Chinese Version Light学术出版中心
Latest Issue
Issue 12 ， 2015
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Fast optical delay line device based on involute principle
Abstract：To improve the performance of optical delay line devices, a Fast Optical Delay Line(FODL) device was designed on the basis of the principle of involutes. After analysis of the basic principle of involutes, a mathematical model was established and the delay distance formula of the designed FODL device was comprehensively derived. The light spot distortion resulted from the incident light through the FODL device was theoretically and experimentally analyzed. Finally, a Michelson interference system was built to test the specifications of the device, including delay linearity, delay stability, delay distance and scanning frequency. The results demonstrate that the light spot distortion of the FODL device is linked closely to the radius of the incident light spot and the rotation angle interval of the rotating plane mirror. The smaller of the two factors are, the smaller of the light spot distortion will be. As shown by the data analysis, the delay distance is 40.036 mm while the delay time is 133.453 ps. The errors of linearity and stability are 0.419% and 0.806%, respectively. Moreover, the scanning frequency reaches 20 Hz. As compared with the common optical delay line device, the device in this paper provides with a larger delay range and a higher scanning frequency. Meanwhile, it has advantages in scanning linearity and stability, which meets the use requirements of fast optical delay lines.Keywords：optical delay line device;involute;linearity;delay distance;scanning frequency;light spot distortion- 66
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Published：2020-08-13 -
Tunable spatial heterodyne spectroscopy with grating-mirror structure
Abstract：As Spatial Heterodyne Spectroscopy (SHS) technology has a narrower spectral bandpass (about 10 nm) and its applications are restricted generally, this paper proposes a tunable SHS with a grating-mirror structure to widen the application ranges of the spectrometer. The tunable structure in the spectrometer is implemented by taking a plane mirror to replace a grating in the traditional double grating SHS system, meanwhile allowing another grating to rotate. It switches measuring band to broaden measurement range and applies a small pitching angle on the plane mirror to ensure the monodromy of the recover spectra, by which the application ranges of the spectroscopy are expanded. A prototype is established to verify the feasibility of the proposed SHS. The experiment result shows that the designed SHS has the bandpass range up to about 100 nm and its spectral resolution is better than 0.29 nm. The spectrometer has a simple structure and its grating production and spectral reduction are easy to be implemented. Moreover, by increasing the rotated times of the grating and introducing methods to eliminate stray light etc, it will expand the its bandpass farther and improve the spectral resolution.Keywords：spatial heterodyne spectroscopy;broadband bandpass spectroscopy;Spectrometer;high spectral resolution;grating dispersion;grating-mirror structure- 75
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Published：2020-08-13 -
Detection of angular tracing precision of rotating mirror house in streak camera
Abstract：On the basis of the theoretic deduction and corresponding reasonable assumption, a mathematic model was built according to the flight model of exterior trajectory to improve the angular tracing precision of rotating mirror house in a streak camera. A test device was designed and developed for the angular tracing precision of rotating mirror house in the streak camera. The measuring principle of the test device was introduced, the angular tracing precision was measured by the developed device and the uncertainty factors of the tested device were analyzed. The tested results show that the angular tracing precision of the high speed rotating mirror in the streak camera is (0.34±0.06)°, the relative uncertainty of the tested device is 3.0" and the main error sources come from interpretation and servo control. It concludes that the tested device designed has higher precision and reliability.Keywords：angular tracing precision detection;high speed rotating mirror photography;measurement uncertainty;projectile flight- 55
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Published：2020-08-13 -
Curve-fitting algorithm of measuring focusing constant of gradient-index fiber lens
Abstract：The curve-fitting algorithms were proposed to measure directly the focusing constant of a gradient-index (GRIN) fiber lens to further design ultra-small GRIN fiber probes. The quadratic polynomial algorithm and linear fitting method for measuring the focusing constant of GRIN fiber lens were investigated based on the characteristics of refractive index profile of the GRIN fiber lens and its model. Then,the effect of the focusing constant on the light-transporting characteristics of ultra-small GRIN fiber probes was discussed. The refractive index profile of the GRIN fiber lens was acquired by using an optical fiber refractive index profile tester. And then the focusing constant and center refractivity were obtained by the quadratic polynomial algorithm and linear fitting method. The results show that the fitted values of the focusing constant are calculated to be 5.587 mm-1and 5.513 mm-1 respectively with the quadratic polynomial algorithm and linear fitting method, which agree well with the nominal value of 5.5 mm-1 provided by the manufacturer. The fitting results show that the proposed curve fitting algorithms are feasible to measure and analyze the focusing constants of GRIN fiber lenses.Keywords：self-focusing lens;optical fiber lens;small optical probe;Curve-fitting;focusing constant- 49
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Published：2020-08-13 -
Widely tunable all-solid-state Cr:LiSAF lasers with external cavities
Abstract：When tuning components are placed out of the main cavity structure in a tunable all-solid-state laser, it will has a smaller insertion loss and is conducive to extend the tuning range. This paper develops a all-solid-state Cr:LiSAF laser to realize its wide tunability. The principle of a external-cavity configuration was explored. A prism and a grating were chosen tunable elements, the Cr:LiSAF lasers with prism-controlled external cavity and the Cr:LiSAF laser with grating-controlled external cavity were presented. The tuning characteristics such as tuning ranges, spectra and output powers of the two kinds of lasers were studied and the effect of coating on their output characteristics was analyzed. Finally, the tuning characteristics of prism-controlled laser and grating-controlled laser were compared. The results under an absorption power of 325 mW show that the tuning range of the Cr:LiSAF laser with prism-controlled external cavity is 785-985 nm and its maximum output power is 21 mW. Moreover, the tuning range of the Cr:LiSAF laser with grating-controlled external cavity is also 785-985 nm, its maximum output power is 20 mW and the Full Width at Half Maximum (FWHM)is 0.12 nm. These results demonstrate that the tunable all-solid-state Cr:LiSAF lasers with external cavities realize narrower linewidths and wider tuning ranges.Keywords：solid-state laser;tunable laser;Cr:LiSAF;external cavity tuning- 52
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Published：2020-08-13 -
Instrument line shape of infrared Fourier transform spectrometer and its engineer applications
Abstract：A spectral correction method was proposed for an infrared space-borne Fourier transform spectrometer by using Instrument Line Shape(ILS). The ILS of the Fourier transform spectrometer was introduced systematically. An ILS model was established based on the instrument characteristics, and the simulation and calculation were carried out by using the MATLAB. The laser spectral peak value difference between the center detector and the edge one was calculated in theory, and the relative error between theoretical calculation value and actual value is just 4.21% and the accuracy of the corrected spectrum by the edge detector reaches 10-5 magnitude. The results verify the validity of the spectrum correction of the plane array Fourier transform spectrometer by using ILS in the theory. Finally, a method was proposed to correct the non-central pixels' spectrum of the plane array Fourier transform spectrometer for engineer applications. The experiments show that the method has stronger universality and both guarantees high spectrum accuracy and improves the efficiency of spectral calibration. Moreover it reduces the workload of spectral calibration.Keywords：Fourier transform spectrometer;instrument line shape;spectral calibration;spectral correction- 79
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Published：2020-08-13 -
Relative wavefront gradient deviation evaluation methods for imaging systems
Abstract：The relative wavefront gradient deviation evaluation methods were proposed to evaluate wavefront errors of imaging systems for characterizing directly the imaging performance of the wavefront. The wavefront gradient deviation was defined as the deviation between each image point and image energy center and the relative wavefront gradient deviation was defined as the ratio of gradient deviation to Airy disk radius. Then, the relative wavefront gradient deviation evaluation methods were given. As the relative wavefront gradient deviation is independent on wavefront dimension, wavefront shape and focal length, the relative wavefront gradient deviation was evaluated by image size, image concentration and image energy distribution in this paper. The evaluations of image concentration and image energy distribution are usually stable enough for different test resolutions. The differences for every double or half resolution differences are usually less than 10%. According to the relative wavefront gradient deviation distribution on an exit pupil and wavefront gradient distribution on an image plane, it can be convenient to operate for optical manufacture and system assembling. The experiments show that the relative wavefront gradient deviation evaluations can be used as the wavefront specifications for quality control.Keywords：optical testing;imaging optical system;wavefront evaluation;wavefront gradient;relative gradient deviation- 43
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Published：2020-08-13 -
High resolution pattern-integrated interference lithography based on blazed grating
Abstract：To improve the quality of pattern interference lithography, a Pattern-integrated Interference Lithographic( PIIL) system based on a blazed grating was proposed, and the theory of optical system and the method to realize a high quality pattern were investigated. Firstly, the optical field properties of the typical PIIL system were analyzed and how to improve the resolution of the system was described. The influences of the system bandwidth and the pattern feature on the image quality were discussed and the process technique to enhance the pattern uniformity in the interference exposure was given. Then, a novel pattern-integrated interference lithographic method was proposed. The blaze grating was used as a diffraction beam splitter to realize the integration of phase and amplitude modulation and the numerical calculation was used to simulate the diffraction properties of the blazed grating and the optical field distribution on an image plane. The parameter optimization of the blazed grating was discussed and the diffraction efficiency up to 92.3% was obtained for ±1 order. Finally, the pattern-integrated interference exposure system was presented based on a Digital Mirror Device(DMD), a micro imaging path and the patterns of pixelated dot-matrix were obtained and the quality of pattern of interference lithography was improved markedly. The results verify the applicability of the method for arbitrary structures.Keywords：pattern-integrated interference lithography;Fourier optics;diffraction efficiency;laser direct writing;Digital Mirror Device(DMD)- 92
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Published：2020-08-13
Modern Applied Optics
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Effect of static magnetic field on surface charges of solid-liquid interfaces
Abstract：As the effect of a static magnetic field on the surface charge of solid-liquid interfaces is related to the fluid drag of micro/nano fluidic systems, this paper researches the effects of the static magnetic field on the viscosity of deionized (DI) water and the surface charges of borosilicate glass-DI water interfaces and analyzes the effect mechanism of static magnetic field on the properties of DI water. The experimental results show that when the DI water is exposed in the static magnetic field with a magnetic field intensity of 0 T to 0.6 T for 30 min, the viscosity of DI water decreases with increasing magnetic field intensity and the surface charge density of borosilicate glass-DI water interface increases with the increasing magnetic intensity. The effect mechanisms of static magnetic field on the properties of DI water are the breaking of hydrogen bond and O-H bond caused by the magnetic field. The research indicates that the static magnetic field changes the surface charge properties of solid-liquid interfaces.The research in this paper provides a possible method to control the fluid drag at micro/nano scales using magnetic fields.Keywords：micro/nano fluidic system;fluid drag;Magnetic field;solid-liquid interface;surface charge- 41
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Published：2020-08-13 -
Interface circuit for digital close-loop capacitive microaccelerometer with time division multiplexing
Abstract：To implement the digital close-loop for a capacitive microaccelerometer, a digital close-loop ASIC(Application Specific Integrated Circuit)was designed to reduce the output niose and to improve the measuring range of the interface circuit. The current interface circuit ASIC for the capacitive microaccelerometer was improved. A differential capacitance readout signal and a feedback signal controlled by Pulse Width Modulation(PWM) wave were applied to a middle plate sequentially, then the controller was used to operate the accelerometer to realize the close-loop configuration and a Sigma Delta modulator was used to perform the analog to digital conversion. The principle and characteristics for the capacitive microaccelerometer and the Sigma Delta modulator were analyzed, and a system model of the proposed digital close-loop capacitive microaccelerometer was built to implement the system design and simulation. The experiment on the capacitive microaccelerometer presents 9.6 μg/ Hz noise and an input range of about ±3g. The results indicate the interface circuit with Time Division Multiplexing works well in microaccelerometers and the proposed system model is correct.Keywords：capacitive microaccelerometer;digital close-loop;interface circuit;sigma delta modulator;time division multiplexing- 59
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Published：2020-08-13 -
Filter wheel mechanism for optical remote sensor in geostationary orbit
Abstract：To achieve the multispectral imaging of a space optical remote sensor in geostationary orbit, multispectral imaging methods of light filtering in the optical system were investigated. By comparing two kinds of filter modes, the transmissive filter program was selected to switch lights in different bands. Combining the characteristics of the optical system, a scheme was chosen to set a filter wheel mechanism in the vicinity of the focal plane where the degree of light concentration is higher. By comparing the characteristics of different rotating mechanisms, a new type of filter wheel mechanism consisting of a filter wheel assembly and a filter wheel driving mechanism was designed based on a regular five truncated pyramid. The composition and working principle of the mechanism were introduced. Then, the comprehensive performance on filter wheel mechanism was tested before and after the environmental simulation tests. The test results show that the Root Mean Square(RMS) value of filter surface accuracy before and after the tests is better than the average value of λ / 30, the body rotation accuracy is better than 25". Moreover, the mechanism has good self-locking performance and meets the requirements of optical remote sensing multispectral imaging under complex space environments.Keywords：geostationary orbit;optical remote sensor;Filter;filter wheel mechanism;regular five truncated pyramid- 48
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Published：2020-08-13 -
Mechanical controlled piezoelectric inertial rotary actuators
Abstract：This study focuses on piezoelectric inertial rotary actuators. The motion characteristics of two kinds of piezoelectric inertial rotary actuators based on asymmetrically clamping structures and changing frictional force were researched. The working principles of two types of actuators were introduced and expounded. To test the performance of the actuators, two prototypes were fabricated and an experimental system was set up. Tested experiments show that the average output stepping angle of the actuator with the asymmetrically clamping structures is bigger than that of the actuator based on the changing frictional force under a square wave signal of 8 Hz, and the rollback rate in each step of the two types reaches 73.19% and 65.67% under a drive voltage of 100 V,respectively. The linearity residual square sum and the repeatability standard deviation are 0.031, 0.069 for the actuator based on the asymmetrically clamping structures, while 0.011、0.063 for the actuator based on the changing frictional force. Experimental results indicate that the average output stepping angle, rollback rate in each step, linearity and repeatability of the former are all greater than those of the latter.Keywords：piezoelectric inertial rotory actuator;asymmetric piezoelectric actuator;variable friction piezoelectric actuator;movement characteristics- 55
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Published：2020-08-13 -
Micro groove structure with multi-station combination electrode by EDM
Abstract：As a complex micro groove cavity made of mold steel with high hardness is difficult to be machined, a kind of electrical discharge machining method by use of a multi-station combination electrode is proposed. The cavity for micro fluidic chip molding is selected as researched object, NAK80 as the cavity material, and copper-tungsten alloy (75%W) as the material of the corresponding electrode with a micro convex structure manufactured by High Speed Milling(HSM). To reduce processing difficulty and ensure processing quality, the complex micro convex structure is decomposed into two groups of four-station combination electrodes. By alternating peripheral milling and end milling, the surface of the micro convex structure generates continuous plastic deformation, which reduces and removes the top processing burr of the micro convex structure and the burr can be reduced and removed. Finally, based on the qualified multi-station combination electrode, the rough, semi-finishing and finish machinings are completed successively by using precision Electrical Discharge Machining(EDM) and transforming the electrode station instead of changing electrodes. Experimental results show that the verticality of the groove sidewall is good enough, the height and width errors are within 3 μm, the root radius is within 15 μm, and all this satisfies the demand of micro fluidic chip molding.Keywords：micro groove structure;micro cavity;multi-station combination electrode;High Speed Machining(HSM);deburring;Electrical Discharge Machining(EDM)- 46
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Published：2020-08-13 -
Stiffness optimization of two-axis flexible supporting platform for fast steering mirror
Abstract：Elliptic flexure hinges have both advantages of larger moving ranges and higher moving accuracy from right-angle flexure hinges and circular flexure hinges. Therefore, this paper designs a two axis flexible supporting platform with an elliptic flexure hinge used in a fast steering mirror system. For a fast response required by the system, the flexible supporting platform needs to maximize its natural frequency within the material's allowable stress. Firstly, the theoretical formulas of the maximum stiffness including the parameters of the allowable stress and rotating angle are deduced. The lumped parameter analysis method is adopted to obtain the relationship between the stiffness of flexible supporting platform and the stiffness of single flexure hinge. Then, the closed-form solution about the low order natural frequency of the two axis flexible support platform is deduced. A finite element model are created to perform experiments to assess those equations . The results compared by finite element analysis and theoretic calculation show that the relative error of the platform's natural frequency and maximum stress is within 5%. The relative errors of platform's stiffness got by the experiment, simulation and the theoretic calculation are 3.86% and 5.75%, respectively. These results indicate that the theoretical formula proposed in this paper is benefit for engineering structural design,it not only meets the requirements of engineering design, but also saves a lot of time .The most important thing is that it can help to achieve the optimal stiffness in theory.Keywords：fast steering mirror;elliptic flexure hinge;flexible supporting platform;stiffness optimization;natural frequency- 60
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Published：2020-08-13 -
Subsurface damage depth of lithium niobate crystal in lapping
Abstract：In consideration of the effect of the Subsurface Damage Depth (SSD)of optical material introduced by lapping on the efficiency of polishing process and surface quality of workpieces, this paper explores laws of the subsurface damages (SSDs) of optical materials in lapping process. An angle polishing method was employed to measure the SSD of a soft-brittle material Lithium Niobate (LN) crystal. The influences of lapping type, grit size and lapping parameter on the SSD were investigated experimentally. The results show that lapping method is the most significant factor on the SSD. The SSD of loose abrasive lapping is about 3-4 times that of fixed abrasive lapping in the same condition. Circular cracks are filled in the subsurface of loose abrasive lapping workpiece, while herringbone cracks are mainly distributed over the subsurface of fixed abrasive lapping workpiece. The effects of grit size are also quit remarkable.With the grit size decreasing from W28 to W14, the damage depths of loose abrasive lapping and fixed abrasive lapping are decreased to 45% and 30%, respectively. Moreover,reducing applied load is beneficial to subsurface defects. This study affords a guidance for lapping method selection and lapping process optimization of LN crystals.Keywords：soft-brittle crystal;lithium niobate crystal;fixed-abrasive lapping;grit size;subsurface damage depth- 58
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Published：2020-08-13 -
Integration of intelligent measurement and detection for sealing rings used in aerospace systems
Abstract：To achieve the intelligent and automatic measurement and detection of 'O' rings used in aerospace systems, a double-station intelligent measuring and detecting system was established. The integrating method of wide-range measurement and defect detection in curved surfaces was proposed, and the autonomous measuring path planning technology was investigated. Aiming at the flexible structure and the curved surface shape of 'O' rings and the wide range of the ratio between the inner diameter and the section diameter, an intelligent measuring and detecting scheme of double-station based on the cooperation of multiple fields of view (FOV) was proposed. The system integrating method and its working principle were introduced. Then, according to the information extracted from the panoramic image of the 'O' rings in the large FOV and the basic rule of path planning, the general calculating method of the acquisition path of small FOVs was derived. Finally, the mapping relationship between the position coordinates of detecting path and their image coordinates in the large FOV was established to realize the intelligent and automatic detection of 'O' rings. The experiment results show that the proposed scheme realizes the autonomous measurement and detection of 'O' rings whose inside diameters are in the range of Φ5.4-Φ140 mm. The average error between actual and ideal locations of detecting path is 0.086 mm. Compared with manual measuring and inspecting, the efficiency has been improved by more than 20 times. It satisfies the smart, efficient and automatic requirements of measuring and detecting precise sealing rings used in aerospace systems.Keywords：sealing ring;seal in aerospace system;intelligent measurement;automatic detection;automatic measurement.- 73
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Published：2020-08-13 -
Ion source with posterior suck sampling and ionization by ionic wind
Abstract：As existing ion source requires a complex external huge gas supply and is not convenient to be carried, this paper proposes a integrated system by an opened ion source and a micro gas pump based on ionic wind. A new needle array-cylinder discharge electrode structure was designed to realize the double functions of the open ion source and the micro air pump in ambient air. When the power supply was served as a negative DC high voltage of 0--20 000 V, and the distance between the needle and the cylinder was 10 mm, the corona discharge was implemented by three types of discharge electrode structures respectively: single-array-needle and single-cylinder, single-array-needle and double-cylinder, double-array-needle and double-cylinder, and the wind velocity was measured by the testo 405-V1 anemometer。The result shows that the maximum wind velocity is produced by the double-array-needle and double-cylinder structure. By using three types of electrode structures, COMSOL multi physic simulation software was applied to simulation of the ion wind and the results show that the simulation is coincided with that of the experimental results well. Based on the double-array-needle and double-cylinder structure, the integrated system experiment of the ion source and the micro air pump was conducted. The results demonstrate that the maximum ion wind generated by the structure discharge is 2.11 m/s,which can suck an acetic acid sample at the bottom into the device. Moreover, the maximum electric current value reaches about -10 nA tested by the Faraday cup, which shows that the device realizes the ionization function. In conclusion, the integrated system of the ion source and the micro air pump in this paper realizes posterior suck sampling and ionization, omits a huge complex external gas supplies, and is expected to be applied to portable analytical instruments.Keywords：ion source;miniature air pump;ionic wind;posterior suck sampling;ionization- 61
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Published：2020-08-13 -
Stress-free alignment of off-axis three-mirror system
Abstract：To overcome the degradations of optical figure accuracy and image quality caused by external or internal stresses from connecting, fastening or temperature changing in the alignment process of an off-axis three-mirror system, stress-free mechanical design and system alignment methods were proposed. The impacts of the stresses on the mirrors were reduced by employing combined inner and outer mounts, setting up flexible links and increasing the delivery distance from stress source to mirror surface. The system frame was positioned without being fastened. Three high precision steel balls and corresponding a conical-hole pedestal, a V-type mount and a plate pedestal were utilized to constrain all six degrees of freedom (DOF) of the system support frame. Two Leica theodolites and two datum cubic prisms were used for monitoring the micro displacement of the support frame. Several digital micrometers were employed to monitor the movement and recovery of six-DOF adjustment mechanisms. Through preliminary and computer-aided alignments, the whole-field-of-view average Root Meant Square(RMS) wavefront error reaches to 0.068λ, and then becames 0.070λ after spacers are ground and connected to the frame. The average Modulation Transfer Function(MTF)(at Nyquist frequency)corresponding to the whole field of view is 0.720. These results meet the performance specifications and verify the feasibility of the proposed methods.Keywords：off-axis three-mirror system;stress-free alignment;computer-aided alignment;wavefront error- 93
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Published：2020-08-13 -
Comprehensive error modeling and compensation for precision polishing platform based on orthogonal experiment and interpolation algorithm
Abstract：To improve the machining precision of four-axis polishing platforms, a geometric and thermal comprehensive error model and an error compensation method were researched for a four-axis polishing platform with a float platform and a rotation platform. Several kinds of instruments such as laser interferometer, temperature sensor were used to repeatedly measure and analyze respectively the positioning errors of X,Z axes at different temperatures and to verify that different feeding speeds were no significant influence on the positioning error. The change rules of between position error and temperature change for the polishing platform in X,Z axes were obtained. Based on orthogonal polynomial and interpolation algorithm, the geometric and thermal comprehensive error model of X,Z axes was established. According to the comprehensive error model, the prediction data curves were calculated, and seven groups of experimental data of X,Z axes were fitted and the fitting residual error absolute value was verified to be less than 0.2 μm. A compensation experiment was carried out according to the forecasting data. The results show that the X axis positioning errors of polishing platform under the normal temperature, the temperature rise of 60 min and steady state are respectively decreased by 89.33%, 92.45% and 85.7% after compensation, and the Z-axis positioning errors are respectively reduced by 89.23%, 93.59% and 93.33% after compensation. The experimental results demonstrate that the presented comprehensive model and compensation method have high precision and good robustness.Keywords：polishing machine;orthogonal polynomial;interpolation algorithm;comprehensive error model;error compensation- 53
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Published：2020-08-13 -
Identification of gear rattle vibration by vibration relative approach
Abstract：Gear rattle vibration signals on the transmission housing caused by unloaded gear pairs are difficult to be identified and the rattle vibration levels can not be evaluated quantitatively, because many vibration signals are included in the transmission housing when the vibration signals are recorded in the full vehicle on a chassis dynamometer. This paper proposes a rattle vibration relative approach to identify the gear rattle vibration signals. Firstly, the vibration signals on the transmission housing were filtered by ear characteristic filtering functions, and steady vibration signals were extracted by regression and smoothing processes. Then, the relative approaches of the unloaded gear vibration were obtained by subtracting the steady vibration signals from all of the filtered vibration signals. The vibration relative approaches were taken as transient vibration signals of the unloaded gear pairs. Finally, the occurrence time, frequency and the level of the gear rattle vibration were identified. Through this method, 134 rattle vibration signals of the highest relative approach were identified within 3.5 s in the full vehicle test. The results show that the rattle occurrence time obtained by the relative approaches is entirely coincided with that of the 134 rattle vibration signals which are gotten by the vibration signal playback. The result of the gear rattle vibration identification is consistent to that of the subjective perception, namely, the gear rattle vibration is identified accurately. The results of the gear vibration identification can be used to quantify the rattle vibration level, verify the theory model of rattle prediction, research the effect rule of different parameters on gear rattle vibration level, find the key factors with high sensitivity to the gear rattle vibration level and to optimize gear rattle performance.Keywords：gear rattle;gear rattle vibration identification;rattle vibration relative approach;manual transmission- 43
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Published：2020-08-13
Micro Nano Technology and Fine Mechanics
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Application of neural network fractional order PIμDλ to piezoelectric stack control
Abstract：To overcome the hysteresis characteristics of a piezoelectric stack and to control the piezoelectric stack more accurately, a control system for the piezoelectric stack was established and corresponding algorithms such as neural network,fractional order differential and integral calculus were investigated. First, a hardware platform was set up to collect displacement data of the piezoelectric stack and a wavelet algorithm was used to removal noise. The Radial Basis Function(RBF) neural network model of piezoelectric stack was built to obtain model parameters. Then, the Jacobain information obtained by RBF neural network model was used to set controller parameters of a fractional order PIμDλ to control the piezoelectric stack. Finally, the comparative work between RBF fractional order PIμDλ and traditional RBF integer order PID was performed to demonstrate the effectiveness of the proposed control methodology. The results show that the RBF model error is only 0.22% that of measured displacement data. The output of fractional order PIμDλcontrol system is stable and has a good follow to the input. It concludes that the RBF neural network fractional order PIμDλ controller has good control performance, and it is more stable and accurate to RBF integer order PID in the control process of piezoelectric stacks.Keywords：piezoelectric stack;hysteresis characteristics;Radial Basis Function(RBF) neural network;fractional order PIμDλ- 36
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Published：2020-08-13 -
Oversampling point target track-before-detect by Multi-Bernoulli filter
Abstract：A oversampling track-before-detect method for point targets was proposed based on the multi-Bernoulli filter to improve the detection performance of an oversampling system. Firstly, the imaging process was analyzed for the temporal-spatial oversampling system, and an imaging model for the point target was established. Then the temporal-spatial oversampling sensor was equivalent to multiple single-sampling sensors. For this, the image processing method used in single-sampling system could be extended to the oversampling system naturally. Furthermore, the prediction step and update step of Multi-Bernoulli filter were given by this proposed model, and the oversampling track-before-detect method was realized by sequential Monte Carlo method. Finally, the simulation experiment was performed to verify the effectiveness of method proposed. The experimental results show that proposed method can effectively detect and track multi point targets at a signal to noise ratio high than 0.25 pixel in oversampling system and the error of target state estimation is less than 0.25 pixel. In comparison with the single-sampling system, the oversampling method can detect and track dimmer targets and meets the requirements of detection and tracking for space point targets.Keywords：temporal-spatial oversampling system;point target;track-before-detection;multi-Bernoulli filter;sequential Monte Carlo method- 71
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Published：2020-08-13 -
Blur identification algorithm to suppress parasitic ripples on infrared images
Abstract：A blur identification algorithm for infrared fuzzy image restoration in military targets was proposed. An appropriate model was established based on the formation mechanism of an aero-optical turbulent field. The point spread function was simplified to a Gaussian function form that could be described by parameters. On the basis of infrared images' edge gradient characteristics, the edge definition improvement was proposed to estimate the blurring parameters and to be acted as the standard of blur identification . When definition improvement was taken its maximum, the corresponding blurring parameter was the optimum parameter of an observation image. For the ringing effects occurred in restoration processing, weighted space restoration algorithm derived from detail regularization was used to adaptively suppress the parasitic ripple. Experimental results show that the algorithm effectively recovers infrared blur images, accurately identifyies the blurring function and the relative errors have reduced to 4.5%.Moreover, the algorithm suppresses perfectly ringing effects during the image restoration process. Data show that all the quality evaluation indicators have been improved, the Peak Signal to Noise Ratio has improved by 9.4 dB and the comprehensive evaluation index ImgeQ improved more than 20.Keywords：aero-optical effect;infrared blur image;blur identification;adaptive restoration;parasitic ripple suppression;ringing effect- 48
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Published：2020-08-13 -
Subjective evaluation of quality for color fusion images
Abstract：In consideration of the important role of human eye subjective evaluation in quality evaluation of color fusion images,a human eye subjective evaluation experiment by 52 people was designed. 240 color fused images gotten by eight kinds of fusion algorithms in three typical scenarios of greenbelts, sea to sky and cities and towns were evaluated subjectively by designed single-evaluation indexes(the perceptual contrast between target and background, sharpness, color harmony and color naturalness) and two comprehensive-evaluation indexes(Perceptual Quality based on Scene Understanding, PQSU and Perceptual Quality based on Target Detectability, PQTD). Then the subjective evaluation data gotten by 52 people for each index score and correlation analysis were carried out and two evaluation models were established. The results show that there is a high correlation between color harmony and color naturalness. The PCTD can be described by the perceptual contrast between target and background and the sharpness and the PQSU can be described by color harmony and sharpness. But,for different scenarios and visual tasks, the weight of each evaluation index is different.Keywords：color fused image;subjective evaluation;subjective evaluation index;comprehensive prediction model;score round and correlation analysis- 51
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Published：2020-08-13 -
Metrics of image background clutter by introducing gradient features
Abstract：To improve the metric precision of image background clutter for target acquisition performance,a metric method of image background clutter by introducing gradient features is proposed in this paper. The method is based on the visual properties of the human eyes sensitive to edges and regards the regional gradient distribution as a new structural characteristic. Firstly, the gradient direction histogram is used to represent goal structure characteristics and the Pap coefficients are selected for measuring the similarity between the image target and the background clutter gradient direction histogram. Then the structure similarity information is weighted with image structure similarity metrics. Finally, the D.L.Wilson target acquisition performance model is taken as prediction models for predicting the target detection probability,false alarm probability and search time to predict the target acquisition performance of the Search-2 database. The results show that the proposed metric method of image background clutter by introducing gradient feature has improved metric precision of prediction models, the linear correlation coefficients are 0.870, 0.845, 0.897 and root mean square errors are 0.056 9, 0.046 9, 2.129, respectively. These data means that the predicted results and the actual observer have good consistency, and the target acquisition performance is superior to those of other methods.Keywords：background clutter metric;structural feature;histogram of oriented gradient;target acquisition- 57
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Published：2020-08-13 -
Automatic corner detection of checkerboard based on LSD
Abstract：To improve the robustness of current automatic corner detection algorithms, a novel algorithm based on Line Segment Detection( LSD ) was proposed to extract the corners automatically. First, the LSD algorithm was used to process a checkerboard image to obtain all lines including checker edges. Then, the pseudo permutation of lengths and angles for obtained lines were done respectively to filter fake edges. Furthermore, the neighboring endpoints of the remaining lines were combined, and the coordinates of the corners were optimized with the sub-pixel algorithm. Finally, an energy method was utilized to recover the chessboard's structure and the corner points were ranked at the same time. Experimental results indicate that method proposed here automatically detects corners in images with noises and shadows. The maximum locating error and average error for the corner coordinate extraction are less than 0.2 pixels and 0.15 pixels respectively as compared with those of modified Harris method. This method has a higher robustness and its locating accuracy is almost as the modified Harris method, which shows it is suitable for a real factory environment.Keywords：Line Segment Detection(LSD);checkerboard;corner detection;robustness;automatic extraction- 95
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Published：2020-08-13 -
Blind restoration of nature optical images based on non-convex high order total variation regularization
Abstract：Influence by noise and image edge structure information, traditional blind image restoration methods usually result in special phenomena of ringing, tail and ladder. To solve these problems, this paper proposes a more general blind restoration model of nature optical images based on non-convex high order total variation regularization by using the posteriori information of an image, the sparse property of a Point Spread Function(PSF) and different advantages of norm l1 and norm l2 in restriction. In the numerical solving process, the Split-Bregman iteration method was introduced by improving the norm of the model structure to improve the calculation accuracy and to solve the non-convex optimization. The experimental test between artificial simulation degradation images and real images was performed. Results show that the proposed method restores effectively variety types of degenerated images, and the restored images have well edges and their texture details are better than that of the models in recent literatures. The objective appraisal indicates that the peak signal-to-noise ratio has increased by 2.08 dB and the largest improvement of the information entropy reaches to 1.14 units as compared to the latest literature models.Keywords：nature optical image;image blind restoration;point spread function;regularization;total variation;Split-Bregman- 92
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Published：2020-08-13 -
HEVC rate control for unmanned aerial vehicle airborne reconnaissance
Abstract：A High Efficiency Video Coding (HEVC) rate control algorithm with a low-delay was proposed based on buffer status and a gradient operator to improve the poor video quality of the current HEVC rate control scheme caused by the improper bit allocation in Unmanned Aerial Vehicle (UAV) airborne reconnaissance. First, both the buffer state and the remained bits were used to pre-allocate the frame layer target bits. Then, the time and space complexity of the Largest Coding Unit (LCU) in each frame was taken as the weight, layer bits hierarchically with the reconnaissance video features was evaluated by a gradient value. Finally, Quantization Parameter (QP) was derived from R-λ model, the encoder in the LCU and the model parameter updating were implemented. Experimental results show that the proposed algorithm reduces mismatch ratio to 2/5 that of the rate control scheme in HM16.0, and PSNR (Peak Signal-to-noise Ratio) fluctuation has been within 1/4 under the 8 Mbps bandwidth. Moreover, the proposed algorithm provides an improvement in subjective quality evaluation and has less bit fluctuation and lower, steadier buffer occupancy, which enables a lower delay of aerial photography applications.- 86
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Published：2020-08-13 -
Corner detection via consistency of local directional differential vectors
Abstract：On the basis of edge contour extraction, a new corner detection algorithm via the consistency of local directional differential vectors of pixels was proposed to eliminate the adverse effects of the edge noise on the corner detection. In the algorithm, the edge contour of an image was extracted to reduce the computation. Then, the Anisotropic Gaussian Directional Derivative( ANDD) filters were used to extract the directional differential vectors at each pixel on contours and the power transformation was employed to the vectors to enhance their anisotropy. Furthermore, the consistency was constructed from the directional differential vectors of adjacent pixels. Finally, the consistency was normalized by the average consistency on the same contour to produce the final corner measure. The experimental results show that the proposed algorithm achieves the average localization error of 1.52 pixel approximately to comparison algorithms. Also the detection accuracy is improved by 58% and 5.5% as compared with those of the Chord-to-point Distance Accumulation (CPDA) algorithm and relative local curvature (He&Yung ) algorithm and it is equal to that of the Residual Area (RA) algorithm. Meanwhile the false detection ratio is 25.5%, 21.6% lower than those of the He & Yung and RA algorithms, respectively. The proposed algorithm accurately detects the true corners in the image and holds a smaller false detection ratio and higher corner repeatability, and it is very robust to the edge noise.Keywords：computer vision;corner detection;anisotropic Gaussian directional derivative;edge contour;vector consistency- 59
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Published：2020-08-13
Information Sciences
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