The output radiation from the 100μm×1μm aperture of a high power Laser Diode (LD) is efficiently coupled into a 50μm multimode optical fiber.The fiber output of the high power LD with high brightness and high ...The output radiation from the 100μm×1μm aperture of a high power Laser Diode (LD) is efficiently coupled into a 50μm multimode optical fiber.The fiber output of the high power LD with high brightness and high power density is achieved.The power density is up to 3 6×104W/cm2 and the coupling efficiency is 70%.The extreme divergence and the astigmatism of high power LDs require the optics with complex lens structures and high performance.A double-curved lens with two crossed cylindrical lenses structured on both sides of the glass substrate is used in the coupling system.展开更多
By calculating the energy distribution of electrons reaching the photocathode surface and solving the Schrodinger equation that describes the behavior of an electron tunneling through the surface potential barrier,we ...By calculating the energy distribution of electrons reaching the photocathode surface and solving the Schrodinger equation that describes the behavior of an electron tunneling through the surface potential barrier,we obtain an equation to calculate the emitted electron energy distribution of transmission-mode NEA GaAs photocathodes. Accord- ing to the equation,we study the effect of cathode surface potential barrier on the electron energy distribution and find a significant effect of the barrier-Ⅰ thickness or end height,especially the thickness,on the quantum efficiency of the cath- ode. Barrier Ⅱ has an effect on the electron energy spread, and an increase in the vacuum level will lead to a narrower electron energy spread while sacrificing a certain amount of cathode quantum efficiency. The equation is also used to fit the measured electron energy distribution curve of the transmission-mode cathode and the parameters of the surface barri- er are obtained from the fitting. The theoretical curve is in good agreement with the experimental curve.展开更多
In order to estimate and detect the surface defect depth of metals, the transmission method of laser ultrasonic surface waves is used in this work. The laser ultrasonic detection platform taking use of thermoelastic m...In order to estimate and detect the surface defect depth of metals, the transmission method of laser ultrasonic surface waves is used in this work. The laser ultrasonic detection platform taking use of thermoelastic mechanism as acoustic signal excitation method and interference receiver as acoustic signal receiver method was built, by which B-scan images of detected specimens with surface defects were collected to establish the relationship between the transmission coefficient and depth of the surface defect. Experimental results show that the amplitude of transmitted acoustic signal is related to the depth of surface defect. At last, a fitted curve of transmission coefficient using measured experimental data is obtained to estimate depth of surface defect on the 6061 aluminum alloy. Furthermore, a surface defect depth of 0.3 mm is estimated by the fitting curve with an estimated error of 16%. Therefore, a experimental method using the transmission method by laser ultrasonic is presented in this paper.展开更多
[Objective] To study the remote sensing information extraction technology for the impervious surface of Erhai basin with the aim to develop dynamic simulation platform for the formation of water pollution. [Method] Li...[Objective] To study the remote sensing information extraction technology for the impervious surface of Erhai basin with the aim to develop dynamic simulation platform for the formation of water pollution. [Method] Linear spectral separation technology was used to achieve Vd-S model solution, extracting remote sensing in- formation of the impervious surface of Erhai basin from the TM data of Landsat5 in 2009. The linear combination of 4 kinds of endmember spectra, namely vegetation, high anti-illumination, low anti-illumination and bare soil, were used to simulate the TM spectral characteristics, and its distribution and spatial characteristics were ana- lyzed. [Result] Middle-resolution image is suitable for the basin-scaled impervious surface extraction with reliable results and satisfactory accuracy. [Conclusion] This study provided basis for deciding the relationship between the regulation strategy on the non-point source pollution of Erhai Lake, coordinated economic development and environmental protection.展开更多
A novel high magnification zoom laser beam expander is proposed originally. The zoom part and fixed part of the beam expander both adopt spherical lens and the compensation part comprising a spherical surface and an a...A novel high magnification zoom laser beam expander is proposed originally. The zoom part and fixed part of the beam expander both adopt spherical lens and the compensation part comprising a spherical surface and an aspherical surface. The structure parameters were given by using geometry optics.The zoom characteristic and image quality were also analyzed.The results show that the magnification of the beam expander can be adjusted continuously from 3 to 20. Compared with other congener spherical zoom system,the beam expander has the advantages of high magnification,compact structure,high beam quality and high transmission efficiency.The novel expander can be used in many fields effectively.展开更多
This paper introduces the application of a slant lens fiber in a reflective fiber optical displacement sensor, namely the receiving fiber use the slant lens fiber. Based on the characteristic formula expression of the...This paper introduces the application of a slant lens fiber in a reflective fiber optical displacement sensor, namely the receiving fiber use the slant lens fiber. Based on the characteristic formula expression of the intensity modulation of planar single fiber pair, a mathematic model of single fiber fair intensity modulation is established. After simulation experiment, the influence of fiber spacing, fiber core diameter and fiber numerical aperture on the modulation characteristics of the sensor is summarized.展开更多
The purpose of this paper is to present a methodology for optimizing the geometry of the LED （light emitting diode） secondary lens. The research objective is to uniform the illumination distribution on a target plan...The purpose of this paper is to present a methodology for optimizing the geometry of the LED （light emitting diode） secondary lens. The research objective is to uniform the illumination distribution on a target plane for nonimaging application. In order to achieve this, a software that simulates ray tracing is used, in conjunction with a heuristic process for enhancing the optimized parameters that form the geometry of the LED secondary lens. Spherical lenses was opted for optimization due to its lower manufacture complexity.展开更多
文摘The output radiation from the 100μm×1μm aperture of a high power Laser Diode (LD) is efficiently coupled into a 50μm multimode optical fiber.The fiber output of the high power LD with high brightness and high power density is achieved.The power density is up to 3 6×104W/cm2 and the coupling efficiency is 70%.The extreme divergence and the astigmatism of high power LDs require the optics with complex lens structures and high performance.A double-curved lens with two crossed cylindrical lenses structured on both sides of the glass substrate is used in the coupling system.
文摘By calculating the energy distribution of electrons reaching the photocathode surface and solving the Schrodinger equation that describes the behavior of an electron tunneling through the surface potential barrier,we obtain an equation to calculate the emitted electron energy distribution of transmission-mode NEA GaAs photocathodes. Accord- ing to the equation,we study the effect of cathode surface potential barrier on the electron energy distribution and find a significant effect of the barrier-Ⅰ thickness or end height,especially the thickness,on the quantum efficiency of the cath- ode. Barrier Ⅱ has an effect on the electron energy spread, and an increase in the vacuum level will lead to a narrower electron energy spread while sacrificing a certain amount of cathode quantum efficiency. The equation is also used to fit the measured electron energy distribution curve of the transmission-mode cathode and the parameters of the surface barri- er are obtained from the fitting. The theoretical curve is in good agreement with the experimental curve.
基金National Natural Science Foundation of China(No.11604304)High School Science and Technology Innovation Project of Shanxi ProvinceApplied Basic Research Project of Shanxi Province(Nos.201701D221127,201801D121160)
文摘In order to estimate and detect the surface defect depth of metals, the transmission method of laser ultrasonic surface waves is used in this work. The laser ultrasonic detection platform taking use of thermoelastic mechanism as acoustic signal excitation method and interference receiver as acoustic signal receiver method was built, by which B-scan images of detected specimens with surface defects were collected to establish the relationship between the transmission coefficient and depth of the surface defect. Experimental results show that the amplitude of transmitted acoustic signal is related to the depth of surface defect. At last, a fitted curve of transmission coefficient using measured experimental data is obtained to estimate depth of surface defect on the 6061 aluminum alloy. Furthermore, a surface defect depth of 0.3 mm is estimated by the fitting curve with an estimated error of 16%. Therefore, a experimental method using the transmission method by laser ultrasonic is presented in this paper.
基金Supported by the Special Program for Pilot Study of the National Basic Research Program(973Program)(2010CB434803)~~
文摘[Objective] To study the remote sensing information extraction technology for the impervious surface of Erhai basin with the aim to develop dynamic simulation platform for the formation of water pollution. [Method] Linear spectral separation technology was used to achieve Vd-S model solution, extracting remote sensing in- formation of the impervious surface of Erhai basin from the TM data of Landsat5 in 2009. The linear combination of 4 kinds of endmember spectra, namely vegetation, high anti-illumination, low anti-illumination and bare soil, were used to simulate the TM spectral characteristics, and its distribution and spatial characteristics were ana- lyzed. [Result] Middle-resolution image is suitable for the basin-scaled impervious surface extraction with reliable results and satisfactory accuracy. [Conclusion] This study provided basis for deciding the relationship between the regulation strategy on the non-point source pollution of Erhai Lake, coordinated economic development and environmental protection.
文摘A novel high magnification zoom laser beam expander is proposed originally. The zoom part and fixed part of the beam expander both adopt spherical lens and the compensation part comprising a spherical surface and an aspherical surface. The structure parameters were given by using geometry optics.The zoom characteristic and image quality were also analyzed.The results show that the magnification of the beam expander can be adjusted continuously from 3 to 20. Compared with other congener spherical zoom system,the beam expander has the advantages of high magnification,compact structure,high beam quality and high transmission efficiency.The novel expander can be used in many fields effectively.
基金Youth Science and Technology Research Foundation of Shanxi Province(No.2015021104)Programs for Science and Technology Development of Shanxi Province(No.201703D121028-2)
文摘This paper introduces the application of a slant lens fiber in a reflective fiber optical displacement sensor, namely the receiving fiber use the slant lens fiber. Based on the characteristic formula expression of the intensity modulation of planar single fiber pair, a mathematic model of single fiber fair intensity modulation is established. After simulation experiment, the influence of fiber spacing, fiber core diameter and fiber numerical aperture on the modulation characteristics of the sensor is summarized.
文摘The purpose of this paper is to present a methodology for optimizing the geometry of the LED （light emitting diode） secondary lens. The research objective is to uniform the illumination distribution on a target plane for nonimaging application. In order to achieve this, a software that simulates ray tracing is used, in conjunction with a heuristic process for enhancing the optimized parameters that form the geometry of the LED secondary lens. Spherical lenses was opted for optimization due to its lower manufacture complexity.
