2016 Vol. 45, No. 10
column
- Invited paper
- Infrared technology and application
- Laser technology and application
- Laser radar technology
- Photoelectric devices and microsystem
- Advanced optical materials
- Optical design and simulation
- Adaptive optics
- Terahertz technology and application
- Photoelectric navigation and control
- Photoelectric measurement
- Information acquisition and identification
- Scene information processing
2016, 45(10): 1003001.
doi: 10.3788/IRLA201645.1003001
Single-frequency distributed Bragg reflector(DBR) fiber lasers were systematically investigated with rare-earth-doped silica fibers. The commercial Nd3+, Yb3+, Er3+/Yb3+ and Tm3+-doped silica fibers were applied in this demonstration to achieve the monolithic all-silica glass fiber lasers operating on single longitudinal mode. In the experiment, single-frequency operation was characterized, linewidth of tens of kilohertz was obtained (especially for the Er3+/Yb3+ co-doped fiber laser, the linewidth was narrow to 7 kHz) and the measured relative intensity noise approached the shot noise limit. The result confirms that commercial rare-earth-doped silica fiber can be an efficient gain medium to achieve single-frequency fiber laser with the wavelength range from 930 nm to 2m, which can be further commercialized for a wide range of applications.
2016, 45(10): 1003002.
doi: 10.3788/IRLA201645.1003002
Imaging lidars, operating at an active imaging approach, are capable of obtaining high resolution 3D images of objects at far distance even under low illuminance and complicated background conditions, thus it has been an inevitable trend for imaging lidars to be used as mission payloads in the UAS field with extensive application prospects. The types of imaging lidars were summarized and categorized, with technical analysis carried out on relevant research progresses both at home and abroad. On this basis, discussions are made in the view of system design and general structural formats, typical technical architectural options and platform suitability requirements for the UAV-borne imaging lidars were put forward, in combining the features of the UAV-borne environment and in association with comprehensive considerations of the factors as imaging distance, imaging resolution, imaging range and imaging speed (or frame rate) related to typical application situations, with an expectation to provide reference for relevant technology research and equipment development.
2016, 45(10): 1003003.
doi: 10.3788/IRLA201645.1003003
Multi-grain diamond grits were prepared through binding micro diamond particles with binder. SEM(Scanning Electron Microscope) was adopted to observe their microscopic morphology, and both multi-grain diamond grits and single diamond grits are made into fixed abrasive pads (FAP). The lapping performance of FAP embedded with multi-grain diamond particles was compared with that with single diamond particles. Results show that the average surface roughness lapped with multi-grain diamond FAP is almost the same as that lapped with single diamond FAP, and the multi-grain diamond FAP shows a higher and more stable material removal rate. The micro-fracture of multi-grain diamond grit in lapping process guarantees the realization of self-conditioning of hydrophilic FAP. In addition, the subsurface damage depth of quartz glass lapped with multi-grain diamond FAP is much smaller, which is only about 1/2 of that with single diamond FAP.
2016, 45(10): 1004001.
doi: 10.3788/IRLA201645.1004001
A new absolute calibration method based on the parametric down-conversion was introduced. In the parametric down-conversion process, two correlated-photons were produced whose wavelengths were 0.631 m and 3.39 m, the average photon countsper mode of the 3.39 m were obtained by measuring the ratio of 0.631 m photon counts in the two processes including the spontaneous parametric down-conversion and the stimulated parametric down-conversion, and further radiance of the infrared source could be calculated. In this paper, the calibration principle and experimental device were described and the uncertainty of this method was analyzed. The results show that relative combined uncertainties of a OPO laser was better than 1.18% and prove the feasibility of radiance calibration of the infrared radiation by detecting the photon counting in the visible band. The study results are expected to be used in the field of high precision calibration of infrared band based on stimulated parametric down-conversion and infrared OPO laser and other fields.
2016, 45(10): 1004002.
doi: 10.3788/IRLA201645.1004002
Adequate IR data set are essential to design the algorithms of ballistic targets detection, trace and recognition. In traditional IR image stimulations, the systems often emphasize optical imaging research of some specific scenario in order to solve the related image processing problems involving targets detection and data association. But for target recognition, the required data stimulation model would place emphasis on the study of change rule of radiant power in all of the potential dynamic parameters. To satisfy the requirements of data simulation for target recognition, the research emphasis in this paper was put on the study of scenario parameters and radiant dynamic characteristics. Meanwhile, the underlying factors were analyzed for the aid to design the widely-used recognition algorithm.
2016, 45(10): 1004003.
doi: 10.3788/IRLA201645.1004003
Measure body surface temperature with uncooled infrared thermal imager has many features such as fast, non-contact, short scope of measurement and higher accuracy requirement. But temperature of core and environment will interfere the accuracy of micro-bolometer to a great degree. A new method was proposed to correct temperature error caused by the difference of temperature between calibration and measurement. The data of core temperature, environment temperature and grayscale were measured and recorded, and then error correction parameter was calculated by using SVM. In the course of measurement, the environment temperature and core temperature were obtained with thermocouple and sensor in micro-bolometer, and then error correction of environment temperature and core temperature were finished by error correction parameter. By this way more accurate data of human body surface temperature field were gained. Experimental results shows that the error of new corrected method can be decreased at least 50% when the distance of measurement is about 2m, compared with thermocouple of high precision which had been calibrated.
2016, 45(10): 1006001.
doi: 10.3788/IRLA201645.1006001
The modeling and optimizing of fuse and warhead coordination of combination laser proximity fuze, which detects a warship target with ship-borne radar, were discussed. By means of building the 3D model of warship and the detecting model of laser proximity fuse, a better solution was provided to the problem of the damage effectiveness analysis, which was due to the complex surface of warships and the strong coupling between laser beam and vehicle body. Then, the Monte Carlo simulation, which has been widely used in the guidance accuracy evaluation, was used to calculate damage probability with different fuse-warhead coordination models. The modeling and simulation method provides an effective and universal way to optimize the coordination of any kind of fuse and warhead.
2016, 45(10): 1006002.
doi: 10.3788/IRLA201645.1006002
Laser pulse encoding of laser semi-active guided weapon is an important measure to resist the laser decoy jamming. To a certain extent, existing laser pulse encoding methods have regularity, are identified and cracked by jamming system easily, making laser semi-active guided weapons threatened. A time-controlled laser pulse interval encoding method was proposed. First the encoder was timed by BeiDou module to get absolutely precise time, taking the precision moment (hour, minute, second) as parameters, according to the encoding base frequency, time intervals of the pulses required were generated at the current precision moment by the encoding function only once. Then in the subsequent precision moment, pulse signals with pulse width adjusted were generated at time interval using the timer. Finally, the effectiveness and superiority of the method were verified by numerical simulation and real experiments. Experimental results indicate that timing accuracy is 20 ns, and pulse encoding accuracy is less than 30 ns. The method is characterized by various time intervals of pulses, without any regularity and period, small calculating amount of the encoding function, easy to implement, and strong anti-decoding capability.
2016, 45(10): 1006003.
doi: 10.3788/IRLA201645.1006003
The Coptis chinensis is one of the traditional Chinese medicine, which has the property of clearing heat and expelling toxi. It has the strong enrichment effect on the heavy metal during the growth process. In order to quickly identify the heavy metal elements in traditional Chinese medicine, taking Pb as an example, used laser induced breakdown spectroscopy(LIBS) as the detection method to detect it. The experiment took the Nd:YAG solid pulse laser as the excitation light source, eight channel spectrometer for spectral collection, the characteristic spectrum line Pb 405.7 nm was used for analysis. The following results were obtained through experiments. The optimal laser energy of the experimental condition is 60 mJ, and the optimal delay time is 1 s. The quantitative analysis was carried out on 6 different concentrations of samples under the optimum experimental conditions, and the calibration curves of the spectral intensity and concentration were fitted. The results show that the linear fitting degree R2=0.976, and the detection limit is 0.19%. The following conclusions can be drawn from the experimental results, LIBS can be used for the rapid determination of Pb pollution in Coptis chinensis, and LIBS also has great potential for rapid detection of heavy metals in traditional Chinese medicine.
2016, 45(10): 1006004.
doi: 10.3788/IRLA201645.1006004
The ultrasonic surface wave induced by the laser shock processing and its propagation in half-space elastic plate with micro crack were simulated with Abaqus software based on equivalent load method, and the effects of the size of the micro cracks on the ultrasonic signal were also discussed. The pulsed laser was equivalent to a load with Gaussian profile in time and space, and the relationship between the physical parameters of the laser and the load was established by the correction factor. On the basis of verifying the correctness of the finite element model and equivalent load method, the effect of the crack width and depth on the acoustic characteristics of reflection wave and transmission wave was discussed. The results show that the equivalent load method is effective to simulate the process of laser ultrasonic crack detection, and it is very important for the numerical simulation of laser ultrasonic and the application in the detection of the crack.
2016, 45(10): 1006005.
doi: 10.3788/IRLA201645.1006005
In order to improve the wear performance of 304 stainless steel, a method of laser shock processing(LSP) was put forward. The microstructure and performances of 304 stainless steel which are treated with and without laser shock peening were examined by electron backscattering diffraction(EBSD), microhardness and the ball milling experiment, the wear mechanism of 304 stainless steel produced by laser shock peening was discussed. The result shows that the wear rate of samples is decreases and microhardness is increased from 200 HV in primitive state to 260 HV which is treated by LSP. Under the action of grain fragmentation, a large number of sub structure formation at surface and the martensitic phase transformation, the microhardness and wear resistance of 304 stainless steel are improved.
2016, 45(10): 1030001.
doi: 10.3788/IRLA201645.1030001
Synthetic aperture ladar is a generalization of the synthetic aperture technique in the field of laser coherent detection with a higher resolution compared to the conventional synthetic aperture ladar.Compared with airborne and ground-based applications, there was no atmospheric turbulence and mechanical vibration in space. It's very suitable for the application of synthetic aperture ladar. At the same time, synthetic aperture ladar's advantages that the resolution doesn't change with distance change can also be conducive to large scale spatial distance detection. Non-cooperative target high resolution imaging model was established with analysis on the key parameters of the system and a geostationary orbit system was designed. The system engineering need further breakthrough key technology. Combined with theoretical analysis, a scaling model validation experiment was carried on with space satellite motion simulated by the turntable and the cross-range resolution of 1 mm was obtained, proving the practicability of the system analysis and rationality of the system. The space-based synthetic aperture ladar technology has great promotion in applications.
2016, 45(10): 1030002.
doi: 10.3788/IRLA201645.1030002
The near-space wind measurement is important to atmospheric dynamics, numerical weather prediction and guarantee of aerospace system. A 60 km Rayleigh Doppler lidar was developed to measure the wind of near space. This lidar was based on theory of the double-edge molecular technique. The system included three independent subsystems:one points to the zenith; the two others were tilted at 30 from the zenith with eastward and northward pointing, respectively. It emited 355 nm laser and could measure the wind within 15 km to 60 km. To validate the performance of the lidar and achieve wind data, field experiment of three months was carried out in the second half year of 2014, comparison of the wind data which showed good agreement with radiosonde.
2016, 45(10): 1030003.
doi: 10.3788/IRLA201645.1030003
According to the characteristics of high speed scanning of laser beam of the optical waveguide phased array, a staring single aperture, direct detection of the receiving system was designed with a linear APD array for target detection and target location. Considering the structure characteristics of the linear APD array and the demand of target detection, the micro lens array(MLA)was used to reduce the light loss, improve the receiving signal-to-noise ratio(SNR) in design scheme. Based on the ladar equation and considering of the influence of background noise, the influence of the received angle of view on signal-to-noise ratio was calculated and analyzed, the method of target location(Angle) based on single aperture receiving system with the linear APD array was analyzed. The results showed that increasing the pixel number of an APD array, namely reducing the field of view of the APD pixel, could improve the output SNR of the detection system, and improve the target location accuracy at the same time when the field of view of the optical receiving system is fixed. On this basis, considering of the demand of detection range, signal-to-noise ratio, and target location accuracy, the size of the detector array and the receive field of view are chosen. Finally, the performance of the design receiving system has carried on the comprehensive analysis and calculation, the indicators met the design requirements of the system.
2016, 45(10): 1030004.
doi: 10.3788/IRLA201645.1030004
The sporadic sodium layers(SSL) caused by atmospheric gravity waves over Langfang(39N, 116E) is studied by using the sodium fluorescence Doppler lidar and the meteor radar detection data of the near space environment comprehensive exploration station, Chinese Academy of Sciences. Firstly, the phase relationship between the atmospheric horizontal wind and vertical wind field was calculated and analyzed by the atmospheric gravity wave equation. Secondly, the SSL caused by atmospheric gravity waves was analyzed by the experimental data of the sodium fluorescence lidar and the meteor radar. The results show that the accumulation and joint action of the strong horizontal wind shear and vertical wind field direction caused by the atmospheric gravity wave increases the density of sodium atoms and form the SSL.
2016, 45(10): 1030005.
doi: 10.3788/IRLA201645.1030005
The imaging lidar has some advantages such as long detect distance, high frequency, narrow wave, high precision of distance and angle and less influence of illumination. So the imaging lidar is applied more and more in space. The application status of the imaging lidar was firstly introduced in space at home and abroad. Then the key technologies of relative navigation based on imaging lidar for space non-cooperative target were described. Finally, the simulation experiment of the spacecraft simulator was given. The simulation experiment result shows that the precision of relative navigation based on the imaging lidar for non-cooperation target is high. Then this relative navigation method is reasonable and feasible and meets the relative navigation mission requirements. So it could be applied to on-orbit spacecraft maintenance and serving, spatial manipulation of close distance space target, and so on. The research of this method provides the technology reference for the engineering implementation in future.
2016, 45(10): 1020001.
doi: 10.3788/IRLA201645.1020001
Total-internal-reflection(TIR) concentrator for solar concentration was designed, and a series of measures was adopted to optimize. Then lots of TIR concentrators was superimposed and assembled on the waveguide slab to form the waveguide concentrating module. Collected by the TIR concentrator array, the sun light incident on the waveguide slab continued to propagate in it, and was absorbed by the photovoltaic cells in the end. The experimental result shows that when the length of the waveguide slab increased from 400 mm to 4 800 mm, the optical efficiency decreased from 88.6% to 40.2%, while the irradiance concentration grew from 212 W/m2 to 980 W/m2. Thus different lengths of the waveguide slab can be selected according to different requirements. While getting the high output power, the area of photovoltaic cells used is decimated. At the same time, the TIR concentrator can be just placed on the waveguide slab, avoiding the demand of aligning strictly the lens array and the waveguide slab, which is convenient in installation and adjustment.
2016, 45(10): 1020002.
doi: 10.3788/IRLA201645.1020002
The design of the radio frequency attenuator was based on the MEMS switch. First of all, the basic structure of the electronic circuit was presented with CPW as the transmission line, the contact MEMS switch as the controller and the electric capacity in the switch as the balance criteria to match the Q value. Secondly, the size of cross section of waveguide was calculated abstractly. Thirdly, the resistance values in the T system were calculated according to the reduction. From the simulation on the CST microwave studio, the comparison of S values of first-order and second-order attenuator revealed that the radio frequency could keep a stable reduction in the wider band after the Q values were matched. Finally, the attenuator was sampled and tested. The result shows that the work frequency range of attenuator could be extended by Q value match which is a new feasibility for the stable attenuation of high frequency signal.
2016, 45(10): 1020003.
doi: 10.3788/IRLA201645.1020003
Space-borne laser ranging could measure the distance between laser range finder and detection target through the transmitter emitted by a high degree of stability of laser pulse, which related to the design and application of laser. In particular, in order to achieve the function and performance of laser power supply was the most important. Therefore, the realization of the external control and real-time status of the amount of the acquisition become particularly important in space-borne laser power supply. Based on FPGA technology, by use of AC/DC power supply module, remote telemetry components and display control module, a system was designed to provide external signal, Q-signal and AD/DA control signal of the laser power supply, in order to achieve the real-time telemetry of the status of amount of laser power supply, and the real-time adjustment and control of LD current signal and Q-signal. The system could be set to control the laser repetition rate and laser emission times, can also be related to real-time display of the number of the laser repetition rate and laser emission times, could also be related to real-time display of number of the laser pulses and the remote measurement of the laser power supply. At the same time, the design and implementation of the system which involved in laser power supply were described in details, and they would further propose the improvement program of high reliability performance and functionality, in order to enhance remote control and telemetry system of the laser power supply.
2016, 45(10): 1020004.
doi: 10.3788/IRLA201645.1020004
Existing laser warning based on the diffraction grating has the following disadvantages. The diffraction efficiencies of 1 order based on sinusoidal grating are low and the diffraction efficiencies of -1 order and 0 order based on blazed grating are very low. These shortcomings have reduced the reliability of the laser warning. A method for improving the blazed grating was presented. The two blazed gratings inverted docking, some no grating space was vacated in the middle of the grating. This improvement can increase the diffraction efficiencies of -1 order and 0 order. This grating will effectively overcome the missing alarm. The improved blazed grating was designed and processed with blazed wavelength =800 nm. The diffraction efficiencies of 0 order and 1 order were derived. This grating was tested by two-dimensional laser warning using the laser with =808 nm and =850 nm. When wavelength of the incident light close to the blaze wavelength, the experimental results show that the improved blazed grating diffraction efficiencies of -1 order and 0 order have greatly improved, and they can be effectively detected by CCD. The reliability of two-dimensional laser warning is improved using this improved blazed grating.
2016, 45(10): 1020005.
doi: 10.3788/IRLA201645.1020005
In order to reduce the transmission loss, strengthen the medium loaded plasma waveguide mode field constraint and optimize the plasma waveguide transmission performance, a further research on waveguide transmission characteristics of the dielectric loaded surface plasmon was studied. A waveguide with spine type medium load plasma was designed and the relationship between the geometric parameters and the geometrical parameters of the waveguide in the mode field distribution and its transmission parameters were studied. The simulation results show that the electric field component of the base mode is mainly distributed in the metal/dielectric layer 1 interface. As a result, the transmission characteristic of the model changes with the variations of the geometrical parameters of waveguide. Hence, the field can be effectively controlled by shifting the geometrical parameters of the waveguide and localization can be enhanced obviously.
2016, 45(10): 1021001.
doi: 10.3788/IRLA201645.1021001
In order to research the surface thermal stress in Sapphire/AlN/GaN epilayer and the stress influence factor, the surface stress in materials with diameter of 40 mm were respectively calculated and studied by the finite element modeling method, and the rationality of the model was proved. The dependence between the epilayer surface thermal stress and different parameters were respectively analyzed including growth temperature, AlN transition layer thickness and Sapphire substrate thickness. The results indicated that the epilayer radial stress was an order of magnitude greater than the epilayer axial stress on 1 200℃; and the stress was uniform in the radial direction with the variation of 0.38% in the area with diameter of 32 mm; the epilayer surface thermal stress was in direct proportion to growth temperature during the temperature from 600℃ to 1 200℃. The results are helpful for study on new technology of epitayers growth and establish the quality choice standard of low stress epilayer.
2016, 45(10): 1018001.
doi: 10.3788/IRLA201645.1018001
Head mounted display (HMD) as a kind of visual systems requires a large field of view (FOV), a large exit pupil distance, a small volume, and light in weight. In order to meet these requirements, a compact two-mirror structure and free form surfaces were introduced to the system. Two-mirror structure was benefit to minmize the weight and volume of the system. Free form surfaces was used to correcte the aberrations introduced by wide FOV and non-rotationally symmetry of the HMD. The abberation compensate theory and design method were also described in detail. An achromatic HMD with 5025 FOV, 8 mm pupil, 27 mm eye clearance was designed. The modulation transfer function (MTF) value was more than 0.4 within the entire FOV. The system could be applied to the next generation HMD technology.
2016, 45(10): 1018002.
doi: 10.3788/IRLA201645.1018002
An off-axis three-mirror system with large linear field of view was designed. The system is with a focal length of 1 200 mm, a F-number of 12, a linear field of view of 301. In the system, x-y polynomial freeform surface was applied as the tertiary mirror surface type to increase the system design degree of freedom, furthermore, in order to bring considerable convenience to alignment, and obtain an axial symmetrical imaging quality about the tangential plane, the x-y polynomial was modified. The design results show that system modulation transfer function value is above 0.45@50 lp/mm, wavefront error maximum value is 0.056(=0.632 8 m), RMS wavefront error value is 0.036, maximum distortion value is 0.8%, and the imaging quality is symmetrical about the tangential plane. The realizable tolerance values are allocated, and based on Monte Carlo analysis method the tolerance analysis results show that the system RMS wavefront error is less than /14. The off-axis three-mirror system has a certain reference value for remote sensor optical system design, and it is suitable for wide swath linear pushbroom imaging system.
2016, 45(10): 1018003.
doi: 10.3788/IRLA201645.1018003
A visible infrared integrated optical system of a large field of view is designed by using optical software, and the FOVs of the visible system and infrared system are 5.2 degrees and 5.12 degrees respectively. The orbit of the system is 675 kilometers, and have a large width of 61.3 kilometers and 60.36 kilometers respectively can be observed. The system uses a partial field to separate the field of visible light and infrared light respectively, and realize dual optical paths, dual bands and double fields of view imaging at the same time, which improve utility of visible light and infrared light by avoid the use of dividing light elements. Visible light system selects a three mirror system with a focal length of 9 000 mm. The infrared system uses two three mirror systems with a total focal length of 2 025 mm, and the entrance pupil of the rear system has the same position and size with the exit pupil of the former system. After optimizing, the modulation transfer function of the visible system is more than 0.45 at 50 lp/mm, and the infrared system's modulation transfer function is above 0.65 at 25 lp/mm respectively. The imaging quality of both systems reaches the diffraction limit.
2016, 45(10): 1018004.
doi: 10.3788/IRLA201645.1018004
Rhomboid micro stroke amplifier was designed in order to raise the tilting range of fast steering mirror driven by piezoelectric. Firstly, the theory of stroke amplifier was expounded and the key factors were analyzed with the help of energy method. Secondly, the connection between the performance requirement of fast steering mirror system and key factors of rhomboid mechanism was built. Then, key factors were resolved for self-designed fast steering mirror system. Finally, mode finite element analysis was made for both rhomboid mechanism and fast steering mirror and the experiment was carried out for testing the tilting range of fast steering mirror. The analysis and experiment shows that the tilting range is more than 6' and the frequency of first mode is about 400 Hz which satisfied the need of fast steering mirror system. The conclusion is that the multiple and the maximum driving force of rhomboid mechanism conflict with each other which can be coordinated by resolving the key factors of rhomboid micro stroke amplifier in order to meet the need of the whole system.
2016, 45(10): 1018005.
doi: 10.3788/IRLA201645.1018005
To achieve dynamic performance improvement of the cross-spring compliant micro-displacement magnifying mechanism(CMDMM), response surface methodology(RSM) was used to optimize the structure parameters for multi-objective analysis. Firstly the parametric analysis FEA model was built, and the working principle of the mechanism was analyzed. Having analyzed the kinematics, dynamics with the ANSYS software, the design performance parameters of the mechanism were determined. The standard response surface were established adopting the inscribed central composite designs methods, and the optimize parameters were extracted. The 8 groups of cross-spring thicknesses were selected to be the design variables. The former three steps natural characteristics were taken as optimal objective. The stiffness of the mechanism was used as the constraint function. A multi-objective optimization design was proposed by Nonlinear Programming by Quadratic Lagrangian(NLPQL) method. Three candidate points were given after thousands iterations. One best candidate point was chose to be corrected as the final design point. The whole optimization program was established from all above steps. Compared the former three steps natural frequency of vibration before and after optimization, the first order frequency raised by 80%, the second and third orders become more than 4% increase. From those discussions above, a positive correlation between thethickness of the cross-spring and the dynamic performance can be concluded. It also showed that the thicknesses from different kinematic pairs had different effects on the dynamic. The response surface methodology was effective in dynamics optimization design.
2016, 45(10): 1018006.
doi: 10.3788/IRLA201645.1018006
Highly integrated TDI CCD focal plane system was proposed, the thick-film integrated module of TDI CCD driving unit is applied successfully in the domestic. The research was finished on highly integrated high-speed and multi-spectral TDI CCD focal plane system, including 16 channel CCD output signals and pixel read-out frequency of 20 MHz. The use of dual-channel CCD signal processing analog front end, thick-film integrated drive unit module, high-speed image data transmission LVDS interface and mechanical, electrical, thermal integrated and simulated design approach greatly increases the integration of TDI CCD focal plane system and reduces the complexity of system interconnection. The system includes four image data transmission interfaces, each transmission capacity is 1.6 Gbps to 2.5 Gbps. It is up to 10 Gbps total of the image data bandwidth, ensuring high data rates and improving anti-interference performance of data transmission. The system design and multi-spectral TDI CCD detector working principle was described. As the key technologies, mechanical and electrical integrated design, thick-film integrated technology of drive unit and high-speed serial transmission bus technology were analyzed. The system was tested by using TDI CCD transfer function test chip, average value of modulation transfer function is 0.511 in the total focal plane system.
2016, 45(10): 1018007.
doi: 10.3788/IRLA201645.1018007
When a planar optical wavefront is made to propagate through a supersonic turbulent boundary, affected by the density fluctuation, its propagation direction and phase will change, which make target image blur, shifting, jitter et al and bring problems for target identification. By using the BOS-based Wavefront Sensing(BOS-WS) technique based on the principle of Background Oriented Schlieren(BOS), the optical wavefront propagated through a Ma=3.0 supersonic turbulent boundary layer was acquired. Based on the wave optics principles, the corresponding Point Spread Function(PSF) distribution and degraded image were computed. The research results show that many changes are found on the PSF peak value, peak value location and shape. The PSF peak value deceases largely, the PSF value peak position appears a significant move, the PSF shape appears multi peaks phenomenon, the spatial randomness of turbulent boundary layer density distribution is obtained, the image appears to a certain degree degradation after the PSF processing.
2016, 45(10): 1018008.
doi: 10.3788/IRLA201645.1018008
For the random vibration response of a micro satellite loaded antenna and S-flywheel supporting structure does not meet the criteria for system design of the micro-satellite based on integrated design concept, a co-supporting structure design of the satellite borne antenna and the flywheel was presented. The support structure sensitive point of random response RMS value as the optimization objective, the volume integral number and frequency constraints, the optimization mathematical model was established, the structure was optimized by using OptiStruct software, the support structure optimization treated by finite element analysis, the fundamental frequency reach 200 Hz, the quality is reduced by 65.6%; the vibration test of support structure performance was verified, the maximum relative amplification rate of x, y, z three direction acceleration response RMS value is 0.54. Results show that the optimization method is effective and feasible, and the supporting structure dynamic performance meets the requirements of a micro satellite design index optimization design well.
2016, 45(10): 1032001.
doi: 10.3788/IRLA201645.1032001
The numerical model of correlation wave-front sensing algorithm (COR) based adaptive optics (AO) system was established. Collimated uplink propagation beam corrected by AO was numerically simulated. The influence of photon noise and read-out noise on AO correction efficiency under different thermal blooming strength was analyzed, and compared with the results based on center of gravity(COG) algorithm and threshold center of gravity(TCOG) algorithm. The results show that the COR which is more robust to variety of the noise strength and thermal blooming strength, can improve the wave-front sensing precision of the Shack-Hartmann wave-front sensor(SH-WFS) under low signal-to-noise ratio (SNR) circumstance and restrain the phase compensation instability (PCI) induced by noise either, which will improve the AO correction efficiency and stability under low SNR circumstances.
2016, 45(10): 1025001.
doi: 10.3788/IRLA201645.1025001
Terahertz(THz) wave generation by organic crystal 2-[3-(4-hydroxystyryl)-5,5-dimethylcyclohex-2-enylidene]malononitrile(OH1) with a collinear phase-matching scheme based on cascaded difference frequency generation(DFG) processes was theoretically analyzed. The cascaded Stokes interaction processes and the cascaded anti-Stokes interaction processes were investigated from coupled wave equations. THz intensities and quantum conversion efficiency were calculated. Compared with non-cascaded DFG processes, THz intensities from 13-order cascaded DFG processes were increased to 15.96. The quantum conversion efficiency of 1 377% in cascaded processes can be realized, which exceeds the Manley-Rowe limit.
2016, 45(10): 1031001.
doi: 10.3788/IRLA201645.1031001
According to the problem of disturbance rejection rate(DRR) within strapdown imaging seeker due to different scales and dynamic error between sensors of missile, the mechanism of DRR was expounded, and the methods of estimating the sensors' scale factors and compensating the dynamic of seeker to inhibit the effect of DRR were proposed. Firstly, the mathematics platform of the seeker was established, and the unsented Kalman filter(UKF) to estimate the scale of sensors and line of sight rate was used, then matched filter to compensate the dynamic of seeker was applied. Finally, numerical simulations were performed to testify the effectiveness of the proposed methods on the aspects of missile body attitude stability and the guidance system accuracy. The simulation results indicated that DRR could be inhibited and the performance of the missile system is also improved after the filtering technique is applied.
2016, 45(10): 1017001.
doi: 10.3788/IRLA201645.1017001
A novel hyperbolic-circular flexure hinge was presented. According to the Castigliano's second theorem, the compliance calculations of the flexure hinge were derived. From the deduced equations, the effects of radius, minimum thickness and depth of cut on the hinge for flexibilities were deeply researched. Meanwhile, the finite element model of the flexible hinge was also built by adopting solid element, and then the simulations of different geometric parameters were obtained. Comparing simulations and analytical solutions explained that:the maximum error is below 8%, which verified the correctness of the equations. In addition, the comparisons on the flexibilities of flexure hinges with various shapes showed that:the hyperbolic-circular flexure hinge had better ability to rotate and higher sensitivity to load. Thus, the design of the new hyperbolic-circular flexure hinges in this paper is more suitable for support structure of Fast Steering Mirror and provides a theoretical basis for design and optimization of hybrid flexure hinges.
2016, 45(10): 1017002.
doi: 10.3788/IRLA201645.1017002
To research the technology of displacement sensing based on near-infrared microscopic interferometry in spectral domain, the impact of fringe carrier on extracting displacement is analyzed, the formula of spectral central wavelength and displacement range was deduced. Also the crosstalk of interference fringes caused by the visible light from illuminant recorded by the spectrometer was discussed. The near-infrared microscopic interference experiment system of Michelson type in the spectral domain is built up, the precision of displacement sensing at one time is 0.02 m. The measured deviation of a standard step whose nominal value is 7.732 m can reach 0.044 m. No axial scanning was needed to realize displacement sensing with adopting device of near-infrared microscopic interference in the spectral domain. Through analyzing character of interference fringes in the near-infrared band, a conclusion that the accuracy of displacement sensing will enhance effectually can be drawn if the recorded fringes were transformed to fringes of linear carrier frequency for resolving, the range of displacement sensing was increased effectively by enlarging the center wavelength, and the crosstalk of interference fringes caused by the visible light can be restrained with a short-wave pass filter.
2016, 45(10): 1017003.
doi: 10.3788/IRLA201645.1017003
To measure accurately dynamic thermal focus length of laser crystal in solid state laser, a new and accurate method for measuring dynamic thermal focus length by means of the indicator light polarization converted was presented in the paper. A formula of dynamic thermal focus length was established based on imaging theory of geometrical optics. An indicator light was traveled through laser medium which possessed thermal lens effect round trips. The measuring beam was separated from the optical path by a method of polarization converted. Then, the measuring beam was detected by CCD camera. The experiment setup for measuring dynamic thermal focus length of laser crystal was put up and the dynamic thermal focus length of laser crystal end-pumped and side-pumped were measured respectively. The measuring error was analyzed at last. The result showed that the measuring error of dynamic thermal focus length is only 0.8 mm by means of the indicator light polarization conversion, and the error can completely meet the design requirements for laser cavity.
2016, 45(10): 1017004.
doi: 10.3788/IRLA201645.1017004
A high precision laser screen dispersion measurement method based on the line laser parallel detector array composite was presented to solve the difficulty of barrage weapons location dispersion test. The principle of measuring shell coordinate based on line laser parallel detector array composite was researched. Impact points coordinate algorithm was derived and the impact points coordinate algorithm flow chart was presented. Algorithm errors caused by laser detector array precision was analyzed, coordinate errors distribution of coordinates positions and target area were researched. The analysis results indicate that maximum theoretical x negative innate errors increases by 3.44 mm, from 1.56 mm to 5 mm and the maximum y innate errors was 2 mm when the regular target area increased from 3 m3 m to 10 m10 m unless small area with high errors. Tests have done with the proto whose target area was 1 m1 m, the results show that the maximum x errors was 3.6 mm, and the maximum y errors was 2.8 mm when the precision of detector array was 1.6 mm. This measuring method has the advantages of high measuring precision, easy to construct large target area, easy to install.
2016, 45(10): 1026001.
doi: 10.3788/IRLA201645.1026001
Many computer vision algorithms need to measure the scene radiance accurately, and the camera response function can achieve this result by establishing the mapping between image brightness and scene radiance. Camera response function calibration is the key to high dynamic range image fusion. The properties that all camera response functions share were analyzed in the paper, which helps us to find the constraints that any camera response function must satisfy and establish the theoretical space model of camera response function. Firstly, the database of real-world camera response functions was analyzed by principal component analysis algorithm and low-parameter empirical model of response was established combined with constraints; secondly, appropriate parameter number was chosen according to input images; finally, the coefficients to the low-parameter empirical model of camera response function was solved by least square method. The algorithm proposed in this paper could establish camera response function of the imaging system accurately by interpolating to sparse samples or multiple images with different exposures in arbitrary environment. The effectiveness of this camera response function calibration algorithm was verified by different experiments, which proved high-accuracy and high computational efficiency of this algorithm.
2016, 45(10): 1026002.
doi: 10.3788/IRLA201645.1026002
Aiming at improving the PIR array's detectivity and perception, reducing the domain in detect cost, a PIR single node array was put forward to push the target trajectory. In order to simplify the structure, only four dual pyroelectric infrared sensors were used to compose a single node array. Meanwhile, when the PIR is in the stationary state, it can detect the direction of the movement and the distance from the target to the panel point. And when the PIR is in rotational state, it can detect the angle and time of the moving target. Then they can use these data to achieve the target trajectory only by a single node. After pushing a target's trajectory, it continues the detection to the target, and will get new data. Thus it can correct the trajectory step by step, which will increase the reliability of the trajectory pushing. Proved by experiment, this method breaks through the past multi-node localization and trajectory pushing. Meanwhile, instead of the previous eight PIR sensor-four dynamic four static, the author innovatively come up with the single node array just containing four PIR sensors, which greatly reduces the detect cost and has a very high practical value and reliability.
2016, 45(10): 1028001.
doi: 10.3788/IRLA201645.1028001
In the existing automatic focusing systems, the traditional evaluation functions are sensitive to noise and have small focusing range which will affect the accuracy of the auto-focusing results. An autofocus evaluation function based on gradient operator with variable frequency was proposed. It solved the problem that the coverage of the evaluation functions is small when the fuzzy degree is larger by sampling frequency reducing method in the image space. As mentioned above, an absolute value gradient operator with threshold value selection was adopted, which not only improved the noise resistance but also reduced the complexity. Then, the simulation experiments and actual tests were carried out to validate the satisfactory performance of the method. The experimental results indicate that it can meet the characteristics of wide focusing range and high sensitivity at the same time when the gradient operator with different sampling frequencies was used and then compared with the existing traditional methods. The quantitative indicators were used to illustrate that the calculation speed of the evaluation function were improved a lot compared with the existing evaluation function. The autofocus evaluation function proposed was demonstrated has better anti-noise performance and has variable focusing range with high sensitivity and high real-time, which can evaluate the sharpness degree of the images in the process of automatic focus accurately.
2016, 45(10): 1028002.
doi: 10.3788/IRLA201645.1028002
In order to realize real-time and accurate detection of water turbidity in the water treatment process, the turbidity detection system was designed based on infrared light scattering and the turbidity forecasting model was put forward based on clustering grey fusion. The infrared light emitting diode with 890 nm wavelength was used as the light emitting device, the photosensitive diode was used as the receiver, and the response time of the detector was short, and the zero error was small. The data collected by the sensor was processed by the method of grey prediction algorithm and cluster fusion. The data processed by the cluster fusion were as the input data of the grey predictive control, and the output data of the grey predictive control and the fusion data were compared and analyzed. Data tracking and operation were carried out through the actual project. The average error of the measured value and the output value of the turbidity prediction is 0.008 7 NTU. Grey fusion algorithm is superior to the single grey prediction algorithm, to ensure that the water quality turbidity parameters are stable and meet the requirements of water quality, and ensures that the water quality turbidity parameters are more stable and meet the requirements of water quality.
2016, 45(10): 1028003.
doi: 10.3788/IRLA201645.1028003
For the feature extraction methods of hyperspectral remote sensing data, a new method, called supervised neighbor reconstruction analysis(SNRA), was proposed. First, this method reconstructs each point with neighbor points from the same class. Then, it preserves the reconstruction relationship and separates the data points from different classes as far as possible in low-dimension embedding space. And a total scatter matrix is used to constrain the correlation between data points. Finally, it obtains an optimized projection matrix and extracts the discriminating feature. SNRA not only preserves the local structures of intraclass data but also enhances the separability of interclass data. And it reduces the redundant information. The experiments on Indian Pine and KSC hyperspectral remote data sets show that the proposed method can better reveal the intrinsic property of hyperspectral remote sensing data and effectively extract the discriminating feature to improve the classification result.
