- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Interferometric step gauge for CMM verification
摘要： The verification of the measurement capability of coordinate measuring machines (CMM) is usually performed using gauge blocks or step gauges as reference standards. Gauge blocks and step gauges are robust and easy to use, but have some limitations such as finite lengths and uncertainty of thermal expansion. This paper describes the development, testing and uncertainty evaluation of an interferometric step gauge (ISG) for CMM verification. The idea of the ISG is to move a carriage bearing a gauge block along a rail and to measure the position with an interferometer. For a displacement of 1 m the standard uncertainty of the position of the gauge block is 0.2 μm. A short range periodic error of CMM can also be detected.
关键词： verification,CMM,metrology
更新于2025-09-09 09:28:46
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Improving the precision of frequency estimation via long-time coherences
摘要： In the last years several estimation strategies have been formulated to determine the value of an unknown parameter in the most precise way, taking into account the presence of noise. These strategies typically rely on the use of quantum entanglement between the sensing probes and they have been shown to be optimal in the asymptotic limit in the number of probes, as long as one performs measurements on shorter and shorter time scales. Here, we present a different approach to frequency estimation, which exploits quantum coherence in the state of each sensing particle in the long time limit and is obtained by properly engineering the environment. By means of a commonly used master equation, we show that our strategy can overcome the precision achievable with entanglement-based strategies for a finite number of probes. We discuss a possible implementation of the scheme in a realistic setup that uses trapped ions as quantum sensors.
关键词： quantum coherence,frequency estimation,trapped ions,quantum metrology
更新于2025-09-09 09:28:46
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Competing optical instruments for the estimation of Full Field FRFs
摘要： Thanks to the progress of optical measurement systems, known to use non-contact transducers (with their own peculiarities, application domains and drawbacks), nowadays addressing complex testing problems, especially direct dynamic measurements and modal analyses on lightweight structural components, is becoming even more common than in the recent past. Furthermore, obtaining vibration patterns with optical gears, in broad frequency bands with high spatial resolution, is easier than before, for the advantage of many advanced applications in vibration engineering, testing and product development.
关键词： Full Field Operative Deflection Shapes,Full Field Frequency Response Functions,Dynamic ESPI,Full field vibration measurements,Surface structural dynamics,Optical metrology,Hi-Speed DIC,SLDV
更新于2025-09-09 09:28:46
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OSNR monitoring technique based on multi-order statistical moment method and correlation function for PM-16QAM in presence of fiber nonlinearities
摘要： We propose an improved optical signal-to-noise ratio (OSNR) monitoring technique in presence of optical fiber nonlinearity-induced distortions, in which traditional multi-order statistical moments based (MOSMB) OSNR monitoring method is corrected by a calibration factor α and correlation functions between neighboring received symbols. This OSNR monitoring technique is performed for the first time in a 224-Gb/s polarization-multiplexed quadrature amplitude modulation (PM-16QAM) system. We explore relationships between α, transmission distances and channel launch powers for further convenient usage considerations. The proposed monitoring technique shows much better performances than existing OSNR monitoring techniques in highly nonlinear systems, where OSNR estimation errors are below 1dB with actual OSNR ranging 18-28dB and the channel launch powers reach as highly as 4dBm and the transmission distances are up to 2000km. Besides, this proposed technique is applicable to different modulation formats and corresponding performances are compared.
关键词： Coherent system,Metrology,Fiber transmission systems,Correlation function
更新于2025-09-09 09:28:46
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Photon-recoil spectroscopy: Systematic shifts and nonclassical enhancements
摘要： In photon-recoil spectroscopy, signals are extracted from recoils imparted by the spectroscopy light on the motion of trapped ions as demonstrated by Hempel et al. [C. Hempel et al., Nat. Photon. 7, 630 (2013)] and Wan et al. [Y. Wan et al., Nat. Commun. 5, 3096 (2014)]. The method exploits the exquisite efficiency in the detection of phonons achievable in ion crystals and is thus particularly suitable for species with broad noncycling transitions where detection of fluorescence photons is impractical. Here we develop a theoretical model for the description of photon-recoil spectroscopy based on a Fokker-Planck equation for the Wigner function of the phonon mode. Our model correctly explains systematic shifts due to Doppler heating and cooling as observed in the experiment. Furthermore, we investigate quantum metrological schemes for enhancing the spectroscopic sensitivity based on the preparation and detection of nonclassical states of the phonon mode.
关键词： Wigner function,quantum metrology,Doppler effect,nonclassical states,Fokker-Planck equation,trapped ions,photon-recoil spectroscopy
更新于2025-09-09 09:28:46
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Analytical Analysis of Residual Chromatic Dispersion and Self-Phase Modulation Optimal Compensation in the Fractional Domain
摘要： We present an analytical expression of residual chromatic dispersion and self-phase modulation optimal compensation with a chirped Gaussian pulse in the fractional domain. The accuracy of the expression is con?rmed by the simulation platform, which is based on the split-step Fourier method. Moreover, the simulation of a 28-GBd RZ-DQPSK optical ?ber communication system is carried out to verify the correctness when the transmission distance is less than 800 km in a standard single-mode ?ber and non-zero dispersion-shifted ?ber.
关键词： Metrology,?ber optics,fractional Fourier transform,?ber nonlinear optics
更新于2025-09-09 09:28:46
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Extracting Displacement and Strain Fields from Checkerboard Images with the Localized Spectrum Analysis
摘要： The performance of white-light full-field measurement methods strongly depends on the nature of the pattern used to mark the surface on which displacements and strains are measured. Finding optimized patterns is therefore a topical question. The aim of this study is to examine the case of the checkerboard pattern. It is first shown that this periodic pattern can be processed with a Fourier-based technique such as LSA. Experiments are then carried out to compare the noise level in displacement and strain maps obtained by processing classic 2D grid and checkerboard images. The conclusion is that the noise level observed in displacement and strain maps is significantly lower with a checkerboard than with a classic 2D grid. A notched specimen is finally tested to illustrate that very low strain levels can be measured with checkerboard patterns.
关键词： Grid method,Checkerboard,Localized spectrum analysis,Optimal pattern,Digital image correlation,Heteroscedastic noise,Metrology,Pattern optimization,Windowed Fourier transform
更新于2025-09-04 15:30:14