Laser interferometry with higher resolution,faster update rate,and larger dynamic range is highly anticipated in the exploration of physics frontiers,advanced manufacturing,and precision sensing.Real-time dispersive s...Laser interferometry with higher resolution,faster update rate,and larger dynamic range is highly anticipated in the exploration of physics frontiers,advanced manufacturing,and precision sensing.Real-time dispersive spectral interferometry(DSI)shows promise for high-speed precision measurements,whereas the resolution of subnanometers has not yet been achieved.We present a comprehensive theoretical framework to analyze the limitations of real-time DSI based on the signal-to-noise ratio and data volume.A real-time orthogonal polarization spectral interferometry technique is proposed,which utilizes a pair of interferograms with the pi-phase shift to effectively mitigate the phase noise embedded in real-time spectral envelopes,thereby enabling the precise measurements with subnanometer resolution at megahertz frame rates.The recorded time series data are processed through interpolation,segmentation,time–frequency mapping,and de-enveloping to regain the typical cosine-shaped spectral evolution,followed by a fitting-based phase retrieval method to extract the interference phase.The phase resolution of 1.1 mrad(0.91 as for time delay and 0.3 nm for distance)is obtained at the update rate of 22.2 MHz even under the detection bandwidth of 500 MHz,and can be further enhanced to 0.29 mrad(0.24 as for time delay)after 500 times averaging(∼0.5 MHz).Our approach is validated through periodic phase modulations and applied to measure the rapid damped oscillations of a piezo stage,yielding results consistent with those obtained from a commercial picometer interferometer.展开更多
For land seismic surveys, the surface waves are the dominant noises that mask the effective signals on seismograms.The conventional methods isolate surface waves from the effective signals by the differences in freque...For land seismic surveys, the surface waves are the dominant noises that mask the effective signals on seismograms.The conventional methods isolate surface waves from the effective signals by the differences in frequencies or apparent velocities,but may not perform well when these differences are not obvious. Since the original seismic interferometry can only predict inter-receiver surface waves, we propose the use of super-virtual interferometry(SVI), which is a totally data-driven method, to predict shot-to-receiver surface waves, since this method relieves the limitation that a real shot should collocate with one of the receivers for adaptive subtraction. We further develop the adaptive weighted SVI(AWSVI) to improve the prediction of dispersive surface waves, which may be generated from heterogeneous media at the near surface. Numerical examples demonstrate the effectiveness of AWSVI to predict dispersive surface waves and its applicability to the complex near surface. The application of AWSVI on the field data from a land survey in the east of China improves the suppression of the residual surface waves compared to the conventional methods.展开更多
Ranging is indispensable in a variety of fields,encompassing basic science,manufacturing,production,and daily life.Although traditional methods based on the dispersive interferometry(DPI)in the frequency domain provid...Ranging is indispensable in a variety of fields,encompassing basic science,manufacturing,production,and daily life.Although traditional methods based on the dispersive interferometry(DPI)in the frequency domain provide high precision,their measurement speed is slow,preventing the capture and measurement of dynamic displacements.Here,we propose a fast and precise ranging method based on the dispersion-controlled dual-swept laser(DCDSL),which allows the dynamical displacement measurement of the target under test.Due to the slight frequency sweeping speed difference between the signal and reference lights,there is a zero-frequency point of the oscillation(ZPO)generated in the interference signal,whose position in the time domain is linearly related to the relative delay between the signal and reference lights.Utilizing phase demodulation of the interference signal from the DCDSL and the fitting algorithm,the time-domain position of ZPO is accurately found,which precisely maps to the displacement of the target in real time without direction ambiguity.The fast frequency sweeping rate ensures fast ranging with the MHz order refresh frame.We have experimentally demonstrated its capabilities for precise measurement of static distances and the capture of dynamic displacement processes through simulations and experiments,with the measurement range encompassing the entire interference period(56 mm).Compared to a calibrated motorized displacement platform,the residual error for full-range distance measurements is within 10μm,and the error in average speed during dynamic processes is 0.46%.Additionally,the system exhibits excellent stability,achieving a minimum Allan deviation of 4.25 nm over an average duration of approximately 4 ms.This method ensures high precision while maintaining a simple system,thereby advancing the practical implementation of ultrafast length metrology.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.61705193)the Natural Science Foundation of Zhejiang Province(Grant No.LGG20F050002)the Jinhua Science and Technology Plan(Project No.2024-1-064).
文摘Laser interferometry with higher resolution,faster update rate,and larger dynamic range is highly anticipated in the exploration of physics frontiers,advanced manufacturing,and precision sensing.Real-time dispersive spectral interferometry(DSI)shows promise for high-speed precision measurements,whereas the resolution of subnanometers has not yet been achieved.We present a comprehensive theoretical framework to analyze the limitations of real-time DSI based on the signal-to-noise ratio and data volume.A real-time orthogonal polarization spectral interferometry technique is proposed,which utilizes a pair of interferograms with the pi-phase shift to effectively mitigate the phase noise embedded in real-time spectral envelopes,thereby enabling the precise measurements with subnanometer resolution at megahertz frame rates.The recorded time series data are processed through interpolation,segmentation,time–frequency mapping,and de-enveloping to regain the typical cosine-shaped spectral evolution,followed by a fitting-based phase retrieval method to extract the interference phase.The phase resolution of 1.1 mrad(0.91 as for time delay and 0.3 nm for distance)is obtained at the update rate of 22.2 MHz even under the detection bandwidth of 500 MHz,and can be further enhanced to 0.29 mrad(0.24 as for time delay)after 500 times averaging(∼0.5 MHz).Our approach is validated through periodic phase modulations and applied to measure the rapid damped oscillations of a piezo stage,yielding results consistent with those obtained from a commercial picometer interferometer.
基金supported by the National Basic Research Program of China (Grant No. 2013CB228602)the National Science and Technology Major Project of China (Grant No. 2016ZX05004003-002)the National High Technology Research and Development Program of China (Grant No. 2013AA064202)
文摘For land seismic surveys, the surface waves are the dominant noises that mask the effective signals on seismograms.The conventional methods isolate surface waves from the effective signals by the differences in frequencies or apparent velocities,but may not perform well when these differences are not obvious. Since the original seismic interferometry can only predict inter-receiver surface waves, we propose the use of super-virtual interferometry(SVI), which is a totally data-driven method, to predict shot-to-receiver surface waves, since this method relieves the limitation that a real shot should collocate with one of the receivers for adaptive subtraction. We further develop the adaptive weighted SVI(AWSVI) to improve the prediction of dispersive surface waves, which may be generated from heterogeneous media at the near surface. Numerical examples demonstrate the effectiveness of AWSVI to predict dispersive surface waves and its applicability to the complex near surface. The application of AWSVI on the field data from a land survey in the east of China improves the suppression of the residual surface waves compared to the conventional methods.
基金Graduate Research and Innovation Foundation of Chongqing(CYB240013)Graduate Funding Program in the College of Optoelectronic Engineering(Chongqing University)(GDYKC202409)+1 种基金National Natural Science Foundation for Distinguished Young Scholars(61825501)Chongqing Natural Science Foundation of Innovative Research Groups(cstc2020jcyj,cxttX0005)。
文摘Ranging is indispensable in a variety of fields,encompassing basic science,manufacturing,production,and daily life.Although traditional methods based on the dispersive interferometry(DPI)in the frequency domain provide high precision,their measurement speed is slow,preventing the capture and measurement of dynamic displacements.Here,we propose a fast and precise ranging method based on the dispersion-controlled dual-swept laser(DCDSL),which allows the dynamical displacement measurement of the target under test.Due to the slight frequency sweeping speed difference between the signal and reference lights,there is a zero-frequency point of the oscillation(ZPO)generated in the interference signal,whose position in the time domain is linearly related to the relative delay between the signal and reference lights.Utilizing phase demodulation of the interference signal from the DCDSL and the fitting algorithm,the time-domain position of ZPO is accurately found,which precisely maps to the displacement of the target in real time without direction ambiguity.The fast frequency sweeping rate ensures fast ranging with the MHz order refresh frame.We have experimentally demonstrated its capabilities for precise measurement of static distances and the capture of dynamic displacement processes through simulations and experiments,with the measurement range encompassing the entire interference period(56 mm).Compared to a calibrated motorized displacement platform,the residual error for full-range distance measurements is within 10μm,and the error in average speed during dynamic processes is 0.46%.Additionally,the system exhibits excellent stability,achieving a minimum Allan deviation of 4.25 nm over an average duration of approximately 4 ms.This method ensures high precision while maintaining a simple system,thereby advancing the practical implementation of ultrafast length metrology.
