2016 Vol. 37, No. 4
Display Method:
2016, 37(4): 495-502.
doi: 10.5768/JAO201637.0401001
Abstract:
In order to increase the field of view(FOV) of imaging spectrometer and improve the efficiency of the remote sensing, a wide FOV imaging spectrometer using innerstitching was designed and developed. First, the constitution of the pushbroom imaging spectrometer using innerstitching was analyzed. Then two Offnertype dispersion systems using convex grating were stitched and a prototype of the imaging spectrometer based on innerstitching was developed. The pixel misalignment, the spectral resolution and the modulation transfer function (MTF) of the prototype were measured in the laboratory. Finally, the outdoor spectral imaging experiment was accomplished. The measurements show that the pixel misalignment in spectral dimension is about 0.15 pixel (the wavelength is 479 nm) and the misalignment in spatial dimension is about 0.16 pixel and 0.19 pixel for crosstrack and alongtrack direction respectively. The spectral resolution of the prototype is about 1.6 nm and its MTF value at Nyquist frequency is about 0.2. The development and the experiment validate the effectiveness of using innerstitching to increase the FOV for imaging spectrometer, and lay the foundation for the future work.
In order to increase the field of view(FOV) of imaging spectrometer and improve the efficiency of the remote sensing, a wide FOV imaging spectrometer using innerstitching was designed and developed. First, the constitution of the pushbroom imaging spectrometer using innerstitching was analyzed. Then two Offnertype dispersion systems using convex grating were stitched and a prototype of the imaging spectrometer based on innerstitching was developed. The pixel misalignment, the spectral resolution and the modulation transfer function (MTF) of the prototype were measured in the laboratory. Finally, the outdoor spectral imaging experiment was accomplished. The measurements show that the pixel misalignment in spectral dimension is about 0.15 pixel (the wavelength is 479 nm) and the misalignment in spatial dimension is about 0.16 pixel and 0.19 pixel for crosstrack and alongtrack direction respectively. The spectral resolution of the prototype is about 1.6 nm and its MTF value at Nyquist frequency is about 0.2. The development and the experiment validate the effectiveness of using innerstitching to increase the FOV for imaging spectrometer, and lay the foundation for the future work.
2016, 37(4): 503-509.
doi: 10.5768/JAO201637.0401002
Abstract:
In order to improve the design efficiency of control loop in optoelectronic tracking system that fixed on mobilebase, considering the angular disturbance of the moving platform,the target movement and tracking precision of system, based on system experimental modeling and parameter identification, an integrated design method of control loop was put forward, every controllers expression and a set of empirical formula were also provided.Additional, a semiphysical simulation system was verified.The maximum tracking error of sine input 2000sin(t)/3 mrad with equal disturbance 125sin(0.4t) mrad is less than 0.5 mrad，which can satisfy the rootmeansquare requirement for 0.5 mrad. The certain simulated test result of this hardwareinloop tracking test proves the validity of integrated design method.
In order to improve the design efficiency of control loop in optoelectronic tracking system that fixed on mobilebase, considering the angular disturbance of the moving platform,the target movement and tracking precision of system, based on system experimental modeling and parameter identification, an integrated design method of control loop was put forward, every controllers expression and a set of empirical formula were also provided.Additional, a semiphysical simulation system was verified.The maximum tracking error of sine input 2000sin(t)/3 mrad with equal disturbance 125sin(0.4t) mrad is less than 0.5 mrad，which can satisfy the rootmeansquare requirement for 0.5 mrad. The certain simulated test result of this hardwareinloop tracking test proves the validity of integrated design method.
2016, 37(4): 510-516.
doi: 10.5768/JAO201637.0401003
Abstract:
Polarization imaging has a lot of advantages while ordinary imaging has no, especially to highlight target in a kind of special background, which is a good auxiliary means of studying the earth's surface and atmosphere. At the 3 typical bands, visible red (670 nm), green (530 nm), blue (450 nm), through adopting the method of rotating the polarizer for calculating the Stokes vector,the polarization experiments were carried out in 6 kinds of materials which are lawn, stone, asphalt surface, glass, rubber and iron plate respectively, and the degree of polarization and the contrast of polarization degree were analyzed in details.The experimental results show that part of target cannot be observed easily in intensity image under a certain background,however, polarization images have enough brightness information and contains rich details to identify target for the eyes easily. In addition, there is a stong relationship between the polarization imaging features and the material, imaging band, observing time.
Polarization imaging has a lot of advantages while ordinary imaging has no, especially to highlight target in a kind of special background, which is a good auxiliary means of studying the earth's surface and atmosphere. At the 3 typical bands, visible red (670 nm), green (530 nm), blue (450 nm), through adopting the method of rotating the polarizer for calculating the Stokes vector,the polarization experiments were carried out in 6 kinds of materials which are lawn, stone, asphalt surface, glass, rubber and iron plate respectively, and the degree of polarization and the contrast of polarization degree were analyzed in details.The experimental results show that part of target cannot be observed easily in intensity image under a certain background,however, polarization images have enough brightness information and contains rich details to identify target for the eyes easily. In addition, there is a stong relationship between the polarization imaging features and the material, imaging band, observing time.
2016, 37(4): 517-522.
doi: 10.5768/JAO201637.0401004
Abstract:
The progressive addition lenses(PAL) have been used widely because of the advantage which can meet the requirements of distant and near vision both at the same time.The basic structure,design and evaluation method of progressive addition lenses were introduced. Based on the national standard that the difference between actual diopter and theoretical value should be less than 0.1 m-1 within the lens effective area, the tolerance analysis of progressive addition lenses was realized.The tolerance formula related to diopter and surface was derived from the surface equation and sphere equation. As an example,a progressive addition lens with 2.5 m-1 addition (6.5 m-1~9 m-1) was designed and evaluated, the tolerance was analyzed. The analysis result shows that tolerance value should be less than 0.1 m at the most sensitive area of lens surface, which provides theoretical basis for the control precision of lens processing.
The progressive addition lenses(PAL) have been used widely because of the advantage which can meet the requirements of distant and near vision both at the same time.The basic structure,design and evaluation method of progressive addition lenses were introduced. Based on the national standard that the difference between actual diopter and theoretical value should be less than 0.1 m-1 within the lens effective area, the tolerance analysis of progressive addition lenses was realized.The tolerance formula related to diopter and surface was derived from the surface equation and sphere equation. As an example,a progressive addition lens with 2.5 m-1 addition (6.5 m-1~9 m-1) was designed and evaluated, the tolerance was analyzed. The analysis result shows that tolerance value should be less than 0.1 m at the most sensitive area of lens surface, which provides theoretical basis for the control precision of lens processing.
2016, 37(4): 523-526.
doi: 10.5768/JAO201637.0401005
Abstract:
To meet the small size and light weight requirement of the sighting telescope, the objective using the telephoto type structure was needed. The optical characteristics and aberration characteristics of telephoto lens with relay lens were analyzed, the configuration of telephoto lens, positive field lens, and symmetric relay lens was proposed.According to the imaging features of the system, the optical power distribution formula and dimension calculation formula were derived. The telephoto lens with relay lens was designed with optical design software Zemax, the focal length was -100 mm,the entrance pupil diameter was 25 mm, the view angle was 8, and the total length was only 99.92 mm. Designing results show that the modulation transfer function of every field is above 0.2 at 40 lp/mm, satisfing the application requirements of visual optical instrument.
To meet the small size and light weight requirement of the sighting telescope, the objective using the telephoto type structure was needed. The optical characteristics and aberration characteristics of telephoto lens with relay lens were analyzed, the configuration of telephoto lens, positive field lens, and symmetric relay lens was proposed.According to the imaging features of the system, the optical power distribution formula and dimension calculation formula were derived. The telephoto lens with relay lens was designed with optical design software Zemax, the focal length was -100 mm,the entrance pupil diameter was 25 mm, the view angle was 8, and the total length was only 99.92 mm. Designing results show that the modulation transfer function of every field is above 0.2 at 40 lp/mm, satisfing the application requirements of visual optical instrument.
2016, 37(4): 527-531.
doi: 10.5768/JAO201637.0401006
Abstract:
In order to meet the requirement of the miniaturization and light weight for field projector both at home and abroad,we designed a short focal digital projection lens for the 1.19 cm (0.47 inch),1080 pixel digital micromirror device (DMD) chip from TI.It is composed of 7 glass lenses (all common glass) and 2 plastic lenses (4 aspheric surface) with simple structure,and is easy to process.The projection ratio is 0.66:1 and it can project a 111.76 cm (44 inch) picture at the distance of 600 mm. The effect focal lenth is 6.4 mm,the Fnumber is:F/2.1,the full field of view(FOV) is 86,the total length is 46mm,the full aperture is 22 mm,the modulation transfer function (MTF) is more than 0.62 at the spatial frequency of 93 lp/mm within 0.8 FOV, the MTF of 1 field is 0.43,the distorition of the full FOV is less than 2%, and the vertical chromatic aberration is less than 0.18 m.
In order to meet the requirement of the miniaturization and light weight for field projector both at home and abroad,we designed a short focal digital projection lens for the 1.19 cm (0.47 inch),1080 pixel digital micromirror device (DMD) chip from TI.It is composed of 7 glass lenses (all common glass) and 2 plastic lenses (4 aspheric surface) with simple structure,and is easy to process.The projection ratio is 0.66:1 and it can project a 111.76 cm (44 inch) picture at the distance of 600 mm. The effect focal lenth is 6.4 mm,the Fnumber is:F/2.1,the full field of view(FOV) is 86,the total length is 46mm,the full aperture is 22 mm,the modulation transfer function (MTF) is more than 0.62 at the spatial frequency of 93 lp/mm within 0.8 FOV, the MTF of 1 field is 0.43,the distorition of the full FOV is less than 2%, and the vertical chromatic aberration is less than 0.18 m.
2016, 37(4): 532-536.
doi: 10.5768/JAO201637.0401007
Abstract:
The inherent structure resonance has an impressive influence on the bandwidth of the optoelectronic stabilized tracking system. Aiming at the problem,a method for controlling the bandwidth expanding under structure resonance was proposed. In the method, the measurement of frequency characteristic and the least squares parameters identification algorithm were utilized. The results of experiment show that，by the method proposed in the paper, the resonance peak can reduce to 1/3 in speed closeloop and the control bandwidth can increase to about twice of the former, which prove that the method can suppress the structure resonance efficaciously, thereby improve the system control bandwidth, as well as ensure the system stability.
The inherent structure resonance has an impressive influence on the bandwidth of the optoelectronic stabilized tracking system. Aiming at the problem,a method for controlling the bandwidth expanding under structure resonance was proposed. In the method, the measurement of frequency characteristic and the least squares parameters identification algorithm were utilized. The results of experiment show that，by the method proposed in the paper, the resonance peak can reduce to 1/3 in speed closeloop and the control bandwidth can increase to about twice of the former, which prove that the method can suppress the structure resonance efficaciously, thereby improve the system control bandwidth, as well as ensure the system stability.
2016, 37(4): 537-541.
doi: 10.5768/JAO201637.0402001
Abstract:
In order to improve the accuracy of recognition of camouflaged target，the method of camouflage target recognition based on the fusion of spectral and polarization information was proposed. A polarization spectral imaging system based on liquid crystal tunable filter（LCTF）was constructed. The polarization spectral detecting experiment of plants was conducted by the system. Band selection for the target spectral image of each polarization direction was conducted by the principal component analysis （PCA）. The degree of polarization of spectral fusion image was calculated, and the polarization spectral fusion image was finally obtained. The result shows that, compared with the spectral fusion image, the information entropy of polarization spectral fusion image improves by 72%, and the average gradient improves by 250%.
In order to improve the accuracy of recognition of camouflaged target，the method of camouflage target recognition based on the fusion of spectral and polarization information was proposed. A polarization spectral imaging system based on liquid crystal tunable filter（LCTF）was constructed. The polarization spectral detecting experiment of plants was conducted by the system. Band selection for the target spectral image of each polarization direction was conducted by the principal component analysis （PCA）. The degree of polarization of spectral fusion image was calculated, and the polarization spectral fusion image was finally obtained. The result shows that, compared with the spectral fusion image, the information entropy of polarization spectral fusion image improves by 72%, and the average gradient improves by 250%.
2016, 37(4): 542-548.
doi: 10.5768/JAO201637.0402002
Abstract:
When measuring step samples by using microscope, a wealth of step information of threedimensional shape itself is highly vulnerable to be interfered by highfrequency noise. How to maintain the step characteristics of threedimensional shape while filtering noise and achieve highprecision measurement of threedimensional shape of the sample surface information is an important research question. We did the research on wavelet denoising method based on modulus square threshold method for step threedimensional shape information by using good spacedomain and frequencydomain localization properties of wavelet function. Haar wavelet was selected for the step characteristics of the sample. The method was applied in the threedimensional height profile which was obtained through laser differential confocal microscope developed by our research group. The height measurement result of the sample after denoising is consistent with the scanning result of OLYMPUS confocal microscope. The deviation is 0.146 8 nm. It can satisfy the requirement of the followup measurement analysis of threedimensional shape information and prove the effectiveness of the algorithm.
When measuring step samples by using microscope, a wealth of step information of threedimensional shape itself is highly vulnerable to be interfered by highfrequency noise. How to maintain the step characteristics of threedimensional shape while filtering noise and achieve highprecision measurement of threedimensional shape of the sample surface information is an important research question. We did the research on wavelet denoising method based on modulus square threshold method for step threedimensional shape information by using good spacedomain and frequencydomain localization properties of wavelet function. Haar wavelet was selected for the step characteristics of the sample. The method was applied in the threedimensional height profile which was obtained through laser differential confocal microscope developed by our research group. The height measurement result of the sample after denoising is consistent with the scanning result of OLYMPUS confocal microscope. The deviation is 0.146 8 nm. It can satisfy the requirement of the followup measurement analysis of threedimensional shape information and prove the effectiveness of the algorithm.
2016, 37(4): 549-554.
doi: 10.5768/JAO201637.0402003
Abstract:
In the case of lowlight conditions, the quality of the output image is not satisfactory provided by complementary metal oxide semiconductor (CMOS) imaging device.An image enhancement algorithm based on Kmeans clustering was proposed according to the characteristics of low illumination image, and the analysiscomparison of various algorithms.The clustering center k can be automatically determined by the histogram feature of original image,and the sub images can be enhanced by histogram equalization according to the information content of each sub image after pixel sets are divided into several nonoverlapping subsets by clustering.The experiment was carried out in CMOS imaging device using this method,the results shows that this algorithm can enhance the contrast of the image to 17 times of the original image, and the average gradient can be increased to 4 times under the condition of preserving the details of the image (information entropy) to about 98.6%.
In the case of lowlight conditions, the quality of the output image is not satisfactory provided by complementary metal oxide semiconductor (CMOS) imaging device.An image enhancement algorithm based on Kmeans clustering was proposed according to the characteristics of low illumination image, and the analysiscomparison of various algorithms.The clustering center k can be automatically determined by the histogram feature of original image,and the sub images can be enhanced by histogram equalization according to the information content of each sub image after pixel sets are divided into several nonoverlapping subsets by clustering.The experiment was carried out in CMOS imaging device using this method,the results shows that this algorithm can enhance the contrast of the image to 17 times of the original image, and the average gradient can be increased to 4 times under the condition of preserving the details of the image (information entropy) to about 98.6%.
2016, 37(4): 555-560.
doi: 10.5768/JAO201637.0402004
Abstract:
Large optical aspheric mirrors are manufactured by the technology of processing，measuring，reprocessing and remeasuring in order to meet the profile accuracy requirements，so an accurate evaluation of surface shape based on profile data after measuring is the key to improve the precision of reprocessing．To solve the problem of evaluating rough machining surface of mirrors，the LevenbergMarquardt (LM) algorithm based on the trustregion rule was applied to data fitting，error compensation and surface shape evaluation． Simulation by Code V was carried out to analyze the algorithm performance,and a paraboloid workpiece was measured in surface profiler which was designed by ourselves．The parameters and residual variance curve of surface were obtained through 32 times of iteration and the convergence precision is 1.1610-21. Experiments show that the algorithm can efficiently and accurately evaluate the contour data of large aspherics ，which can provide the reliable foundation for surface shape convergence in the process of rough machining．
Large optical aspheric mirrors are manufactured by the technology of processing，measuring，reprocessing and remeasuring in order to meet the profile accuracy requirements，so an accurate evaluation of surface shape based on profile data after measuring is the key to improve the precision of reprocessing．To solve the problem of evaluating rough machining surface of mirrors，the LevenbergMarquardt (LM) algorithm based on the trustregion rule was applied to data fitting，error compensation and surface shape evaluation． Simulation by Code V was carried out to analyze the algorithm performance,and a paraboloid workpiece was measured in surface profiler which was designed by ourselves．The parameters and residual variance curve of surface were obtained through 32 times of iteration and the convergence precision is 1.1610-21. Experiments show that the algorithm can efficiently and accurately evaluate the contour data of large aspherics ，which can provide the reliable foundation for surface shape convergence in the process of rough machining．
2016, 37(4): 561-566.
doi: 10.5768/JAO201637.0403001
Abstract:
Workspace measuring and positioning system (wMPS) is a multistation intersection system based on photoelectric scanning. Since wMPS is dependent on the multistation synergy to achieve the coordinate measuring, the station layout optimization is an important problem. Optimal station topological geometry based on improved adaptive genetic algorithm was proposed. Firstly, the positioning accuracy, coverage area and cost were taken as objectives to establish the multiobjective optimization function. Secondly, through combining evolving algebra attenuation factor with adaptive genetic algorithm, improved adaptive genetic algorithm optimization process was established according to multiobjective function. Finally, simulation analysis for layout optimization algorithm of 2~4 stations was performed. The results show that compared with adaptive genetic algorithm, the proposed method can converge to the optimal solution within 10~20 generations and get better objective function value. Therefore, this method is able to improve wMPS measuring performance in spatial layout design.
Workspace measuring and positioning system (wMPS) is a multistation intersection system based on photoelectric scanning. Since wMPS is dependent on the multistation synergy to achieve the coordinate measuring, the station layout optimization is an important problem. Optimal station topological geometry based on improved adaptive genetic algorithm was proposed. Firstly, the positioning accuracy, coverage area and cost were taken as objectives to establish the multiobjective optimization function. Secondly, through combining evolving algebra attenuation factor with adaptive genetic algorithm, improved adaptive genetic algorithm optimization process was established according to multiobjective function. Finally, simulation analysis for layout optimization algorithm of 2~4 stations was performed. The results show that compared with adaptive genetic algorithm, the proposed method can converge to the optimal solution within 10~20 generations and get better objective function value. Therefore, this method is able to improve wMPS measuring performance in spatial layout design.
2016, 37(4): 567-572.
doi: 10.5768/JAO201637.0403002
Abstract:
A large field 3D displacement measurement method based on binocular stereo vision technology was proposed to measure the displacement of the seismic shaking table experiment. First of all, a robust marking point stereo matching algorithm was proposed. Besides, based on the VS2010 development environment, the threedimensional full field displacement measurement system was developed for seismic shaking table experiment. Finally, in order to verify the methods accuracy in the experiment of large view, the accuracy evaluation experiment was designed. And the shaking table experiment of high slope model was measured by the developed experimental system. Experimental results show that the static displacement measurement error is less than 0.4 mm, the dynamic displacement measurement error is less than 0.5 mm, which can meet the requirements of shaking table experiment in the field of 3 m1.5 m. Moreover the method proposed can be convenient and intuitive to measure the displacement field of the high slope model in earthquake shaking table experiment. And the X, Y, Z three direction displacement curves and the total displacement curve are reasonable. It is an effective method to measure the full field displacement of the seismic shaking table experiment.
A large field 3D displacement measurement method based on binocular stereo vision technology was proposed to measure the displacement of the seismic shaking table experiment. First of all, a robust marking point stereo matching algorithm was proposed. Besides, based on the VS2010 development environment, the threedimensional full field displacement measurement system was developed for seismic shaking table experiment. Finally, in order to verify the methods accuracy in the experiment of large view, the accuracy evaluation experiment was designed. And the shaking table experiment of high slope model was measured by the developed experimental system. Experimental results show that the static displacement measurement error is less than 0.4 mm, the dynamic displacement measurement error is less than 0.5 mm, which can meet the requirements of shaking table experiment in the field of 3 m1.5 m. Moreover the method proposed can be convenient and intuitive to measure the displacement field of the high slope model in earthquake shaking table experiment. And the X, Y, Z three direction displacement curves and the total displacement curve are reasonable. It is an effective method to measure the full field displacement of the seismic shaking table experiment.
2016, 37(4): 573-577.
doi: 10.5768/JAO201637.0403003
Abstract:
To achieve the large dynamic range and highprecise test for the cutoff depth of the outband of solar blind untraviolet(UV) filters, a system which not only used xenon lamp with a monochromator as the standard light, but also used photon counter as the detector was proposed. Additional, the error of the system was analyzed. The major equipments were the xenon lamp with a monochromator, the standard reflective neutral attenuator and the single photo counter. Based on the substitution method the measurement was carried out. The photo counter detected the number of the xenon lamp through the attenuator as the reference to substitute the initial photo number of xenon lamp, then the cutoff depth of filters could be acquired. Results show that the test system can extend the testing dynamic range of filter optical density to 0~-11OD, it realizes the continuous measurement the visible spectral bands at 1 nm intervals, and greatly reduces the test error of the system.Compared with the test system using narrow band LED as the light source, the test uncertainty reduces from 2% to 0.5%,and the relative repeatability error is from 0.2% down to 0.13%.
To achieve the large dynamic range and highprecise test for the cutoff depth of the outband of solar blind untraviolet(UV) filters, a system which not only used xenon lamp with a monochromator as the standard light, but also used photon counter as the detector was proposed. Additional, the error of the system was analyzed. The major equipments were the xenon lamp with a monochromator, the standard reflective neutral attenuator and the single photo counter. Based on the substitution method the measurement was carried out. The photo counter detected the number of the xenon lamp through the attenuator as the reference to substitute the initial photo number of xenon lamp, then the cutoff depth of filters could be acquired. Results show that the test system can extend the testing dynamic range of filter optical density to 0~-11OD, it realizes the continuous measurement the visible spectral bands at 1 nm intervals, and greatly reduces the test error of the system.Compared with the test system using narrow band LED as the light source, the test uncertainty reduces from 2% to 0.5%,and the relative repeatability error is from 0.2% down to 0.13%.
2016, 37(4): 578-583.
doi: 10.5768/JAO201637.0403004
Abstract:
Compared with the conventional system of secondary imaging spectrum, the full polarization imaging spectrum of acoustooptic tunable filter (AOTF) based on the wavelength scanning of a type of AOTF and phase modulation of the double liquid crystal variable retarder (LCVR) has many advantages, for example, the larger limiting aperture,high light utilization and the electronic tuning of full system. Besides, it can meet the small incident angle of AOTF and LCVR so as to greatly improve the spectral measurement precision and polarization measurement precision. The experiment results show that its relative error can be reduced an order of magnitude by using the revised equation of the wavelength 0 and the driving frequency fa to measure the spectrum. Through calculation, we can calculate all the parameters S=[S0 S1 S2 S3]T of Stokes in only 4 groups of phase delay and 4 intensity images. When considering the incident angle, the maximum relative error of the degree of polarization, the degree of linear polarization, the degree of circular polarization and the degree of angle polarization respectively reduced about 0.306%,0.130%,10.96% and 3.783% than that we only considered the light vertical incidence. This can provide a theoretical basis in order to further improve the measurement precision.
Compared with the conventional system of secondary imaging spectrum, the full polarization imaging spectrum of acoustooptic tunable filter (AOTF) based on the wavelength scanning of a type of AOTF and phase modulation of the double liquid crystal variable retarder (LCVR) has many advantages, for example, the larger limiting aperture,high light utilization and the electronic tuning of full system. Besides, it can meet the small incident angle of AOTF and LCVR so as to greatly improve the spectral measurement precision and polarization measurement precision. The experiment results show that its relative error can be reduced an order of magnitude by using the revised equation of the wavelength 0 and the driving frequency fa to measure the spectrum. Through calculation, we can calculate all the parameters S=[S0 S1 S2 S3]T of Stokes in only 4 groups of phase delay and 4 intensity images. When considering the incident angle, the maximum relative error of the degree of polarization, the degree of linear polarization, the degree of circular polarization and the degree of angle polarization respectively reduced about 0.306%,0.130%,10.96% and 3.783% than that we only considered the light vertical incidence. This can provide a theoretical basis in order to further improve the measurement precision.
2016, 37(4): 584-589.
doi: 10.5768/JAO201637.0403005
Abstract:
To realize locating and heading determination fast, a twodimensional referrence transfer system was proposed which can achieve realtime transferring of heading determination information for Beidou satellite navigation system (BDS) by linear charge coupled device (CCD).This system consists of the BDS heading determination aerials,the light source part, the optical measuring part and so on. It can realize 2D measurement rapidly and accurately by using the N shape light source and linear CCD splicing technology. A precision testing experiment was designed based on the 2D reference transfer system. The test results shows that on the condition of 8m measuring distance, the measuring range is 1.5, and the measuring accuracy is no more than 5. This system provides an effective technical solution for 2D determination heading reference widefield transferring.
To realize locating and heading determination fast, a twodimensional referrence transfer system was proposed which can achieve realtime transferring of heading determination information for Beidou satellite navigation system (BDS) by linear charge coupled device (CCD).This system consists of the BDS heading determination aerials,the light source part, the optical measuring part and so on. It can realize 2D measurement rapidly and accurately by using the N shape light source and linear CCD splicing technology. A precision testing experiment was designed based on the 2D reference transfer system. The test results shows that on the condition of 8m measuring distance, the measuring range is 1.5, and the measuring accuracy is no more than 5. This system provides an effective technical solution for 2D determination heading reference widefield transferring.
2016, 37(4): 590-594.
doi: 10.5768/JAO201637.0403006
Abstract:
According to the optoelectronic requirement of minimum control speed flight test for civil planes, an accurate measurement technology of department distance from aircraft to runway centerline based on images of forwardlooking runway was proposed. A highspeed digital camera was mounted on the ventral centerline to obtain the forwardlooking images of runway and aircraft landing gear of the running plane. With image interpretation, subpixels coordinates of intersection on aircraft main wheel connection and runway flag line were identified. With the highaccuracy calibration of camera measurement parameters and singlestation location theory of photogrammetry, the object space coordinates of the intersection could be accurate calculated, and then the distance from aircraft to runway centerline could be obtained. The measurement result of flight tests shows that this measurement scheme is feasible, the measurement result is reliable, and the measurement accuracy of 3 cm can be realized, which can meet the requirements of flight tests.
According to the optoelectronic requirement of minimum control speed flight test for civil planes, an accurate measurement technology of department distance from aircraft to runway centerline based on images of forwardlooking runway was proposed. A highspeed digital camera was mounted on the ventral centerline to obtain the forwardlooking images of runway and aircraft landing gear of the running plane. With image interpretation, subpixels coordinates of intersection on aircraft main wheel connection and runway flag line were identified. With the highaccuracy calibration of camera measurement parameters and singlestation location theory of photogrammetry, the object space coordinates of the intersection could be accurate calculated, and then the distance from aircraft to runway centerline could be obtained. The measurement result of flight tests shows that this measurement scheme is feasible, the measurement result is reliable, and the measurement accuracy of 3 cm can be realized, which can meet the requirements of flight tests.
2016, 37(4): 595-601.
doi: 10.5768/JAO201637.0405001
Abstract:
A method for designing the lens for uniform illumination with extended source based on natural selection particle swarm optimization (SelPSO) algorithm was proposed.The point light source lens profile was treated as the optimized object by this method. Firstly, we established a mechanism of exchanging information between Matlab and TracePro based on dynamic data exchange (DDE) technology.The characteristic advantages of both Matlab and TracePro were combined by the mechanism, so that we could construst the optimzation model easily. Then, we used the SelPSO algorithm to optimize system globally until the optimization results met the illumination requirements. In order to verify the feasibility of the system, we designed a compact uniform lens whose h/d was equal to 2.5:1. The results show that when the SelPSO and PSO are used to optimize system under the same parameters, it is found that SelPSO has faster and better global convergence capability, and its uniformity and efficiency can reach 87.566% and 89.536%,respectively. After lens installation tolerance analysis, the transverse and longitudinal displacement errors should be controlled between 0 mm and 2 mm so as to get a better lighting effect. Additionally, the method can be used for optimizing lens systems in different illuminance ranges with good illuminance effect.
A method for designing the lens for uniform illumination with extended source based on natural selection particle swarm optimization (SelPSO) algorithm was proposed.The point light source lens profile was treated as the optimized object by this method. Firstly, we established a mechanism of exchanging information between Matlab and TracePro based on dynamic data exchange (DDE) technology.The characteristic advantages of both Matlab and TracePro were combined by the mechanism, so that we could construst the optimzation model easily. Then, we used the SelPSO algorithm to optimize system globally until the optimization results met the illumination requirements. In order to verify the feasibility of the system, we designed a compact uniform lens whose h/d was equal to 2.5:1. The results show that when the SelPSO and PSO are used to optimize system under the same parameters, it is found that SelPSO has faster and better global convergence capability, and its uniformity and efficiency can reach 87.566% and 89.536%,respectively. After lens installation tolerance analysis, the transverse and longitudinal displacement errors should be controlled between 0 mm and 2 mm so as to get a better lighting effect. Additionally, the method can be used for optimizing lens systems in different illuminance ranges with good illuminance effect.
2016, 37(4): 602-606.
doi: 10.5768/JAO201637.0405002
Abstract:
Aiming at the problem that the stabilization precision of the zoom optical system is difficult to control, the critical factors influencing the stabilization of optical axis were analyzed.A 3D entity model of the curve sleeve and guide rod of the TV optical zoom system was simulated in UG, after that the thermodynamic analysis was done with the finite element method. A method of adjustment measure and the control data which were different from the original one were proposed,the fixing method combining the glue with the follower ring was utilized to fix the front group of mirror.Results show that the research can improve the stabilization precision of the zoom optical system during the assembling, it increases the stabilization of optical axis from 12 to 5; Thereby the results establish the assembling foundation and theoretical basis for the development of following similar products. Additional,the validity of this method was verified by several experiments.
Aiming at the problem that the stabilization precision of the zoom optical system is difficult to control, the critical factors influencing the stabilization of optical axis were analyzed.A 3D entity model of the curve sleeve and guide rod of the TV optical zoom system was simulated in UG, after that the thermodynamic analysis was done with the finite element method. A method of adjustment measure and the control data which were different from the original one were proposed,the fixing method combining the glue with the follower ring was utilized to fix the front group of mirror.Results show that the research can improve the stabilization precision of the zoom optical system during the assembling, it increases the stabilization of optical axis from 12 to 5; Thereby the results establish the assembling foundation and theoretical basis for the development of following similar products. Additional,the validity of this method was verified by several experiments.
2016, 37(4): 607-611.
doi: 10.5768/JAO201637.0405003
Abstract:
To solve the alignment for the offaxis mirror with more variable and high sensitivity, we introduced the computeraided interferometry technology, built the relationship between the misalignment and primary aberration, as well as the mutual compensatory relationship of each element.Moreover,we accomplished the systematic assembly and adjustment efficiently and speedily by collecting systems wavefront aberration through interferometry, obtained the misalignment of each element through the reverse optimizing analysis.Results show that the final wavefront error of the afocal compressed optical path system is better than 0.055 RMS at = 632.8 nm across all image plane, and the compression ratio is less than 5.
To solve the alignment for the offaxis mirror with more variable and high sensitivity, we introduced the computeraided interferometry technology, built the relationship between the misalignment and primary aberration, as well as the mutual compensatory relationship of each element.Moreover,we accomplished the systematic assembly and adjustment efficiently and speedily by collecting systems wavefront aberration through interferometry, obtained the misalignment of each element through the reverse optimizing analysis.Results show that the final wavefront error of the afocal compressed optical path system is better than 0.055 RMS at = 632.8 nm across all image plane, and the compression ratio is less than 5.
2016, 37(4): 612-617.
doi: 10.5768/JAO201637.0405004
Abstract:
In order to decrease the power consumption of the electrooptical and resolve the high consistency with halfwave voltage of the inner MachZehnder (MZ) modulators in the phase encoder, using two biased MZ modulators, a 2bits electrooptical phase encoder for electrooptical analogtodigital conversion (EO ADC) was set up. The construction methods, features and performances of the 2bits electrooptical phase encoder were analyzed theoretically. The simulation results verified the feasibility of the 2bits electrooptical phase encoding method. The simulation experiments also fulfilled analogtodigital conversion for signals at 1 GHz with sampling rate of 12 GS/s. The analysis and simulation results show that the proposed method has low requirement for the consistency of the modulators and the input signal power is lower than 0.32 W. The analysis results also show that the quantization of the least significant bit is immune from the modulators directcurrent(DC) drift, while the decision uncertainty of the most significant bit influenced by the DC drift is lower than 3.8 %.
In order to decrease the power consumption of the electrooptical and resolve the high consistency with halfwave voltage of the inner MachZehnder (MZ) modulators in the phase encoder, using two biased MZ modulators, a 2bits electrooptical phase encoder for electrooptical analogtodigital conversion (EO ADC) was set up. The construction methods, features and performances of the 2bits electrooptical phase encoder were analyzed theoretically. The simulation results verified the feasibility of the 2bits electrooptical phase encoding method. The simulation experiments also fulfilled analogtodigital conversion for signals at 1 GHz with sampling rate of 12 GS/s. The analysis and simulation results show that the proposed method has low requirement for the consistency of the modulators and the input signal power is lower than 0.32 W. The analysis results also show that the quantization of the least significant bit is immune from the modulators directcurrent(DC) drift, while the decision uncertainty of the most significant bit influenced by the DC drift is lower than 3.8 %.
2016, 37(4): 618-622.
doi: 10.5768/JAO201637.0406001
Abstract:
The layer controlled graphene film CaF2 mirrors were prepared by chemical vapor deposition method to study optical limiting mechanism of the graphene devices in 3 m~5 m infrared band, and an allsolidstate infrared optical parametric oscillator was builted based on a periodic polarization crystal MgO∶PPLN. The experiment about scattering of graphene films in the integrating sphere was carried out by using the idler light in 3 m ~5 m wave band. The normalized curve of scattering signal of graphene films and changes of the incident light were measured. It was found that when the idle light energy was more than 1 J/cm2, and the scattering energy signal with the incident light intensity exhibited a fast nonlinear growth trend. In addition, the growth rate of the scattering energy signal was inversely proportional to the incident wavelength of the idle frequency light, which was proportional to the number of layers of graphene. Results show that the optical limiting mechanism of graphene films in 3 m~5 m in the infrared band might be due to the rapidlyvaporized graphene, the formation of micro plasma ionization and the nonlinear scattering.
The layer controlled graphene film CaF2 mirrors were prepared by chemical vapor deposition method to study optical limiting mechanism of the graphene devices in 3 m~5 m infrared band, and an allsolidstate infrared optical parametric oscillator was builted based on a periodic polarization crystal MgO∶PPLN. The experiment about scattering of graphene films in the integrating sphere was carried out by using the idler light in 3 m ~5 m wave band. The normalized curve of scattering signal of graphene films and changes of the incident light were measured. It was found that when the idle light energy was more than 1 J/cm2, and the scattering energy signal with the incident light intensity exhibited a fast nonlinear growth trend. In addition, the growth rate of the scattering energy signal was inversely proportional to the incident wavelength of the idle frequency light, which was proportional to the number of layers of graphene. Results show that the optical limiting mechanism of graphene films in 3 m~5 m in the infrared band might be due to the rapidlyvaporized graphene, the formation of micro plasma ionization and the nonlinear scattering.
2016, 37(4): 623-627.
doi: 10.5768/JAO201637.0406002
Abstract:
Lowtemperature infrared radiators have been used widely with the rapid development of space infrared detection, satellite remote sensing. One kind of lowtemperature infrared radiator based on liquidcirculation temperature control was developed. The range of radiant temperature for this radiator is -60 ℃~50 ℃，the temperature control accuracy reaches 0.01 ℃, and the effective emissivity is better than 0.999 7. First, the design principle of this radiator was described, and the structure characteristic for the radiation cavity was depicted, the calculation by using STEEP3 software based on the MonteCarlo algorithm for emissivity was also given. The temperature characteristic for inner part of radiation cavity was then studied, the temperature uniformity of the inner cavity verified by valid testing was better than 0.02 ℃, the temperature stability for bottom of cavity was 0.05 ℃/h. Finally, the normal spectral emissivity of the radiator at the temperature of 29.76 ℃ was obtained by comparing its radiance with a gallium melting point blackbody, the experimental value was the same with the result calculated by STEEP3.
Lowtemperature infrared radiators have been used widely with the rapid development of space infrared detection, satellite remote sensing. One kind of lowtemperature infrared radiator based on liquidcirculation temperature control was developed. The range of radiant temperature for this radiator is -60 ℃~50 ℃，the temperature control accuracy reaches 0.01 ℃, and the effective emissivity is better than 0.999 7. First, the design principle of this radiator was described, and the structure characteristic for the radiation cavity was depicted, the calculation by using STEEP3 software based on the MonteCarlo algorithm for emissivity was also given. The temperature characteristic for inner part of radiation cavity was then studied, the temperature uniformity of the inner cavity verified by valid testing was better than 0.02 ℃, the temperature stability for bottom of cavity was 0.05 ℃/h. Finally, the normal spectral emissivity of the radiator at the temperature of 29.76 ℃ was obtained by comparing its radiance with a gallium melting point blackbody, the experimental value was the same with the result calculated by STEEP3.
2016, 37(4): 628-632.
doi: 10.5768/JAO201637.0406003
Abstract:
Based on the principle of radiation temperature measurement, we introduced the theory of infrared temperature measurement and sparse decomposition denoising principle in order to improve the molten steel temperature measuring accuracy and remove the noise of infrared image of molten steel. Having set up the experimental platform, we obtained different steel infrared images at different temperatures and experimental conditions, and used the sparse decomposition denoising for molten steel infrared image denoising processing.Compared with the Wiener filter denoising, the noise in the molten steel infrared image can be better removed by sparse decomposition and the peak signal to noise ratio increases by 10 dB.
Based on the principle of radiation temperature measurement, we introduced the theory of infrared temperature measurement and sparse decomposition denoising principle in order to improve the molten steel temperature measuring accuracy and remove the noise of infrared image of molten steel. Having set up the experimental platform, we obtained different steel infrared images at different temperatures and experimental conditions, and used the sparse decomposition denoising for molten steel infrared image denoising processing.Compared with the Wiener filter denoising, the noise in the molten steel infrared image can be better removed by sparse decomposition and the peak signal to noise ratio increases by 10 dB.
2016, 37(4): 633-638.
doi: 10.5768/JAO201637.0408001
Abstract:
To fabricate the Bragg grating on the sidepolished fiber(SPF) and improve the flexibility of grating design, a novel method for fabricating surface Bragg grating on SPF with dichromate gelatin(DCG) was demonstrated. SPF was fabricated by wheel polishing method and DCG was spin coated on the polished surface of SPF as photoresist. Using holography technique, Bragg grating was fabricated on the polished surface. Spectral measurement results show that a significant reflection peak can be observed at 1 480.2 nm, which is well corresponding to the transmission valley. The modulation amplitude of this reflection peak is up to 15.9 dB, due to the reflection of surface Bragg grating. Temperature sensing experiment results show that with temperature increasing, the reflection peak can have red shift. its sensitivity is 17.84 pm/℃. This fiber sensor has good potential in the application of fiber sensor and fiber filter.
To fabricate the Bragg grating on the sidepolished fiber(SPF) and improve the flexibility of grating design, a novel method for fabricating surface Bragg grating on SPF with dichromate gelatin(DCG) was demonstrated. SPF was fabricated by wheel polishing method and DCG was spin coated on the polished surface of SPF as photoresist. Using holography technique, Bragg grating was fabricated on the polished surface. Spectral measurement results show that a significant reflection peak can be observed at 1 480.2 nm, which is well corresponding to the transmission valley. The modulation amplitude of this reflection peak is up to 15.9 dB, due to the reflection of surface Bragg grating. Temperature sensing experiment results show that with temperature increasing, the reflection peak can have red shift. its sensitivity is 17.84 pm/℃. This fiber sensor has good potential in the application of fiber sensor and fiber filter.
New website launched!
陕公网安备 61011302001501号