In order to study the evolution of the freezing fringe and final lenses of frost susceptible soils and advance the understanding of frost heave and mechanism of frost heave control, we used an open one-dimensional fro...In order to study the evolution of the freezing fringe and final lenses of frost susceptible soils and advance the understanding of frost heave and mechanism of frost heave control, we used an open one-dimensional frost heave test system of infrared radiation technology, instead of a traditional thermistor method. Temperatures of the freezing fringe and segregated ice were measured in a non-contact mode. The results show that accurate and precise temperatures of ice segregation can be obtained by infrared thermal imaging systems. A self-developed inversion program inverted the temperature field of frozen soils. Based on our analysis of temperature variation in segregated ice and our study of the relationship between temperature and rate of ice segregation in cooling and warming processes during intermittent freezing, the mechanism of decreasing frost heave of frozen soils by controlling the growth of final lenses with an intermittent freezing mode, can be explained properly.展开更多
A key limitation in the observation of instruments used in operations and heart sutures during a procedure is the scattering and absorption during optical imaging in the presence of blood.Therefore,we propose a novel ...A key limitation in the observation of instruments used in operations and heart sutures during a procedure is the scattering and absorption during optical imaging in the presence of blood.Therefore,we propose a novel real-time fiber-optic infrared imaging system simultaneously capturing a flexible wide field of view(FOV) and large depth of field infrared image in real time.The assessment criteria for imaging quality of the objective and coupling lens have been optimized and evaluated.Furthermore,the feasibility of manufacturing and assembly has been demonstrated with tolerance sensitivity and the Monte Carlo analysis.The simulated results show that the optical system can achieve a large working distance of 8 to25 mm,a wide FOV of 120°,and the relative illuminance is over 0.98 in the overall FOV.To achieve high imaging quality in the proposed system,the modulation transfer function is over 0.661 at 16.7 Ip/mm for a 320×256 short wavelength infrared camera sensor with a pixel size of 30 μm.展开更多
In the practical application,a wide-angle absorption with simple structure is still crucial property of metamaterial absorbers(MAs).A single-band infrared MA is introduced to analyze the angle insensitive mechanism.Nu...In the practical application,a wide-angle absorption with simple structure is still crucial property of metamaterial absorbers(MAs).A single-band infrared MA is introduced to analyze the angle insensitive mechanism.Numerical simulation reveals that a perfect absorption peak with 99.9%(7.55μm)is achieved at normal incidence,as well as the absorptivity is respectively 69.7%(7.46μm)and 93.5%(7.46μm)for transverse electric(TE)and transverse magnetic(TM)modes at 70°incidence.By changing substrate thickness,the absorption ratio at 70°is increased to 91%(7.46μm)for TE mode.Our design can also keep the good absorption stability for the geometric parameters.The E z-field distributions for different incident angles are given to investigate the physical mechanism.The designed MA can realize good wide-angle tolerance.This MA owns great applications,including infrared spectroscopy,solar harvester and plasmonic sensors.展开更多
基金supported by the Key Project of the National Natural Science Foundation of China (No. 50534040)the Project of the National Natural Science Foundation of China (No. 40471021)
文摘In order to study the evolution of the freezing fringe and final lenses of frost susceptible soils and advance the understanding of frost heave and mechanism of frost heave control, we used an open one-dimensional frost heave test system of infrared radiation technology, instead of a traditional thermistor method. Temperatures of the freezing fringe and segregated ice were measured in a non-contact mode. The results show that accurate and precise temperatures of ice segregation can be obtained by infrared thermal imaging systems. A self-developed inversion program inverted the temperature field of frozen soils. Based on our analysis of temperature variation in segregated ice and our study of the relationship between temperature and rate of ice segregation in cooling and warming processes during intermittent freezing, the mechanism of decreasing frost heave of frozen soils by controlling the growth of final lenses with an intermittent freezing mode, can be explained properly.
基金supported by the Shanghai Science and Technology Committee Innovation Grant (No. 19ZR1404600)the National Natural Science Foundation of China (No. 52075100)
文摘A key limitation in the observation of instruments used in operations and heart sutures during a procedure is the scattering and absorption during optical imaging in the presence of blood.Therefore,we propose a novel real-time fiber-optic infrared imaging system simultaneously capturing a flexible wide field of view(FOV) and large depth of field infrared image in real time.The assessment criteria for imaging quality of the objective and coupling lens have been optimized and evaluated.Furthermore,the feasibility of manufacturing and assembly has been demonstrated with tolerance sensitivity and the Monte Carlo analysis.The simulated results show that the optical system can achieve a large working distance of 8 to25 mm,a wide FOV of 120°,and the relative illuminance is over 0.98 in the overall FOV.To achieve high imaging quality in the proposed system,the modulation transfer function is over 0.661 at 16.7 Ip/mm for a 320×256 short wavelength infrared camera sensor with a pixel size of 30 μm.
文摘In the practical application,a wide-angle absorption with simple structure is still crucial property of metamaterial absorbers(MAs).A single-band infrared MA is introduced to analyze the angle insensitive mechanism.Numerical simulation reveals that a perfect absorption peak with 99.9%(7.55μm)is achieved at normal incidence,as well as the absorptivity is respectively 69.7%(7.46μm)and 93.5%(7.46μm)for transverse electric(TE)and transverse magnetic(TM)modes at 70°incidence.By changing substrate thickness,the absorption ratio at 70°is increased to 91%(7.46μm)for TE mode.Our design can also keep the good absorption stability for the geometric parameters.The E z-field distributions for different incident angles are given to investigate the physical mechanism.The designed MA can realize good wide-angle tolerance.This MA owns great applications,including infrared spectroscopy,solar harvester and plasmonic sensors.
