The principle and application of optical interferometry to measure the coating thickness of color-coated plates were introduced in this paper.Additionally,several factors affecting the test results,including coating r...The principle and application of optical interferometry to measure the coating thickness of color-coated plates were introduced in this paper.Additionally,several factors affecting the test results,including coating refractive index,wavelength range,and film thickness range setting,were analyzed.Among these,the refractive index of the color coating,which cannot be measured directly,was identified as the key factor.A solution to this problem was proposed.Finally,the optical interference method and the current detection methods,including the micrometer method and the magnetic eddy current method,were analyzed and compared.The results show that optical interferometry has better repeatability and reproducibility than the current methods and show no significant difference from the current methods through statistical tests.Therefore,the method can be applied to the detection of the coating thickness of color-coated plates.展开更多
The interfacial debonding in fiber-reinforced plastic(FRP)strengthened repair material will affect the bonding strength and lead to failure of the repair without warning.Unfortunately the interfacial damage is normall...The interfacial debonding in fiber-reinforced plastic(FRP)strengthened repair material will affect the bonding strength and lead to failure of the repair without warning.Unfortunately the interfacial damage is normally invisible and often in the form of a patch rather than a through-width crack.Therefore,a debonding patch detection technique based on fiber optic interferometry is proposed.A quasi-impulse loading is applied with a rubberhead hammer and the total elongation of a surface-mounted optical fiber along the length of the repair material is measured as a function of load position.When a debonding patch is present,the induced sudden slope or sign change on the plot of fiber integral strain v.s.load position will reveal the extent and the location of the debonded area.The results of the study indicate that the proposed technique is applicable for debonding patch detection in repaired members under various support conditions.展开更多
We present a simple but effective method for small-angle measurement based on optical feedback interferometry （or laser self-mixing interferometry）. The absolute zero angle can be defined at the biggest fringe ampli...We present a simple but effective method for small-angle measurement based on optical feedback interferometry （or laser self-mixing interferometry）. The absolute zero angle can be defined at the biggest fringe amplitude point, so this method can also achieve absolute angle measurement. In order to verify the method, we construct an angle measurement system. The Fourier-transform method is used to analysis the interference signal. Rotation angles are experimentally measured with a resolution of 10^-6 rad and a measurement range of approximately from -0.0007 to ＋0.0007 rad.展开更多
We perform an experimental study of two-dimensional（2D） electron density profiles of the laser-induced plasma plumes in air by ordinarily laboratorial interferometry. The electron density distributions measured show...We perform an experimental study of two-dimensional（2D） electron density profiles of the laser-induced plasma plumes in air by ordinarily laboratorial interferometry. The electron density distributions measured show a feature of hollow core. To illustrate the feature, we present a theoretical investigation by using dynamics analysis. In the simulation, the propagation of laser pulse with the evolution of electron density is utilized to evaluate ionization of air target for the plasma-formation stage. In the plasma-expansion stage, a simple adiabatic fluid dynamics is used to calculate the evolution of plasma outward expansion. The simulations show good agreements with experimental results, and demonstrate an effective way of determining 2D density profiles of the laser-induced plasma plume in gas.展开更多
Attosecondattosecond science;extreme ultraviolet;high-order harmonic generation;Ramsey-type spectroscopy Optical and Ramsey-Type Interferometry by Postgeneration Splitting of Harmonic PulseTime domain Ramsey-type inte...Attosecondattosecond science;extreme ultraviolet;high-order harmonic generation;Ramsey-type spectroscopy Optical and Ramsey-Type Interferometry by Postgeneration Splitting of Harmonic PulseTime domain Ramsey-type interferometry is useful for investigating spectroscopic information of quantum states in atoms and molecules.The energy range of the quantum states to be observed with this scheme has now reached more than 20 eV by resolving the interference fringes with a period of a few hundred attoseconds.This attosecond Ramsey-type interferometry requires the irradiation of a coherent pair of extreme ultraviolet(XUV)light pulses,while all the methods used to deliver the coherent XUV pulse pair until now have relied on the division of the source of an XUV pulse in two before the generation.In this paper,we report on a novel technique to perform attosecond Ramsey-type interferometry by splitting an XUV high-order harmonic(HH)pulse of a sub-20 fs laser pulse after its generation.By virtue of the postgeneration splitting of the HH pulse,we demonstrated that the optical interference emerging at the complete temporal overlap of the HH pulse pair seamlessly continued to the Ramsey-type electronic interference in a helium atom.This technique is applicable for studying the femtosecond dephasing dynamics of electronic wavepackets and exploring the ultrafast evolution of a cationic system entangled with an ionized electron with sub-20 fs resolution.展开更多
The propagating of laser-generated ultrasonic waves in K9 glass was investigated. Many methods have been developed to detect the laser ultrasound since laser ultrasonic waves can be used to measure material parameters...The propagating of laser-generated ultrasonic waves in K9 glass was investigated. Many methods have been developed to detect the laser ultrasound since laser ultrasonic waves can be used to measure material parameters or characterize materials properties. In order to reduce the measuring time, a Mach–Zehnder interferometer, a full field measuring tool,was preferred in this paper. The ultrasonic wave was produced on the K9 glass surface by a Q-switched Nd:YAG laser absorbed in a liquid layer. The interferograms were then taken at various delay times by a CCD camera after single pulse induced laser ultrasonic waves. Ultrasonic waves in the K9 glass can be observed from interferogram images. The results provide an understanding of laser ultrasound propagation in K9 glass in the lifetime.展开更多
Optical interferometry is a powerful tool for measuring and characterizing areal surface topography in precision manufacturing.A variety of instruments based on optical interferometry have been developed to meet the m...Optical interferometry is a powerful tool for measuring and characterizing areal surface topography in precision manufacturing.A variety of instruments based on optical interferometry have been developed to meet the measurement needs in various applications,but the existing techniques are simply not enough to meet the ever-increasing requirements in terms of accuracy,speed,robustness,and dynamic range,especially in on-line or on-machine conditions.This paper provides an in-depth perspective of surface topography reconstruction for optical interferometric measurements.Principles,configurations,and applications of typical optical interferometers with different capabilities and limitations are presented.Theoretical background and recent advances of fringe analysis algorithms,including coherence peak sensing and phase-shifting algorithm,are summarized.The new developments in measurement accuracy and repeatability,noise resistance,self-calibration ability,and computational efficiency are discussed.This paper also presents the new challenges that optical interferometry techniques are facing in surface topography measurement.To address these challenges,advanced techniques in image stitching,on-machine measurement,intelligent sampling,parallel computing,and deep learning are explored to improve the functional performance of optical interferometry in future manufacturing metrology.展开更多
In this study, we present speed and displacement measurements of micro-fluid in a hollow-core optical fiber, where an optical interference signal is created by two guided beams reflected at a fixed facet and a moving ...In this study, we present speed and displacement measurements of micro-fluid in a hollow-core optical fiber, where an optical interference signal is created by two guided beams reflected at a fixed facet and a moving fluid end. By counting the number of intensity oscillations of the signal, the movement of the fluid end is successfully traced with high accuracy. Furthermore, we could detect the change in curvature diameters of the fluid end depending on the flow direction by monitoring the visibility of the interference signal.展开更多
In this paper,we investigate the phase sensitivities in two-path optical interferometry with asymmetric beam splitters.Here,we present the optimal conditions for the transmission ratio and the phase of the beam splitt...In this paper,we investigate the phase sensitivities in two-path optical interferometry with asymmetric beam splitters.Here,we present the optimal conditions for the transmission ratio and the phase of the beam splitter to gain the highest sensitivities for a general class of non-classical states with parity symmetry.Additionally,we address the controversial question of whether the scheme with a combination of coherent state and photon-added or photon-subtracted squeezed vacuum state is better or worse than the most celebrated one using a combination of coherent state and squeezed vacuum state.展开更多
Oil-air lubrication supplies lubricants in the form of droplets to elastohydrodynamic lubrication (EHL)contacts,such as those in high-speed spindle bearings.However,there is a paucity of information related to underst...Oil-air lubrication supplies lubricants in the form of droplets to elastohydrodynamic lubrication (EHL)contacts,such as those in high-speed spindle bearings.However,there is a paucity of information related to understanding the lubrication behaviors of oil droplets within EHL contacts.In this study,behaviors of lubricant droplets,in terms of spreading around a static contact as well as passing through a roiling contact,were studied with an optical ball-on-disk EHL test rig.Influences of oil droplet size,viscosity,and surface tension on droplet spreading were examined.Lubricating film formation was also investigated when droplets traveled through the EHL contact region.The results indicated that droplet size and running speed significantly influenced film profiles.With increasing entrainment speeds,a small droplet passed through the contact without spreading and generated films with a significant depression in the central contact region.展开更多
We present an interferometry setup and the detailed fringe analysis method for intense short pulse(SP) laser experiments.The interferometry scheme was refined through multiple campaigns to investigate the effects of p...We present an interferometry setup and the detailed fringe analysis method for intense short pulse(SP) laser experiments.The interferometry scheme was refined through multiple campaigns to investigate the effects of pre-plasmas on energetic electrons at the Jupiter Laser Facility at Lawrence Livermore National Laboratory. The interferometer used a frequency doubled(λ=0.527 μm) 0.5 ps long optical probe beam to measure the pre-plasma density, an invaluable parameter to better understand how varying pre-plasma conditions affect the characteristics of the energetic electrons. The hardware of the diagnostic, data analysis and example data are presented. The diagnostic setup and the analysis procedure can be employed for any other SP laser experiments and interferograms, respectively.展开更多
文摘The principle and application of optical interferometry to measure the coating thickness of color-coated plates were introduced in this paper.Additionally,several factors affecting the test results,including coating refractive index,wavelength range,and film thickness range setting,were analyzed.Among these,the refractive index of the color coating,which cannot be measured directly,was identified as the key factor.A solution to this problem was proposed.Finally,the optical interference method and the current detection methods,including the micrometer method and the magnetic eddy current method,were analyzed and compared.The results show that optical interferometry has better repeatability and reproducibility than the current methods and show no significant difference from the current methods through statistical tests.Therefore,the method can be applied to the detection of the coating thickness of color-coated plates.
基金supported by the National Natural Science Foundation of China(No.51278156)the Basic Project of Shenzhen Science & Technology Program(No.JCYJ2017030155815876)
文摘The interfacial debonding in fiber-reinforced plastic(FRP)strengthened repair material will affect the bonding strength and lead to failure of the repair without warning.Unfortunately the interfacial damage is normally invisible and often in the form of a patch rather than a through-width crack.Therefore,a debonding patch detection technique based on fiber optic interferometry is proposed.A quasi-impulse loading is applied with a rubberhead hammer and the total elongation of a surface-mounted optical fiber along the length of the repair material is measured as a function of load position.When a debonding patch is present,the induced sudden slope or sign change on the plot of fiber integral strain v.s.load position will reveal the extent and the location of the debonded area.The results of the study indicate that the proposed technique is applicable for debonding patch detection in repaired members under various support conditions.
基金supported by the National Natural Science Foundation of China under Grant No.60677019.
文摘We present a simple but effective method for small-angle measurement based on optical feedback interferometry （or laser self-mixing interferometry）. The absolute zero angle can be defined at the biggest fringe amplitude point, so this method can also achieve absolute angle measurement. In order to verify the method, we construct an angle measurement system. The Fourier-transform method is used to analysis the interference signal. Rotation angles are experimentally measured with a resolution of 10^-6 rad and a measurement range of approximately from -0.0007 to ＋0.0007 rad.
基金supported by National Natural Science Foundation of China(Nos.11264036,11465016 and 11364038)
文摘We perform an experimental study of two-dimensional（2D） electron density profiles of the laser-induced plasma plumes in air by ordinarily laboratorial interferometry. The electron density distributions measured show a feature of hollow core. To illustrate the feature, we present a theoretical investigation by using dynamics analysis. In the simulation, the propagation of laser pulse with the evolution of electron density is utilized to evaluate ionization of air target for the plasma-formation stage. In the plasma-expansion stage, a simple adiabatic fluid dynamics is used to calculate the evolution of plasma outward expansion. The simulations show good agreements with experimental results, and demonstrate an effective way of determining 2D density profiles of the laser-induced plasma plume in gas.
基金supported by the Core Research for Evolutional Science and Technology(JPMJCR15N1)of JSTthe Center of Innovation Program(JPMJCE1313)of JST+2 种基金a Grant-in-Aid for Specially Promoted Research(JP15H05696)from MEXTGrants-in-Aid for Scientific Research(19H00869,19H05628,20H00371,26247068,20H05670)from MEXTthe Quantum Leap Flagship Program(JPMXS0118068681,JPMXS0118067246)of MEXT,Japan.
文摘Attosecondattosecond science;extreme ultraviolet;high-order harmonic generation;Ramsey-type spectroscopy Optical and Ramsey-Type Interferometry by Postgeneration Splitting of Harmonic PulseTime domain Ramsey-type interferometry is useful for investigating spectroscopic information of quantum states in atoms and molecules.The energy range of the quantum states to be observed with this scheme has now reached more than 20 eV by resolving the interference fringes with a period of a few hundred attoseconds.This attosecond Ramsey-type interferometry requires the irradiation of a coherent pair of extreme ultraviolet(XUV)light pulses,while all the methods used to deliver the coherent XUV pulse pair until now have relied on the division of the source of an XUV pulse in two before the generation.In this paper,we report on a novel technique to perform attosecond Ramsey-type interferometry by splitting an XUV high-order harmonic(HH)pulse of a sub-20 fs laser pulse after its generation.By virtue of the postgeneration splitting of the HH pulse,we demonstrated that the optical interference emerging at the complete temporal overlap of the HH pulse pair seamlessly continued to the Ramsey-type electronic interference in a helium atom.This technique is applicable for studying the femtosecond dephasing dynamics of electronic wavepackets and exploring the ultrafast evolution of a cationic system entangled with an ionized electron with sub-20 fs resolution.
基金This work was supported by the National Natural Science Foundation of China(NNSFC)(Nos.61975080 and 11774176).
文摘The propagating of laser-generated ultrasonic waves in K9 glass was investigated. Many methods have been developed to detect the laser ultrasound since laser ultrasonic waves can be used to measure material parameters or characterize materials properties. In order to reduce the measuring time, a Mach–Zehnder interferometer, a full field measuring tool,was preferred in this paper. The ultrasonic wave was produced on the K9 glass surface by a Q-switched Nd:YAG laser absorbed in a liquid layer. The interferograms were then taken at various delay times by a CCD camera after single pulse induced laser ultrasonic waves. Ultrasonic waves in the K9 glass can be observed from interferogram images. The results provide an understanding of laser ultrasound propagation in K9 glass in the lifetime.
基金funding from the Enterprise Ireland and from the European Union’s Horizon 2020 Research and Innovation Programme under the Marie Skłodowska-Curie grant agreement(Grant No.713654)the National Natural Science Foundation of China(Grant No.51705070)the Science Foundation Ireland(SFI)(Grant No.15/RP/B3208).
文摘Optical interferometry is a powerful tool for measuring and characterizing areal surface topography in precision manufacturing.A variety of instruments based on optical interferometry have been developed to meet the measurement needs in various applications,but the existing techniques are simply not enough to meet the ever-increasing requirements in terms of accuracy,speed,robustness,and dynamic range,especially in on-line or on-machine conditions.This paper provides an in-depth perspective of surface topography reconstruction for optical interferometric measurements.Principles,configurations,and applications of typical optical interferometers with different capabilities and limitations are presented.Theoretical background and recent advances of fringe analysis algorithms,including coherence peak sensing and phase-shifting algorithm,are summarized.The new developments in measurement accuracy and repeatability,noise resistance,self-calibration ability,and computational efficiency are discussed.This paper also presents the new challenges that optical interferometry techniques are facing in surface topography measurement.To address these challenges,advanced techniques in image stitching,on-machine measurement,intelligent sampling,parallel computing,and deep learning are explored to improve the functional performance of optical interferometry in future manufacturing metrology.
文摘In this study, we present speed and displacement measurements of micro-fluid in a hollow-core optical fiber, where an optical interference signal is created by two guided beams reflected at a fixed facet and a moving fluid end. By counting the number of intensity oscillations of the signal, the movement of the fluid end is successfully traced with high accuracy. Furthermore, we could detect the change in curvature diameters of the fluid end depending on the flow direction by monitoring the visibility of the interference signal.
基金supported by the National Natural Science Foundation of China(Grant Nos.11747161,and 11974189)the Priority Academic Program Development of Jiangsu Higher Education Institutions.Peng Xu acknowledges the support from the National Natural Science Foundation of China(Grant No.11847050)Natural Science Foundation of Jiangsu Province in China(Grant No.BK20180750)。
文摘In this paper,we investigate the phase sensitivities in two-path optical interferometry with asymmetric beam splitters.Here,we present the optimal conditions for the transmission ratio and the phase of the beam splitter to gain the highest sensitivities for a general class of non-classical states with parity symmetry.Additionally,we address the controversial question of whether the scheme with a combination of coherent state and photon-added or photon-subtracted squeezed vacuum state is better or worse than the most celebrated one using a combination of coherent state and squeezed vacuum state.
基金The authors would like to express their thanks to the financial supports from the Natural Science Foundation of China，Doctoral Scientific Fund Project of the Ministry of Education of China，Outstanding Young Scientist in Shandong Province
文摘Oil-air lubrication supplies lubricants in the form of droplets to elastohydrodynamic lubrication (EHL)contacts,such as those in high-speed spindle bearings.However,there is a paucity of information related to understanding the lubrication behaviors of oil droplets within EHL contacts.In this study,behaviors of lubricant droplets,in terms of spreading around a static contact as well as passing through a roiling contact,were studied with an optical ball-on-disk EHL test rig.Influences of oil droplet size,viscosity,and surface tension on droplet spreading were examined.Lubricating film formation was also investigated when droplets traveled through the EHL contact region.The results indicated that droplet size and running speed significantly influenced film profiles.With increasing entrainment speeds,a small droplet passed through the contact without spreading and generated films with a significant depression in the central contact region.
基金support from the LDRD (15-ERD-054) program to finish the manuscriptthe auspices of the US DOE by LLNL under contract no.DEAC52-07NA27344funded by the LDRD (12-ERD-062) program
文摘We present an interferometry setup and the detailed fringe analysis method for intense short pulse(SP) laser experiments.The interferometry scheme was refined through multiple campaigns to investigate the effects of pre-plasmas on energetic electrons at the Jupiter Laser Facility at Lawrence Livermore National Laboratory. The interferometer used a frequency doubled(λ=0.527 μm) 0.5 ps long optical probe beam to measure the pre-plasma density, an invaluable parameter to better understand how varying pre-plasma conditions affect the characteristics of the energetic electrons. The hardware of the diagnostic, data analysis and example data are presented. The diagnostic setup and the analysis procedure can be employed for any other SP laser experiments and interferograms, respectively.
