Chinese Version Light学术出版中心
Latest Issue
Issue 2 ， 2009
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Research on some new mechanisms of slow light and its applications
Abstract：The last decade is of great significance for the development of slow light technology. In order to study on the slow light technology deeply, several kinds of slowing light technologies, such as Electromagnetically Induced Transparency(EIT), Coherent Population Oscillation(CPO), Stimulated Brillouin Scattering(SBS) and photonic crystal waveguide, were contrasted and analyzed. Also some important theoretical and technical developments to improve performance of slow light in last decade were introduced, and then problems and shortcomings existing in slowing technology were discussed. Finally,this paper focuses on some novel technologies of slowing down light velocity and their primary applications. Moreover, it forecasts the future developing trends of slow light and its potential applications. Through research on slow light, results show that slow light will realize more and more significant application values in the field of optical fiber sensing and other fields.- 32
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Published：2020-08-13 -
The simulation of NLOS light propagation for multiple-scattering instance
Abstract：It is very significant to simulate non-line-of-sight (NLOS) light propagation in complex terrain. The single-scatter theory is always used to study the NLOS light propagation inland and abroad now, but only single-scattering photons are calculated approximately by the method. Furthermore, if the weather is bad or the transmission distance is large comparatively, much larger error will occur. So the single-scatter model is unfeasible when photons enter the detector inevitably by multiple scattering (two or more). In the paper, considering emission and detector don’t have the visual angle in common, the multiple-scattering theory based on Monte Carlo (MC) method is described here to calculate two typical instances: the detector and emission are in opposite directions and the visual angle of the detector is limited by the obstacles in front. Accordingly, a solution is presented in detail to simulate the light propagation when the detector and emission do not have mutual scattering-substance. And the correct results are obtained according to the comparative experimental results, which is very practicable in complicated conditions.Keywords：multiple-scattering;light propagation;Monte Carlo method;effective scattering-substance- 43
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Published：2020-08-13 -
Iterative stitching algorithm for annular subaperture testing with experimental verification
Abstract：In order to satisfy high precision and fast optical surface measuring, an iterative algorithm for annular subaperture stitching is discussed, this is based on the subaperture stitching and localization (SASL) algorithm. Firstly, the basic theory of annular subaperture stitching is introduced, this can be divided two parts, one is how to determine the overlapping points precisely and the other is how to find optimal configuration. Then the new problem which was arising in annular subaperture stitching, i.e., determination of the overlapping points, is studied. The detailed procedure of the iterative stitching algorithm is presented. At last, a paraboloid of 160mm aperture is tested with annular subapertures, which gives consistent result with the auto-collimated full aperture testing. The PV value is 0.186λ and the RMS value is 0.019λ. It proves that the iterative annular subaperture stitching algorithm meets the requirement for high precision testing of aspherical surfaces.Keywords：Annular subaperture;Stitching;iterative algorithm;Asperical testing- 36
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Published：2020-08-13 -
Design of the driving system in spinning prism Q-switch and the stable analysis
Abstract：The design of driving system of the high-speed motor is very important in the design of the spinning prism Q-switch. The high-speed motor controlled by three-phase frequency conversion was designed, and the stability of the motor was analyzed. The results showed: the motor drive system can work stably and the maximum speed of rotation arrived 60 KRPM, which realized “fast” shutoff of the Q-switch. The designed Q-switch was applied in DPSSL, and realized the 14 KHz turning-off-ability of Q-switch in the high repetition rate high-power DPSSL in the experiment, which is the best results in the rotating mirror Q-switch by now.Keywords：spinning prism Q-switch;high speed motor;stability- 52
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Published：2020-08-13 -
Light Distribution Test System Based on Moving in Two-dimentional Plane
Abstract：In order to raise the accuracy of light distribution test of automotive lamp and cut the cost about test system, a new-style system for light distribution test of automotive lamp was reserched, which could test luminance of every poit on light screen,and used two servo motors to control shaft with screw thread ,based on moving in two-dimentional plane. After comparing to accuracy of the curent rotating desk system with the best precision in China ,the best test distance of automotive signal light luminous intensity to two kinds of test systems was analyzed.Through director test and angle transformation of headlamp,the coordinate error of test points was caculated according to national standard,as well as luminance with standard lumeter. Experimental results indicate that the position precision of the system is 0.1 mm with an increase of 42 times over the curent rotating desk system,and luminance accuracy is 0.02lx tripled that of ones. Experiment to automotive signal light shows that the best test distance about the rotating desk system is found instead of 3.16m currently in China, and the luminance accuracy of new-style system is direct proportion to test distance. It can satisfy the system requirements of national standard with higher precision and rapid speed, the adjustable lamp tested distance as well as easy control.Keywords：Moving in plane;Light distribution;Rotating desk;Luminance- 52
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Published：2020-08-13 -
Research on electrostatic deformation of membrane mirror
Abstract：The control method of Stretched Membrane with Electrostatic Curvature (SMEC) Mirror has advantages of simple structure and easy membrane mirror figure cybernation. Its principle is to make membrane mirror figure change with the sequence of electrostatic force to get the needed optical curvature figure. As for the complexion of membrane shaping mechanics and electrostatic field theory, there is no quantitative theory analysis in membrane shaping and mirror figure cybernation. In this article, the distribution characteristic of space electric potential is analyzed in theory, and the electrostatic force distribution is obtained by numerical calculation. Considering single electrode mode, after electrostatic force calculation with MATLAB, the membrane mirror figure is mainly inspected by finite element method. Then the analysis result of finite element method is compared with ideal paraboloid figure, the differences between them will perceptibly show that the surface shape control force in single electrode mode is simplex. To get flexible modulation, multi electrode mode control is an advisable option. It is also proposed that higher control precision can be acquired by using closed loop multi electrode control, which is instructive to the study of SMEC mirror.Keywords：space optics;membrane mirror;electrostatic stretch;mirror figure control- 30
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Published：2020-08-13 -
Spectra unfolded study for elliptical crystal spectrometer measurement
Abstract：The elliptical bent crystal spectrometer (EBCS) is coupled to X-ray CCD, and a set of system (EBCS-XCCD) for measuring X-ray spectra is briefly described. The unique advantages of the elliptical crystal spectrometer for precise and absolute spectral measurement are noted. The X-ray spectrum from the laser-produced plasma has first been measured by the EBCS-XCCD on the "ShenGuang II" Facility. In order to obtain truly experimental results, an originally spectral photograph measured by the EBCS-XCCD must be calibrated. The calibration procedures for absolute line and line intensity measurement are studied and formulae of identification signal are deduced according to the geometrical parameter of the EBCS-XCCD and physical optics. The example of calibrating spectra is presented as measured with elliptical crystal of α-quartz （1010，2d = 0.852 nm ) for the 0.399 — 0.736 nm photon wavelength region. The intensity of spectrum from laser plasma X-ray source is also obtained by the formula, based on known the integrated reflectivity of the crystal, the transmission of the foil which blocks out visible and ultraviolet (UV) portions of the spectrum, and the responsivity of X-ray CCD photodiode to photons. The spectra of Al laser-produced plasma and good spectral resolution better than 1000 are shown. The unfolded spectra by the method are compared with that of the reference [1]. Their results are basically identical. It is shown that the instrument is particularly suitable for high-precision measurements of the spectral line profiles and positions in nonhomogeneous plasmas. The examples of experimental results, which are superior to those obtained in earlier measurements, demonstrate the EBCS-XCCD performance and suggest a broad field of possible application.Keywords：X-ray source;spectra unfolded method;identification spectrum;spectral intensity- 28
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Published：2020-08-13 -
The study of infrared camouflage technology based on the performance parameters of the camouflage coating
Abstract：As the infrared homing technology is maturating day by day, it challenges the viability of the military target more than before. Based on the simulated results of surface temperature of target, the influence of the performance parameters( 、 、 ) of camouflage coating on the surface temperature of target and lock-on range of infrared detection system was analyzed. The analytical results show that all , and will affect the temperature of target and lock-on range, the surface temperature of target will rise as , are increscent and will reduce as the are increscent. For definite temperature of background and span of 、 、 ,the bigger and are, the bigger the lock-on range is, as the increases gradually, the lock-on range will firstly decrease and then increase. It is also discovered that there is an optimal emissivity to make lock-on range least. These results will be of great importance in the design, selection and application of infrared camouflage coating.Keywords：infrared camouflage technology;ground target;camouflage coating;performance parameters;lock-on range- 29
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Published：2020-08-13 -
Effect of incident angle varying on cube corner retro-reflector measurement accuracy
Abstract：In order to describe the relationship between the incident angle of cube corner retro-reflector (CCR) and the measurement accuracy of CCR using in laser tracker system, the working principle and reflective characteristic of CCR are analyzed. A novel approach has been proposed to determine the effective reflection area of CCR with an arbitrary beam incidence angle. The formula of ray cross section of CCR with incident angle varying is derived according to the effective reflective area. Accordingly, the relationship between CCR measuring accuracy and incident beam angle is established. The experimental results have demonstrated that the CCR measuring accuracy reduces as the incident angle increases, the CCR measuring error is largest when the maximal incident angle is reached. The measuring error of CCR at maximal incident angle ±35.26° is 0.050mm, but the measuring accuracy of a CCR is better than 0.010mm when the incident angle is within ±20°, and the measuring accuracy and the stability is best only when the incident angle within ±15°. The results have shown that CCR can maintain the manufacturer specifications of LTS only when the incident angle is within ±20°, which provides a very useful guidance for design and application for CCR.Keywords：cube corner retro-reflector;measurement accuracy;incident angle;effective reflection area;laser tracker- 47
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Published：2020-08-13 -
Research of actuator arrangements for shaping aspheric surface
Abstract：First of all a new method, namely aspheric gradient method, is presented to determine actuator arrangements for shaping aspheric surface, and the theoretical analysis and two calculating formulas of this method are described. Secondly, based on an example of off-axis ultra-thin large-aperture spherical mirror, the initial solution of actuator arrangements is given by the aspheric gradient method, and the finite element analysis and the surface errors for shaping aspheric surface are accomplished. Thirdly, the optimizations of actuator arrangement are done. Finally, three methods of actuator arrangements, namely aspheric gradient, square and circular methods are compared using finite element analysis. The results show that the initial solution based on average value of aspheric gradient is most alike with the final solution, and it is in accord with the relation that the greater the aspheric gradient the greater the surface density of actuator arrangements. Meantime, the optimization can also further reduce the number of actuators and further improve the form errors. The aspheric gradient method has more advantages than the square and annulus methods, which makes it suitable for incorporation in the field of the shaping aspheric surface to determine the initial solution of actuator arrangements.Keywords：shaping aspheric surface;actuator arrangements;aspheric gradient method;finite element method（FEM）- 31
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Published：2020-08-13 -
Structural Optimization Design of Double Wavelength Optical Fiber F-P Sensing System Based on DE Algorithm
Abstract：DE algorithm has strong capability of global search, fast convergence speed, good robustness and easy to use. It can resolve complex optimization problem efficiently. The technology of double wavelength stabilization is put forward according to existing problems that optical fiber F-P sensor deviates from working point easily. The mathematic optimal model of double wavelength stabilization system is established. And this system’s structure is optimized by using DE algorithm. The results show the global optimal solution can be attained in shorter run time and the object is decreased by 98.375%. The results prove this algorithm to be proper and feasible, high efficiency and reliable way. It can be used for the structural optimization design of optical fiber F-P sensor.Keywords：differential evolution algorithm;optical fiber F-P sensor;structural optimization;global optimization- 36
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Published：2020-08-13 -
Error analysis of structured light system
Abstract：Structured light system is one of the common vision measurement systems. Its precision directionally affects it application, so error analysis is a key during designing system and calibration method. The paper proposed the error propagation model of structured light system about calibration method using the cross-ratio invariant; it is in the aspects of system measuring error and light-plane calibration. Those analyses were based on the error theory and matrix disturbance. According to the proposed error propagation model, the error analyses in a special condition were presented. It was the precision demand of calibration parameters and samples under the conditions of acquisition of ±0.5mm precision in the measuring distance of 1000mm. The experimental results validated those error analyses in the paper, and those would provide the principle basis for system designing.Keywords：error propagation analysis;Mont Carlo method;matrix disturbance;cross-ratio invariant;structured light system- 53
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Published：2020-08-13 -
Influence analysis of vibration to optics imaging system transfer function
Abstract：The working condition of the aircraft-borne or vehicle carries imaging systems is very complex, it has the great band width and the frequency crowded vibration, the performance of optical imaging system always been limited by these mechanical vibrations. The article started in the form of vibration of the optical imaging system as relatively, based on the knife-edge theory (line spread function), used the optical modulation transfer function (MTF) as evaluate function, to make quantitative analysis of the impact on the various forms of the mechanical vibration, and analyze the influence of each kind of parameter to the modulation transfer function. Provided the rationale for optics machinery's intensity、the rigidity、and the precision design. Combining engineering practice, proposed the concrete measures to reduce the impact of vibration on the imaging quality.- 36
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Published：2020-08-13 -
Processing method of precision and ultra-precision cylindrical involute gear
Abstract：The development level of a country’s manufacturing is reflected by the machining quality of ultra-precision gear. Work principle of several gear-grinding and machining status of ultra-precision cylindrical involute gear at home and abroad are analyzed and compared, and machining of ultra-precision gear above quality 2(ISO1328-1997) is probed. China-made gear grinder Y7125 with big plan grinding wheel which is provided with the advantages of streamline structure, high rigidity of transmission chain, high accuracy of gear-grinding as well as being easy to modify, has the ability to be master grinder of ultra-precision cylindrical involute gear by a series of research work, which can produce ultra-precision gear from quality 2 to quality 1.- 45
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Published：2020-08-13 -
The Study on the servo system of large telescope based on the internal model PID control method
Abstract：This paper develops the internal model PID control for large telescope control system considerations in more parameters adjustment in servo control loop at present. This simplifies the debug process; the feasibility and robustability are also verified by the analyses and simulation results that satisfy the high precision demand. The practicability of this algorithm is verified in an actual project. The application shows that this system runs stably and accurately. The technology and methods adopted in the system are practical and worthy of using abroad.Keywords：internal model control;PID;large telescope;Servo Control- 46
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Published：2020-08-13 -
Characteristic research of the integrating positioning XY-Stage based on bulk machining
Abstract：In order to realize the miniaturized nano-positioning stage, a novel 2-DOF single crystal silicon (SCS) nano-positioning micro x-y stage with the function of displacement detection was successfully developed using silicon bulk machining, electrostatics comb actuator is used to drive x-y stage. The theory of electromechanical coupling and energy conservation are used to analyze electrostatic actuated mechanism, x-y stage static characteristic, and x-y stage dynamic characteristic. Some failure modes of x-y stage are also presented and the electromechanical side instability and the stable travel range of comb-drive actuators are investigated. The stable travel range depends on the finger gap spacing, the initial finger overlap, and the spring stiffness ratio of the compliant suspension. Additionally, the effect of the air damping is taken into account during the analyzing the x-y stage dynamic characteristic, under which the maximum velocity and stable travel range are proposed.Keywords：silicon bulk micromachining;nano-positioning stage;electrostatics comb actuator;actuated mechanism;characteristic analysis- 32
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Published：2020-08-13 -
A design of airborne DIRCM laser pointer
Abstract：High-precision airborne laser pointer is a tri-axis operating system. Based on the Lagrange theorem, the tri-axis, coupling, nonlinear dynamics model is derived, and by analyzing the velocity coupling and the dynamics coupling relationships among axis of the frames deduces their analytical relationships in theory. According to the electrics and mechanics equations of the actuator-torque motor, the open-loop transfer function matrix of the control variable is established, and next a cascade compensator is designed to decouple the control system. After decoupling, another compensator is cascaded to the system to satisfy the quick-response requirement, also the system is stable at the same time. At last, the electro-mechanical model is verified by computer simulation, and sets a foundation and provides theoretical references for further research and design of the control system of the high-precision airborne laser pointer.Keywords：three-axis;model;couple;laser pointer- 26
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Published：2020-08-13 -
Operating characteristic of rotary piezo impact drive mechanism
Abstract：A rotary piezo motor with adjustable preload function is designed to study the rotational motion of an Impact Drive Mechanism (IDM). The motion principles of this Rotary Impact Drive Mechanism (RIDM) are investigated, the influencing factors of driving signal, structural parameters as well as piezoelectric element on motion characteristics of the mechanism are analyzed. The research results reveal that the rotational velocity of this motor is in proportion to the frequency or the voltage of driving signal, and in inverse proportion to M/m (the ratio of the main body and the weight). The velocity decreases as the charge time increasing of piezo element. Furthermore, the results also show that the torque-speed property and forward-backward rotation of rotary motor are both different from that of traditional motor. The torque-speed curve of the rotary motor is a fold line, and the forward rotational velocity is larger than the backward rotation velocity all the time. When the frequency,voltage and the charge time are 1100 Hz,50 V and 70 μs,respectively, and M/m is equal to 8.9, rotational velocity is about 1.75°/s and the maximum torque is 0.13 N·m.These results reported here show that the rotary impact drive mechanism is a multivariable system, whose performance is decided by many factors.Keywords：impact drive mechanism;piezo motor;rotation motion;operating characteristic- 35
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Published：2020-08-13 -
Study on edge detection algorithms of micro accessory
Abstract：Objective: In order to realize edge detection for micro accessory, a new edge detecting algorithm of micro accessory is proposed based on the process characteristic of micro accessory. Method: First, this algorithm extracts the transition region of different parts. The polynomial regression mathematics models of transition region in the different parts are built and then the accurate position is got by process character from the mathematics model. Result: Experimental results indicate that the measurement error of 1mm standard gauge block is 0.395μm. Conclusion: It draws that the process characteristic has greater influence for the edge of micro accessory and so the edge detection of micro accessory should consider the influence of process characteristic by the common process methods—lapping, stamping and wire-cutting. The actual processing condition and statistics are added in this algorithm. The edge detection result can reach the inferior pixel level by building the mathematics model of transition region.Keywords：Complex Edge;edge transition region;polynomial regression;edge detection- 34
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Published：2020-08-13 -
Application of Graphite Fiber Reinforced Aluminium Matrix Composite to Space Remote Sensor Structure
Abstract：In order to design and manufacture more excellent space remote sensor, a new type astronautics material- graphite fiber reinforced aluminium matrix composite (for short Gr/Al composite) is investigated. Firstly, crucial technologies that interface reaction control of graphite fiber and aluminium alloy, design of fiber laminate and winding have been studies. Gr/Al composite has been prepared, which is destiny of 2.12×10^3 Kg/m^3; modulus of elasticity of 129 GPa and thermal expansion coefficient of 5.0×10^-6/K. Secondly, according to this composite, a whole set of manufacture and post-processing technology has been groped in detail. Thirdly, this composite has been applied to design the body tube of space infrared remote sensor for the first time. The weight of Gr/Al composite body tube is lighter 31.8% than Titanium alloy that. Finally, the body tube’s produce and integration, lenses’ setting and calibration, random vibration test have been achieved. Experimental results indicate that, the first order resonance frequency of body tube component is 284Hz, more than 100Hz (design requirement). Optical system does not change after vibration test. Accordingly, the Gr/Al composite has been proved with important utility value in space remote sensing field by above work.Keywords：Gr/Al composite;preparation method;processing technology;space remote sensor;body tube structure- 53
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Published：2020-08-13 -
Rotary Stepping Ultrasonic Motors Driven by Single-phase Signal
Abstract：A rotary stepping ultrasonic motor composite the futures of the modal shift ultrasonic motor and the self-correction ultrasonic motor was proposed in this paper. It has no cumulative errors in open-loop control. An operating pattern was used to avoid miss steps which presented usually in the self-correction ultrasonic motors, and ameliorate the conflict between the output force and the step span which is a disadvantage of the modal shift ultrasonic motors. The prototype runs steadily without miss-step on trial, and the stall torque, single-step angler displacement, and the error of one step are 0.0032Nm,7.5°,and0.6°.- 41
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Published：2020-08-13 -
The research on profile tolerance measurement and evaluation method based on the images
Abstract：It is very difficult to measure and evaluate the profile tolerance of complicated curve parts .Having low precision or efficiency ,the available measurement and evaluation can’t meet the high precision required by the on-line parts' profile measurement. This paper provides profile measurement and evaluation method for the micro-parts based on the images. This method includes the method of profile data modeling on theory, also includes bound searching method of expansion polar angle for the related theoretical points and an evaluation method of the least -deviation method for profile errors. Moreover, the analysis and comparison between the evaluation method of least deviation profile errors and the evaluation method of classical least -squares method profile errors are performed. The experiments on actual image show that Least Deviation Method converges faster and more accurately to the minimum.Keywords：Profile tolerance error;image processing;micro-parts;Least-deviation method(LDM);Least–squares method(LSM)- 32
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Published：2020-08-13 -
Aircraft Recognition Base on Affine Transform
Abstract：According to the characteristics of aircraft structure and the characteristic of its affine transform, a novel method of aircraft recognition is presented. By this method a projective of the target image which is the same as the transform of the aircraft in the sample image in the same pose can be got. Through the comaprasion of the transform image and the target image we can judge wether the type of the aircraft in the target image is the same as the one in the sample image. The computer simulation results show that the algorithm presented by this article is steady and it has great practicablity.Keywords：image processing;aircraft recognition;affine transform- 64
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Published：2020-08-13 -
A super-resolution reconstruction method based on Image registration
Abstract：In order to improve the precision of the registration algorithm and the quality of the super-resolution reconstructed image, an image registration method with sub-pixel precision is proposed. First, the image registration method based on three-parameter model is introduced and optimized. Then, the image registration algorithm based on four-parameter model is proposed. Because the rotation angle is not directly included in the movement model, the hypothesis of small rotation angle while Taylor series expanding in the original method is avoided effectively. Finally, according to the movement information with sub-pixel precision gained by these two registration algorithms respectively, super-resolution reconstruction is performed by the adoption of iterative back projection algorithm. Experimental results indicate that this image registration algorithm achieves higher precision. The average translation error is reduced 0.0297 pixels and the average rotation angle error is decreased 0.3564 degree. The reconstructed image has better visual effect and the average PSNR is increased 0.75dB. It can be extensively used in the large multiple super-resolution reconstruction of low-resolution images from which differs mostly by translation and big rotation, which satisfies the requirements of practical application.- 66
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Published：2020-08-13 -
Image Restoration Based on Modified Paik Boltzmann Machine
Abstract：Image restoration can be regarded as a minimization problem, which can be solved by Boltzmann machine, since it is certainly fall into global minimum not local minimum by its inherent random neural network. Following improvements are done on traditional Boltzmann Machine: firstly integrate Paik into Boltzmann Machine; secondly extend serial model to parallel model; thirdly subunit step is adopted to increase precision; finally make the step adaptive to trade off the contradiction of convergence precision and convergence velocity. Each improvement was expatiated via theories, convergence analysis, and residual. Experiments demonstrate that this proposed method can approximate the overall minimum of the energy function infinitely, and the restored image by this method is superior to that of traditional Boltzmann.Keywords：image restoration;Boltzmann machine;neural network;full parallel algorithm- 31
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Published：2020-08-13 -
A real-time compression scheme for aerial-video
Abstract：A scheme of aerial-video codec was presented to realize two PAL videos simultaneously real time compression on the industrial embedded computer. The scheme chose discrete cosine transform (DCT) to decorrelate the image data. After comparison among many fast DCT algorithms, AAN’ approach was locked to be optimized and implemented, and the procedure of the optimization was presented. Scheme also improved the search method of variable-length code (VLC) table in variable-length encoding. Through the optimizations of DCT and the search method of VLC table, the two largest computational algorithm modules in our scheme, a 768x576 color video frame can be compressed in 8ms with P4 3.0G CPU. Under the compression ratio of 32:1, the PSNR of the scheme reached 30.18 which is extremely close to the performance of the algorithms based on wavelet, and it is the guarantee to the decoding quality of image. The experiment result shows our scheme fetch a better balance among compression speed, compression ratio and compression performance in video encoding, and testify it can be suitable for practical implementation in the aerial-video compression.Keywords：aerial video;real-time compression;video codec;DCT- 37
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Published：2020-08-13 -
Relationship between stereo depth and parallax image capture in stereoscopic display
Abstract：In stereoscopic displays, stereo depth is associated with parallax image’s parallax, and parallax is related with camera’s layout when the parallax images are captured. In the paper, the parallel camera configuration is adopted. By setting proper space between cameras and shifting the images reasonably, the objects with a certain depth have zero parallax and the objects with other depth have expected parallax. The parallax embodies the stereo depth, so the quantitative relationship between stereo depth and distance of two cameras which capture the parallax images is calculated. Experiments were carried out to verify the theory. The results help to shoot good parallax images for stereoscopic displays by laying out cameras suitably.Keywords：autostereoscopic display;stereo depth;parallax image;layout of camera- 52
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Published：2020-08-13 -
SIFT features matching algorithm with global information
Abstract：When an image has multiple similar regions, SIFT descriptors are similar, which results in much mismatches. Aiming at the problem presented above, a improved SIFT features matching algorithm with global context vector is presented. Firstly, detect feature points in scale space . Then descriptors which consist of a SIFT descriptor representing local properties and a global context vector to disambiguate locally similar features are computed. Finally, according to BBF searching strategy, match the feature vectors using Euclidean distance. The experimental results show that the improved algorithm which can describe feature points in a larger region reduces mismatch probability of experimental images from 19% to 11%, which improves matching results greatly.Keywords：SIFT;global information;BBF- 35
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Published：2020-08-13 -
The Spacecraft TT&C Ship Hull Deformation Measurement Data Processing Methods
Abstract：To reduce the influence of hull deformation to the data of TT&C shipborne outer-trajectory measuring equipments, hull deformation correction mathematical model needs to be established. Firstly, in this paper, the basic structure, measurement principle and measurement elements of hull deformation measurement system are briefly introduced; Secondly, hull deformation measurement coordinate system is established; Thirdly, relationship between deformation measurement angles and Euler’s angles is discussed; Finally, hull deformation data processing calculation formula is deduced in detail and data processing mathematical model is presented. Engineering application result shows: the influence of hull deformation to spacecraft initial orbit semi-major axis “a” is comparatively greater, to near earth and near circular orbit, the influence is hundreds of meters magnitude, whose maximum value is 800-900m; as to big elliptical orbit, the influence reaches 20km or higher. However, the influence can be eliminated after hull deformation correction. The established mathematical model reflects the objective law of hull deformation, which can be used to effectively eliminate the influence of hull deformation to measurement data so as to improve data processing precision.- 34
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Published：2020-08-13 -
The analysis of image motion compensation accuracy for Aerial Pushbroom Sensor
Abstract：Pushbroom imaging is an important way for aerial remote sensing;The changes about the speed, attitude and attitude variation of vehicle will affect the image quality of pushbroom imager,so the error budget and synthesis of these factors are important in developing pushbroom imager.Using the light vector and optic axis revolution alternation method in this ,to establishe a mathematical model of image motion for this system,which consider the drift angle.Analysing image motion compensation error by apply Mont Carlo method with the error budget and synthesis of these factors at last.- 46
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Published：2020-08-13
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