With the development of new materials and ultra-precision processing technology, the sizes of mea- sured objects increase, and the requirements for machining accuracy and surface quality become more exacting. The trad...With the development of new materials and ultra-precision processing technology, the sizes of mea- sured objects increase, and the requirements for machining accuracy and surface quality become more exacting. The traditional measurement method based on reference datum is inadequate for measuring a high-precision object when the quality of the reference datum is approximately within the same order as that of the object. Self-referenced measurement techniques provide an effective means when the direct reference-based method cannot satisfy the required measurement or calibration accuracy. This paper discusses the reconstruction algorithms for self-referenced measurement and connects lateral shearing interferometry and multi-probe error separation. In lateral shearing interferometry, the reconstruction algorithms are generally categorized into modal or zonal methods. The multi-probe error separation techniques for straightness measurement are broadly divided into two-point and three-point methods. The common features of the lateral sheafing interferometry method and the multi-probe error separation method are identified. We conclude that the reconstruction principle in lateral shearing interferometry is similar to the two-point method in error separation on the condition that no yaw error exists. This similarity may provide a basis or inspiration for the development of both classes of methods.展开更多
A nuclear spin gyroscope based on an alkali-metal–noble-gas co-magnetometer operated in spin-exchange relaxationfree(SERF) regime is a promising atomic rotation sensor for its ultra-high fundamental sensitivity. Howe...A nuclear spin gyroscope based on an alkali-metal–noble-gas co-magnetometer operated in spin-exchange relaxationfree(SERF) regime is a promising atomic rotation sensor for its ultra-high fundamental sensitivity. However, the fluctuation of probe light intensity is one of the main technical error sources that limits the bias stability of the gyroscope. Here we propose a novel method to suppress the bias error induced by probe light intensity fluctuations. This method is based on the inherent magnetic field response characteristics of the gyroscope. By the application of a bias magnetic field, the gyroscope can be tuned to a working point where the output signal is insensitive to probe light intensity variation, referred to herein as ‘zero point’, thus the bias error induced by intensity fluctuations can be completely suppressed. The superiority of the method was verified on a K–Rb–21 Ne co-magnetometer, and a bias stability of approximately 0.01°/h was obtained. In addition, the method proposed here can remove the requirement of the closed-loop control of probe light intensity, thereby facilitating miniaturization of the gyroscope volume and improvement of reliability.展开更多
In this paper,the following problems are discussed:the mounting conditionsof three probes,the transmission characteristics of measuring system,the elimination ofmounting eccentricity,and so forth.The measures for solv...In this paper,the following problems are discussed:the mounting conditionsof three probes,the transmission characteristics of measuring system,the elimination ofmounting eccentricity,and so forth.The measures for solving these problems are also pres-ented.At last,the author gives some ideas about the solubility and the correlations of theoutput equations.展开更多
Flow around a 2-D cylinder pressure probe placed in uniform flow,free jet flow,and wind tunnel flow was analyzed with potential flow theory and simulated with numerical method.Blockage effect was investigated under se...Flow around a 2-D cylinder pressure probe placed in uniform flow,free jet flow,and wind tunnel flow was analyzed with potential flow theory and simulated with numerical method.Blockage effect was investigated under several typical flow Mach numbers.The result from numerical simulation shows a similar trend to the one from potential flow method while varies in quantity.Wind tunnel walls accelerate the flow near the probe and thus produce a blockage effect;Boundary of free jet flow,however,decelerates the flow and thus produces a 'negative' blockage effect.A maximum incoming Mach number exists when the probe is calibrated in wind tunnel in high subsonic condition due to choking caused by shocks and shock induced separation.The critical Mach number varies with blockage ratio,which makes high Mach number impossible to achieve in large blockage ratio condition.The blockage effect itself is unavoidable for calibration or measurement although a sufficiently small blockage ratio brings minor effect.Correction can be implemented based on the numerical simulation result presented in this paper and further works.展开更多
In this paper, an effective technique to compensate the positioning errors in a near-field—far-field (NF-FF) transformation with helicoidal scanning for elongated antennas is presented and validated both numerically ...In this paper, an effective technique to compensate the positioning errors in a near-field—far-field (NF-FF) transformation with helicoidal scanning for elongated antennas is presented and validated both numerically and experimentally. It relies on a nonredundant sampling representation of the voltage measured by the probe, obtained by considering the antenna as enclosed in a cylinder ended in two half-spheres. An iterative scheme is used to reconstruct the helicoidal NF data at the points fixed by the representation from the acquired irregularly spaced ones. Once the helicoidal data have been retrieved, those needed by a classical NF-FF transformation with cylindrical scanning are efficiently evaluated by using an optimal sampling interpolation algorithm. Some numerical tests, assessing the accuracy of the approach and its stability with respect to random errors affecting the data, are reported. Experimental tests performed at the Antenna Characterization Lab of the University of Salerno further confirm the validity of the proposed technique.展开更多
文摘With the development of new materials and ultra-precision processing technology, the sizes of mea- sured objects increase, and the requirements for machining accuracy and surface quality become more exacting. The traditional measurement method based on reference datum is inadequate for measuring a high-precision object when the quality of the reference datum is approximately within the same order as that of the object. Self-referenced measurement techniques provide an effective means when the direct reference-based method cannot satisfy the required measurement or calibration accuracy. This paper discusses the reconstruction algorithms for self-referenced measurement and connects lateral shearing interferometry and multi-probe error separation. In lateral shearing interferometry, the reconstruction algorithms are generally categorized into modal or zonal methods. The multi-probe error separation techniques for straightness measurement are broadly divided into two-point and three-point methods. The common features of the lateral sheafing interferometry method and the multi-probe error separation method are identified. We conclude that the reconstruction principle in lateral shearing interferometry is similar to the two-point method in error separation on the condition that no yaw error exists. This similarity may provide a basis or inspiration for the development of both classes of methods.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2016YFB0501600 and 2017YFB0503100)the National Natural Science Foundation of China(Grant Nos.61773043,61673041,and 61721091)
文摘A nuclear spin gyroscope based on an alkali-metal–noble-gas co-magnetometer operated in spin-exchange relaxationfree(SERF) regime is a promising atomic rotation sensor for its ultra-high fundamental sensitivity. However, the fluctuation of probe light intensity is one of the main technical error sources that limits the bias stability of the gyroscope. Here we propose a novel method to suppress the bias error induced by probe light intensity fluctuations. This method is based on the inherent magnetic field response characteristics of the gyroscope. By the application of a bias magnetic field, the gyroscope can be tuned to a working point where the output signal is insensitive to probe light intensity variation, referred to herein as ‘zero point’, thus the bias error induced by intensity fluctuations can be completely suppressed. The superiority of the method was verified on a K–Rb–21 Ne co-magnetometer, and a bias stability of approximately 0.01°/h was obtained. In addition, the method proposed here can remove the requirement of the closed-loop control of probe light intensity, thereby facilitating miniaturization of the gyroscope volume and improvement of reliability.
文摘In this paper,the following problems are discussed:the mounting conditionsof three probes,the transmission characteristics of measuring system,the elimination ofmounting eccentricity,and so forth.The measures for solving these problems are also pres-ented.At last,the author gives some ideas about the solubility and the correlations of theoutput equations.
文摘Flow around a 2-D cylinder pressure probe placed in uniform flow,free jet flow,and wind tunnel flow was analyzed with potential flow theory and simulated with numerical method.Blockage effect was investigated under several typical flow Mach numbers.The result from numerical simulation shows a similar trend to the one from potential flow method while varies in quantity.Wind tunnel walls accelerate the flow near the probe and thus produce a blockage effect;Boundary of free jet flow,however,decelerates the flow and thus produces a 'negative' blockage effect.A maximum incoming Mach number exists when the probe is calibrated in wind tunnel in high subsonic condition due to choking caused by shocks and shock induced separation.The critical Mach number varies with blockage ratio,which makes high Mach number impossible to achieve in large blockage ratio condition.The blockage effect itself is unavoidable for calibration or measurement although a sufficiently small blockage ratio brings minor effect.Correction can be implemented based on the numerical simulation result presented in this paper and further works.
文摘In this paper, an effective technique to compensate the positioning errors in a near-field—far-field (NF-FF) transformation with helicoidal scanning for elongated antennas is presented and validated both numerically and experimentally. It relies on a nonredundant sampling representation of the voltage measured by the probe, obtained by considering the antenna as enclosed in a cylinder ended in two half-spheres. An iterative scheme is used to reconstruct the helicoidal NF data at the points fixed by the representation from the acquired irregularly spaced ones. Once the helicoidal data have been retrieved, those needed by a classical NF-FF transformation with cylindrical scanning are efficiently evaluated by using an optimal sampling interpolation algorithm. Some numerical tests, assessing the accuracy of the approach and its stability with respect to random errors affecting the data, are reported. Experimental tests performed at the Antenna Characterization Lab of the University of Salerno further confirm the validity of the proposed technique.
