The electromagnetic parameters of microwave absorbing materials are important criteria when appraising the properties of absorbents. For reconstruction of parameters which belongs to the inverse scattering problem, th...The electromagnetic parameters of microwave absorbing materials are important criteria when appraising the properties of absorbents. For reconstruction of parameters which belongs to the inverse scattering problem, the test data in requirement of traditional impedance method are "just enough" and not "redundant" to comprehensively evaluate the electromagnetic properties of materials. A novel optimization approach involving multiple impedance measurements is introduced in this paper to implement automatic measurement for electromagnetic parameters on microwave slot-line. Some results for standard samples and microwave absorbing materials are given.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
I. INTRODUCTION In recent years, relativistic Vlasov equation combined with classical electromagnetic theory has found its wide application in electron cyclotron resonance maser (ECRM).As we all know, the significance...I. INTRODUCTION In recent years, relativistic Vlasov equation combined with classical electromagnetic theory has found its wide application in electron cyclotron resonance maser (ECRM).As we all know, the significance of the first order perturbation展开更多
文摘The electromagnetic parameters of microwave absorbing materials are important criteria when appraising the properties of absorbents. For reconstruction of parameters which belongs to the inverse scattering problem, the test data in requirement of traditional impedance method are "just enough" and not "redundant" to comprehensively evaluate the electromagnetic properties of materials. A novel optimization approach involving multiple impedance measurements is introduced in this paper to implement automatic measurement for electromagnetic parameters on microwave slot-line. Some results for standard samples and microwave absorbing materials are given.
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.
文摘I. INTRODUCTION In recent years, relativistic Vlasov equation combined with classical electromagnetic theory has found its wide application in electron cyclotron resonance maser (ECRM).As we all know, the significance of the first order perturbation
