2015 Vol. 44, No. S1
2015, 44(S1): 1-7.
An analysis model about the effects of the temperature on the imaging and detection performance of the space infrared optical system was established. Firstly, on the basis of the finite element analysis, the optical surface deformation was characterized by Zernike polynomials. Considering the effect of temperature on materials' refractivity, the analytical method of MTF was improved, and then the changing rule of system MTF with the variation of thermodynamics and inertial load was presented. Secondly, the calculation model of camera background radiation was established by integrating the spontaneous radiation of the system, based on the heat transfer mechanics. This model can be used to calculate the irradiance generated by the spontaneous thermal radiation in image plane. Then the performance analysis method of infrared optical system was proposed. Finally, experiments were conducted using a real space infrared optical system. Experimental results indicate that when the system thermal control temperature is set at 10 ℃, the background radiation can be decreased by 48.6%, as MTF can be decreased by 30% as well. The proposed method can be used to study the background radiation of space infrared optical system and the changing rule of the system's imaging quality, and then optimize the system's working temperature, which provides theoretical guidance for thermal control design.
2015, 44(S1): 8-12.
The vignetting effect is a widespread phenomenon in the process of infrared imaging. Because the output brightness or contrast of the infrared imaging system is low, the impact of vignetting effect on the performance of the system is very serious. Therefore, it is particularly important to correct the vignetting effect. The cause of the generation of the vignetting effect was analyzed. Firstly, a fast correction method was proposed. The difference between scene was used to get background information. The background gray level distribution was approximated by the two-dimensional Gauss distribution, and the correction factor was obtained. Then the background extraction method was improved by using the variance information, and the method was applied to a more complex scene. The concept of the sum of pixel difference was presented. After correction, the sum of pixel difference decreaseal to 1/5-1/2 of the sum of pixel difference before correction. The correction effect of the two methods is better without using a reference scene of uniform gray distribution.
2015, 44(S1): 13-16.
To deal with the requirements of automatic control and failure protection during the reliable test of IR component, a system to monitor the testing was proposed. Programmable logic controller (PLC) was used as the control center. By use of the profibus-DP bus as the communication bus, the field device was monitored in real time and coordinated to operate in sequence. And then the testing environment was automatically maintained. The failure protection would automatically run when the testing environment failures. Meanwhile, based on Wincc flexible, the operational status of equipment was displayed and stored the operational status of equipment in real-time with the human-machine interface. Finally, a reliable experiment was performed by use of the monitoring system, and the results show that the monitoring system can run stably. By use of which the auto maintaining vacuum is superior to 10-4 Pa, and the auto maintaining temperature is lower than 90 K, which can satisfy the requirements of the reliable test of IR component.
2015, 44(S1): 17-22.
The infrared radiation property of solid propellant plume was measured by a BOMEN MR-254 infrared spectrometer. At the resolution of 4 cm-1 and the testing distance of 5 m between the plume and the spectrometer, the infrared emission spectra of aluminized solid propellant and NEPE solid propellant were recorded in real time. The radiation intensities of the plume vs. combustion time in 3-5 m band region were obtained by calibrating the original spectra by instrument response function. The temperatures of the propellant plumes were calculated using the molecular fine structure emission spectral lines of the gaseous products released during combustion. Factors influencing the radiant energy and temperature of solid propellant were discussed. The experimental results show that the passive remote sensing FTIR, as a rapid, in situ and non-intrusive technology, can be used to study the infrared radiation characteristics of solid propellant plume in an effective way.
2015, 44(S1): 23-28.
Considering the existence of a large number of outliers caused by the difference of infrared spectral radiation properties of cloud background and using different sensors, a new multi-modal registration method with the introduction of outliers rejection mechanism was proposed in order to realize the accurate registration of dual band infrared images. First, outliers was robustly estimated by computing dense SIFT flow. Then, through gradient based framework with the cost function of normalized correlation coefficient the accurate registration of dual band infrared images was achieved. Experimental results show that the registration parameters can converge to the global optimization fleetly after the rejection of outliers, and the algorithm can still maintain high registration accuracy to dual band infrared images with poor correlation.
2015, 44(S1): 29-34.
Under the ocean background, a segmentation method was proposed based on the fusion of multiple features for infrared ship segmentation. This method is used to extract horizontal edge information and vertical edge information from infrared image. First of all, the mean of the data collected on different scales was got, and the result image was seen as the first feature. Furthermore, for the problem of ship targets with different sizes, the improved multistage filters was employed for infrared image, so as to prohibit background and highlight target. The multistage filtered image was identified as the second feature. Finally, the local maximum gray value of infrared image was identified the third feature. Then these three features would be normalized and integrated. During the process of infusion, firstly, each featue image was given weight; then, an appropriate infusion coefficient for fused image was selected. The fused image was segmented by adaptive threshold, followed by a morphological plastic in order to remove isolated areas, supplement holes and improve the segmentation results. The simulation results show that, compared with traditional segmentation strategies, the proposed segmentation method based on multiple features fusion is more likely to meet the demands of segmentation.
2015, 44(S1): 35-40.
The key results of multiple saturation output characterization campaigns of charge coupled device(CCD) were presented. These characterizations encompassed proton, neutron and cobalt-60 irradiation tests at room temperature and annealing. This gives us the opportunity to discuss differences and similarities on CCDs of degradation of saturation output induced by proton, neutron and cobalt-60 radiation. The experiments show that the saturation output is degraded markedly induced by total ionizing dose, degradations of saturation output at different total dose and the recovery after annealing were compared, while no obvious degradation after neutron irradiation(neutron irradiation only induced displacement damage). Mechanisms for these saturation output changes were discussed, saturated output degradation mainly caused by threshold voltage decreases of irradiation, resulting in full-well capacity decline. In addition, the gain of the output amplifier was decreased by total ionizing dose. Further insight on the underlying physical mechanisms could be gained by simulating the charged particle track influence on the pixel electric fields, along with the diffusion, drift, and recombination processes that occur between charge generation and collection.
2015, 44(S1): 41-45.
When the high energy laser propagates through the atmosphere, many atmospheric turbulence effects appear, including the beam drift, beam jitter, beam expansion and so on. Based on the wave optical theory, a four-dimensional computer code simulating the turbulence effect was established in this work. The influence of turbulence on different waveform laser, such as the Gaussian laser and the rectangle laser, was calculated. The numerical results show that when the turbulence becomes stronger, the phase aberration of laser become larger and the power in the bucket and the focusing ability become weaken. A comparison between the Gaussian beam and rectangle beam indicates that the turbulence effect on the latter is weaker under the same other conditions and it may be a better candidate to reduce the turbulence effect.
2015, 44(S1): 46-49.
In the 4D numerical simulation of laser atmosphere propagation, for considering the effect of laser beams jittering, the relation was discussed between jittering angle of laser and low order coefficient Zernike polynomial. A simulation method of laser beams jittering was given. For proving the correctness of the method, the beam expansion angular radius was calculated with atmosphere turbulence and jittering effect. It is basal consistent with the result of numerical simulation and theory, the all validate that the method is effective.
2015, 44(S1): 50-56.
In order to predict multi-micro laser shock forming, finite element model of multi-micro laser shock forming was built using ABAQUS software and simulation results were validated by experiment. On this basis, influence law of process parameters on micro laser shock forming was discussed. The results show that numerical simulation of multi-micro laser shock forming effectively shows three-dimensional deformation characteristics of laser impact area, and distribution of surface morphology under characteristic path is consistent with the experimental results. The influence law of sheet maximum deformation with laser energy, overlapping rate and diameter of laser spot conforms to experiment results. It confirms that numerical simulation can correctly predict the morphology of multi-micro laser shock forming, and provide good guidance for research on multi-micro laser shock forming.
2015, 44(S1): 57-62.
Laser ultrasonic(LU) three-dimensional (3D) imaging system combining wavelet threshold method(WTM) was presented, in which a laser beam was used to irradiate the aluminum(Al) block as a scanner and an interferometer as a receiver. Ultrasonic signals saved were processed by wavelet threshold for reducing noise. And data processed constitutes a 3D matrix in the scanning sequence, which could be sliced along the time axis to yield spreadsheets and be superposed in a 3D space using the MATLAB procedure. Then, artificial defects can be modelled and visualized. Ultrasonic signals were incorporated with algorithm to successfully reconstruct the 3D object model, which could contain the defect information, indicating that laser ultrasonic 3D imaging is more intuitive and effective than the traditional laser ultrasonic method of identifying defects.
2015, 44(S1): 63-67.
The physical and technology temporal resolution of pulse dilation frame tube were studied by the classic formula, the mean field theory and the pulse dilation model. The influence of the parameters on temporal resolution was analyzed, which are the initial energy, the cathode biased, the ramp pulse and the drift distance, etc. The effect of the physical and technology temporal resolution in picosecond (ps) and the sub-ps time scale and the possibility of achieving sub-ps of temporal resolution were discussed. The results show that the physical and technology temporal resolution are restricted each other. The temporal resolution of tube is decided by the technology temporal resolution when temporal resolution is 5 ps time scale. The temporal resolution of tube is decided by the physical and technology temporal resolution when the temporal resolution is sub-ps time scale.
2015, 44(S1): 68-72.
In order to test the key technologies of long-range LADAR, the experimental system was proposed based on the Nd:YAG laser. The system was combined with optical sub-system, control sub-system and signal process sub-system, and directed by charge-coupled device(CCD) when working. Coarse and fine dual-axis structure was adopted to realize the precise tracking of the target. Meanwhile, in order to increase the detection precision, the laser signal was processed in digital domain. At last, the detection range of the system was analyzed versus different laser cross section targets(LCS). The result shows that if the LCS is 1 m2 and the atmosphere is first order, the detection range of the system is 22 km.
2015, 44(S1): 73-79.
In order to enhance the weak and asymmetrical image of small laser spot and suppress the noise information, eliminate unstable laser spot effect on the calculation results, a new method was proposed in this paper. Firstly, a multi-dimensional image cube was constructed by many images captured in different time, the primary information was concentrated in the first dimensional image, the correlation of each dimensional image was removed. Secondly, the first dimensional image was divided into laser spot and background by Kmeans method, the classified image was processed by mathematical morphology, the edge of largest spot was searched as edge of small laser spot. Finally, the least square method of circle fitting was used to calculate small laser spot center. The experimental results show that the method can improve the accurate rate on checking the weak and asymmetrical laser spot, the binary laser spot area obtained by new method is 97.15% of ideal spot area, the error of small laser spot center and radius is less than 2 pixels, and realize the accuracy measure of small laser spot in the integrated diagnostic system.
2015, 44(S1): 80-85.
The cat-eye effect based active laser detection technique has a broad prospect in antimissile and air defense field, while the distortion effect on the incident and reflected waves caused by aerodynamic flow field around the planes and missiles is an important part of the echo wave characteristic analysis. Facing the complicated physical process of the laser waves in the cat-eye lenses and aerodynamic flow field both in the incidence and reflection propagation, a Zemax based aero-optical distortion calculation method was proposed. Firstly, based on finite element theory, the aero-optical flow field was divided into multiple layers according to the refractive index gradient. Secondly, curve surface fitting of the interfaces between the layers was done with standard, even asphere and Zernike polynomial surface, then a multilayer lens group model with different refractive index was established in Zemax, and the whole incidence and reflection Zemax model was accomplished with imaging optical system added in. Take a typical missile model as the example, the computational fluid dynamics and optical propagation distortion simulation in Zemax were performed, the feasibility of this method was validated after comparing with the analytical results of ray tracing.
2015, 44(S1): 86-92.
The maximum range of active and passive laser range-gated detection system consists of the most far detection range of the visible/infrared system and the laser system. The furthest distance function of visible/infrared detector and the laser imaging were established respectively. The influence of the detector sensitivity, the transmission power, the laser emission angle and the atmospheric visibility on the maximum range was simulated. Two sets of range-gated system of 532 nm YAG laser and 860 nm solid-state laser were established. Simulation analysis system farthest distance is 11.2 km and 5.5 km respectively. 15.7 km, 10.9 km and 13 km targets are imaged using YAG laser. 1.3 km, 5.1 km and 6 km targets are imaged using solid-state laser. The most remote of the system is verified by comparing the distance between the targets. The experimental results show that the furthest distance from the theoretical calculation is basically consistent with the actual distance. The furthest distance function can reflect the actual performance of the system. It can be used as the basic reference for the evaluation of the system and it is an important reference for the design of the system.
2015, 44(S1): 93-98.
Based on the coupled wave equation of Stimulated Brillouin Scattering (SBS), the models of Brillouin frequency shift, the pump wave, Stokes wave and the acoustic field in multimode fiber were built. Analysis and comparison of the Brillouin sepectrum frequency, peak gain, linewidth and SBS threshold between the multimode and single mode fiber were conducted. And then the influences of optical fiber length, attenuation coefficient and numerical aperture on the SBS threshold were discussed. The results show that, multiple modes of the Brillouin scattering superposition lead to spectrum broadening, linewidth increase, peak gain decrease and frequency shift reduce. The SBS threshold of the graded index multimode optical fiber is larger than 80 mW, which is far larger than the single mode fiber. When the core diameter is same, the graded index multimode fiber is more susceptible to take place the SBS effect, whose numerical aperture has more influences on SBS threshold than the step index multimode fiber. The reported measurement results validate the theoretical analysis. The studies in this paper laid a theoretical foundation for the distributed Brillouin scattering sensing system based on multimode fiber.
2015, 44(S1): 99-103.
A distributed measurement system used in shooting range was introduced. A low-cost high-speed imaging equipment setting was set on the shooting range end. Through high-speed fiber optic imaging device, real-time data was transmitted to the remote safety zone that receives high-speed real-time data for storage and processing. The low-cost close-range setting method by more camera was presented. Besides, the front-end high speed camera, central optical fiber transmission, the composition and performance indicators of back-end acquisition system were also presented. Finally, two experiments were conducted for testing the bit error rate of the whole system, and a method to improve the bit error rate was advanced. This system not only can be used in the shooting range measuring target, but also has practical significance in the transmission and storage of large volume of data over a long distance.
2015, 44(S1): 104-108.
In the Gobi region of Xinjiang, the system of atmospheric coherent lengh measurement and micro-thermal meter were set up in the surface of lake for measuring atmospheric turbulence. The refractive index structure parameter was used to compute the atmospheric coherence length, the distinctness was analyzed also. The result shows that the time-interval of weak atmospheric turbulence is not obvious at sunset and sunrise in the autumn. At sunset, the time-interval of weak atmospheric turbulence mainly distributes about 9:00; at sunrise, the time-interval of weak atmospheric turbulence mainly distributes about 21:00. In the daytime, The time-interval of strong atmospheric turbulence lasts six to eight hours, and mainly distributes from 12:00 to 20:00. The strength of atmospheric turbulence in the nighttime is obvious stronger in the daytime, it is stabler by in the land.
2015, 44(S1): 109-112.
A non-gain microchannel plate (MCP) gated X-ray framing camera was reported. It is made up of four basic components, the non-gain MCP imager, the pinhole array, the picosecond gating pulse generator, and the CCD camera system. The temporal resolution was measured by using a fiber bunch. While the gating pulse with width of 145 ps and amplitude of -1.5 kV plus -300 V bias were applied on the non-gain MCP, the measured temporal resolution of this camera was about 59 ps. Furthermore, the relationship between the temporal resolution and the MCP bias voltage was obtained. The variation of the temporal resolution with the intensity of the output signal was also provided. The experimental results show that the temporal resolution is improved while the MCP bias voltage is decreased. However, the intensity of the output signal is reduced while the MCP bias voltage is decreased.
2015, 44(S1): 113-118.
Pose(relative attitude and position) estimation is one of the key technologies in space missions, such as on-orbit servicing, rendezvous and docking, etc. One of the most efficient way to solve this problem is observation on the target by monocular vision such as single CCD measurement. Aiming at the pose estimation of space target based on feature points, an iteration algorithm using obverse projection and orthogonal Procrustes analysis was introduced. Turning the original pose estimation problem to a standard form of orthogonal Procrustes problem, the orthogonal Procrustes problem was solved in the way of successive projection. The key of successive projection method was optimized the attitude matrix row by row. Each row can be solved as a least square problem constrained by a quadratic equation. This algorithm has a global updating and result will be given when errors are within permission. At last, under the background of pose estimation between non-cooperative spacecraft, the simulation experiment shows that this algorithm has both fast convergence speed and strong robustness.
2015, 44(S1): 119-125.
Multipath interference was one of the main error in GNSS. From the multipath signal characteristics, analysed the effect of multipath interference on carrier tracking loop and code tracking loop. And the anti-multipath performance with vector tracking loop(VTL) was studied. By analyzing the structure of VTL and scalar tracking loop(STL), a linear system model was established, and the effect of code tracking error on VTL was deduced. In VTL, the affected channels were assisted by other channels, weakening the multipath positioning errors. One and more affected channels by multipath had been established. Under these scenes, the simulations had been made to compare the positioning errors between STL and VTL. The experiments proved that, relative to the STL, the fewer affected channels, the better the anti-multipath performance with VTL. And when all channels are affected by multipath, the positioning accuracy of VTL is not worse than the STL.
2015, 44(S1): 126-130.
In order to explore the significance of X-ray pulsar spectra for X-ray pulsar navigation, an X-ray pulsar energy simulation method was proposed. In this paper, X-ray tube was used to produce X-ray signals, and emission spectroscopy was controlled with anode voltage. To achieve X-ray pulsar spectrum simulation, least squares was used to obtain anode voltage curve, and then ground experiment was realized. Mathematical modeling and simulation were implemented, and the corresponding results prove the feasibility of this method. Furthermore, ground experiments were carried out, experimental results show that the similarity of X-ray pulsar spectra between experimental and actual is almost 79%. In addition, a scheme of simulating X-ray pulsar energy and flow simultaneously was proposed based on above energy simulation. These works can provide an experimental platform for future X-ray detector and navigation algorithm.
2015, 44(S1): 131-136.
Integrity is one of the most key factors of satellite navigation system. Moreover, satellite autonomous integrity is an important part of operational controlling and monitoring the global navigation satellite system(GNSS). This monitoring of the satellite autonomous integrity monitoring(SAIM) observations was concentrated on, including the specific monitoring methods and detection tests of pseudo-range, carrier phase, carrier-code coherence and multichannel code phase coherence. According to the civil aviation integrity regulations, the detection threshold and the minimum detectable abnormity were calculated, which provided some theoretical reference for terminal design of SAIM.
2015, 44(S1): 137-142.
Reducing the measurement error of BeiDou Navigation Satellite System(BDS) receiving module is an effective method to improve its performance. Time series analysis method was utilized to model the measurement error generated from the measuring results of BDS receiving module UM220 and Kalman filtering was used to reduce the measurement error of BDS receiving module according to the built error models. The experiment results show that measurement error of BDS receiving module can be modeled with ARMA(2,2) or ARMA(1,1), and through Kalman filtering the standard deviation of static sequence is reduced by at least 28.86% and the standard deviation of dynamic sequence is reduced by at least 48.63% compared with the original sequence.
2015, 44(S1): 143-146.
Mars probe after brake automatically enters around a large oval orbit, requires the ability to independently determine the position of the detector, speed navigation information. A new autonomous navigation method based on landmarks measurements and X-ray pulsar measurements was proposed. Aimed at the elliptical orbit when brake passing through atmosphere, the landmarks-based navigation was used at perigee and X-ray pulsar-based navigation was used at apogee. According to the principle and measurement of pulsars and landmarks navigation, the extended Kalman filter(EKF) was designed to get the navigation information. Under the existing navigation sensor level, the integrated navigation system can get near the perigee 100 m, 1 km far from the apogee of the navigation accuracy. Simulation results show that this method was a promising and attractive scheme for autonomous navigation of Mars circle satellites.
2015, 44(S1): 147-151.
The technological process of guided missile defense systems(DSP) was analyzed, and the impact-point prediction and orbit determination of strategic missile theory based DSP satellite were proposed. Thus, with the mode of two satellites spaced, the measurement model of DSP satellite was put forward. In order to calculate the orbit of the missile, the dynamic model with multi-parameters of the powered phase and free section of the missile were created. For simplifying the calculation, the reduced dynamic model of missile was put forward in order to reconstruct the whole simulation of ballistic missile early warning system, which was ballistic determination and the impact-point prediction. Then the UKF filter algorithm was used to calculate the position and velocity of missile on real time. Finally, the simulation experiment based on STK was generated, and the results show that the impact-point prediction precision can be 10-50 km, which can satisfy the basic military requirement.
2015, 44(S1): 152-157.
For the problem of relative navigation for space debris, cubature Kalman filter have been introduced based on the angle measurements and range measurements of on-orbit servicing spacecraft which is a numerical approximation algorithm using cubature law, resolving the problem of target missing with the larger error of initial measurement. In order to improve the field of application, a universal variable state transition equation was adopted to extrapolate the state, avoiding the limitation of near-circle orbit type. The simulation results show that the cubature Kalman filter has higher filtering accuracy and faster convergence speed than traditional extended Kalman filter in the situation of the larger error of initial estimation, which provides a theoretical basis for the implementation of the project in future.
2015, 44(S1): 158-162.
Celestial navigation technology has entered a new stage of development with the development of electronic technology and computer technology. Otherwise it has been widely used in satellite, space shuttle, long-range missiles and other spacecraft. Star centroid location for celestial navigation is the key technologies. Due to the strong sky background, near-infrared stellar images which are taken during the day have the low signal noise ratio. First, this paper adopts the method of information entropy to make analysis the stellar images energy distribution. And then we proposed a method for star target centroid located based on multi-step minimum energy difference. This method uses the linear superposition to narrow the centroid area, using the symmetry of the stellar energy distribution to obtain the centroid when the minimum difference appears. We test the modal on natural pictures to verify the accuracy. Experiments show that it has good effect to calculate the centroid with low SNR conditions.
2015, 44(S1): 163-167.
LEO hazard space debris can present catastrophic danger to operational spacecraft, and the detection of the space debris is the first and most important step in the process of collision avoidance and elimination. The object signal of these debris is faint. Besides, its optical character is uncertain and will change momently because of its high velocity and unknown attitude, all of which will bring serious challenge to the detection and identification. For fulfilling the demand of surveillance in real time, identification, collision alarm and accurate orbit ascertain, it needs to design and develop a space-based optical observation system. This article aims at providing a reference to this system, which summarizes the main characters of typical detectors, such as charge-coupled devices, avalanche photodiodes, position readout photon-counting detectors. The observation ability of space-based optical observation system based on these different detectors to LEO hazard space debris was analyzed.
2015, 44(S1): 168-172.
The modulation effect of defect on the filter properties of one-dimensional photonic crystal was studied by transfer matrix theory and numerical simulation method. The result shows that when the defect unit is located in the center of the periodically arranged structure of photonic crystal, defect modes number and filtering quality are changed with the number of defect, but the transmittance remains the same; with the increasing deviation of defect unit from the photonic crystal center, the transmittance of each filter channel in photonic crystal will be lower, but the distance between the filter channels is unchanged; the filtering quality of each filter channel is improving with the increasing distance between two defect units, and the defect modes are degenerating; when defect thickness multiply increases, filtering quality of each channel is improving and multi-channel filtering appears. Effect of defect on filter properties of one-dimensional photonic crystal can provide theoretical guidance and modulation mechanism to design high quality optical filters and optical switches
2015, 44(S1): 183-188.
Optical coatings were fabricated by ion assisted deposition technology based on the largest platform of ZZS3600 high vacuum coating machine. Properties of the deposited films as well as thickness uniformity were researched. The familiar optics as Ta2O5 and SiO2 were produced by the ion bombardment of MARK Ⅱ ion sources. Several properties related with the optical coatings were analyzed. It suggests that great improvement achieved of the coating structure and properties of the deposited coatings under the condition that the distance between the substrate and the evaporation sources are extremely large. Based on the geometric configurations of the platform, the coating uniformity research of planetary system and single axis coating system were performed, respectively. The thickness nonuniformity is better than 0.4% without mask under the planetary system. As for single axis system, the thickness nonuniformity can be obtained less than 0.6%. High-quality large optical coatings can be acquired with the aid of double ion sources.
2015, 44(S1): 189-195.
Polarization detecting technology has become an important means of detection, the research on its detecting mechanism has important theoretical significance and practical value, it will guide the practical application and results analysis of visible and near-infrared polarization detection. With the rapid development of micro-lens array technology, micro-polarizer array focal plane has become a new type of detector. A lot of literature on the study of the micro-lens array technology, micro-polarizer array focal plane is only involved in design and the optical performance analysis, but the exact theoretical formula for the noise equivalent degree of linear polarization(NeDoLP) was not given. The factors, such as focal plane array size, polarizer extinction ratio(ER), pixel crosstalk, and processing algorithms were analyzed aiming to micro-polarizer array focal plane. The accurate theoretical expression of the noise equivalent degree of linear polarization was given, and simulation analysis was completed with computer. The study has important guiding for improving the performance of the micro-polarizer array focal plane.
2015, 44(S1): 173-177.
A high birefringence and high negative dispersion photonic crystal fiber (PCF) was investigated, which adopted both squeezed triangular lattice and two kinds of elliptical air holes in the cladding. The supercell lattice method was used to investigate the influence of the fiber parameters on the birefringence and dispersion properties. The simulation results show that the birefringence can reach the magnitude of 10-2 in a broad range of wavelengths from 1.1 m to 1.9 m, and the dispersion can achieve high negative dispersion in a broad range of wavelengths form 1.4 m to 1.8 m. This PCF also has high birefringence (3.410-2 at 1.55 m), high negative dispersion (-428.2 ps/(nmkm)and -126.9 ps/(nmkm) and in y- and x- polarizations at 1.55 m, respectively). Moreover, the effective area was also discussed. This PCF can be widely used as dispersion compensation PCF and polarization dependent communication system.
2015, 44(S1): 178-182.
A new laser diode feature in low cost, shock resistance, narrow pulse was introduced. The laser diode was packaged with epoxy resin which can not only satisfies the requirement of the space but also makes the packaging easier for the shaper could be fabricated with the packaging. To reduce the size and the influence of the parasitic effect of the circuit, a multi-chip module was used to make up the driving circuit and a set of unpacked chip was used to replace the common packed chip. A metal bracket was used as the pins and the cooler of the laser diode. In the test of the laser diode, the divergence angle of the laser diode with the shaper is 1.1 in the fast-axial direction and 3.3 in the slow-axial direction. The max peak power of the laser diode in this kind of packaging is 35 W and the width of the optical pulse is less than 50 ns.
2015, 44(S1): 196-198.
A double loop optimization apodized lens was designed in this paper. The apodized lens was composed of a concentric alternating arrangement of the transparent ring and annular ring. After bicyclic apodization mirror modulated light is incident to the optical receiver system, the optical imaging system of the received light imaging focuses, data acquisition and processing system for collecting and processing curren signal, isoplanatic angle can be given along the measurement path. Relative to the domestic existing single aperture apodization mirror, the apodized lens is able to simulate the aperture filter function W(z)cz5/3 well at all. The relative error of the resulting isoplanatic angle is significantly smaller. The high-precision measurement of isoplanatic angle can be achieved.
2015, 44(S1): 199-204.
A new method for exposure time control by driver timing was proposed for non-electronic shutter frame transfer area CCD imaging detector. Based on the Sarnoff's back illuminated frame transfer array CCD sensor, the charge will be drained quickly in the excess period, with the driver timing controlled by the software. Selecting exposure time as 2 ms, 4 ms, 6 ms and 9.96 ms, the CCD output signal amplitude was measured under system frame frequency of 100 fps. The gray value of continuous 100 frame image calculated by the Matlab. Results show that the method can control the CCD exposure time effectively, and can be implemented by software. It can be widely used in the frame transfer area CCD imaging device without electronic shutter.
2015, 44(S1): 205-212.
In order to simulate the effect of orbital motion on the laser communication terminal's PAT system performance, a high precision one dimensional turntable was developed. GEO-LEO and LEO-LEO satellite relative motion angular velocities were analyzed, and the requirement of turntable's angular velocity range was proposed accordingly. Based on the digital control technology, compound control and high level input cascade compensation were used to achieve the stable control with super-low speed. To meet high precision demand in angular location accuracy measurement, the influence of adjustment and alignment error in test procedure was studied. According to the results, the max turntable angular velocity was 2 ()/s; the angle position measurement error of adjustment and alignment error could be ignored; the actual turntable position precision was superior to 2.5. The turntable meets the requirements of high-precision and low-speed for the orbital simulation of space laser communication terminal.
2015, 44(S1): 213-219.
The colors that can be distinguished by human eyes are much more than the gray levels that can be distinguished. More objects information of the gray image can be obtained through the pseudo-color processing. In a fundamental departure from the current pseudo-color processing methods, quantitative metrics for human visual detection and recognition were devised to measure perceivable objects information after pseudo-color processing, and a pseudo-color processing method was proposed under the metrics. At first, it was ensured that different gray levels were mapped to distinguishable colors. Then, a gray-to-color mapping function was created to make more objects information be perceived. In the comparison experiments, the proposed method can make more objects noticed by people. The proposed method can process images in real time.
2015, 44(S1): 220-224.
The atmospheric turbulence profile Lidar is a new technique presented near ten years which is used to measure the optical turbulence altitude profile. Nowadays data processing becomes a significant problem of this technique. The data processing methods of the turbulence profile lidar were described in detail. Methods to calculate threshold values of dual light spot images and inversion of atmospheric turbulence profile were studied mainly. These threshold values calculated by iterative method, maximum classes variance method and statistic method were compared with each other, statistic method was an appropriate method to calculate threshold values of dual light spot images. And then coordinates of dual light spot were obtained and centroid distances were calculating based this threshold values. Arrival angle fluctuations were computed with centroid distances of multiple images. Inversion of atmospheric turbulence profile from arrival angle fluctuations was simulated with HV-21 model. These values retrieved and original data were in same magnitudes and same integrative trend but differed in partial curvilinear trend.
2015, 44(S1): 225-229.
As the precondition of carring out the target precision strike in the information war era, target location is an important part of information security work. At present, the fast target location is achieved for image registration, but the traditional methods are single image feature registration, the registration result can not be assured, and then the target location precision can be effected. To solve these problems, a fast target location method of the global image registration was proposed, the image registration method based on the combination of spot and corner features was adopted, the target location precision can be assured through measuring the similarity of two feature matching. Finally, the experiment of image registration performance and target location precision was realized which use of aerial remote sensing images. Experiments show that the improved methods are steady and the aerial remote sensing images can be located effectively.
2015, 44(S1): 230-235.
Accurate recognition and location of randomly placed industrial parts is the key technology to realized intelligent bin-picking of industrial robot. An approach to recognition and location of target object in randomly placed industrial parts using monocular camera. Efficient recognition of industrial parts with distinct profile could be realized when the geometric information based on 3D CAD model is used to train the temple. The most appropriate temple was obtained after the combination of a pyramid approach with hierarchical model views and the matching mode characterize by normalized similarity measure. The tested objective is a metal couple cage with distinct profile and reflective feature. Some experiments were carried out for randomly placed parts. Experimental results show that the target can be recognized accurately in randomly placed parts. The average location errors of target parts in X, Y and Z direction are 0.948 mm, 1.078 mm and 2.175 mm.
2015, 44(S1): 236-240.
In order to implement the automatic target detection in hyperspectral image, a target detection algorithm was proposed based on spatial-contextual one classification. Features of combining space and spectrum were used for the algorithm, principles of SVDD classifier and the algorithm process were studied. Firstly, the single class classification principle of support vector data description(SVDD) was analyzed this paper. Secondly, considering the characteristics of hyperspectral image, how to use spatial and spectral features as the SVDD classifier input was introduced. Then, the principle of the algorithm was explained by comparing and analyzing the single class classifier performance combined space and spectrum. Last, the concrete realization method of the algorithm was given. Experimental results show that, this method is superior to the conventional CEM algorithm, in a foreign naval base'data in AVIRIS imaging, the accuracy that detects the aircraft target is more than 90%, which can meet the requirement of stablility and reliability, low false alarm rate, high recognition rate of the target detection.
