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Issue 10 ， 2007
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Antireflective film prepared by periodic ion beam assisted deposition
Abstract：The HfO2 and SiO2 films were coated using ion beam assisted deposition and e-beam deposition,and the antireflective films were coated by periodic ion beam assisted deposition and e-beam deposition also. The weak absorption,residual stress and Laser-Induced Damage Thresholds(LIDT) were measured. Comparing with e-beam deposition,the measured results show that the films coated by ion beam assisted deposition have a higher weak absorption,lower tensile stress and lower LIDT,and the antireflective films prepared by periodic ion beam assisted deposition have a lower residual stress also,but the weak absorption of the films increases a little,and LIDT increases from 10.91 J/cm2 to 18 J/cm2. The results indicate the periodic ion beam assisted deposition can improve the LIDT effectively,which provides a new way for application of ion beam assisted deposistion to preparation of high threshold laser films.Keywords：ion assisted deposition;Laser-Induced Damage Threshold(LIDT);antireflective film;weak absorption;stress- 62
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Published：2020-08-12 -
All-solid-state single-longitudinal-mode 593.5 nm sum-frequency laser
Abstract：A single-longitudinal-mode sum-frequency 593.5 nm laser was developed using a Fabry-Perot etalon as the frequency selector. For a single Nd:YVO4 crystal, stable dual-wavelength operation of 1 064 nm and 1 342 nm was obtained in a linear cavity by optimally designing the films on the output mirror of a cavity. The sum-frequency generation was realized using a type-I phase-matching LBO crystal for the sum-frequency mixing of 1 064 nm and 1 342 nm. Under the pump power of 2 W, 52 mW yellow-orange light at 593.5 nm was generated with a RMS noise of 6.8%. Then a 400 μm thick fused quartz was inserted into the cavity for frequency selection, 34 mW single-longitudinal-mode light with a linewidth of about 600 MHz at 593.5 nm was obtained by tuning the tilt angle of the etalon. The noise of the output light was remarkably reduced to the RMS noise of 0.3%. The results show that it is an easy and efficient way to employ a single Fabry-Perot etalon as the frequency selector to obtain single-longitudinal operation of the sum-frequency light in the process of sum-frequency generation.Keywords：solid laser;LD pumping;sum-frequency;single-longitudinal mode laser;593.5 nm laser- 25
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Published：2020-08-12 -
Calcium fluoride crystal growth with multi-hole-crucible
Abstract：By using a multi-hole-crucible and a furnace designed by ourselves, the CaF2 crystals were grown by Bridgman-Stockbarger method under the vacuum condition. Under the growing condition of the vacuum below 3×10-3 Pa, the axial gradient in growing zone about 1.8~2.5 ℃/mm, radial gradient below 0.5 ℃/mm, growing velocity of 3~4 mm/h and pre-annealing temperature descending velocity below 20 ℃/h, 7 ingots of CaF2 crystals with size of Φ57 mm×190 mm were grown in single process by melting,scavenging,homogenizing,controlling velocity and pre-annealing. The results show that the grown crystals with a wide transparent band have a good performance from 190 nm in ultra-violet to 9 000 nm in infra-red. The transmissivity is about 81% at 190 nm and 83% at 9 000 nm. The rate of mono-crystal is about 80%. The dislocation is about 30/mm2. The proposed equipment and technology are suited to batch production of CaF2 crystals.Keywords：multi-hole-crucible;calcium fluoride crystal;Bridgman-Stockbarger method- 40
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Published：2020-08-12 -
Fabrication and optical properties of three-dimensional Ta2O5/SiO2 photonic crystal
Abstract：Three-dimensional (3D) photonic crystals in the visible spectral region were fabricated by an auto-cloning technique.The optical properties of the crystals were studied by measuring the reflection spectra,and the Photonic Bandgap (PBG) was calculated using a plane-wave-expansion method. The experimental results coincide well with the theory. A two-step deposition method was used to insert rhodamine 590 into the photonic crystal,the result shows that the photoluminescence spectra is strongly modified by the photonic crystal.Keywords：photonic crystal;Photonic Bandgap (PBG);photoluminescence (PL) spectra- 39
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Published：2020-08-12 -
Mounting system design for 1.3 m primary mirror
Abstract：According to technical requirements of 1.3 m primary mirror’s supporting, a type of mounting system was designed and analyzed. A technical plan of center bearing with 18-point axial and mercury tube lateral support system was determined. For the light-weight primary mirror with complex structure, the 18-point support positions of axial mounting system were decided by equilibrium principle, structure analysis and interpolation. After the 18-point axial support system was described in detail, the structural deformation and design error were also analyzed. Three design variables on mercury tube lateral support system were selected according to force analysis of the primary mirror at vertical direction. Mercury tube lateral support system was designed according to the requirement of minimum deformation results at Z direction and 12 load cases finite element analysis results. Finally, in order to reduce the effect of temperature variation on the center bearing design, the invar steel was chosen. Meanwhile, a transitional fit shaft housing was designed to reduce the influences on the direct contact between support sphere and primary mirror in detailed design. The experiment results have been obtained with mirror surface PV error of 0.7 λ and RMS error of 0.15 λ using Zygo interferometer. The experimental results indicate that the mounting structure can satisfy the system requirement with excellent stabilization and reliability. Based on the analysis results, thickness of the primary mirror can be reduced more for designing light-weight mirror.Keywords：optical design;1.3 m primary mirror;18-point axial support system;mercury tube lateral support system;center bearing- 59
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Published：2020-08-12 -
Effect of axial temperature difference on imaging quality of space remote sensor optical system
Abstract：The Finite Element Analysis(FEA) method is used in thermal analysis on axial temperature difference effects on the imaging quality of space remote sensor optical system, and deformations of Primary Mirror(PM) surface and Second Mirror(SM) surface. The FEA model was set up by PATRAN software,and temperature distribution calculation was completed by NASTRAN/NT software. The thermal elasticity deformations of main surfaces were expressed in Zernike polynomial and the analysis results were computed by ZEMAX optical design software to carry out the interface between the thermal analysis and the optical analysis. The results show that the axial temperature difference not only brings the defocus, but also effects on the image quality of the optical system. So temperature control is needed in focusing.Finally, this paper suggests that the axial temperature difference requirement of the PM is 0.8 ℃, the SM is 1.0 ℃,and between PM and SM is 3.0 ℃.Keywords：space remote sensor;axial temperature difference;optical system;image quality;thermal-optical analysis- 41
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Published：2020-08-12 -
Implementation of two-dimensional perfect shuffle transform using step-based micro-blazed grating planar-array
Abstract：Based on some interesting properties of a micro-blazed grating planar-array such as high diffraction efficiency, small size, high degree of integration and easy to fabricate, a 2D Perfect Shuffle(PS) transform method was proposed.The mathematic principles and the mapping rule of 1D and 2D PS transform were defined, respectively. Then, 1D and 2D PS transforms were realized in free space using micro-blazed grating arrays by controling and modulating the grating's etching direction and period to direct the signal beams to reach to the desired position. Finally, compared with the conventional method (depend on the operation of dividing, magnification, interlacing and superimposing), this method mainly relying on the diffractive properties of signal beams and the distribution of light intensity presents a single diffractive element to perform 1D and 2D PS transform. The theoretical analysis and experimental results show this method has the advantages of more higher energy efficiency, high feasibility, compact structure, easy to integrate etc., which should be helpful in a optical interconnection network, especially, in a perfect shuffle omega network.Keywords：optical communication;optical network;micro-blazed grating;Perfect Shuffle(PS) transform- 59
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Published：2020-08-12 -
Testing and simulation of focusing circuit of optical remote sensor
Abstract：A new method using the data sampling card and simulation technology was given to test the focusing circus of a optical remote sensor. By analyzing the theory of focuing circuit and measuring the circuit practically, the mathematic models were established for testing the focusing circuit and feeding back the value of the coder based on symbolic logic, information technology and system technology. Using the high-speed disposal and the intelligent control with PC, the testing system for focusing circuit was developed. The experimental results show that the system can exactly test the focusing circuit with work frequency less than 1.2 kHz and control voltage less than 40 V.It can satisfy the requirements for testing and simulation of focusing circuit of optical remote sensor, and the testing system can also automatically monitor the focusing circuit for a long period.Keywords：optical remote sensor;focusing circuit;testing and simulation- 33
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Published：2020-08-12 -
Dynamic modeling and compensation for thermal error of three-axis ring laser gyro
Abstract：A new dynamic modeling and testing scheme for the thermal error of three-axis ring laser gyro were presented. The experimental results show that the gyro drift under harsh working environment can be effectively compensated using the new dynamic model, the gyro error can be reduced below 0.05 °/h. Compared with the static model, the dynamic one has advantages in a shorter test time, higher model accuracy and easier implementation.Keywords：ring laser gyro;temperature model;error compensation- 32
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Published：2020-08-12 -
Infrared horizontal ATR instrument used in Fourier transform spectroscopy
Abstract：The general consideration and design ideas for an infrared horizontal Attenuation Total Reflection(ATR) instrument used in the Fourier transform spectroscopy were introduced, and the penetrating depth and reflective times affecting on the spectrum intensity were analyzed. The facula was reduced three times and focalized on samples, the optical system was restored and focalized to a receiver,and the energy usage ratio can be calculated and analyzed. Several samples were tested by the FTS-7 Fourier transform spectroscopy,the results show that the energy usage ratio is 5%, the total reflection is fifteen times,and the quality of the spectrum is close to the level of the similar instrument.Keywords：Fourier transform spectrometer;Attenuation Total Reflection(ATR) instrument;energy usage ratio;spectrogram- 32
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Published：2020-08-12 -
Material removal property in ion figuring process for optical components
Abstract：The material removal property with three important performance factors, the material removal efficiency, depth of the sub-surface damage and thermal effect, in the ion figuring process was analyzed. Based on the Sigmund sputtering theory, the relation models of these three factors with respect to ion energy and incident angle were established. The sputtering process of SiO2 bombarded by Ar+ was simulated with the software TRIM,and the parameters of the above theory models were synthesized with the simulated data. Then the relationships among the three factors and the two process parameters were researched by the theory models. The models and simulation results indicate that the removal efficiency increases slowly with the ion energy and fast with the incident angle in some range, the removal efficiency at 60° is about 4.5 times as high as that at 0°; the depth of sub-surface damage increases with the ion energy linearly but decreases with the incident angle; the thermal effect increases with the ion energy linearly approximately but reduces with the incident angle. Therefore, in order to improve the three performance factors at the same time, a larger incident angle should be the best choice.Keywords：optical component;ion sputtering;removal efficiency;sub-surface damage;thermal effect- 59
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Published：2020-08-12 -
Computer-controlled polishing technology for small aspheric lens
Abstract：Based on the computer controlling method,the polishing technology and pertinent researches for small aspheric lens were studied. The material removing function of computer-controlled polishing tool was simulated with computer at length. Then, according to the simulating results, polishing correction was accomplished after adjusting the function of tool resident time. Finally, a 70 mm aspheric lens was polished on our self-made and computer-controlled polishing machine with three universal driving shafts.Experimental results show that the polishing technology has higher efficiency and precision. The precision of profile measurement is 0.45 μm and the precision of surface roughness is 2.687 nm. Furthermore, a high repeatable accuracy is obtained also. The results also indicate that the polishing technology can improve remarkably the batch-quantity manufacturing efficiency of small aspheric lens.Keywords：computer controlled polishing;aspheric;resident time;correction- 53
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Published：2020-08-12 -
Measurement of ultralow spectral transmissivity by high-precision spectral radiometer
Abstract：Based on a grating double-monochromator, a high-precision, automated and single-beam spectral radiometer was designed for the high-accuracy measurement of ultralow spectral transmissivity of ultraviolet filter. It mainly consists of a xenon arc lamp with high stabilization, a one-aperture screen with shutter, quartz lenses, a neutral density degradation plate, an ultraviolet grating double-monochromator, a photodetector and an electronic control system,and the spectral transmissivity is 10-6~10-8 in spectral ranges from 200 nm to 400 nm. Measurement process can be controlled by a computer with special software. The principle, measurement method and datum processing method of the instrument were provided, and measurement uncertainty was analyzed. A filter sample was measured with this instrument, the measured results demonstrate that the spectral instrument has high precision, fast speed, and the measurement combined standard uncertainty is less than 3.16×10-3, which meets the requirements of measurement precision. This instrument can be used to measure the spectral transmissivity of ultraviolet filter with high precision requirement.Keywords：spectral radiometer;double-monochromator;transmissivity measurement;optical filter;solar blindness- 28
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Published：2020-08-12 -
H-type air-bearing motion stage driven by linear motors
Abstract：An H-type air bearing precise positioning stage driven by dual linear motors is established. Some key techniques, including design method of air bearing slider and synchronic-motion control of dual linear motors, are studied. The air-bearing sliders are designed by finite element method,and the pressure field distribution of gas film in the bearing gap is analyzed. Preload technologies are adopted to improve air bearing’s static performance. The static experimental results show that the preload sliders developed by finite element method have high load capability and stiffness. The static stiffness in the vertical direction of X-slider is 276.9 N/μm and the Y-slider is 333.3 N/μm. The improved parallel structure synchronous controller based on velocity synchro-error is designed, which adaptively tunes the PID parameters on-line by the fuzzy controllers. The motion experimental results show that the improved synchronous controller has high synchronous precision, the velocity synchronous precision is higher three times than the common parallel control, and will be suitable for multi-motor synchronization control with strong mechanical coupling. The H-type air bearing positioning stage driven by linear motors has high load capability and high precision, and can be used in precision engineering area such as photoetching machine and optical inspecting equipments.Keywords：linear motor;H-type motion table;synchronous control;air bearing slider;preload- 27
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Published：2020-08-12 -
PZT actuator control complex arithmetic based on nonlinear model
Abstract：A new nonlinear mathematical model descripting the comparability between minor loop curves and mean loop curves of the PZT actuator was establised. With the model, the minor loop curves can be expressed by multiplying each point while the mean loop curves by a sequential factor. The maximum relatively errors of the model are 1.2% in ascending curves and 2% in descending curves respectively. A new PID complex control arithmetic to the PZT actuator was setup referencing feed-forward loop. The experimental results show that 280 Hz closed loop bandwidth is available with 4 μm peak-to-peak input,and the band width is 30% wider than that of a general PID feedback control arithmetic.Keywords：PZT actuator;actuator;nonlinear model;complex control- 31
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Published：2020-08-12 -
Adjustment of stylus in double-disc involute measuring instrument
Abstract：The measurement error caused by the stylus position deviation in the double-disc involute measuring intrument was analyzed, and two methods,the test method and the error compensation method, for adjusting the stylus position accurately were introduced. In test method, with the angle of tooth profile being less than its real value when the stylus deviates the rails surface,the same involute tooth profile is measured repeatedly when the stylus is at different positions. The result shows that the stylus is in the best position when the angle of the tooth profile is maximal. In the error compensation method, the involute tooth profile is measured when the stylus is at two different positions over the rails,the results are compensated by attempting different values of the stylus deviation to get two results same, and the real deviation value can be obtained. The limited deviations of the two methods for adjusting the stylus position are ±0.010 mm and ±0.015 mm, which can meet demands for measuring level 1(GB/T10 095.1-2 001) involute tooth profile.Keywords：involute gear;error of gear tooth profile;double-disc device;stylus adjustment- 37
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Published：2020-08-12 -
Hysteresis compensation of giant magnetostrictive actuator based on Jiles-Atherton model
Abstract：The hysteresis compensation method is studied.A control system is established based on Jiles-Atherton hysteresis model and its main parameters are introduced. Then, according to Jiles-Atherton hysteresis model, the variation relation between magnetization and field intensity is analyzed. Finally, based on above analysis, a hysteresis compensation method using the width of hysteresis ring to recalculate the initial value for recursive algorithm at turning point is proposed. The experiment results indicate that,comparing with a actuator without hysteresis compensation, there is no time delay in proposed system and the settled time is 12 ms reduced for step response, Also, there is no time delay and the MSE is 0.19 μm improved for sine wave tracking, which shows that the compensation method can overcome the hysteresis effect and improve positioning precision effectively.Keywords：giant magnetostrictive actuator;hysteresis compensation;Jiles-Atherton model- 35
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Published：2020-08-12 -
Research on a multiway fluid joint mechanism
Abstract：According to the temperature control requirements of a large photoelectric theodolite, a compact multiway fluid joint mechanism with skillful structure is researched and designed. The mechanism research background is introduced and the composition and principle of the mechanism are presented.The feasibility of the structure is verified through calculating the friction resistance torque. Finally, the reasonability of the structural design is verified through the theoretical analysis and experimental results. The experimental results indicate that the mechanism is no leak when the sealing ring made of PTFE combined with the bronze is utilized to seal, and the friction resistance torque is only 1.666 N·m.The mechanism runs reliably and realizes the fluid transmission from static state to the continuous rotated state,which can meet the performance requirements of large photoelectric instrumentations properly.Keywords：photoelectric theodolite;photoelectric tracking;temperature control;friction resistance torque;PTFE- 56
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Published：2020-08-12 -
Optimization design of sealed cowling structure for magnetic bearing reaction flywheel
Abstract：In order to minimize the mass and optimize the dynamic performance of the sealed cowling for a magnetic bearing reaction flywheel, the optimum design method for sealed cowling structure is researched. The Finite Element Models(FEM) for the sealed cowling of two outline design schemes are established based on the FEM theory. The static intensity in one of the sealed cowlings is analyzed, and the stability of each sealed cowling to contract compressive stress is analyzed using an eigenvalue buckling technique. Then the two design schemes are compared each other,the optimum design of variable parameter outline is obtained.The effects of two key outline parameters and the thickness of the shell on the whole performance of the sealed cowling are analyzed,the results show that the optimum design scheme is in the shell mass of 0.197 kg, and the stability coefficient of 5.374. The method improves the reliability and efficiency of sealed cowling design, and has important significance in optimization design of the flywheel system.Keywords：magnetic bearing reaction flywheel;sealed cowling;Finite Element Model(FEM);buckling analysis;optimization design- 38
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Published：2020-08-12 -
Electromechanical dynamic modeling and coupling for optoelectronic theodolite
Abstract：The tracking servo system of an optoelectronic theodolite is studied based on the momentum moment theorem and Euler dynamic equation. The mathematical relationship and the nonlinear biaxial coupling dynamic model of gimbal system are derived by analysis and research of the coupling action of inertia moment, velocity and dynamics of axes in gimbal system. Then a electromechanical dynamic model for describing the dynamic characteristics of tracking servosystem is established according to the torque motor equation of execute component and is verified by comparison of testing method and computer simulation respectively. The model can set up a foundation for the further simulation and experimental research and can provide theoretical references for the design and simulation verification of the tracking servosystem of optoelectronic theodolite.Keywords：optoelectronic theodolite;electromechanical dynamics;coupling;modeling- 35
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Published：2020-08-12 -
Effect of several processing parameters on material removal ratio in ultrasonic-magnetorheological compound finishing
Abstract：A new optical polishing method for aspheric surface, Ultrasonic-Magnetorheological Compound finishing (UMC finishing), is presented. The machining principle and the experimental procedure of UMC finishing are introduced. Then the material removal profile for optical glass in UMC finishing is measured by a profile meter (Form Talysurf PGI 1240), and the material removal ratio in UMC finishing is calculated. The effect of several processing parameters (magnetic flux density, ultrasonic vibration amplitude, minimum gap between polishing head and workpiece, rotational speed of polishing head and rotational speed of workpiece) on the material removal ratio for optical glass in UMC finishing is researched. The results show that the material removal ratio in UMC finishing is 0.139 μm/min under some experimental conditions. The rules of material removal ratio for optical glass in UMC finishing are obtained,which provides a foundation for further research of UMC finishing technology.Keywords：material removal ratio;ultrasonic-magnetorheological compound finishing;ultrasonic polishing;magnetorheological finishing;Ultraprecision machining- 38
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Published：2020-08-12 -
Precision servo control of GMA based on compounding feedforward compensation
Abstract：A Giant Magnetostrictive Actuator(GMA) driven mechanism for piston noncircular pin hole boring is presented. In order to attain desired radial displacement of the boring bar accurately, a compounding feedforward compensation method is proposed. The classical Preisach model for the hysteresis of GMA is introduced briefly, and a novel iterative compensation algorithm is proposed to avoid calculating Preisach converse model directly. Then the implement procedure of the iterative algorithm is discussed and the block diagram is given. A good linearization between the input current of GMA and its hysteresis output is found, the effect of the algorithm is valided by experiment. A repetitive control compensator is designed to improve the control performance of the GMA further, and then a compounding feedforward compensation method is presented based on the two compensators. Experiment results show that, at the case of open loop control, the iterative compensation algorithm can reduce the hysteresis nonlinearization of GMA from -15.7%~+11.8% to -4.6%~+5.2%, and the PID control based on compounding feedforward compensation can reduce the tracking error of GMA to 1 μm. These conclusions indicate that the iterative compensation algorithm is effective, it can avoid calculating the Preisach converse model directly and the PID control based on compounding feedforward compensation can improve the control performance of GMA further.Keywords：GMA;iterative compensation;feedforward compensation;repetitive control compensator;PID control- 36
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Published：2020-08-12 -
Modeling method of micro-displacement stage driven by piezoelectric ceramic
Abstract：The piezoelectric ceramics have the property of hysteresis and nonlinearity, and the change rule is unknown and uncertain. It is difficult to build a high accuracy mathematical model simply using the traditional method. In order to improve the model accuracy of micro-displacement stage driven by piezoelectric ceramics, a new modeling method based on neural network is proposed in this paper. The structure and the modeling method of the stage are analyzed. Because of the advantages of the neural network in self-learn and self-adapting, the structure and the parameters can be adjusted on line to reduce the error of the stage model, and more exact information can be provided for the control system. Through training the net model by the stage displacement data, experiment results show that the average error and the maximum error are reduced to 80nm and 100 nm within 80 μm journey respectively, which satisfies the precision requirement of nanometer positioning.Keywords：precision stage;piezoelectric ceramic;nano positioning;neural network;system identification- 33
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Published：2020-08-12 -
Control mechanism based on differential electromagnet actuator for a room-sized optical instrument vibration isolation foundation
Abstract：In order to improve further vibration isolation performance, a new active vibration control mechanism based on differential electromagnet actuator is presented for room-sized vibration isolation foundation. By using the differential scheme, the output force of the actuator is linear with control current. Because absolute velocity feedback method and Skyhook method have the similar performance in the weak damping conditions and the former method is more easier to realize, the absolute velocity feedback method is selected as the control strategy. The control strategy can efficiently improve the performance in resonance area without losing the performance of high frequency area. Experiment results show that by using the proposed mechanism, the mean square roots of velocity or angle velocity at the three degree-of-freedom z, θx and θy fall to 3.38μm/s,1.76×10－6rad/s and 1.49×10－6rad/s from 10.06μm/s,4.16×10－6rad/s and 4.65×10－6rad/s in time domain, and the vibration isolation performance in resonance area improves 10dB in frequency domain.Keywords：room-sized optical instrument vibration isolation foundation;active vibration control;differential electromagnet actuator- 54
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Published：2020-08-12 -
A robust hyperspectral image compression method
Abstract：A robust hyperspectral image compression method is proposed for the detection of small target and abnormity. The virtual dimensionality of original data is estimated, then the endmember vectors are extracted using an unsupervised orthogonal subspace projection method. Fast-ICA transformation is performed with the endmember vectors as initialization matrix, and the IC images are coded by 2D Set Partitioning in Hierarchical Trees (SPIHT). The experiment results show that the algorithm has a high compression ratio (40∶1), while the spectral characteristics are preserved. This algorithm is an efficient 3D compression method for the detection of small target and abnormity.Keywords：image compression;hyperspectral image;independent component analysis;initialization- 75
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Published：2020-08-12 -
Image feature extraction in insect kinetic deformation measurement
Abstract：An image processing method for extracting sub-pixel of wing veins and vein junctions of insect images is proposed. The image of wing veins is denoised by wavelet, and then enhanced by wavelet homomorphic filter and bilinear generalized fuzzy.The center positions of wing veins are extracted by the sub-pixel extracting algorithm based on Hession matrix, and vein junctions are determined by the neighboring angle constraint and continuity of vein direction. The experiment results show that compared with other methods, the proposed approach can extract wing veins and vein junctions successfully, and can suppress the noise and disturbance effectively.Keywords：image processing;wing vein;wavelet homomorphic filtering;generalized fuzzy enhancement;feature extraction- 44
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Published：2020-08-12 -
Novel fast motion estimation algorithm based on optimizing predictive motion vector
Abstract：A new Optimizing Predictive Motion Vector Fast Motion Estimation Algorithm (OPMVFMEA) is proposed. Based on the center-median-biased distributed characteristic of the motion vector of real-world sequences and the high space-time correlation of adjacent block’s motion vector, combined with similar analysis of the motion vectors, the center, median, forward vector are selected as the basic predictive motion vector to predict the current one, then the similar threshold is set to reduce the redundant information from the three space adjacent block motion vectors. In addition, the adaptive threshold to enable half-stop is also represented. Experiment results show that the algorithm is able to adapt to all types of video sequences and can offer a high performance of PSNR.The search speed of the algorithm is faster than that of the existing well-known algorithms.For case examined, it is about 208 times faster than that of FS in average, which is superior to that of 146 times for PMVFAST, 77 times for MVFAST and 55 times for DS. Therefore, the algorithm improves the performance of existing motion estimation algorithms.Keywords：motion estimation;block matching;video compression;predictive motion vector;redundant information- 47
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Published：2020-08-12 -
Calibration of geometric parameters of line-array CCD camera based on exact measuring angle in lab
Abstract：A calibration system for geometric calibration of line-array CCD camera is established.The equipment,environment, algorithm based on exact measuring angle and calibration precision are investigated. According to the requirement of calibration precision, equipment and environment are confirmed. The field angles and image heights are tested by combining high-accuracy two-dimension turn-table with CCD subdivision measurement. Finally, the geometric parameters of the camera are calculated by a least square regression analysis. The analysis results show that the calibration precision of principal distance and principal point have reached micron level and the calibration precision of relative distortion is smaller than 1×10-4. This method can meet the requirements of high precision calibration of line-array CCD and has higher practical application value.Keywords：line-array;CCD camera;geometric parameter;calibration;angle measurement- 52
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Published：2020-08-12 -
Digital image correlation search method based on genetic algorithm
Abstract：A new search method based on genetic algorithm is proposed, and the experiment is done. The experiment results indicate that the stand deviation of u is 0.022 pixel, and the stand deviation of v is 0.032 pixel. The method can meet the requirements of nonlinear and multi-peak global optimization in the digital image correlation with high precision and rapid speed,and can avoid the initial value selection,which is better than the conventional search methods.Keywords：genetic algorithm;digital image correlation method;deformation;optimization- 62
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Published：2020-08-12
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