2018 Vol. 39, No. 3
Display Method:
2018, 39(3): 301-308.
doi: 10.5768/JAO201839.0301001
Abstract:
A calibration method for deflection angle of mini-type optical seeker is presented. This method firstly obtains the images from the camera in the seeker when the seeker is rotating with its own rotation axis, and then calculates the placement points of central line of sight and the origin of the camera coordinate system in different rotation angles, finally gets the geometric relationship by fitting the distribution of these two groups of points, and then the deflection angle can be calculated. Three sets of experimental data are presented, which give the calibration error of this method, the number of sampling points needed in practice, and the application, respectively. The experimental results show that this method can be used to calibrate the deflection angle of the optical seeker fastly, and the calibration absolute error is less than 0.10 °.
A calibration method for deflection angle of mini-type optical seeker is presented. This method firstly obtains the images from the camera in the seeker when the seeker is rotating with its own rotation axis, and then calculates the placement points of central line of sight and the origin of the camera coordinate system in different rotation angles, finally gets the geometric relationship by fitting the distribution of these two groups of points, and then the deflection angle can be calculated. Three sets of experimental data are presented, which give the calibration error of this method, the number of sampling points needed in practice, and the application, respectively. The experimental results show that this method can be used to calibrate the deflection angle of the optical seeker fastly, and the calibration absolute error is less than 0.10 °.
2018, 39(3): 309-315.
doi: 10.5768/JAO201839.0301002
Abstract:
At present, there is an insufficient understanding of the use and maintenance of the land based high-performance inertial navigation equipment domestically. Additionally, there is no accurate theoretical analysis on the effects of improper or non-standard maintenance on the performance of inertial equipment. In order to solve the problem, taking a certain type of land-based high-precision laser gyro positioning and orientation system as the research object, combined with the status quo of domestic inertial sensors, the demand for maintenance of land-based high-precision laser inertial navigation equipment and the importance of standard maintenance operations was analyzed in detail.After electricity maintenance and system calibration at regular intervals, the performance of malfunction equipment was restored.The test data shows that, the horizontal positioning accuracy of the system can be typically improved from 8.35 m(CEP) to 2.9 m(CEP)by maintenance. This paper can provide references and theoretical supports for the design and production of similar equipment in domestic, and utilization for army.
At present, there is an insufficient understanding of the use and maintenance of the land based high-performance inertial navigation equipment domestically. Additionally, there is no accurate theoretical analysis on the effects of improper or non-standard maintenance on the performance of inertial equipment. In order to solve the problem, taking a certain type of land-based high-precision laser gyro positioning and orientation system as the research object, combined with the status quo of domestic inertial sensors, the demand for maintenance of land-based high-precision laser inertial navigation equipment and the importance of standard maintenance operations was analyzed in detail.After electricity maintenance and system calibration at regular intervals, the performance of malfunction equipment was restored.The test data shows that, the horizontal positioning accuracy of the system can be typically improved from 8.35 m(CEP) to 2.9 m(CEP)by maintenance. This paper can provide references and theoretical supports for the design and production of similar equipment in domestic, and utilization for army.
2018, 39(3): 316-320.
doi: 10.5768/JAO201839.0301003
Abstract:
The optical information of object includes the polarization information in addition to the common spectral information. The acquisition of polarization information can achieve information extraction for a specific target in a complex background, especially the extraction of metal target information. Combined with the principle, composition and characteristics of polarization imaging, a common-aperture common-detector long-wave infrared polarization imaging system was used to extract the target information. Through simulation software analysis, the system can detect a vehicle target of 3 km away, and the imaging quality is good.
The optical information of object includes the polarization information in addition to the common spectral information. The acquisition of polarization information can achieve information extraction for a specific target in a complex background, especially the extraction of metal target information. Combined with the principle, composition and characteristics of polarization imaging, a common-aperture common-detector long-wave infrared polarization imaging system was used to extract the target information. Through simulation software analysis, the system can detect a vehicle target of 3 km away, and the imaging quality is good.
2018, 39(3): 321-325.
doi: 10.5768/JAO201839.0301004
Abstract:
Aiming at the selection of the working band in the infrared system design, the mid-wave and long-wave infrared were compared and analyzed from several aspects such as detector performance, optical diffusion spot, atmospheric transmission characteristics, target and background radiation characteristics, and sea clutter interference. The detailed test schemes to get the day-night detection effect of mid-wave and long-wave infrared thermal imager were formulated, and a great deal of data of the two detectors at different times and different weathers was obtained.Combined with experimental data and theoretical analysis, the proposal of band selection for infrared system using in remote day and night detection on the other shore was put forward.
Aiming at the selection of the working band in the infrared system design, the mid-wave and long-wave infrared were compared and analyzed from several aspects such as detector performance, optical diffusion spot, atmospheric transmission characteristics, target and background radiation characteristics, and sea clutter interference. The detailed test schemes to get the day-night detection effect of mid-wave and long-wave infrared thermal imager were formulated, and a great deal of data of the two detectors at different times and different weathers was obtained.Combined with experimental data and theoretical analysis, the proposal of band selection for infrared system using in remote day and night detection on the other shore was put forward.
2018, 39(3): 326-331.
doi: 10.5768/JAO201839.0301005
Abstract:
The yaw angle of projectile is a key parameter that affects the launch accuracy of the electromagnetic rail launcher. In order to measure the yaw angle of the projectile timely and precisely, and to improve the launch accuracy of the electromagnetic rail launcher, a method based on binocular vision theory without target velocity was proposed. Utilizing the high-speed projectile trajectory images and establishing the camera linear imaging model to solve the high-speed projectile image coordinates, the measurement of the target yaw angle was realized. According to the proposed method, the influences of the optical system parameters on the measurement accuracy were also analyzed, with a theoretical error of approximately 14.5 μrad. The experiment of the yaw angle measurement shows that this method can calculate the yaw angle of the projectile with accuracy and timeliness, and the average of the calculated deviation is 0.58 mrad.
The yaw angle of projectile is a key parameter that affects the launch accuracy of the electromagnetic rail launcher. In order to measure the yaw angle of the projectile timely and precisely, and to improve the launch accuracy of the electromagnetic rail launcher, a method based on binocular vision theory without target velocity was proposed. Utilizing the high-speed projectile trajectory images and establishing the camera linear imaging model to solve the high-speed projectile image coordinates, the measurement of the target yaw angle was realized. According to the proposed method, the influences of the optical system parameters on the measurement accuracy were also analyzed, with a theoretical error of approximately 14.5 μrad. The experiment of the yaw angle measurement shows that this method can calculate the yaw angle of the projectile with accuracy and timeliness, and the average of the calculated deviation is 0.58 mrad.
2018, 39(3): 332-338.
doi: 10.5768/JAO201839.0301006
Abstract:
The portable spatial heterodyne Raman spectrometer integrates optical lens, interferometer, and thermal radiation devices such as detector and laser. Therefore, the spectrometer has a complex thermal environment, and the change of the ambient temperature can lead to the decline of optical system performance.Aiming at this problem, the method of thermal/ structural/optical (TSO) integrated analysis was used to study the influence of ambient temperature and thermal radiation devices on the performance of imaging lens. Based on the design of the optical system and mechanical structure of the spectrometer, the thermal-structure coupling model of the lens was established, and the changes of the lens spacing and the surface shape were obtained by simulation surface change imaging lens, the Zernike polynomial was used to fit their changes. Finally, the results were coupled in the optical design software to evaluate and analyze the imaging quality. The analysis results show that, in the working ambient temperature(-10℃~40℃), the design value of the modulation transfer function (MTF) at 76.9 lp/mm is better than 0.38, which meets the requirement of the portable spatial heterodyne Raman spectrometer.
The portable spatial heterodyne Raman spectrometer integrates optical lens, interferometer, and thermal radiation devices such as detector and laser. Therefore, the spectrometer has a complex thermal environment, and the change of the ambient temperature can lead to the decline of optical system performance.Aiming at this problem, the method of thermal/ structural/optical (TSO) integrated analysis was used to study the influence of ambient temperature and thermal radiation devices on the performance of imaging lens. Based on the design of the optical system and mechanical structure of the spectrometer, the thermal-structure coupling model of the lens was established, and the changes of the lens spacing and the surface shape were obtained by simulation surface change imaging lens, the Zernike polynomial was used to fit their changes. Finally, the results were coupled in the optical design software to evaluate and analyze the imaging quality. The analysis results show that, in the working ambient temperature(-10℃~40℃), the design value of the modulation transfer function (MTF) at 76.9 lp/mm is better than 0.38, which meets the requirement of the portable spatial heterodyne Raman spectrometer.
2018, 39(3): 339-342.
doi: 10.5768/JAO201839.0301007
Abstract:
In order to calibrate the consistency of optical axes of the field vehicle photoelectric tracker, a method for using the multi-spectral common-aperture infinity collimator, reflex light tubes, and moving mechanism was put forward to realize the calibration of each optical axis, and the optical design of collimator and the overall structural design were performed.In addition, the main errors affecting the calibration were analyzed. Results show that the overall size of the target is 750 mm ×120 mm × 100 mm, it uses an off-axis hyperboloidal reflective optical system with a focal length of 1 200 mm, an aperture of 50 mm and a field of view of 2°. The reticle uses ZnS and the light source uses tungsten bromine lamp.The system is optimized with Zemax optical design software, the maximum focal spot root-mean-square(RMS) achieves 35.766 μm, and the optical transfer functions (OTFs) are all higher than 0.3 at the spatial frequency of 5 lp/mm. All the indicators meet the calibration requirements.
In order to calibrate the consistency of optical axes of the field vehicle photoelectric tracker, a method for using the multi-spectral common-aperture infinity collimator, reflex light tubes, and moving mechanism was put forward to realize the calibration of each optical axis, and the optical design of collimator and the overall structural design were performed.In addition, the main errors affecting the calibration were analyzed. Results show that the overall size of the target is 750 mm ×120 mm × 100 mm, it uses an off-axis hyperboloidal reflective optical system with a focal length of 1 200 mm, an aperture of 50 mm and a field of view of 2°. The reticle uses ZnS and the light source uses tungsten bromine lamp.The system is optimized with Zemax optical design software, the maximum focal spot root-mean-square(RMS) achieves 35.766 μm, and the optical transfer functions (OTFs) are all higher than 0.3 at the spatial frequency of 5 lp/mm. All the indicators meet the calibration requirements.
2018, 39(3): 343-348.
doi: 10.5768/JAO201839.0301008
Abstract:
In order to ensure the safety of plant protection unmanned aerial vehicles (UAVs), it was required to have the ability of the automatic obstacle avoidance. So a new obstacle detection method based on structured light vision was proposed. In order to improve the real-time performance of obstacle detection, based on the analysis of the latest general processor unit (GPU), the obstacle detection system of plant protection UAVs based on embedded platform was studied mainly. By mapping the obstacle image processing algorithm to GPU hardware resources to complete the parallel computation, the efficiency of the algorithm was greatly improved. Experiments show that the obstacle detection system based on embedded CPU-GPU achieves a speedup rate of about 46.15 by comparing the processing algorithms of CPU and CPU-GPU on the premise of ensuring the complete outline of the obstacle, and time-consuming of the acquisition and processing is about 48.985 ms. The system has the advantages of obvious effect of processing and good real-time performance, which lays the foundation for real-time obstacle detection and further obstacle avoidance of plant protection UAVs.
In order to ensure the safety of plant protection unmanned aerial vehicles (UAVs), it was required to have the ability of the automatic obstacle avoidance. So a new obstacle detection method based on structured light vision was proposed. In order to improve the real-time performance of obstacle detection, based on the analysis of the latest general processor unit (GPU), the obstacle detection system of plant protection UAVs based on embedded platform was studied mainly. By mapping the obstacle image processing algorithm to GPU hardware resources to complete the parallel computation, the efficiency of the algorithm was greatly improved. Experiments show that the obstacle detection system based on embedded CPU-GPU achieves a speedup rate of about 46.15 by comparing the processing algorithms of CPU and CPU-GPU on the premise of ensuring the complete outline of the obstacle, and time-consuming of the acquisition and processing is about 48.985 ms. The system has the advantages of obvious effect of processing and good real-time performance, which lays the foundation for real-time obstacle detection and further obstacle avoidance of plant protection UAVs.
2018, 39(3): 349-354.
doi: 10.5768/JAO201839.0302001
Abstract:
In response to the problems which exist in traditional triangle star identification algorithms including redundant matching and poor anti-noise performance, an efficient star identification algorithm based on shape factor feature was proposed. The algorithm presents the shape factor characteristic parameter of triangle and the direction information based on traditional triangle algorithm. Based on the traditional triangle algorithm, this algorithm introduces the feature parameters of shape factor and the direction information, and selects 4 observation stars in the field of view to form a pair of observation triangles, and then performs star point matching and recognition. Compared with the traditional triangle algorithm, the algorithm proposed increases the feature information amount of the star map when identifying star, reduces the redundancy when matching, and has the advantages of small storage space and high identification speed. The experimental results show that under the simulation conditions of standard deviation of 2 pixels and standard noise of 0.7 magnitude at the star position, the identification rate of the algorithm is more than 99%. Through the physical verification of the ground experiment, the average time of self-identification of star map is about 47 ms in the operation based on the FT-C6713 DSP hardware platform of 300 MHz, which has obvious advantages over traditional triangle star identification algorithm.
In response to the problems which exist in traditional triangle star identification algorithms including redundant matching and poor anti-noise performance, an efficient star identification algorithm based on shape factor feature was proposed. The algorithm presents the shape factor characteristic parameter of triangle and the direction information based on traditional triangle algorithm. Based on the traditional triangle algorithm, this algorithm introduces the feature parameters of shape factor and the direction information, and selects 4 observation stars in the field of view to form a pair of observation triangles, and then performs star point matching and recognition. Compared with the traditional triangle algorithm, the algorithm proposed increases the feature information amount of the star map when identifying star, reduces the redundancy when matching, and has the advantages of small storage space and high identification speed. The experimental results show that under the simulation conditions of standard deviation of 2 pixels and standard noise of 0.7 magnitude at the star position, the identification rate of the algorithm is more than 99%. Through the physical verification of the ground experiment, the average time of self-identification of star map is about 47 ms in the operation based on the FT-C6713 DSP hardware platform of 300 MHz, which has obvious advantages over traditional triangle star identification algorithm.
2018, 39(3): 355-358.
doi: 10.5768/JAO201839.0302002
Abstract:
Diffractive optical elements (DOEs), with their excellent optical properties, can modulate the ideal wavefront, and have greater advantages in correcting chromatic aberration than spherical or aspherical optical systems.The difficulty in the processing of DOE lies in the fact that its processing accuracy requires not only that the surface shape of the aspherical substrate satisfies the accuracy requirements, but also that the phase saltation position and the height of the diffractive structure satisfy the requirements.Due to the discontinuity of the surface and the phase saltation position, the traditional detection method is difficult to meet the requirements.The detection error source of the profiler was analyzed, and the machining error data was analyzed in combination with the detection data. Based on this, the data processing was performed. The error data obtained by this method was applied to the part processing, and the surface shape error of the 120 mm diffractive surface was 0.539 μm.
Diffractive optical elements (DOEs), with their excellent optical properties, can modulate the ideal wavefront, and have greater advantages in correcting chromatic aberration than spherical or aspherical optical systems.The difficulty in the processing of DOE lies in the fact that its processing accuracy requires not only that the surface shape of the aspherical substrate satisfies the accuracy requirements, but also that the phase saltation position and the height of the diffractive structure satisfy the requirements.Due to the discontinuity of the surface and the phase saltation position, the traditional detection method is difficult to meet the requirements.The detection error source of the profiler was analyzed, and the machining error data was analyzed in combination with the detection data. Based on this, the data processing was performed. The error data obtained by this method was applied to the part processing, and the surface shape error of the 120 mm diffractive surface was 0.539 μm.
2018, 39(3): 359-365.
doi: 10.5768/JAO201839.0302003
Abstract:
The imaging spectrometer based on acoustic-optic tunable filter (AOTF) is a new detector which integrates image, spectrum and polarization information. Because the acousto-optical crystal is the core optical splitter, its performance can affect the acquisition ability of the target information. Therefore, the key point of AOTF imaging spectrometer development is to study the method for improving the diffraction efficiency of acousto-optical crystal. Firstly we introduced the working principle of AOTF imaging spectrometer, derived the acousto-optical crystal diffraction efficiency equation based on coupled wave theory, then analyzed the influencing factors of the AOTF imaging spectrometer on acousto-optical diffraction efficiency by numerical simulation. Finally, through using TracePro software, we simulated and calculated different incident light. The analysis results show that when the AOTF imaging spectrometer works at the wavelength range of 0.4 μm~0.9 μm, in order to make the diffraction efficiency reach the maximum value and the various influence factors reach the optimal values, the transducer length is d=2.5 mm, the tilt angle of grating selects 80 °and the incident light selects o light.
The imaging spectrometer based on acoustic-optic tunable filter (AOTF) is a new detector which integrates image, spectrum and polarization information. Because the acousto-optical crystal is the core optical splitter, its performance can affect the acquisition ability of the target information. Therefore, the key point of AOTF imaging spectrometer development is to study the method for improving the diffraction efficiency of acousto-optical crystal. Firstly we introduced the working principle of AOTF imaging spectrometer, derived the acousto-optical crystal diffraction efficiency equation based on coupled wave theory, then analyzed the influencing factors of the AOTF imaging spectrometer on acousto-optical diffraction efficiency by numerical simulation. Finally, through using TracePro software, we simulated and calculated different incident light. The analysis results show that when the AOTF imaging spectrometer works at the wavelength range of 0.4 μm~0.9 μm, in order to make the diffraction efficiency reach the maximum value and the various influence factors reach the optimal values, the transducer length is d=2.5 mm, the tilt angle of grating selects 80 °and the incident light selects o light.
2018, 39(3): 366-372.
doi: 10.5768/JAO201839.0302004
Abstract:
Non-dispersive infrared SF6 gas sensor has many advantages, such as wide measurement range, high sensitivity, strong anti-interference ability and so on. It has been widely used in power system. However, in the actual detection process, the change of the ambient pressure has a great impact on the detection accuracy of the gas sensor.Aiming at this, an air pressure compensation model of gas sensor was established by using radial basis function (RBF) neural network, and its measurement error is compensated by the good generalization and non-linear mapping ability. The experimental results show that when the designed air pressure compensation model of gas sensor is in the gas concentration of 3 260 mg/m3~9 781 mg/m3, and the air pressure is in the range of 100 kPa~120 kPa, the maximum measurement error is reduced from ±646 mg/m3 to ±52 mg/m3, the measurement accuracy is ±0.53%FS. Compared with the empirical formula method and the constant air pressure compensation, this method has higher measurement accuracy and stability, and reduces the volume and cost of the sensor.
Non-dispersive infrared SF6 gas sensor has many advantages, such as wide measurement range, high sensitivity, strong anti-interference ability and so on. It has been widely used in power system. However, in the actual detection process, the change of the ambient pressure has a great impact on the detection accuracy of the gas sensor.Aiming at this, an air pressure compensation model of gas sensor was established by using radial basis function (RBF) neural network, and its measurement error is compensated by the good generalization and non-linear mapping ability. The experimental results show that when the designed air pressure compensation model of gas sensor is in the gas concentration of 3 260 mg/m3~9 781 mg/m3, and the air pressure is in the range of 100 kPa~120 kPa, the maximum measurement error is reduced from ±646 mg/m3 to ±52 mg/m3, the measurement accuracy is ±0.53%FS. Compared with the empirical formula method and the constant air pressure compensation, this method has higher measurement accuracy and stability, and reduces the volume and cost of the sensor.
2018, 39(3): 373-378.
doi: 10.5768/JAO201839.0303001
Abstract:
Structured light fringe projection methods have been commonly used for three-dimensional (3D) shape measurements. However, for objects with large surface reflectivity range, saturation of the captured fringe pattern images leads to the phase information unavailable. The traditional high dynamic range scanning (HDRS) technique is complicated and time-consuming. An adaptive fringe-pattern projection method is proposed. Firstly, a sequence of phase-shifted fringe patterns with high gray level is projected onto surface of the measured object, which is used to predict and mark the overexposed points. Subsequently, the maximum input gray level (MIGL) of each saturated pixels is determined by the nonlinear least squares (NLS) fitting method based on the captured images with middle exposure level. Finally, the adapted fringe patterns are projected for phase calculation and 3D shape recovery. The experimental results demonstrate that the proposed method effectively achieved 3D shape measurement of object by avoiding image saturation in high-reflective surface regions. The simulation error of the proposed method is within the range of 0.02 mm. Compared with this, the actual measurement error is 0.14 mm, and the compensation rate for the over-exposure points can reach 99% in the actual experiment.
Structured light fringe projection methods have been commonly used for three-dimensional (3D) shape measurements. However, for objects with large surface reflectivity range, saturation of the captured fringe pattern images leads to the phase information unavailable. The traditional high dynamic range scanning (HDRS) technique is complicated and time-consuming. An adaptive fringe-pattern projection method is proposed. Firstly, a sequence of phase-shifted fringe patterns with high gray level is projected onto surface of the measured object, which is used to predict and mark the overexposed points. Subsequently, the maximum input gray level (MIGL) of each saturated pixels is determined by the nonlinear least squares (NLS) fitting method based on the captured images with middle exposure level. Finally, the adapted fringe patterns are projected for phase calculation and 3D shape recovery. The experimental results demonstrate that the proposed method effectively achieved 3D shape measurement of object by avoiding image saturation in high-reflective surface regions. The simulation error of the proposed method is within the range of 0.02 mm. Compared with this, the actual measurement error is 0.14 mm, and the compensation rate for the over-exposure points can reach 99% in the actual experiment.
2018, 39(3): 379-384.
doi: 10.5768/JAO201839.0303002
Abstract:
For the problem that in a certain type of aircraft flight test, the conventional airborne image measurement method can not be used to accurately calculate the eccentric positioning distance during aircraft running, a set of image measurement scheme based on ground multi-camera field stitching was designed.Through installing the high-speed camera array at the runway side, the high-speed camera control network was composed to achieve the full coverage of the image during aircraft running.By using the way of multi-camera intersection relay measurement and data stitching, the measurement of aircraft eccentric positioning distance was achieved. The simulation results show that using this program the maximum measurement error of aircraft eccentric positioning distance is less than 3 cm, which can meet the flight test accuracy requirements.
For the problem that in a certain type of aircraft flight test, the conventional airborne image measurement method can not be used to accurately calculate the eccentric positioning distance during aircraft running, a set of image measurement scheme based on ground multi-camera field stitching was designed.Through installing the high-speed camera array at the runway side, the high-speed camera control network was composed to achieve the full coverage of the image during aircraft running.By using the way of multi-camera intersection relay measurement and data stitching, the measurement of aircraft eccentric positioning distance was achieved. The simulation results show that using this program the maximum measurement error of aircraft eccentric positioning distance is less than 3 cm, which can meet the flight test accuracy requirements.
2018, 39(3): 385-391.
doi: 10.5768/JAO201839.0303003
Abstract:
In order to avoid the influence of robot model error on the hand-eye calibration of a three-dimensional shape flexible measurement system, the hand-eye calibration method was investigated. A calibration method based on the feature points fitting was proposed. The 3D shape measurement robotic system was established with a 3D shape scanner mounted on the robot end. In the calibration, the robot end coordinate system was measured with a laser tracker to obtain their transformation relationship. Then, 3D shape scanner and laser tracker were used for measuring feature points which fixed in the measurement field, and the transformation relationship between them could be identified by the constraint of feature points and the algorithm of Rodrigues matrix. Consequently, the hand-eye relationship was established directly. Experiment of hand-eye calibration was based on ATOS 3D optical scanner, Yaskawa-Hp20D robot and API laser tracer, and accuracy verification experiments were carried out. The verification experimental results show that the repeatability accuracy (3σ) of 3D shape robotic measurement system is better than 0.1 mm, the root-mean-square (RMS) error of distance is within 0.2 mm, and the accuracy of point cloud stitching is better than 0.7 mm after calibration. Meanwhile, this method can effectively avoid robotic model error which can be introduced in the process of traditional hand-eye calibration, the solution procedure adopts the linear method, and this method adapts to the 3D shape measurement robotic system.
In order to avoid the influence of robot model error on the hand-eye calibration of a three-dimensional shape flexible measurement system, the hand-eye calibration method was investigated. A calibration method based on the feature points fitting was proposed. The 3D shape measurement robotic system was established with a 3D shape scanner mounted on the robot end. In the calibration, the robot end coordinate system was measured with a laser tracker to obtain their transformation relationship. Then, 3D shape scanner and laser tracker were used for measuring feature points which fixed in the measurement field, and the transformation relationship between them could be identified by the constraint of feature points and the algorithm of Rodrigues matrix. Consequently, the hand-eye relationship was established directly. Experiment of hand-eye calibration was based on ATOS 3D optical scanner, Yaskawa-Hp20D robot and API laser tracer, and accuracy verification experiments were carried out. The verification experimental results show that the repeatability accuracy (3σ) of 3D shape robotic measurement system is better than 0.1 mm, the root-mean-square (RMS) error of distance is within 0.2 mm, and the accuracy of point cloud stitching is better than 0.7 mm after calibration. Meanwhile, this method can effectively avoid robotic model error which can be introduced in the process of traditional hand-eye calibration, the solution procedure adopts the linear method, and this method adapts to the 3D shape measurement robotic system.
2018, 39(3): 392-399.
doi: 10.5768/JAO201839.0303004
Abstract:
The optical imaging system with large viewing angle, high resolution and low distortion is the most critical core device for the full-view and high-precision three-dimensional measuring instrument. The current 3D measuring instruments inevitably produce various errors in the actual use process. Therefore, it is of great scientific and engineering significance to evaluate and reduce the measurement errors producing by the full-view and high-precision 3D measuring instrument scientifically and reasonably.The influence of the camera calibration error of inner orientation elements on the geometric positioning error, and the effects of the modulation transfer function (MTF) analysis for the camera optical system, the point spread function(PSF) analysis, the wave aberration and tolerance analysis on the matching error were studied. The research results show that the camera MTF is the most important factor affecting the three-dimensional positioning error of the system among various factors affecting the measurement error of the optical imaging system for three-dimensional measuring instrument.When the MTFN value of system is greater than 0.4 lp/mm and the geometric distortion of the system is less than 1 pixel, the PSF energy is concentrated in the ring with a radius of 3 μm(less than 1 pixel) and the PSF peak reaches 0.9, the positioning error of the 3D instrument can reach the second-order accuracy.
The optical imaging system with large viewing angle, high resolution and low distortion is the most critical core device for the full-view and high-precision three-dimensional measuring instrument. The current 3D measuring instruments inevitably produce various errors in the actual use process. Therefore, it is of great scientific and engineering significance to evaluate and reduce the measurement errors producing by the full-view and high-precision 3D measuring instrument scientifically and reasonably.The influence of the camera calibration error of inner orientation elements on the geometric positioning error, and the effects of the modulation transfer function (MTF) analysis for the camera optical system, the point spread function(PSF) analysis, the wave aberration and tolerance analysis on the matching error were studied. The research results show that the camera MTF is the most important factor affecting the three-dimensional positioning error of the system among various factors affecting the measurement error of the optical imaging system for three-dimensional measuring instrument.When the MTFN value of system is greater than 0.4 lp/mm and the geometric distortion of the system is less than 1 pixel, the PSF energy is concentrated in the ring with a radius of 3 μm(less than 1 pixel) and the PSF peak reaches 0.9, the positioning error of the 3D instrument can reach the second-order accuracy.
2018, 39(3): 400-404.
doi: 10.5768/JAO201839.0303005
Abstract:
In order to investigate the influencing factors on the surface roughness of titanium dioxide (TiO2) films, deposition of titanium dioxide (TiO2) films on K9 glass with different and the same substrate roughness was completed by ion beam assisted deposition electron beam thermal evaporation.The surface roughness of substrate and film were measured by TalySurf CCI non-contact surface profiler.The experimental results show that the surface roughness of TiO2 film increases with the increase of substrate surface, but is always less than the substrate surface roughness, indicating that TiO2 film has the function of smoothing base surface roughness.With the increase of deposition rate, the surface roughness of film decreases firstly and then tends to be smooth.For the substrate with a roughness of 2 nm, the change of the energy of the ion beam has little effect, and the surface roughness of the film is about 1.5 nm.With the increase of film thickness, the surface roughness of film decreases firstly and then increases.
In order to investigate the influencing factors on the surface roughness of titanium dioxide (TiO2) films, deposition of titanium dioxide (TiO2) films on K9 glass with different and the same substrate roughness was completed by ion beam assisted deposition electron beam thermal evaporation.The surface roughness of substrate and film were measured by TalySurf CCI non-contact surface profiler.The experimental results show that the surface roughness of TiO2 film increases with the increase of substrate surface, but is always less than the substrate surface roughness, indicating that TiO2 film has the function of smoothing base surface roughness.With the increase of deposition rate, the surface roughness of film decreases firstly and then tends to be smooth.For the substrate with a roughness of 2 nm, the change of the energy of the ion beam has little effect, and the surface roughness of the film is about 1.5 nm.With the increase of film thickness, the surface roughness of film decreases firstly and then increases.
2018, 39(3): 405-411.
doi: 10.5768/JAO201839.0305001
Abstract:
In order to obtain a large aperture zoom projection lens after optimizing a large aperture fixed focal length projection lens as the initial structure, a reasonable initial structure of fixed focal length lens was selected.According to DMD diagonal size, the dimension mapping of initial structure was done using AUTOCAD, the material of each lens was initially selected, and 5 zoom components were programmed in this system. The design was carried out by limiting the basic parameters and dimensions of lens with various operations, and 2 aspheric surfaces were used reasonably. After the optimization by using the optical design software ZEMAX and CODE V, a zoom projection lens system in visible light band was obtained. The system has a short focal length of 14.61 mm with 60° field of view(FOV) and 1.5 F number, while it has a long focal length of 29.31 mm with 30° FOV and 1.6 F number. The design results show that the modulation transfer function (MTF) of each FOV at each focal length is not less than 0.46 at the cut-off frequency 60 lp/mm. The dispersion angle at each focal length is not more than 1.6'. The projection lens achieves high quality of image. This lens system consists of 11 pieces of lenses and 1 piece of parallel plate, and the lens 2 uses aspheric surface. The system has less chips of lenses with low refractive index, and the material of each lens is easy to choose.
In order to obtain a large aperture zoom projection lens after optimizing a large aperture fixed focal length projection lens as the initial structure, a reasonable initial structure of fixed focal length lens was selected.According to DMD diagonal size, the dimension mapping of initial structure was done using AUTOCAD, the material of each lens was initially selected, and 5 zoom components were programmed in this system. The design was carried out by limiting the basic parameters and dimensions of lens with various operations, and 2 aspheric surfaces were used reasonably. After the optimization by using the optical design software ZEMAX and CODE V, a zoom projection lens system in visible light band was obtained. The system has a short focal length of 14.61 mm with 60° field of view(FOV) and 1.5 F number, while it has a long focal length of 29.31 mm with 30° FOV and 1.6 F number. The design results show that the modulation transfer function (MTF) of each FOV at each focal length is not less than 0.46 at the cut-off frequency 60 lp/mm. The dispersion angle at each focal length is not more than 1.6'. The projection lens achieves high quality of image. This lens system consists of 11 pieces of lenses and 1 piece of parallel plate, and the lens 2 uses aspheric surface. The system has less chips of lenses with low refractive index, and the material of each lens is easy to choose.
2018, 39(3): 412-417.
doi: 10.5768/JAO201839.0305002
Abstract:
To meet the market demand of large aperture and wide field zoom projection lens, we designed a zoom lens based on ZEMAX optical software.The zoom range is 16.27 mm~22.77mm, its field of view (FOV) is 63.7°~47.8°, the F number is 1.75-1.95.Working with a 1.55 cm (0.61 inch) LCOS projection display chip, a 190.5 cm(75 inch) picture can be projected at a distance of 2000mm.The total length of optical system is less than 160mm, it is composed of 10 lenses, which include 8 glass lenses and 2 plastic lenses.Design results show that at the space frequency limit 71lp/mm, the full FOV MTF is greater than 0.5 and the field curvature of each zoom section is within 0.1mm, the distortion is within 3%, and the imaging quality is good.Finally, we conducted the tolerance analysis of the optical system, and obtained a set of loose machining tolerances.
To meet the market demand of large aperture and wide field zoom projection lens, we designed a zoom lens based on ZEMAX optical software.The zoom range is 16.27 mm~22.77mm, its field of view (FOV) is 63.7°~47.8°, the F number is 1.75-1.95.Working with a 1.55 cm (0.61 inch) LCOS projection display chip, a 190.5 cm(75 inch) picture can be projected at a distance of 2000mm.The total length of optical system is less than 160mm, it is composed of 10 lenses, which include 8 glass lenses and 2 plastic lenses.Design results show that at the space frequency limit 71lp/mm, the full FOV MTF is greater than 0.5 and the field curvature of each zoom section is within 0.1mm, the distortion is within 3%, and the imaging quality is good.Finally, we conducted the tolerance analysis of the optical system, and obtained a set of loose machining tolerances.
2018, 39(3): 418-422.
doi: 10.5768/JAO201839.0305003
Abstract:
According to the requirements of small size and large field of view(FOV) for subminiature fiber soft endoscope, the fundamental design criteria was analyzed, the retrofocus objective with a "negative-positive" form was utilized as the initial structure, and the telecentric optical system in image space was determined for this design.Through theoretical calculation and continuous optimization with Zemax optical design software, a designed subminiature endoscope objective lens sample was fabricated finally, with operation wavelength, focal length, FOV and relative aperture of 0.48 μm~0.65 μm, 0.37 mm, 90° and 1:4, respectively.The optical system is composed of 4 pieces of lenses, including two single lenses and one cemented doublet.The result shows that its total length is 3.89 mm and maximum cross sectional diameter is 0.95 mm, which can satisfy the initial design requirements of image telecentric structure.The modulation transferfunction (MTF) value of the lens is approximately 0.7 at Nyquist spatial frequency of 77 lp/mm, near the diffraction limit. Furthermore, the designed lens has the peculiarity of wide FOV, short focal length, fine quality of imaging, reasonable structure and uniform illumination at image plane. It is suitable for the subminiature fiber endoscope demand.
According to the requirements of small size and large field of view(FOV) for subminiature fiber soft endoscope, the fundamental design criteria was analyzed, the retrofocus objective with a "negative-positive" form was utilized as the initial structure, and the telecentric optical system in image space was determined for this design.Through theoretical calculation and continuous optimization with Zemax optical design software, a designed subminiature endoscope objective lens sample was fabricated finally, with operation wavelength, focal length, FOV and relative aperture of 0.48 μm~0.65 μm, 0.37 mm, 90° and 1:4, respectively.The optical system is composed of 4 pieces of lenses, including two single lenses and one cemented doublet.The result shows that its total length is 3.89 mm and maximum cross sectional diameter is 0.95 mm, which can satisfy the initial design requirements of image telecentric structure.The modulation transferfunction (MTF) value of the lens is approximately 0.7 at Nyquist spatial frequency of 77 lp/mm, near the diffraction limit. Furthermore, the designed lens has the peculiarity of wide FOV, short focal length, fine quality of imaging, reasonable structure and uniform illumination at image plane. It is suitable for the subminiature fiber endoscope demand.
2018, 39(3): 423-428.
doi: 10.5768/JAO201839.0305004
Abstract:
In order to make sure of adequate lighting for the driver in the fog, snow, rain or dust and other terrible weather conditions, and prevent the opposite driver from glaring, a front fog lamp system with a cut-off line was designed. Based on the theory of non-imaging optics, an optimal illumination design method was adopted and numerical coordinates were used to solve the coordinates of each point on the free-form surface mirror (FFR). To achieve light distribution requirement, the fundamental surfaces were divided legitimately and the spread angle of surfaces were adjusted. Through tracing the light with Monte Carlo simulation method, the simulation result shows that the final effect of light distribution fully fulfills the photometric characteristics of power-driven vehicle front fog lamps regulations(GB4660-2016), the optical system has a clear cut-off line, the volume is small, the edge area also has higher light energy, and the light utilization rate reaches 52.7%.
In order to make sure of adequate lighting for the driver in the fog, snow, rain or dust and other terrible weather conditions, and prevent the opposite driver from glaring, a front fog lamp system with a cut-off line was designed. Based on the theory of non-imaging optics, an optimal illumination design method was adopted and numerical coordinates were used to solve the coordinates of each point on the free-form surface mirror (FFR). To achieve light distribution requirement, the fundamental surfaces were divided legitimately and the spread angle of surfaces were adjusted. Through tracing the light with Monte Carlo simulation method, the simulation result shows that the final effect of light distribution fully fulfills the photometric characteristics of power-driven vehicle front fog lamps regulations(GB4660-2016), the optical system has a clear cut-off line, the volume is small, the edge area also has higher light energy, and the light utilization rate reaches 52.7%.
2018, 39(3): 429-435.
doi: 10.5768/JAO201839.0307001
Abstract:
The laser eavesdropping technology does not directly irradiate the eavesdropping target and due to the scattering of the glass, the existing intercepted laser warning technology has no ability to obtain any information of the eavesdropping source. Aiming at this problem, an anti-laser eavesdropping warning system by staring at the windows using a charged coupled-device(CCD) camera and optical filter was proposed. At the same time, the space geometric model for the eavesdropping laser source, the scattered spot on glass and the anti-laser eavesdropping system was built, the image feature extraction algorithm such as the edge extraction and the least squares image fitting algorithm were used to fit the scattered laser spot contours, and finally, the mathematical model of eavesdropping laser light source was deduced. The experimental results show that, the laser eavesdropping warning system not only can detect the eavesdropping spot which is irradiated on the glass, but also can be traced back to the azimuth angle and pitch angle information of the laser beam, with positioning accuracy ≤ 4°, thus the purpose for locating the eavesdropping source position is achieved. The anti-laser eavesdropping early warning system and eavesdropping source localization technology mentioned can help to promote the further development of the existing laser warning technology, and play an active role in national defense security and other fields.
The laser eavesdropping technology does not directly irradiate the eavesdropping target and due to the scattering of the glass, the existing intercepted laser warning technology has no ability to obtain any information of the eavesdropping source. Aiming at this problem, an anti-laser eavesdropping warning system by staring at the windows using a charged coupled-device(CCD) camera and optical filter was proposed. At the same time, the space geometric model for the eavesdropping laser source, the scattered spot on glass and the anti-laser eavesdropping system was built, the image feature extraction algorithm such as the edge extraction and the least squares image fitting algorithm were used to fit the scattered laser spot contours, and finally, the mathematical model of eavesdropping laser light source was deduced. The experimental results show that, the laser eavesdropping warning system not only can detect the eavesdropping spot which is irradiated on the glass, but also can be traced back to the azimuth angle and pitch angle information of the laser beam, with positioning accuracy ≤ 4°, thus the purpose for locating the eavesdropping source position is achieved. The anti-laser eavesdropping early warning system and eavesdropping source localization technology mentioned can help to promote the further development of the existing laser warning technology, and play an active role in national defense security and other fields.
2018, 39(3): 436-441.
doi: 10.5768/JAO201839.0307002
Abstract:
In order to reduce the wastage due to mixing oil in long distance transportation of crude oil, it is necessary to detect the pipeline crude oil composition in time to determine whether there is a mixed oils accident. Routine examination of crude oil components in oil pipelines need to obtain sample from the field pipeline and make test in laboratory. This technology operation is complicated and easily affected by environmental factors, and failed to reflect the real-time changes of oil composition after oils are mixed.The application of laser Raman spectroscopy for the detection and identification of crude oil has been studied experimentally. In the experiment, two kinds of crude oils were selected from different blocks of Liaohe oil field. Identification of different types of crude oils was carried out through characteristic peaks and spectral analysis. The results show that the characteristic peak of 2 800 cm-1~3 000 cm-1 region is an important sign for the identification of saturated hydrocarbons by laser Raman spectroscopy. This section of Raman spectrum represents the diversity of saturated hydrocarbons components and distinguish between different types of crude oils. Further research is expected to form a set of rapid and real-time detection methods during transportation of crude oils.
In order to reduce the wastage due to mixing oil in long distance transportation of crude oil, it is necessary to detect the pipeline crude oil composition in time to determine whether there is a mixed oils accident. Routine examination of crude oil components in oil pipelines need to obtain sample from the field pipeline and make test in laboratory. This technology operation is complicated and easily affected by environmental factors, and failed to reflect the real-time changes of oil composition after oils are mixed.The application of laser Raman spectroscopy for the detection and identification of crude oil has been studied experimentally. In the experiment, two kinds of crude oils were selected from different blocks of Liaohe oil field. Identification of different types of crude oils was carried out through characteristic peaks and spectral analysis. The results show that the characteristic peak of 2 800 cm-1~3 000 cm-1 region is an important sign for the identification of saturated hydrocarbons by laser Raman spectroscopy. This section of Raman spectrum represents the diversity of saturated hydrocarbons components and distinguish between different types of crude oils. Further research is expected to form a set of rapid and real-time detection methods during transportation of crude oils.
2018, 39(3): 442-446.
doi: 10.5768/JAO201839.0307003
Abstract:
Aiming at the poor quality and low efficiency of PMMA microfluidic channel machining, the fabrication process technology of PPMA microfluidic channel with direct-writing femtosecond laser was studied. The effects of different laser parameters on the width, depth, roughness of the microfluidic channel, and the crater height of the deposits on both sides of the micro-channel were analyzed, as well as the changing rules.The experimental results show that when the laser scanning speed is 20 mm/s and the laser power is 0.5 W, the roughness of the microfluidic channel is low and the variation range is not obvious; when the laser energy increases from 0.5 W to 0.75 W, the width and depth of the microfluidic channel increase linearly with laser energy; when the laser power is greater than 0.5 W, the width, depth, roughness of the microfluidic, and the height of the crater of the deposits gradually increase with the increase of the laser power and the number of processing times. After calculation, the ablation threshold of PMMA is 0.357 J/cm2. By optimizing the process parameters, the microfluidic channel chip with low roughness, smooth surface and depth of 16 μm was prepared.
Aiming at the poor quality and low efficiency of PMMA microfluidic channel machining, the fabrication process technology of PPMA microfluidic channel with direct-writing femtosecond laser was studied. The effects of different laser parameters on the width, depth, roughness of the microfluidic channel, and the crater height of the deposits on both sides of the micro-channel were analyzed, as well as the changing rules.The experimental results show that when the laser scanning speed is 20 mm/s and the laser power is 0.5 W, the roughness of the microfluidic channel is low and the variation range is not obvious; when the laser energy increases from 0.5 W to 0.75 W, the width and depth of the microfluidic channel increase linearly with laser energy; when the laser power is greater than 0.5 W, the width, depth, roughness of the microfluidic, and the height of the crater of the deposits gradually increase with the increase of the laser power and the number of processing times. After calculation, the ablation threshold of PMMA is 0.357 J/cm2. By optimizing the process parameters, the microfluidic channel chip with low roughness, smooth surface and depth of 16 μm was prepared.
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