragg grating (FBG) is proposed. The adoption of the optical frequency-domain reflectometry (OFDR) technology makes the spatial resolution of this measurement method reach 15.13 µm, and the offline and online measurement accuracies are 30 µm and 100 µm, respectively. The systematic error of the FBG length measuring system is within 30 µm. Because the length measurement is done with a short FBG instead of a much longer fiber, the measurement error induced by the time-varying temperature or strain is significantly reduced in the proposed method. The spatial resolution and accuracy of this method is suitable for wear measurements of various parts in the mechanical field, such as bearings, gears, and pistons.

Laser confocal auto-collimation decentration measurement for spherical lens

A high-precision confocal auto-collimation decentration measurement method (CADM) for spherical lens is proposed. In comparison with the traditional auto-collimation method, this method employs confocal technology to accurately locate the center of the tested lens, which reduces the focusing error. The radius of curvature and center bias measurements are integrated into one measurement system, which eliminates the random errors introduced by multiple installations. This method also enables the measurement of every surface in the lens group. Theoretical analysis and experiments show that the measurement accuracy of this method reaches 0.335 arcsec. CADM effectively improves measurement efficiency and accuracy, providing a reliable and effective method for the decentration measurement of optical systems.

9 ps TDC based on multiple sampling in 0.18 μm complementary metal–oxide–semiconductor

A high-precision measurement method, based on multiple sampling, is proposed for the time interval of two signals in this study. A time interval measurement circuit integrated into the time-to-digital converter (TDC), is designed based on this high-precision measurement method. In the TDC, the authors use two identical delay lines as the holding module to ensure the two signals with a constant time interval. The TDC samples the two signals multiple times by a clock signal, whose period is shorter than that of the delay line. Consequently, the problem of limited resolution caused by a mismatch between delay lines in the delay-line structure can be avoided, and the precision of the output can be improved. The proposed TDC is designed and simulated in Semiconductor Manufacturing International Corporation (SMIC) 0.18 μm complementary metal-oxide-semiconductor process. Simulation results show that the differential non-linearity and the integral non-linearity are always less than one least significant bits. The proposed TDC achieves input dynamic range of 0-32.13 ns and time resolution of 9 ps.

High-precision laser differential confocal measurement method for multi-geometric parameters of inner and outer spherical surfaces of laser fusion capsules.

We propose a well-integrated, high-efficiency, high-precision, and non-destructive differential confocal measurement method for the multi-geometric parameters of the inner and outer spherical surfaces of laser fusion capsules. Based on the laser differential confocal measurement system with high tomography fixed-focus ability and high spatial resolution, the proposed method is used to perform the fixed-focus trigger measurement of the outer vertex, the inner vertex, and the spherical center of the capsule. From the rotation measurement around the Y-axis and the transposition measurement around the Z-axis, the inner and outer diameters, the three-dimensional inner and outer profiles, the shell thickness uniformity, and the shell non-concentricity of the capsule are measured with high precision and no damage. To the best of our knowledge, this is the first method to achieve the high-precision measurement for the multi-geometric parameters of the capsule inner and outer spherical surfaces with the same instrument.

Non-contact and high-precision displacement measurement based on tunnel magnetoresistance

High-precision displacement measurement is essential to various industrial fields, but the drawbacks of existing sensors like bulkiness, low compatibility and high cost limit their applications. In this study, a non-contact and high-precision displacement measurement method based on tunnel magnetoresistance is introduced to achieve high accuracy and small size. The displacement of a permanent magnet changes the spatial distribution of the magnetic field and thus the output of the full-bridge tunnel magnetosresistance (TMR)-based component varies. Based on the theoretical analysis, the highest sensitivity of the measurement system is obtained and the corresponding layout of the permanent magnet and TMR component to ensure the system achieves such sensitivity is determined. The results are validated by experiments, and the highest sensitivity is 17.15 mV m−1. The system shows stable and high-quality frequency response below 300 Hz. The resolution reaches to 33 nm and the system is of high resolution compared with the eddy current sensor. The time drift is determined to be 0.121 m h−1, which is 30% lower than the existing laser sensor. All the features of the measurement system imply that it is of high accuracy and robustness. The compact structure and low cost make it a promising alternative to existing displacement sensors and demonstrates its potential for integration with the actuator.

A Method of FPGA-Based Extraction of High-Precision Time-Difference Information and Implementation of Its Hardware Circuit.

The positioning technology to find shallow underground vibration sources based on a wireless sensor network is receiving great interest in the field of underground position measurements. The slow peaking and strong multi-waveform aliasing typical of the underground vibration signal result in a low extraction accuracy of the time difference and a poor source-positioning accuracy. At the same time, the transmission of large amounts of sensor data and the host computer’s slow data processing speed make locating a source a slow process. To address the above problems, this paper proposes a method for high-precision time-difference measurements in near-field blasting and a method for its hardware implementation. First, based on the broadband that is typical of blast waves, the peak frequency of the P-wave was obtained in the time–frequency domain, taking advantage of the difference in the propagation speed of the P-wave, S-wave, and the surface wave. Second, the phase difference between two sensor nodes was found by means of a spectral decomposition and a correlation measurement. Third, the phase ambiguity was eliminated using the time interval of the first break and the dynamic characteristics of the sensors. Finally, following a top-down design idea, the hardware system was designed using Field Programmable Gate Array(FPGA). Verification, using both numerical simulations and experiments, suggested that compared with generalized cross-correlation-based time-difference measurement methods, the proposed method produced a higher time-difference resolution and accuracy. Compared with the traditional host computer post-position positioning method, the proposed method was significantly quicker. It can be seen that the proposed method provides a new solution for solving high-precision and quick source-location problems, and affords a technical means for developing high-speed, real-time source-location instruments.

High-precision iron isotope analysis of whole blood, erythrocytes, and serum in adults

BackgroundIron isotopic composition serves as a biological indicator of Fe metabolism in humans. In the process of Fe metabolism, essential carriers of Fe circulate in the blood and pass through storage organs and intestinal absorptive tissues. This study aimed to establish an analytical method for high-precision Fe isotopic measurement, investigate Fe concentration and isotopic composition in different parts of whole blood, and explore the potential of Fe isotopic composition as an indicator for Fe status within individuals. Analytical methodsA total of 23 clinically healthy Taiwanese adults of Han descent were enrolled randomly and Fe isotopic compositions of their whole blood, erythrocytes, and serum were measured. The Fe isotopic analysis was performed by Neptune Plus multiple-collector inductively coupled plasma mass spectrometry with double-spike technique. The precision and reproducibility of the Fe isotopic analysis were monitored by international biological and geological reference materials. Main findingsHigh-precision Fe isotopic measurements were achieved alongside with high consistency in the isotopic data for well-characterized reference materials. The Fe isotopic signatures of whole blood and erythrocytes were resolvable from that of serum, where both whole blood and erythrocytes contained significantly lighter Fe isotopic compositions compared to the case of serum (P = 0.0296 and P = 0.0004, respectively). The δ56/54Fe value of the serum sample was 0.2‰ heavier on an average than those of whole blood or erythrocytes. This isotopic fractionation observed in different parts of whole blood may indicate redox processes involved in Fe cycling, e.g. erythrocyte production and Fe transportation. Moreover, the δ56/54Fe values of whole blood and serum significantly correlated with the hemoglobin level (P = 0.0126 and P = 0.0020, respectively), erythrocyte count (P = 0.0014 and P = 0.0005, respectively), and Mentzer index (P = 0.0055 and P = 0.0011, respectively), suggesting the Fe isotopic composition as an indicator of functional Fe status in healthy adults. The relationships between blood Fe isotopic compositions and relevant biodemographic variables were also examined. While the average Fe concentration of whole blood was significantly higher in males than in females (P = 0.0028), females exhibited a heavier Fe isotopic composition compared to that of males in whole blood (P = 0.0010) and serum (P < 0.0001). A significantly inverse correlation of the whole blood δ56/54Fe value with body mass index of individuals (P = 0.0095) was also observed. ConclusionThe results presented herein reveal that blood Fe isotopic signature is consequentially linked to baseline erythrocyte parameters in individuals and is significantly affected by the gender and body mass index in the adult population. These findings support the role of Fe isotopic composition as an indicator for the variance of Fe metabolism among adult individuals and populations and warrant further study to elucidate the underlying mechanisms.

The principle, present and prospect of IMCL measurement based on&amp;lt;sup&amp;gt;1&amp;lt;/sup&amp;gt;H MRSI technology

It has been found that, as a main mechanism for diabetes, insulin resistance may have appeared more than a decade before the onset of diabetes. Therefore, early detection of insulin resistance has vital significance for the early prevention, diagnosis, and treatment of diabetes. The content of intramyocellular lipid (IMCL) in human calf muscle has close and complex relationship with insulin resistance and metabolic disorders and, therefore, is associated with type 2 diabetes mellitus and even a variety of mental diseases. However, the current “gold standard” for IMCL measurement is the invasive biopsy technology, which is not suitable for large-scale basic research and long-term clinical applications. IMCL measurement technology based on proton magnetic resonance spectroscopy and spectroscopic imaging (1H MRSI) provides a radiation-free, non-invasive, and high-precision detection method. More than this, 1H MRSI has been expected to clarify the relationship between IMCL content and insulin resistance, as well as the relationship between insulin resistance and type 2 diabetes mellitus, and has the potential to be applied in clinical practice. This paper describes and summarizes the technical development of 1H MRSI-based IMCL content measurement. It also points out the challenges and the latest solutions of this technique from the aspects of physiological and structural characteristics of calves, muscle fiber direction, the bulk fat distribution, and the demand for precise quantification of IMCL content. In addition to reviewing the latest technical solutions to these problems, we particularly discuss the combination of 1H MRSI with some new technologies such as multi-mode magnetic resonance imaging (MRI) and magnetic resonance fingerprinting spectroscopy (MRFS), which will synergically provide more diversified, multi-dimensional and multi-scale measurement method for high-precision measurement of IMCL.