- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
High-precision FBG demodulation using amplitude ratio curve with sharp peak
摘要： For the fiber Bragg grating (FBG) sensor based on the reflection peak position searching demodulation algorithms, a key problem is that the demodulation precision of measurement signal is seriously limited by the full width half maximum (FWHM) of the FBG reflection spectrum. In this paper, in order to overcome this problem and enhance the measurement precision, we proposed a high-precision demodulation method based on amplitude ratio curve to instead of the FBG reflection spectrum, which can increase the sensing precision significantly. In this method, the Bragg wavelength of FBG is modulated periodically with a sinusoidal function to obtain a series of reflection spectra. Then at each wavelength the amplitude ratio between second harmonic frequency component and fundamental frequency component is calculated to create the amplitude ratio curve. Here, we present a comprehensive theoretical analysis and experimental demonstration to verify the advantages of this method. Comparing with the demodulation method based on the FBG reflection spectrum, the average maximum measure error (MME) of Bragg wavelength is reduced from ± 1.54 pm to ± 0.15 pm, which improved by 10.3 times. In addition, the influence of the modulation amplitude and sampling frequency on demodulation accuracy are also studied in this paper.
关键词： Amplitude ratio curve,High precision temperature measurement,Fiber Bragg grating
更新于2025-09-23 15:23:52
-
Small-sized visual angular displacement measurement technology
摘要： Visual angular displacement measurement methods are a popular approach to photoelectric displacement measurement technology, as they provide significantly higher precision than traditional angular displacement measurement methods. This paper proposes a small-sized high-precision angular displacement measurement technology based on the sub-pixel level varying principle. The small-sized visual angular displacement measurement mechanism is first established without lens near-field imaging. A coding method based on the varying principle is then developed in order to decrease the ruled grating density. A sub-pixel angular displacement calculating model based on uniline pix is built to decrease the pixel data and enhance the frequency response of the measurement system; the corresponding data combination and correction algorithms are proposed. The error analysis is proposed. Tests on an angular displacement measurement device prototype showed a resolution of 20-bit and precision of 20.400. The device also outperformed traditional angular displacement measuring devices of similar size, but features low ruled grating density and miniaturization. The results presented here may thus provide a workable foundation for further research on small-size visual angular displacement measurement devices.
关键词： High-precision,Image detector,High-resolution,Varying principle
更新于2025-09-23 15:22:29
-
Accurate Gap Determination in Monolayer and Bilayer Graphene/h-BN Moiré Superlattices
摘要： High mobility single and few-layer graphene sheets are in many ways attractive as nanoelectronic circuit hosts but lack energy gaps, which are essential to the operation of field-effect transistors. One of the methods used to create gaps in the spectrum of graphene systems is to form long period moiré patterns by aligning the graphene and hexagonal boron nitride (h-BN) substrate lattices. Here, we use planar tunneling devices with thin h-BN barriers to obtain direct and accurate tunneling spectroscopy measurements of the energy gaps in single- and bi-layer graphene-h-BN superlattice structures at charge neutrality (first Dirac point) and at integer moiré band occupancies (second Dirac point, SDP) as a function of external electric and magnetic fields and the interface twist angle. In single-layer graphene we find, in agreement with previous work, that gaps are formed at neutrality and at the hole-doped SDP, but not at the electron-doped SDP. Both primary and secondary gaps can be determined accurately by extrapolating Landau fan patterns to zero magnetic field and are as large as ≈ 17 meV for devices in near perfect alignment. For bilayer graphene, we find that gaps occur only at charge neutrality where they can be modified by an external electric field.
关键词： graphene-h-BN moiré superlattice,Landau level tunneling spectroscopy,bilayer graphene-h-BN superstructure,high-precision measurement,graphene energy gap
更新于2025-09-23 15:21:21
-
High-precision collinear laser spectroscopy at the Collinear Apparatus for Laser Spectroscopy and Applied Physics (COALA)
摘要： COALA is a new offline collinear laser spectroscopy setup for high-precision measurements and development work at TU Darmstadt, Germany. An introduction to the technique and the experimental setup is given and an overview of current projects with recent results is presented. The idea of a novel all-optical absolute charge radius determination is discussed.
关键词： Nuclear charge radii,High voltage evaluation,High precision spectroscopy,Collinear laser spectroscopy
更新于2025-09-23 15:21:01
-
[IEEE 2019 2nd World Conference on Mechanical Engineering and Intelligent Manufacturing (WCMEIM) - Shanghai, China (2019.11.22-2019.11.24)] 2019 2nd World Conference on Mechanical Engineering and Intelligent Manufacturing (WCMEIM) - Deep Sea Laser Scanning System for Underwater In-Situ Measurement
摘要： In this paper, a novel laser scanning system for deep sea in-situ measurement was developed. Firstly, the main components of the prototype were introduced separately. Then, the performance of the system was tested and analyzed in a tank filled with water with a standard ball bar. Results showed that the laser scanning system in water can achieve high precision. In addition, the prototype was placed in deep sea to verify the performance of the in-situ measurement and the measured targets are well reconstructed.
关键词： high precision,laser scanning system,in-situ measurement,deep sea
更新于2025-09-23 15:19:57
-
High-Precision 3D Object Capturing with Static and Kinematic Terrestrial Laser Scanning in Industrial Applicationsa??Approaches of Quality Assessment
摘要： Terrestrial laser scanning is used in many disciplines of engineering. Examples include mobile mapping, architecture surveying, archaeology, as well as monitoring and surveillance measurements. For most of the mentioned applications, 3D object capturing in an accuracy range of several millimeters up to a few centimeters is sufficient. However, in engineering geodesy, particularly in industrial surveying or monitoring measurements, accuracies in a range of a few millimeters are required. Additional increased quality requirements apply to these applications. This paper focuses on the quality investigation of data captured with static and kinematic terrestrial laser scanning. For this purpose, suitable sensors, which are typically used in the approach of a multi-sensor-system, as well as the corresponding data capturing/acquisition strategies, are presented. The aim of such systems is a geometry- and surface-based analysis in an industrial environment with an accuracy of +/? 1–2 mm or better.
关键词： synchronization,quality analysis,laser tracker,high-precision terrestrial laser scanning,multi-sensor-systems,calibration,industrial surveying,kinematic laser scanning,forward modeling,backward modeling
更新于2025-09-23 15:19:57
-
[IEEE 2019 Tenth International Conference on Intelligent Control and Information Processing (ICICIP) - Marrakesh, Morocco (2019.12.14-2019.12.19)] 2019 Tenth International Conference on Intelligent Control and Information Processing (ICICIP) - An Improved Scan Matching Method Based on Laser Reflection Intensity
摘要： High-precision localization performance of mobile robots in featureless environments plays an important role in the field of navigation. This paper describes an effective localization solution using a landmark whose surface is covered with two different materials resulting in different laser reflection intensities. Based on the landmark, a feature extraction algorithm is proposed and an improved scan matching method for mobile robot localization in featureless environments is described. Unlike traditional scan matching methods which only use geometric features, the proposed method mixes geometric information extracted from environment and laser reflection intensity extracted from the landmark to achieve accurate pose estimation. Experiments show that our method has higher precision than previous methods.
关键词： high-precision localization,scan matching,laser reflection intensity,featureless environment
更新于2025-09-23 15:19:57
-
Numerical study of comb-based high-accuracy distance measurement utilizing VIPA interferometry
摘要： The ultrahigh-precision distance measurement based on a single laser frequency comb as the multi-wavelength source together with an ultra-high-resolution dispersive spectrometer utilizing a virtually imaged phase array (VIPA) was studied numerically. The simulations provide the component parameter optimization and the comb spectral images on a CCD camera. An ameliorated scheme was proposed through achieving real-time comparisons between the reference and interference signals captured on a camera simultaneously to improve both the measurement accuracy and the precision signi?cantly. With the optimized data processing, the proposed approach is especially suitable for serving as a ultra-high precision relative distance measurement, and the measurement resolution can reach picometer scale in the optimal cases.
关键词： Ultra-high precision distance measurement,Ultra-high resolution spectroscopy,Laser frequency comb,Virtually imaged phase array interferometry
更新于2025-09-19 17:15:36
-
The Analysis and Design of a Large Stroke with High-Precision Polarized Laser Interferometer System
摘要： The technique utilizing single-frequency laser interferometry has very high measurement accuracy, but it has rigorous requirements for optical design which is affected by many factors. In order to achieve single-frequency laser interferometry with large stroke and high precision, the integral layout, the polarization phase shifting technique and the common mode rejection method are adopted to design the length interferometry system. This paper analyzes factors and design requirements which affect measurement accuracy with large stroke. Based on polarization phase shifting technique, the system employs the four-beam-signal detection technique and the common mode rejection method, to make a differential processing of four mutually orthogonal signals. Thus, the influences of zero-drift of intensity and environmental change on system are reduced. Combined with a 200 phase subdivision, the system achieves the resolution with 0.8 nm. Under the VC++ environment, the displacement measurement results are compensated and corrected according to the environmental parameters. Compared with the Renishaw XL-80 laser interferometer, the system has better stability in short term. In the measuring range of 60 mm, the effectiveness of the system is verified.
关键词： polarized phase shifting,large stroke,interferometry,high-precision,differential processing
更新于2025-09-16 10:30:52
-
Integral fabrication of terahertz hollow-core metal rectangular waveguides with a combined process using wire electrochemical micromachining, electrochemical deposition, and selective chemical dissolution
摘要： The application requirements of terahertz hollow-core metal rectangular waveguides with a high-working frequency have become increasingly urgent with the rapid development of terahertz technology. Integral fabrication of terahertz hollow-core metal rectangular waveguides can improve considerably the transmission performance of terahertz signals. However, with current manufacturing techniques, the high-precision integral fabrication of high-working-frequency terahertz hollow-core metal rectangular waveguides is difficult owing to their characteristically small end face size and the need for strict dimensional accuracy and high internal surface quality. In this paper, an innovative combined process of wire electrochemical micromachining, electrochemical deposition, and selective chemical dissolution is proposed firstly to overcome this puzzle. Taking the fabrication of an integral 1-THz hollow-core metal rectangular waveguide as an example, the manufacturing methods involved in each step are described particularly, together with the corresponding experimental investigations. With the end face size of 127 μm × 254 μm, edge radius less than 5 μm, and internal surface roughness less than 0.08 μm, the experimental results satisfy the design requirements for a 1-THz hollow-core metal rectangular waveguide. This study demonstrates that the proposed combined process is flexible, controllable, and suitable for the high-precision integral fabrication of high-working-frequency terahertz hollow-core metal rectangular waveguides.
关键词： Wire electrochemical micromachining,Copper micro-electroforming,Gold micro-electroplating,Terahertz hollow-core metal rectangular waveguide,High-precision integral fabrication
更新于2025-09-12 10:27:22