Laser display technology is the most promising display technology in the market and is widely used in many fields. However, laser speckle has been troubling the application and expansion of this technology in some fie...Laser display technology is the most promising display technology in the market and is widely used in many fields. However, laser speckle has been troubling the application and expansion of this technology in some fields. In order to better evaluate the speckle, speckle measurement methods must be studied. In this study, a dynamic measurement method for laser speckles is proposed according to the optical superposition characteristics of speckle, which can reduce the influence of non-coherent factors on the speckle measurement results. The feasibility of the dynamic speckle measurement method is verified by designing an experimental scheme.展开更多
We experimentally and numerically investigated the hydrodynamics,fragmentation mechanisms,and debris distribution arising from the interaction of nanosecond laser pulses with a gallium-indium-tin(Ga-In-Sn)liquid film ...We experimentally and numerically investigated the hydrodynamics,fragmentation mechanisms,and debris distribution arising from the interaction of nanosecond laser pulses with a gallium-indium-tin(Ga-In-Sn)liquid film of micron-scale thickness.Highspeed stroboscopic shadow photography was employed to visualize the splash crown and ejection of debris.The velocities of this debris,ranging from 329 to 4211 m s^(-1),were found to scale with laser pulse energy(E_(p)=0.9-36 m J)and film thickness(h)according to U∝E^(5/9)_(p)/h.This velocity was accurately described by a modified ablation and propulsion model.The numerical simulations provided insights into the underlying physics,including the expansion of high-pressure plasma zone,shock wave propagation,and the formation of significant negative pressure regions conducive to cavitation.Furthermore,the direction of minimal debris deposition is found to align with peak plasma luminous intensity,which is normal to the liquid film.展开更多
A new method is described to measure the dynamic shear modulus of underwater acoustic structure materials in a small anechoic water tank by using a broadband parametric source, a precise coordinate installation and te...A new method is described to measure the dynamic shear modulus of underwater acoustic structure materials in a small anechoic water tank by using a broadband parametric source, a precise coordinate installation and techniques of signal processing in the frequency range of 20 kHz - 100 kHz. The typical size of material samples is 500×500 mm2. Basic principles, experiment installation and measured results are also presented展开更多
基金supported by the National Natural Science Foundation of China (No.62076160)the Natural Science Foundation of Shanghai (No.21ZR1424700)。
文摘Laser display technology is the most promising display technology in the market and is widely used in many fields. However, laser speckle has been troubling the application and expansion of this technology in some fields. In order to better evaluate the speckle, speckle measurement methods must be studied. In this study, a dynamic measurement method for laser speckles is proposed according to the optical superposition characteristics of speckle, which can reduce the influence of non-coherent factors on the speckle measurement results. The feasibility of the dynamic speckle measurement method is verified by designing an experimental scheme.
基金supported by the National Natural Science Foundation of China(Grant Nos.12327803,12588301,and 62475111)。
文摘We experimentally and numerically investigated the hydrodynamics,fragmentation mechanisms,and debris distribution arising from the interaction of nanosecond laser pulses with a gallium-indium-tin(Ga-In-Sn)liquid film of micron-scale thickness.Highspeed stroboscopic shadow photography was employed to visualize the splash crown and ejection of debris.The velocities of this debris,ranging from 329 to 4211 m s^(-1),were found to scale with laser pulse energy(E_(p)=0.9-36 m J)and film thickness(h)according to U∝E^(5/9)_(p)/h.This velocity was accurately described by a modified ablation and propulsion model.The numerical simulations provided insights into the underlying physics,including the expansion of high-pressure plasma zone,shock wave propagation,and the formation of significant negative pressure regions conducive to cavitation.Furthermore,the direction of minimal debris deposition is found to align with peak plasma luminous intensity,which is normal to the liquid film.
文摘A new method is described to measure the dynamic shear modulus of underwater acoustic structure materials in a small anechoic water tank by using a broadband parametric source, a precise coordinate installation and techniques of signal processing in the frequency range of 20 kHz - 100 kHz. The typical size of material samples is 500×500 mm2. Basic principles, experiment installation and measured results are also presented
