A piezoelectric platform using function module actuator is presented to achieve nano-positioning and high frequency scanning in large working range. A function module actuator is designed to produce a pair of orthogon...A piezoelectric platform using function module actuator is presented to achieve nano-positioning and high frequency scanning in large working range. A function module actuator is designed to produce a pair of orthogonal bending deformations and a longitudinal deformation through partition exciting. The bending deformations are used to actuate the planar motion,while the longitudinal deformation is utilized to dynamically adjust the driving force and broaden the scanning frequency. The dynamic model of the platform system is developed. The open-loop performances of a prototype are first tested: a scan frequency of 308 Hz in a scanning range of 3.368 μm×3.396 μm is measured in direct actuation mode,and the displacement resolution is measured to be 16 nm;maximum speed is measured to be 3.38 mm s^-1 in the inertial actuation mode. Furthermore,the closedloop experiments are carried out and a switching strategy is proposed to obtain the switching of the inertial and direct actuation modes automatically;the platform achieves the scanning with frequency of 300 Hz at the set position.展开更多
The digital testing technique based on computers for dynamic characteristics of electrohydraulic servovalves via frequency scan method is researched. The no-load piston which measures the servo's transient output ...The digital testing technique based on computers for dynamic characteristics of electrohydraulic servovalves via frequency scan method is researched. The no-load piston which measures the servo's transient output flow is designed properly. The velocity testing method by which the speed signal can be obtained indirectly by means of a piezoelectral accelerometer is given. High speed sampling has been realized in Windows OS. Wavelet denoising and Fourier transform are adopted in data processing and analyses. The testing technique discussed has been applied to actual testing systems and the experimental results have proved it to be correct.展开更多
By, introducing the random and systematic errors in simulated data computed from conventional frequency-scan and laterally resolved modulated free carrier absorption theory models, we investigate the relative determin...By, introducing the random and systematic errors in simulated data computed from conventional frequency-scan and laterally resolved modulated free carrier absorption theory models, we investigate the relative determination sensitivities of three electronic transport properties, namely, carrier lifetime carrier diffusivity and front surface recombination velocity of silicon wafers determined by frequency-scan and laterally resolved techniques. The phase and amplitude data with random errors as functions of the modulation frequency at zero pump-probe-beam separation or of the two-beam separation at four different modulation frequencies are simultaneously fitted to an appreciated carrier diffusion model to extract three transport parameters. The statistical results and fitted accuracies of the transport parameter determined by both techniques are theoretically analysed. Corresponding experimental results are carried out to compare to the simulated results. The simulated and experimental results show that the determination of the transport properties of silicon wafers by the laterally resolved technique are more accurate, as compared with that by the frequency-scan technique.展开更多
One of the most important electron density diagnostics, microwave reflectometry, has been developed on many large and medium nuclear fusion devices in recent years . Not only the electron density profiles with high te...One of the most important electron density diagnostics, microwave reflectometry, has been developed on many large and medium nuclear fusion devices in recent years . Not only the electron density profiles with high temporal and spatial resolutions, but also the profiles of plasma rotation and turbulence can be obtained with this diagnostic system.展开更多
The loss of a high-finesse Fabry-Perot cavity was measured using frequency scan and cavity ring-down techniques.Different transverse modes were examined by sweeping the frequency of the laser across the corresponding ...The loss of a high-finesse Fabry-Perot cavity was measured using frequency scan and cavity ring-down techniques.Different transverse modes were examined by sweeping the frequency of the laser across the corresponding resonances.In addition,cavity ring-down technique was used to measure the loss of the Fabry-Perot cavity and a simple model was employed to remove the influence of finite response time of the optical switch and the detection circuit.展开更多
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.U1913215&51975162)。
文摘A piezoelectric platform using function module actuator is presented to achieve nano-positioning and high frequency scanning in large working range. A function module actuator is designed to produce a pair of orthogonal bending deformations and a longitudinal deformation through partition exciting. The bending deformations are used to actuate the planar motion,while the longitudinal deformation is utilized to dynamically adjust the driving force and broaden the scanning frequency. The dynamic model of the platform system is developed. The open-loop performances of a prototype are first tested: a scan frequency of 308 Hz in a scanning range of 3.368 μm×3.396 μm is measured in direct actuation mode,and the displacement resolution is measured to be 16 nm;maximum speed is measured to be 3.38 mm s^-1 in the inertial actuation mode. Furthermore,the closedloop experiments are carried out and a switching strategy is proposed to obtain the switching of the inertial and direct actuation modes automatically;the platform achieves the scanning with frequency of 300 Hz at the set position.
文摘The digital testing technique based on computers for dynamic characteristics of electrohydraulic servovalves via frequency scan method is researched. The no-load piston which measures the servo's transient output flow is designed properly. The velocity testing method by which the speed signal can be obtained indirectly by means of a piezoelectral accelerometer is given. High speed sampling has been realized in Windows OS. Wavelet denoising and Fourier transform are adopted in data processing and analyses. The testing technique discussed has been applied to actual testing systems and the experimental results have proved it to be correct.
基金Project supported by the Fundamental Research Funds for the Central Universities of China (Grant No. ZYGX2009J051)
文摘By, introducing the random and systematic errors in simulated data computed from conventional frequency-scan and laterally resolved modulated free carrier absorption theory models, we investigate the relative determination sensitivities of three electronic transport properties, namely, carrier lifetime carrier diffusivity and front surface recombination velocity of silicon wafers determined by frequency-scan and laterally resolved techniques. The phase and amplitude data with random errors as functions of the modulation frequency at zero pump-probe-beam separation or of the two-beam separation at four different modulation frequencies are simultaneously fitted to an appreciated carrier diffusion model to extract three transport parameters. The statistical results and fitted accuracies of the transport parameter determined by both techniques are theoretically analysed. Corresponding experimental results are carried out to compare to the simulated results. The simulated and experimental results show that the determination of the transport properties of silicon wafers by the laterally resolved technique are more accurate, as compared with that by the frequency-scan technique.
文摘One of the most important electron density diagnostics, microwave reflectometry, has been developed on many large and medium nuclear fusion devices in recent years . Not only the electron density profiles with high temporal and spatial resolutions, but also the profiles of plasma rotation and turbulence can be obtained with this diagnostic system.
基金Supported by Bureau of Comprehensive Planning,Chinese Academy of Sciences
文摘The loss of a high-finesse Fabry-Perot cavity was measured using frequency scan and cavity ring-down techniques.Different transverse modes were examined by sweeping the frequency of the laser across the corresponding resonances.In addition,cavity ring-down technique was used to measure the loss of the Fabry-Perot cavity and a simple model was employed to remove the influence of finite response time of the optical switch and the detection circuit.
