The low frequency line components of the radiated noise from an underwater target usually have both high spectrum level and sustained stability. This feature could be used to increase the detection performance of conv...The low frequency line components of the radiated noise from an underwater target usually have both high spectrum level and sustained stability. This feature could be used to increase the detection performance of conventional broadband energy integration method. The required spectrum level is theoretically discussed when the detection performance of the known line detection is better than that of broadband energy integration method. Under the condition of the target can be detected in line spectrum band, the relationship between the line spectrum level and signal to noise ratio （SNR） is also discussed. This paper proposes a line spectrum target detection method that a matrix using DC jump to fluctuations ratios of sub-band spatial spectrum and beam space output is constructed. This matrix acts as a filter that the line spectrum target with certain frequency and azimuth is passed at most. By fusing with the other sub band results, the conventional detection performance can be improved. At the same time, the applicable condition and detection performance are analyzed in the paper. The simulation and the sea trial data processing results show that the algorithm can effectively extract weak goal line spectrum target under the condition of multi-interference. The algorithm doesn＇t need multi-frame statistics and the detection performance is closer to the optimal line spectrum method.展开更多
A polymer based horizontal single step waveguide fbr the sensing of alcohol is developed and analyzed.The waveguide is fabricated by 3-dimensional(3D)printing digital light processing(DLP)technology using monocure 3D ...A polymer based horizontal single step waveguide fbr the sensing of alcohol is developed and analyzed.The waveguide is fabricated by 3-dimensional(3D)printing digital light processing(DLP)technology using monocure 3D rapid ultraviolet(UV)clear resin with a refractive index of n=1.50.The fabricated waveguide is a one-piece tower shaped ridge structure.It is designed to achieve the maximum light confinement at the core by reducing the effective refractive index around the cladding region.With the surface roughness generated from the 3D printing DLP technology,various waveguides with different gap sizes are printed.Comparison is done fbr the different gap waveguides to achieve the minimum feature gap size utilizing the light re-coupling principle and polymer swelling effect.This effect occurs due to the polymer-alcohol interaction that results in the diffusion of alcohol molecules inside the core of the waveguide,thus changing the waveguide from the leaky type(without alcohol)to the guided type(with alcohol).Using this principle,the analysis of alcohol concentration performing as a larger increase in the transmitted light in tensity can be measured.In this work,the sensitivity of the system is also compared and analyzed fbr different waveguide gap sizes with different concentrations of isopropanol alcohol(IPA).A waveguide gap size of 300 jim gives the highest in crease in the transmitted optical power of 65%when tested with 10μL(500ppm)concentration of IPA.Compared with all other gaps,it also displays faster response time(/=5seconds)fbr the optical power to change right after depositing IPA in the chamber.The measured limit of detection(LOD)achieved fbr 300μm is 0.366 yL.In addition,the fabricated waveguide gap of 300μm successfully demonstrates the sen sing limit of IPA concentration below 400μpm which is considered as an exposure limit by"National Institute for Occupational Safety and Health".All the mechanical mount and the alignments are done by 3D printing fused deposition method(FDM).展开更多
Beam uniformity is a crucial building block of CO2 experiments aimed at fusing and stretching optical fibers in a lossless manner. When the irradiation beam is expanded through a galvanometer mirror, ways to achieve b...Beam uniformity is a crucial building block of CO2 experiments aimed at fusing and stretching optical fibers in a lossless manner. When the irradiation beam is expanded through a galvanometer mirror, ways to achieve beam uniformity are investigated.展开更多
文摘The low frequency line components of the radiated noise from an underwater target usually have both high spectrum level and sustained stability. This feature could be used to increase the detection performance of conventional broadband energy integration method. The required spectrum level is theoretically discussed when the detection performance of the known line detection is better than that of broadband energy integration method. Under the condition of the target can be detected in line spectrum band, the relationship between the line spectrum level and signal to noise ratio （SNR） is also discussed. This paper proposes a line spectrum target detection method that a matrix using DC jump to fluctuations ratios of sub-band spatial spectrum and beam space output is constructed. This matrix acts as a filter that the line spectrum target with certain frequency and azimuth is passed at most. By fusing with the other sub band results, the conventional detection performance can be improved. At the same time, the applicable condition and detection performance are analyzed in the paper. The simulation and the sea trial data processing results show that the algorithm can effectively extract weak goal line spectrum target under the condition of multi-interference. The algorithm doesn＇t need multi-frame statistics and the detection performance is closer to the optimal line spectrum method.
文摘A polymer based horizontal single step waveguide fbr the sensing of alcohol is developed and analyzed.The waveguide is fabricated by 3-dimensional(3D)printing digital light processing(DLP)technology using monocure 3D rapid ultraviolet(UV)clear resin with a refractive index of n=1.50.The fabricated waveguide is a one-piece tower shaped ridge structure.It is designed to achieve the maximum light confinement at the core by reducing the effective refractive index around the cladding region.With the surface roughness generated from the 3D printing DLP technology,various waveguides with different gap sizes are printed.Comparison is done fbr the different gap waveguides to achieve the minimum feature gap size utilizing the light re-coupling principle and polymer swelling effect.This effect occurs due to the polymer-alcohol interaction that results in the diffusion of alcohol molecules inside the core of the waveguide,thus changing the waveguide from the leaky type(without alcohol)to the guided type(with alcohol).Using this principle,the analysis of alcohol concentration performing as a larger increase in the transmitted light in tensity can be measured.In this work,the sensitivity of the system is also compared and analyzed fbr different waveguide gap sizes with different concentrations of isopropanol alcohol(IPA).A waveguide gap size of 300 jim gives the highest in crease in the transmitted optical power of 65%when tested with 10μL(500ppm)concentration of IPA.Compared with all other gaps,it also displays faster response time(/=5seconds)fbr the optical power to change right after depositing IPA in the chamber.The measured limit of detection(LOD)achieved fbr 300μm is 0.366 yL.In addition,the fabricated waveguide gap of 300μm successfully demonstrates the sen sing limit of IPA concentration below 400μpm which is considered as an exposure limit by"National Institute for Occupational Safety and Health".All the mechanical mount and the alignments are done by 3D printing fused deposition method(FDM).
文摘Beam uniformity is a crucial building block of CO2 experiments aimed at fusing and stretching optical fibers in a lossless manner. When the irradiation beam is expanded through a galvanometer mirror, ways to achieve beam uniformity are investigated.
