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RSS2015 Vol. 39, No. 1
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2015, 39(1): 1-5.
doi: 10.7510/jgjs.issn.1001-3806.2015.01.001
[Abstract]
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Abstract:
A novel method was put forward to weaken the signal fading phenomenon of an acousto-optic coupling fiber optic hydrophone on the water surface when the water fluctuates. The method compensated the signal amplitude by detecting the light intensity of the signal arm. The amendment process of demodulation signal was analysed in theory and bynumerical simulation. A fiber optic hydrophone system based on /2 phase demodulation technique was constructed to test the water constant vibration signal. The results show that, compared with the original demodulation signal, the amplitude of the amended signal is stabilized and increased by 5dB wholly. The distortion degree is reduced, the phase noise is suppressed, the signal to noise ratio is improved and the time range of the identifiable signal is extended to 3.5 times. This method can overcome the signal fading phenomenon caused by surface fluctuation effectively, optimize the signal quality and enhance the ability of anti-wave demodulation for the system.
A novel method was put forward to weaken the signal fading phenomenon of an acousto-optic coupling fiber optic hydrophone on the water surface when the water fluctuates. The method compensated the signal amplitude by detecting the light intensity of the signal arm. The amendment process of demodulation signal was analysed in theory and bynumerical simulation. A fiber optic hydrophone system based on /2 phase demodulation technique was constructed to test the water constant vibration signal. The results show that, compared with the original demodulation signal, the amplitude of the amended signal is stabilized and increased by 5dB wholly. The distortion degree is reduced, the phase noise is suppressed, the signal to noise ratio is improved and the time range of the identifiable signal is extended to 3.5 times. This method can overcome the signal fading phenomenon caused by surface fluctuation effectively, optimize the signal quality and enhance the ability of anti-wave demodulation for the system.
2015, 39(1): 6-12.
doi: 10.7510/jgjs.issn.1001-3806.2015.01.002
Abstract:
In order to analyze effect of random noise of lidar system on oceanic Brillouin scattering spectroscopy and temperature inversion precision, Brillouin scattering spectrum with noise was analyzed theoretically based on Brillouin scattering theory and system noise characteristics. Simulation experiment of signal-to-noise ratio (SNR) from 1dB to 100dB was conducted. The results showed that average error and uncertainty of frequency shift and linewidth can be controlled to the order of MHz when SNR is greater than 16dB. Temperature error and uncertainty can be controlled within 0.2℃. In actual application, the average of multiple measurements is taken. The average of 10 times can ensure the requirement of SNR is smaller than 7dB with measurement accuracy of 0.2℃. The study provides the guidance for lidar remote sensing precision in seawater.
In order to analyze effect of random noise of lidar system on oceanic Brillouin scattering spectroscopy and temperature inversion precision, Brillouin scattering spectrum with noise was analyzed theoretically based on Brillouin scattering theory and system noise characteristics. Simulation experiment of signal-to-noise ratio (SNR) from 1dB to 100dB was conducted. The results showed that average error and uncertainty of frequency shift and linewidth can be controlled to the order of MHz when SNR is greater than 16dB. Temperature error and uncertainty can be controlled within 0.2℃. In actual application, the average of multiple measurements is taken. The average of 10 times can ensure the requirement of SNR is smaller than 7dB with measurement accuracy of 0.2℃. The study provides the guidance for lidar remote sensing precision in seawater.
2015, 39(1): 13-18.
doi: 10.7510/jgjs.issn.1001-3806.2015.01.003
Abstract:
In order to improve the time-efficiency of traditional super-resolution reconstruction based on neighbor embedding, a new method was proposed using direction information of image patches to choose neighborhood and classify the training set. Firstly, the training set was classified through the differences of patches directions. Secondly, the neighborhood used to reconstruct was chosen in the sub-sets by selecting training patches with the similar direction, and then the iterative back-projection was applied during the reconstruction to further enhance the super-resolution image quality. Finally, numerical experiments were conducted to verify the new method. The results show that the proposed algorithm increases time-efficiency more than 10 times and super-resolution performance is improved. The new method has better practical value.
In order to improve the time-efficiency of traditional super-resolution reconstruction based on neighbor embedding, a new method was proposed using direction information of image patches to choose neighborhood and classify the training set. Firstly, the training set was classified through the differences of patches directions. Secondly, the neighborhood used to reconstruct was chosen in the sub-sets by selecting training patches with the similar direction, and then the iterative back-projection was applied during the reconstruction to further enhance the super-resolution image quality. Finally, numerical experiments were conducted to verify the new method. The results show that the proposed algorithm increases time-efficiency more than 10 times and super-resolution performance is improved. The new method has better practical value.
2015, 39(1): 19-22.
doi: 10.7510/jgjs.issn.1001-3806.2015.01.004
Abstract:
To investigate the lag of glucose concentration between interstitial fluid of human skin and blood (peripheral blood and venous blood) during rapid change of blood glucose, optical coherence tomography (OCT) was used to measure attenuation coefficient of human skin with the change of blood glucose in oral glucose tolerance test and glucose clamp in vivo. To reduce error in prediction result, the correlation region used to calculate predicted glucose concentration should be selected below 700m~800m in dermis layer. The results show that lag time decreases with the increases of depth of human skin. It is demonstrated experimentally that the lag time changes at different depths in human skin. The study can improve the accuracy and reliability of measurement value in noninvasive blood glucose sensing.
To investigate the lag of glucose concentration between interstitial fluid of human skin and blood (peripheral blood and venous blood) during rapid change of blood glucose, optical coherence tomography (OCT) was used to measure attenuation coefficient of human skin with the change of blood glucose in oral glucose tolerance test and glucose clamp in vivo. To reduce error in prediction result, the correlation region used to calculate predicted glucose concentration should be selected below 700m~800m in dermis layer. The results show that lag time decreases with the increases of depth of human skin. It is demonstrated experimentally that the lag time changes at different depths in human skin. The study can improve the accuracy and reliability of measurement value in noninvasive blood glucose sensing.
2015, 39(1): 23-27.
doi: 10.7510/jgjs.issn.1001-3806.2015.01.005
Abstract:
Airborne lidar is one of the important reconstruction measures of 3-D building models. Research methods and developing progresses of 3-D building reconstruction based on airborne lidar point cloud data were reviewed. The characteristics and key issues of model-driven, data-driven and hybrid algorithms were analyzed and discussed. The hybrid algorithm integrating the merits of both the other methods is the significant developing trend of 3-D building reconstruction.
Airborne lidar is one of the important reconstruction measures of 3-D building models. Research methods and developing progresses of 3-D building reconstruction based on airborne lidar point cloud data were reviewed. The characteristics and key issues of model-driven, data-driven and hybrid algorithms were analyzed and discussed. The hybrid algorithm integrating the merits of both the other methods is the significant developing trend of 3-D building reconstruction.
2015, 39(1): 28-32.
doi: 10.7510/jgjs.issn.1001-3806.2015.01.006
Abstract:
In order to study the absorption characterisctics of 1-D graphene photonic crystal in the visible band, theoretical analysis and numerical simulation were conducted by using transfer matrix method. The dependance of absorption characterisctics of 1-D graphene on graphene layers, dielectric thickness of defect layers, and electromagnetic mode were obtained. The results show that the absorption with green light of wavelength of about 556nm is enhanced significantly with the increasing of the layers of graphene. The absorption peak will increase with the increasing of dielectric thickness of defect layer. In the TE mode, the angle of incidence has a little effect on the absorption characterisctics of graphene photonic crystal. The results provide the theoretical basis for the study of 1-D graphene photonic crystal absorbers.
In order to study the absorption characterisctics of 1-D graphene photonic crystal in the visible band, theoretical analysis and numerical simulation were conducted by using transfer matrix method. The dependance of absorption characterisctics of 1-D graphene on graphene layers, dielectric thickness of defect layers, and electromagnetic mode were obtained. The results show that the absorption with green light of wavelength of about 556nm is enhanced significantly with the increasing of the layers of graphene. The absorption peak will increase with the increasing of dielectric thickness of defect layer. In the TE mode, the angle of incidence has a little effect on the absorption characterisctics of graphene photonic crystal. The results provide the theoretical basis for the study of 1-D graphene photonic crystal absorbers.
2015, 39(1): 33-38.
doi: 10.7510/jgjs.issn.1001-3806.2015.01.007
Abstract:
Research background and optical structure of an Offner imaging spectrometer were introduced. Aberration of the Offner imaging spectrometer was analyzed by analytical point row graph theory, single grating aberration theory and light path function analysis method respectively. Two special structures (surface inner structure and orthogonal structure) were put forward, which can allow imaging spectrometer with better image quality. It is the research trend to improve the image quality of an imaging spectrometer in the future.
Research background and optical structure of an Offner imaging spectrometer were introduced. Aberration of the Offner imaging spectrometer was analyzed by analytical point row graph theory, single grating aberration theory and light path function analysis method respectively. Two special structures (surface inner structure and orthogonal structure) were put forward, which can allow imaging spectrometer with better image quality. It is the research trend to improve the image quality of an imaging spectrometer in the future.
2015, 39(1): 39-45.
doi: 10.7510/jgjs.issn.1001-3806.2015.01.008
Abstract:
In order to study the laser cladding Fe-based and Ni-based alloy coatings on 35CrMo motor spindle, 3540 Fe-based and Ni00 Ni-based modified coating alloy coatings were prepared on the surface of 35CrMo motor spindle with CO2 laser. After the initial satisfaction of engineering applications, hardness of the modified coating materials at a selected cross-section were tested in both the horizontal and vertical direction,while the metallographic properties were studied by applying etching liquids. The results show that near the junction of the cladding zone and the fusion zone, both hardness of the two cladding materials are about 640HV, which meet the engineering application. Both of the two kinds of the coating materials are better than the base material in terms of corrosion resistance. Microstructures are significant different from the laser clad zone to the fusion zone. The grains become smaller and smaller in size and the Ni-based materials is better than Fe-based materials in corrosion resistance. Comprehensive comparison shows that Ni00 cladding material is better than 3540 material in meeting engineering application.
In order to study the laser cladding Fe-based and Ni-based alloy coatings on 35CrMo motor spindle, 3540 Fe-based and Ni00 Ni-based modified coating alloy coatings were prepared on the surface of 35CrMo motor spindle with CO2 laser. After the initial satisfaction of engineering applications, hardness of the modified coating materials at a selected cross-section were tested in both the horizontal and vertical direction,while the metallographic properties were studied by applying etching liquids. The results show that near the junction of the cladding zone and the fusion zone, both hardness of the two cladding materials are about 640HV, which meet the engineering application. Both of the two kinds of the coating materials are better than the base material in terms of corrosion resistance. Microstructures are significant different from the laser clad zone to the fusion zone. The grains become smaller and smaller in size and the Ni-based materials is better than Fe-based materials in corrosion resistance. Comprehensive comparison shows that Ni00 cladding material is better than 3540 material in meeting engineering application.
2015, 39(1): 46-49.
doi: 10.7510/jgjs.issn.1001-3806.2015.01.009
Abstract:
In order to analyze the influence factors of signal-to-noise ratio(SNR) of balanced coherent detection, balanced coherent detection process was studied and the SNR formula was derived based on the mathematical model. A balanced laser detector for signal receiving was developed, and Mie scattering echo signal of aerosol particles was detected by means of the coherent radar prototype. The results show that balanced laser detector is with very low noise and high sensitivity, and can detect the laser echo signal of Mie scattering of aerosol particles.
In order to analyze the influence factors of signal-to-noise ratio(SNR) of balanced coherent detection, balanced coherent detection process was studied and the SNR formula was derived based on the mathematical model. A balanced laser detector for signal receiving was developed, and Mie scattering echo signal of aerosol particles was detected by means of the coherent radar prototype. The results show that balanced laser detector is with very low noise and high sensitivity, and can detect the laser echo signal of Mie scattering of aerosol particles.
2015, 39(1): 50-56.
doi: 10.7510/jgjs.issn.1001-3806.2015.01.010
Abstract:
In order to improve the performance of multi-modality medical image fusion and multi-focus image fusion, since the shearlet transform can capture the detail information of images, an image fusion algorithm based on shearlet transform was proposed. Firstly, the shearlet transform was used to decompose the two registered original images, thus the low frequency sub-band coefficients and high frequency sub-band coefficients of different scales and directions were obtained. The fusion principle of low frequency sub-band coefficients was based on the method of weighted fusion, using the average gradient to calculate the weighted parameters in order to improve the edge fuzzy of the fused image. As for the high frequency sub-band coefficients, a fusion rule adopting the region variance combining with the region energy to get the detail information was presented. Finally, the fused image was reconstructed by inverse shearlet transform. The results show that the algorithm is superior to other fusion algorithms on subjective visual effect and objective evaluation.
In order to improve the performance of multi-modality medical image fusion and multi-focus image fusion, since the shearlet transform can capture the detail information of images, an image fusion algorithm based on shearlet transform was proposed. Firstly, the shearlet transform was used to decompose the two registered original images, thus the low frequency sub-band coefficients and high frequency sub-band coefficients of different scales and directions were obtained. The fusion principle of low frequency sub-band coefficients was based on the method of weighted fusion, using the average gradient to calculate the weighted parameters in order to improve the edge fuzzy of the fused image. As for the high frequency sub-band coefficients, a fusion rule adopting the region variance combining with the region energy to get the detail information was presented. Finally, the fused image was reconstructed by inverse shearlet transform. The results show that the algorithm is superior to other fusion algorithms on subjective visual effect and objective evaluation.
2015, 39(1): 57-60.
doi: 10.7510/jgjs.issn.1001-3806.2015.01.011
Abstract:
In order to meet the needs of data acquisition and recording of optical path fusing and testing in large-scale optical device production, a data acquisition system was developed based on communication function of welding machine and LabWindows/CVI software development platform. The system has the functions of fusing machine data collection, computer process control, production data electronic report generation and optical device data access and storage. The test results show that the system is stable. It is useful for improving the efficiency and decreasing the error of handmade data recording.
In order to meet the needs of data acquisition and recording of optical path fusing and testing in large-scale optical device production, a data acquisition system was developed based on communication function of welding machine and LabWindows/CVI software development platform. The system has the functions of fusing machine data collection, computer process control, production data electronic report generation and optical device data access and storage. The test results show that the system is stable. It is useful for improving the efficiency and decreasing the error of handmade data recording.
2015, 39(1): 61-64.
doi: 10.7510/jgjs.issn.1001-3806.2015.01.012
Abstract:
In order to study diffraction characteristics of longitudinal chirped volume Bragg gratings, transfer matrix algorithm was used. Effects of the thickness, refractive index modulation and chirped wavelength range on the central diffraction efficiency of the longitudinal chirped volume Bragg gratings were calculated. The results show that central diffraction efficiency increases with the increase of the thickness and the refractive index modulation of the Bragg grating. However, with the increase of the chirped wavelength range, the central diffraction efficiency decreases. The research results have certain reference value for design and manufacture of large size of chirped volume Bragg gratings.
In order to study diffraction characteristics of longitudinal chirped volume Bragg gratings, transfer matrix algorithm was used. Effects of the thickness, refractive index modulation and chirped wavelength range on the central diffraction efficiency of the longitudinal chirped volume Bragg gratings were calculated. The results show that central diffraction efficiency increases with the increase of the thickness and the refractive index modulation of the Bragg grating. However, with the increase of the chirped wavelength range, the central diffraction efficiency decreases. The research results have certain reference value for design and manufacture of large size of chirped volume Bragg gratings.
2015, 39(1): 65-70.
doi: 10.7510/jgjs.issn.1001-3806.2015.01.013
Abstract:
In order to get high quality pulse with narrow linewidth, spectral compression of Gaussian pulse was investigated numerically by solving the nonlinear Schrdinger equation. It was found that, when the Gaussian pulse with the central wavelength of 1550nm successively propagated in a single-mode fiber and a photonic crystal fiber, its spectra would be compressed. Further more, when input peak power, pulse width of Gaussian pulse, and nonlinear coefficient of photonic crystal fibers were fixed, there would exist an optimal photonic crystal fiber length. If peak power of the initial light pulse was the greater, nonlinear coefficients of photonic crystal fiber was the larger, the optimal length of photonic crystal fiber was the shorter, the compression ratio of spectra was the greater. The highest spectral compression ratio of 3.47 was achieved for the Gaussian pulse with the input peak power of 110W and the initial pulse width of 0.65ps, while the optimum length of photonic crystal fibers was only 4.152m. The spectral compression of Gaussian pulse was better than super Gaussian pulse under the same simulation condition because of the pulse shape. The results would provide a significant guidance for making the ultrashort pulse fiber laser with narrow linewidth.
In order to get high quality pulse with narrow linewidth, spectral compression of Gaussian pulse was investigated numerically by solving the nonlinear Schrdinger equation. It was found that, when the Gaussian pulse with the central wavelength of 1550nm successively propagated in a single-mode fiber and a photonic crystal fiber, its spectra would be compressed. Further more, when input peak power, pulse width of Gaussian pulse, and nonlinear coefficient of photonic crystal fibers were fixed, there would exist an optimal photonic crystal fiber length. If peak power of the initial light pulse was the greater, nonlinear coefficients of photonic crystal fiber was the larger, the optimal length of photonic crystal fiber was the shorter, the compression ratio of spectra was the greater. The highest spectral compression ratio of 3.47 was achieved for the Gaussian pulse with the input peak power of 110W and the initial pulse width of 0.65ps, while the optimum length of photonic crystal fibers was only 4.152m. The spectral compression of Gaussian pulse was better than super Gaussian pulse under the same simulation condition because of the pulse shape. The results would provide a significant guidance for making the ultrashort pulse fiber laser with narrow linewidth.
2015, 39(1): 71-75.
doi: 10.7510/jgjs.issn.1001-3806.2015.01.014
Abstract:
In order to improve the measurement precision of optical velocity measurement systems based on grid structure, effect of spacing size of the grid structure on the period of output light intensity signal was studied using mathematical principles. Combined with image processing, optimal spacing size was selected so that the period of the output light intensity signal was optimized and the measurement precision was improved. After relevant theoretical analysis, simulation experiments were carried out for two different kinds of roads. The periodic information of different spacing under different output light intensity was obtained. The results show that when the spacing size of the grid structure is consistent with the surface feature point size, the optimum output light intensity period is obtained. For ordinary asphalt and concrete pavement, the best spacing is 1.0mm~1.5mm corresponding to the ground.
In order to improve the measurement precision of optical velocity measurement systems based on grid structure, effect of spacing size of the grid structure on the period of output light intensity signal was studied using mathematical principles. Combined with image processing, optimal spacing size was selected so that the period of the output light intensity signal was optimized and the measurement precision was improved. After relevant theoretical analysis, simulation experiments were carried out for two different kinds of roads. The periodic information of different spacing under different output light intensity was obtained. The results show that when the spacing size of the grid structure is consistent with the surface feature point size, the optimum output light intensity period is obtained. For ordinary asphalt and concrete pavement, the best spacing is 1.0mm~1.5mm corresponding to the ground.
2015, 39(1): 76-81.
doi: 10.7510/jgjs.issn.1001-3806.2015.01.015
Abstract:
Image registration of infrared images have low contrast, complex background and serious noise interference. Over-segmentation or under-segmentation is prone to occur with traditional segmentation method. In order to solve the problems, an improved infrared image segmentation algorithm was proposed based on pulse coupled neural network (PCNN) and morphological methods. Firstly, texture sub-image was extracted according to energy distribution of the image and the texture sub-image was segmented by PCNN. The adaptive links strength of PCNN was set based on the changes of regional energy in gradient field. Because of the firing position of PCNN focused on infrared target portion, a clear coherent infrared target contour can be obtained from firing maps. Background interference was filtered out by morphological methods and high precision infrared target segmentation was achieved. The experimental results show that infrared image can be segmented accurately based on this method. By comparison, the segmentation result is better than traditional methods.
Image registration of infrared images have low contrast, complex background and serious noise interference. Over-segmentation or under-segmentation is prone to occur with traditional segmentation method. In order to solve the problems, an improved infrared image segmentation algorithm was proposed based on pulse coupled neural network (PCNN) and morphological methods. Firstly, texture sub-image was extracted according to energy distribution of the image and the texture sub-image was segmented by PCNN. The adaptive links strength of PCNN was set based on the changes of regional energy in gradient field. Because of the firing position of PCNN focused on infrared target portion, a clear coherent infrared target contour can be obtained from firing maps. Background interference was filtered out by morphological methods and high precision infrared target segmentation was achieved. The experimental results show that infrared image can be segmented accurately based on this method. By comparison, the segmentation result is better than traditional methods.
2015, 39(1): 82-84.
doi: 10.7510/jgjs.issn.1001-3806.2015.01.016
Abstract:
Because of high dimensions of face image data and large calculation of sparse representation classification for face recognition, in order to improve the efficiency of face recognition system, a new face recognition method based on semi-supervised dimensionality reduction(SSDR) and sparse representation (SR) was proposed. Firstly, SSDR algorithm was used to reduce the image dimensions and achieve higher recognition rate in the lower dimension space quickly. Secondly, SR classification can achieve a higher recognition rate than the nearest neighbor classification in face recognition. And then, the experimental verification was demonstrated on ORL face database. The results show that the fusion algorithm can improve the recognition performance of face images quickly and effectively.
Because of high dimensions of face image data and large calculation of sparse representation classification for face recognition, in order to improve the efficiency of face recognition system, a new face recognition method based on semi-supervised dimensionality reduction(SSDR) and sparse representation (SR) was proposed. Firstly, SSDR algorithm was used to reduce the image dimensions and achieve higher recognition rate in the lower dimension space quickly. Secondly, SR classification can achieve a higher recognition rate than the nearest neighbor classification in face recognition. And then, the experimental verification was demonstrated on ORL face database. The results show that the fusion algorithm can improve the recognition performance of face images quickly and effectively.
2015, 39(1): 85-89.
doi: 10.7510/jgjs.issn.1001-3806.2015.01.017
Abstract:
To improve the blur edge of micro electromechanical systems(MEMS) microstructures image caused by filtering the noise, an improved anisotropic SUSAN filtering algorithm was proposed. In this method, the variances of long axis and short axis were determined in accordance with the independent density spread model, the long axis direction was determined by the gradient direction of the point and the SUSAN filter threshold was determined by the partial average difference between gray value of local image and nucleus. So anisotropic SUSAN filter was constructed. The filter can maintain the edge features as well as process the image smoothing. The experimental results show that anisotropic SUSAN filter could reduce the noise and preserve the edge information at the same time.
To improve the blur edge of micro electromechanical systems(MEMS) microstructures image caused by filtering the noise, an improved anisotropic SUSAN filtering algorithm was proposed. In this method, the variances of long axis and short axis were determined in accordance with the independent density spread model, the long axis direction was determined by the gradient direction of the point and the SUSAN filter threshold was determined by the partial average difference between gray value of local image and nucleus. So anisotropic SUSAN filter was constructed. The filter can maintain the edge features as well as process the image smoothing. The experimental results show that anisotropic SUSAN filter could reduce the noise and preserve the edge information at the same time.
2015, 39(1): 90-95.
doi: 10.7510/jgjs.issn.1001-3806.2015.01.018
Abstract:
Dual-line internal standard algorithm was proposed to improve the stability of laser-induced breakdown spectroscopy. The intensity of analysis line was normalized by the sum of the intensity of both the internal standard spectral lines in order to enhance the stability of the spectrum. The line Si Ⅰ 288.16nm of silicon element in steel was used for theoretical calculation and numerical simulation of dual-line internal standard algorithm, finally the universality of the algorithm was validated by taking manganese and copper lines as an example. The results show that, under the typical temperature and electron density in the laser-induced plasma, the dual-line internal standard algorithm can more effectively improve the stability of spectral lines than ordinary internal standard method.
Dual-line internal standard algorithm was proposed to improve the stability of laser-induced breakdown spectroscopy. The intensity of analysis line was normalized by the sum of the intensity of both the internal standard spectral lines in order to enhance the stability of the spectrum. The line Si Ⅰ 288.16nm of silicon element in steel was used for theoretical calculation and numerical simulation of dual-line internal standard algorithm, finally the universality of the algorithm was validated by taking manganese and copper lines as an example. The results show that, under the typical temperature and electron density in the laser-induced plasma, the dual-line internal standard algorithm can more effectively improve the stability of spectral lines than ordinary internal standard method.
2015, 39(1): 96-99.
doi: 10.7510/jgjs.issn.1001-3806.2015.01.019
Abstract:
In order to analyze effect of refractive index of cement on a Glan-Thompson prism, the field angle of the prism and the relationship between the transmittance of the prism and refractive index of the cement at normal incidence or oblique incidence were obtained after theoretical analysis. On this basis, for several Glan-Thompson prisms which the ratio of length to aperture was determined, the relation curve of field angle and transmittance with the change of refractive index of cement was drawn by means of computer simulation. It is found that with the different ratios of length to aperture, the maximum field angle of the prism is different corresponding to different refractive index of cement. The prism has the maximum transmittance when refractive index of the cement is equal to the main refractive index of e light wave. Due to the mutual restraint relationship of the ratio of length to aperture, the largest field angle, the transmittance and the refractive index, It is optimum when the ratio of length to aperture is 2.5 and the refractive index of the cement is in the range from 1.45 to 1.46. The result is helpful for optimizing the field angle and transmittance of a Glan-Thompson prism.
In order to analyze effect of refractive index of cement on a Glan-Thompson prism, the field angle of the prism and the relationship between the transmittance of the prism and refractive index of the cement at normal incidence or oblique incidence were obtained after theoretical analysis. On this basis, for several Glan-Thompson prisms which the ratio of length to aperture was determined, the relation curve of field angle and transmittance with the change of refractive index of cement was drawn by means of computer simulation. It is found that with the different ratios of length to aperture, the maximum field angle of the prism is different corresponding to different refractive index of cement. The prism has the maximum transmittance when refractive index of the cement is equal to the main refractive index of e light wave. Due to the mutual restraint relationship of the ratio of length to aperture, the largest field angle, the transmittance and the refractive index, It is optimum when the ratio of length to aperture is 2.5 and the refractive index of the cement is in the range from 1.45 to 1.46. The result is helpful for optimizing the field angle and transmittance of a Glan-Thompson prism.
2015, 39(1): 100-103.
doi: 10.7510/jgjs.issn.1001-3806.2015.01.020
Abstract:
In order to study the field characteristics of high energy laser, a device for measuring parameters of large-caliber high energy pulsed laser was developed. The device includes a set of autocalibration system that can conduct on-site calibration of its main coefficients. The measuring principle, performance and structure of the device were described, and the measurement error was analyzed by theoretical analysis and experimental verification. The equipment can simultaneously measure the laser energy and intensity distribution. Finally, measurement errors were verified and analyzed by the method of calibration experiments. Measurement errors of laser energy and intensity distribution are 4.5% and 5% respectively. The results show that the equipment has excellent precision,reliability and stability, which could be used in field measurement.
In order to study the field characteristics of high energy laser, a device for measuring parameters of large-caliber high energy pulsed laser was developed. The device includes a set of autocalibration system that can conduct on-site calibration of its main coefficients. The measuring principle, performance and structure of the device were described, and the measurement error was analyzed by theoretical analysis and experimental verification. The equipment can simultaneously measure the laser energy and intensity distribution. Finally, measurement errors were verified and analyzed by the method of calibration experiments. Measurement errors of laser energy and intensity distribution are 4.5% and 5% respectively. The results show that the equipment has excellent precision,reliability and stability, which could be used in field measurement.
2015, 39(1): 104-108.
doi: 10.7510/jgjs.issn.1001-3806.2015.01.021
Abstract:
In order to analyze the content of metal elements in crude oil, Na in crude oil after thermal process was quantitatively analyzed by calibration curve for integrated intensity and peak intensity of spectrum respectively by using the technology of laser-induced breakdown spectroscopy. 6 elements were quantitatively analyzed on the basis of Na Ⅰ 588.995nm, Mg Ⅰ 383.230nm, Al Ⅰ 308.215nm, K Ⅰ 404.414nm, Ca Ⅰ 364.441nm, Fe Ⅱ 273.955nm in the experiment. The mass fraction of above 6 elements were 0.0592,0.0029,0.0212,0.0019,0.0072,0.1686 according to calibration curves for element content and integrated intensity, and the linear correlation coefficient and the detection limit of calibration curves were also calculated. It turned out that it is better to choose the integrated intensity for calibration curve. Na is also quantitatively analyzed by using the technology of X-ray fluorescence spectroscope. Compared with the measurement results of laser-induced breakdown spectroscopy and X-ray fluorescence spectroscopy, the relative error is 6.28%. The technology of laser-induced breakdown spectroscopy could be applied to measure the content of metal elements in crude oil.
In order to analyze the content of metal elements in crude oil, Na in crude oil after thermal process was quantitatively analyzed by calibration curve for integrated intensity and peak intensity of spectrum respectively by using the technology of laser-induced breakdown spectroscopy. 6 elements were quantitatively analyzed on the basis of Na Ⅰ 588.995nm, Mg Ⅰ 383.230nm, Al Ⅰ 308.215nm, K Ⅰ 404.414nm, Ca Ⅰ 364.441nm, Fe Ⅱ 273.955nm in the experiment. The mass fraction of above 6 elements were 0.0592,0.0029,0.0212,0.0019,0.0072,0.1686 according to calibration curves for element content and integrated intensity, and the linear correlation coefficient and the detection limit of calibration curves were also calculated. It turned out that it is better to choose the integrated intensity for calibration curve. Na is also quantitatively analyzed by using the technology of X-ray fluorescence spectroscope. Compared with the measurement results of laser-induced breakdown spectroscopy and X-ray fluorescence spectroscopy, the relative error is 6.28%. The technology of laser-induced breakdown spectroscopy could be applied to measure the content of metal elements in crude oil.
2015, 39(1): 109-113.
doi: 10.7510/jgjs.issn.1001-3806.2015.01.022
Abstract:
In order to study the influence of nonlinear parameters on the cross-correlation function of two vibrational modes of the trapped ions along mutually orthogonal directions, the exact solution of the nonlinear double-photon Jaynes-Cummings model which describes the interaction between a single two-dimension three-level trapped ion and two classical standing wave lasers was obtained by theoretical analysis and numerical computation. The cross-correlation function of two vibrational modes of the trapped ion was analyzed numerically. The results show that the anticorrelation effect is strengthened at first and then weakened with the increasing of the Lamb-Dicke parameters when initial average quantum number is small. But the correlated effect is always strengthened with the increase of the Lamb-Dicke parameters. The anticorrelation effect will be weakened and then disappear with the increasing of initial average quantum number. The initial average quantum number and Lamb-Dicke parameters characterized by nonlinear effects have obvious influence on cross correlation.
In order to study the influence of nonlinear parameters on the cross-correlation function of two vibrational modes of the trapped ions along mutually orthogonal directions, the exact solution of the nonlinear double-photon Jaynes-Cummings model which describes the interaction between a single two-dimension three-level trapped ion and two classical standing wave lasers was obtained by theoretical analysis and numerical computation. The cross-correlation function of two vibrational modes of the trapped ion was analyzed numerically. The results show that the anticorrelation effect is strengthened at first and then weakened with the increasing of the Lamb-Dicke parameters when initial average quantum number is small. But the correlated effect is always strengthened with the increase of the Lamb-Dicke parameters. The anticorrelation effect will be weakened and then disappear with the increasing of initial average quantum number. The initial average quantum number and Lamb-Dicke parameters characterized by nonlinear effects have obvious influence on cross correlation.
2015, 39(1): 114-118.
doi: 10.7510/jgjs.issn.1001-3806.2015.01.023
Abstract:
In order to develop the carbohydrate as new rapid prototyping material, the physical and chemical properties of sucrose and the effective factors of forming quality of selective laser sintering (SLS) were analyzed. After the experiment, the sucrose models were made by SLS-300 prototyping machine. Some preliminary process parameters were acquired. The effective laws of energy density on forming quality (intensity, color and surface roughness) were gotten. The results confirm that sucrose is available as SLS material. The research provides the experimental basis for the subsequent development of dedicated sucrose 3-D printer.
In order to develop the carbohydrate as new rapid prototyping material, the physical and chemical properties of sucrose and the effective factors of forming quality of selective laser sintering (SLS) were analyzed. After the experiment, the sucrose models were made by SLS-300 prototyping machine. Some preliminary process parameters were acquired. The effective laws of energy density on forming quality (intensity, color and surface roughness) were gotten. The results confirm that sucrose is available as SLS material. The research provides the experimental basis for the subsequent development of dedicated sucrose 3-D printer.
2015, 39(1): 119-123.
doi: 10.7510/jgjs.issn.1001-3806.2015.01.024
Abstract:
In order to satisfy the safety requirement of aircraft taking off and landing under bad weather conditions, a portable lidar visibility meter was designed based on the principle of atmospheric backscatter. Diode pumped solid-state laser with low pulse energy and high pulse repeat frequency and avalanche photo diode detector with low noise and high quantum efficiency were adopted to ensure the precision of system. Specially, the embedded computer was adopted as the core of system controlling and data processing and the timing control of system was realized. The field test results show that the system has high detection accuracy and the overall error is less than 15%. The results show that the system has high detection precision and can satisfy the safety requirements of International Civil Aviation Organization.
In order to satisfy the safety requirement of aircraft taking off and landing under bad weather conditions, a portable lidar visibility meter was designed based on the principle of atmospheric backscatter. Diode pumped solid-state laser with low pulse energy and high pulse repeat frequency and avalanche photo diode detector with low noise and high quantum efficiency were adopted to ensure the precision of system. Specially, the embedded computer was adopted as the core of system controlling and data processing and the timing control of system was realized. The field test results show that the system has high detection accuracy and the overall error is less than 15%. The results show that the system has high detection precision and can satisfy the safety requirements of International Civil Aviation Organization.
2015, 39(1): 124-128.
doi: 10.7510/jgjs.issn.1001-3806.2015.01.025
Abstract:
In order to solve the problem that the existing basic model could not fully express radio propagation characteristics under some typical scenarios (such as sea, mountains, hills and urban), a unified radio propagation model under many typical scenarios was established based on deterministic parabolic equations. Firstly, different typical scenarios were equivalent to lossy dielectric layers to compute the boundary conditions. Then, the corresponding results were solved by Fourier split step algorithm. Finally, radio propagation loss under typical radio scenarios was calculated. After theoretical analysis and experimental verification, the uniform radio propagation model under different transmission scenarios is compared with Miller-Brown model and ray tracing model, the results are in good agreement. The results are helpful to establish a unified radio propagation model under typical radio scenarios to solve the problem of radio propagation loss.
In order to solve the problem that the existing basic model could not fully express radio propagation characteristics under some typical scenarios (such as sea, mountains, hills and urban), a unified radio propagation model under many typical scenarios was established based on deterministic parabolic equations. Firstly, different typical scenarios were equivalent to lossy dielectric layers to compute the boundary conditions. Then, the corresponding results were solved by Fourier split step algorithm. Finally, radio propagation loss under typical radio scenarios was calculated. After theoretical analysis and experimental verification, the uniform radio propagation model under different transmission scenarios is compared with Miller-Brown model and ray tracing model, the results are in good agreement. The results are helpful to establish a unified radio propagation model under typical radio scenarios to solve the problem of radio propagation loss.
2015, 39(1): 129-134.
doi: 10.7510/jgjs.issn.1001-3806.2015.01.026
Abstract:
In order to decrease the byte loss probability, guarantee lower path blocking probability and reduce burst contention of optical burst switching(OBS) networks, a novel burst-segment recombination and controllable retransmission algorithm based on priority in OBS networks was proposed. When the burst contention occurred, the algorithm could divide the burst according to the quality of service, the core node would send the feedback information to the edge node and the edge node would combinate the segmentation according to the priority and retransmit the recombined burst with different probability to improve the performance of OBS networks. The design and calibration were verified by simulation results. Compared with the conventional contention control algorithms, the scheme could obviously reduce the path blocking probability and decrease the byte loss probability especially when the network was extremely busy. The study has an important reference on the improvement of OBS networks.
In order to decrease the byte loss probability, guarantee lower path blocking probability and reduce burst contention of optical burst switching(OBS) networks, a novel burst-segment recombination and controllable retransmission algorithm based on priority in OBS networks was proposed. When the burst contention occurred, the algorithm could divide the burst according to the quality of service, the core node would send the feedback information to the edge node and the edge node would combinate the segmentation according to the priority and retransmit the recombined burst with different probability to improve the performance of OBS networks. The design and calibration were verified by simulation results. Compared with the conventional contention control algorithms, the scheme could obviously reduce the path blocking probability and decrease the byte loss probability especially when the network was extremely busy. The study has an important reference on the improvement of OBS networks.
2015, 39(1): 135-139.
doi: 10.7510/jgjs.issn.1001-3806.2015.01.027
Abstract:
In order to study the temperature-dependent optical properties of dilute magnetic semiconductor Zn0.95-xBe0.05MnxSe (x is 0.05,0.10,0.15,0.20 respectively), based on electric field modulation reflectance spectroscopy, surface photovoltage spectroscopy and fluorescence excitation spectra, theoretical analysis and experimental verification were made and a series of data were obtained. The results show that, the energy gap of the other samples, except the sample of x=0.1, would increase with the increase of Mn doped mole fraction, caused by the slight displacement of exchange interaction between the electrons of the valence band and the conductive band and the electrons of d generation of Mn. Because of the increase of lattice-phonon scattering effect, the transition signal will move to the direction of low energy when temperature elevates.
In order to study the temperature-dependent optical properties of dilute magnetic semiconductor Zn0.95-xBe0.05MnxSe (x is 0.05,0.10,0.15,0.20 respectively), based on electric field modulation reflectance spectroscopy, surface photovoltage spectroscopy and fluorescence excitation spectra, theoretical analysis and experimental verification were made and a series of data were obtained. The results show that, the energy gap of the other samples, except the sample of x=0.1, would increase with the increase of Mn doped mole fraction, caused by the slight displacement of exchange interaction between the electrons of the valence band and the conductive band and the electrons of d generation of Mn. Because of the increase of lattice-phonon scattering effect, the transition signal will move to the direction of low energy when temperature elevates.
2015, 39(1): 140-144.
doi: 10.7510/jgjs.issn.1001-3806.2015.01.028
Abstract:
In order to determine the optimal parameters for three-coordinate laser measurement, and get better measurement effect, theoretical analysis and experimental verification were conducted based on the orthogonal test. The best performance could be achieved under the conditions of speed at the tenth fastest set, frequency at 30Hz, optimum depth-of-field and angle perpendicular to the surface of the workpiece. The results show that it becomes easy to choose parameters in the three-coordinate laser measurement, after qualitative analysis and quantitative analysis.
In order to determine the optimal parameters for three-coordinate laser measurement, and get better measurement effect, theoretical analysis and experimental verification were conducted based on the orthogonal test. The best performance could be achieved under the conditions of speed at the tenth fastest set, frequency at 30Hz, optimum depth-of-field and angle perpendicular to the surface of the workpiece. The results show that it becomes easy to choose parameters in the three-coordinate laser measurement, after qualitative analysis and quantitative analysis.
