Chinese Version Light学术出版中心
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Issue 5 ， 2007
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Remote detecting system for hydrogen based on interferometric spectrometry
Abstract：A remote detecting system for hydrogen based on the interferometric spectrometry is presented. Using quartzose tungsten iodide lamp as lighting, an integrated optical device for collecting energy and interfering is designed for adjusting system and measuring hydrogen gas. Then the optical system is simulated by LightTools, the optical intensity received by a receiver is analyzed and processed by MATLAB, and the arithmetic is also set up. The results demonstrate the possibility of this technique in remote detecting hydrogen and the applicability of the remote detecting system in other fuel.Keywords：interferometric spectrometry;Fourier transform;remote detecting;hydrogen- 45
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Published：2020-08-12 -
Comparison of noise properties in intracavity-doubling quasi-three-level and four-level solid state lasers
Abstract：Based on the different noise machanisms of the intracavity-doubling quasi-three-level and four-level lasers,the blue(473 nm) and green (532 nm)lasers are made to study their noise characteristics using the same laser crystal (Nd∶YAG) and the same doubling crystal(LiB3O5). The magnitude of the noise is >120% at output power of 50 mW in a intracavity-doubling quasi-three-level laser, but in a similar intracavity-doubling four-level laser,it is <5% at output power of 60 mW. It is shown that the noise in intracavity-doubling quasi-three-level laser is larger than that in four-level laser system. These properties of high-frequency noise in intracavity-doubling laser have been analysed through coupled-differential equation models and analysis results point out that these properties are caused by the reabsorption losses in quasi-three-level intracavity-doubling laser system.The noise in tracavity-doubling quasi-three-level laser will be decreased if reabsorption losses are controlled.Keywords：intracavity-doubling laser;Noise;quasi-three-level;coupled-differential equations;reabsorption loss- 31
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Published：2020-08-12 -
Computer controlled manufacturing during fine grinding stage of highly steep off-axis asphere with large aperture
Abstract：By studying and discussing on the technical puzzles of the high sagitta variation rate and the seriously changed removal characteristic of lap in computer controlled optical surfacing of highly steep off-axis aspheres with large aperture, the practicable solutions are given. Decreasing the sagitta variation rate through coordinates transforming, the computer controlled manufacturing method that the lap grinds along the normal of the asphere is carried out, then, revising the figure testing result to project it on the asphere's normal, and the revised result is used in computer controlled optical manufacturing to converge the figure error more precise and effective. Finally, a manufacturing example is given in the final figure precision of PV:10.502 8 μm and RMS:0.829 3 μm during fine grind ing stage. The results show that the methods are practical and have even higher convergence efficiency.Keywords：highly steep asphere;coordinate transforming;figure on normal direction;computer controlled manufacturing- 61
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Published：2020-08-12 -
Quantitative research on higher order harmonics in metrology beamline
Abstract：The synchrotron radiation spectra of spherical grating monochromator (SGM) working in soft X-ray and VUV region are often contaminated by significant amount of higher order harmonics, They cannot be suppressed completely by suitable filters. Higher order contributions in the spectral radiation standard and metrology beamline were researched using transmission grating (made in house) and IRD AXUV100G (USA) photodiode detector. The exit beam was dispersed with the transmission grating behind exit slit of the monochromator, and the contributions of the different orders were analyzed. The higher order distributions were quantitatively determined for three gratings in line densities of 1800, 600 and 200 l/mm. It is shown that in wavelength between 5~15 nm the contributions of the higher orders to the detector signal are restricted to less than 7% even without filters; In wavelength region between 5 nm and 34 nm the contributions of the higher orders to the detector signal are less than 14% with proper Al, Si3N4 and Zr filters; after modified by quantum efficiency of the detector, the higher order contributions are restricted to less than 6.5%. The research also shows that higher orders are almost totally suppressed by MgF2 filter when the wavelength between 115~140 nm.Keywords：spectral radiation standard;Beamline;higher order harmonics;spectral radiation metrology- 34
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Published：2020-08-12 -
Optical design of un-distorted fingerprint scanner using cylindrical system
Abstract：In order to eliminate the distortion caused by the astigmatism from a compensate prism to improve the image quality of the optical system in a old no-distortion fingerprint scanner, a new method for eliminating the distortion using a cylindrical system combined with a telecentric lens is proposed. The double cylindrical system can reduce magnification in one direction that the prism doesn't do it,and the telecentric system can eliminate the trapezoid distortion when the objective and image is tilted. A computer model is established using this idea to adjust the suitable merit function to optimize the aberration,a higher imaging quality result is obtained comparing with the prism compensated method. From the example design,it is shown that using cylindrical system and telecentric lens method,the MTF in finger capture position is bigger than 0.377 in 5 lp/mm(equivalent 40 lp/mm in image area)and bigger than 0.139 lp/mm in 10 lp/mm(equivalent 80 lp/mm in image area) in most of the fields of view,the MTF value is 1.6 times as large as that obtained by the prism compensate method,also the image quality is much even in every field of view.Keywords：finger print scanner;projection distortion;cylindrical system;optical design- 43
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Published：2020-08-12 -
Measurement of temperature-insensitive strain based on reflected bandwidth demodulation of tapered fiber grating
Abstract：A temperature-insensitive strain sensor is presented based on a tunable F-P interferometer to measure the bandwidth of the reflected light from tapered fiber grating(TFG) and the bandwidth demodulating method is demonstrated by a strain loading experiment. Experimental results indicate that the stress sensing system has a high delicacy and the precision of stress measurement is 0.060 N. This sensor has a considerable potential, particularly application for strain sensing in the smart structures. Based on the development of the interrogation system that can demodulate both bandwidth and center wavelength of the reflected light from TFG, a novel sensor that can measure strain and temperature simultaneously is presented.Keywords：Fiber Bragg grating;tapered fiber grating;reflected bandwidth;strain sensing;tunable F-P interferometer- 87
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Published：2020-08-12 -
Steady-state photon transport in multi-layered mismatched medium
Abstract：The diffusion equation of the photon transport in a multi-layered medium with mismatched refractive index is analyzed,and the accurate solution of the diffuse equation is set up. The equation is checked by Monte-Carlo simulation. The comparison between the spatially resolved reflectance of mismatched media and Monte-Carlo simulation shows an excellent agreement between our theory and Monte-Carlo simulation. Meanwhile, the effect of the variety of refractive index on spatially resolved reflectance caused by finite size flat beam is discussed. Experimental results show that diffuse result changes with the variety of the refractive index, while the refractive index is changed at the range of 1.35~1.45, and the maximum error is 7%.- 51
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Published：2020-08-12 -
A quick measuring method for liquid surface tension by laser beam
Abstract：A new quick measuring method for liquid surface tension by a parallel rectangle beam of diode laser and two pieces of linear array CCD sensors is presented. To avoid individual influence, liquid surface tension is measured by detecting angles of incidence at cylindrical liquid menisci instead of detecting climb height of liquid on flashboard. The relation between surface tension and the angle of incidence, and calculation formulas for the incidence angle measured with CCDs are developed based on the fundamentals of plate insertion method, the parameters are designed, and their errors are analyzed.The analysis shows that by a wider laser beam and big incidence angles, as well as keeping a long distance between two CCD sensors, the accuracy of liquid surface tension measurement will be improved. It is also found that the width detecting errors of laser beam is an important factor to accuracy of liquid surface tension measurement. For example, to measure water surface tension with a laser beam width of 1 mm and errors of 5 μm, the surface tension measurement accuracy is 1%. If reduce the beam width errors to 2 μm, the surface tension measurement accuracy will be 0.5%. Experimental results have proved that the surface tension of water measurement accuracy is better than 1% with this method.Keywords：surface tension;quick measuring;measuring with Laser;plate insertion method;CCD- 31
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Published：2020-08-12 -
A calculating method for temperature tolerance of space telescope
Abstract：A calculating method for the permissible temperature tolerance of the space telescope is studied and the temperature fields including every temperature state that the telescope is on orbit are described. The temperature field and thermal elastics based on a coupling model of the space telescope are analysized to abtain the displacement of optics surface and then its corresponding deformation is fitted as Zernike polynomial to use in a optical system. The MTF of telescope is calculated by transforming the coefficient of the polynomial into software CODE V. Experiment results show that when the MTF meets to the optical target, the ultimate temperature tolerance of the space telescope can be obtained, which is the aim temperature scope for the thermal design.Keywords：spacetelescope;temperature tolerance;Thermal control;CAE- 46
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Published：2020-08-12 -
555 nm all solid-state continuous-wave yellow-green laser
Abstract：A 555 nm all solid-state continuous-wave yellow-green laser with 946 nm wavelength from 4F3/2-4I9/2 transition in Nd:YAG and 1 342 nm wavelength from 4F3/2-4I13/2 transition in Nd:YVO4 is reported. 555 nm yellow-green laser is obtained using a doubly folded-cavity and type-I critical phase matching LBO crystal intracavity sum frequency mixing by 946 nm and 1 342 nm.When the incident pumped powers of Nd:YAG and Nd:YVO4 crystals are 12 W and 8 W,respectively,the output power of 555 nm yellow-green laser in TEM00 mode is 542 mW,also its power stability in 4 h is better than ±3.7％. The experimental results show that the intracavity sum-frequency mixing is an effective method for 555 nm laser and it can be applied to other two laser crystals to obtain more all-solid-state lasers with different wavelengths.Keywords：all-solid-state laser;yellow-green laser;doubly resonant;sum-frequency- 48
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Published：2020-08-12 -
Optical properties and material growth of GaAs(110) quantum wells
Abstract：There are two growth modes (monolayer-by-monolayer and bilayer-by-bilayer) under different conditions that correspond to monolayer and bilayer RHEED (Reflection High Energy Electron Diffraction) oscillations when GaAs epitaxial layer grows on GaAs (110) substrate. TEM (Transmission Electron Microscope) and photoluminescence measurements at room temperature and low temperature show that the quantum wells have very bad optical property under bilayer-by-bilayer growth mode and have nice optical property and rough interfaces under monolayer-by-monolayer growth mode. The results show that using different RHEED oscillations under different growth conditions, it is possible to grow high quality quantum wells on GaAs(110) surface.Keywords：photoluminescence;GaAs;quantum well;molecular beam epitaxy- 57
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Published：2020-08-12 -
China in quantum optics and quantum information
Abstract：In order to investigate the development of quantum optics and quantum information all over the world and to evaluate China's present status in the field, the data from the SCI database (1991~2006) was indexed based on 13 subjects categorized by Optical Society of America(OSA). The methods from literature metrology,scientific metrology and information analysis were used to measure the development speed of these disciplines and to compare the number of research papers of those leading countries. Therefore,scientists in China can have a quantitative judgment,a multi-dimensional thinking and more angles of observation. The conclusion is that the field of quantum optics and quantum information is one of the most viable new sciences in the 21st century. China has made some important innovative contributions in both theory and practice,which has been illustrated by the increasing tendency in reseaarch paper citation.Keywords：quantum optics;quantum information;bibliometrics;science metrology- 46
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Published：2020-08-12 -
Effect of mechanical characteristic of an micro-mechanical optically readable infrared imaging array device on its performance
Abstract：For an optically readable infrared imaging array device with a bi-material beam micro-mirror integrated structure, the effect of mechanical characteristic of the pixel on its performance was studied. Thermal-mechanical sensitivity was analyzed by theoretic calculation and ANSYS simulation to optimize the geometric parameter and the thermal-mechanical sensitivity of 2.14×10-3 rad/K was obtained. Based on the study of frequency and damping, the effects of mechanical characteristic on thermal vibration noise and mechanical stability were analyzed. The results show that the mechanical impulse inducing fracture is 8 945 g,and when the working pressure is determined to be 50~200 Pa, the thermal vibration noise and noise induced by ambient mechanical vibration can be neglected. The results satisfy the requirement for infrared imaging device in high sensitivity and low noise.Keywords：infrared imaging device;thermal-mechanical sensitivity;mechanical characteristic;thermal vibration noise;mechanical stability;micro-mechanics- 46
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Published：2020-08-12 -
Generalized nonlinear Preisach model for hysteresis nonlinearity of piezoceramic actuator and its numerical implementation
Abstract：The hysteresis nonlinearity of the piezoceramic actuator can not satisfy the congruency property of the classical Preisach model so that the modeling error is large when applying the classical Preisach model to the piezoceramic actuator. In order to improve the accuracy in hysteresis modeling of the piezoceramic actuator, the generalized nonlinear Preisach model and its new numerical implementation based on the nonlinear Preisach model with some modifications are presented. The new model has equal vertical chord property of minor loops to relax the congruency property of the classical Preisach model.Experimental results show that the maximum of the absolute error predicted by the generalized nonlinearity Preisach model reduces 0.22 μm and the root mean square error reduces 0.11 μm compared to the classical Preisach model. The generalized nonlinear Preisach model can describe the hysteresis of the piezoceramic actuator more accurately.Keywords：piezoceramic actuator;actuator;hysteresis nonlinearity;generalized nonlinearity Preisach model;modeling- 57
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Published：2020-08-12 -
A control system for experimental platform of micro aerial vehicle based on C8051F020
Abstract：A new measuring way different from the traditional deducting method for the angle of blade pitch was proposed based on high-speed camera and image processing. According to the experiment requirement, an experimental platform mainly based on the device of Micro Aerial Vehicle(MAV) and a new control system found on C8051F020 SCM were designed. In the platform, C8051F020 SCM was the MCU; the phase information of the propeller's main-shaft was tested with the micro position sensor and the PCA capture function of C8051F020 SCM. The four phase information of a propeller's main-shaft was gained by collecting the output signal of a position sensor; the motor speed was controlled by the output signal of PWM generated by C8051F020 SCM for controlling the motor speed up; a high-speed camera was touched off by the interrupt signal from the PCA capture in order to realize the synchronization between the speeding up of the motor and the taking pictures of the camera. This control system has compacted configuration and high reliability. Finally, using this system to control the MAV for simulating the forward flying, the electronic collector curve of MAV was obtained. It is proved that the proposed method and the experiment platform based this method can be used to measure the blade pitch and have met the design requirement completely.Keywords：MAV;C8051F020;experimental platform;high-speed camera- 42
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Published：2020-08-12 -
Application of electronic compass to all automated intelligent gyroscope north finder
Abstract：To improve the north-finding speed of the traditional mechanical gyroscope, a coarse north-finding method through electronic compass is presented. Based on the principle of electronic compass, the angle values between the north and heading of the system are real-time acquired through the digital port and serial port of the electronic compass using DSP processor, and the heading of the system is driven to the coarse north direction through the acquired angle values. The automatization of gyroscope coarse north-finding instead of the track reversion point way is achieved successfully. Experiments show that the time of coarse north-finding is reduced from 10 min to 1.5 min, and the precision within 30' can reach the requirement of precise north-finding.Keywords：gyroscope;north-finding ways;electronic compass;coarse north-finding;automatization- 45
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Published：2020-08-12 -
Test and analysis on nanohardness using an AFM-based system
Abstract：A system based on atomic force microscope(AFM) and a (Berkovich) diamond tip was developed for nanohardness and elastic modulus measurements. This system can directly gain the load-displacement curves that couldn't be obtained from indent software of AFM itself. The diamond tip was controlled by sending signal to achieve loading and unloading and gathering the real-time data. In this way the load-displacement curve and data could be acquired directly. Single point experiments were conducted on single-crystal copper and single-crystal aluminum thin films. TriboIndenter produced by Hysitron Inc was used to do the validated experiments. The results show that the system is suited for nanohardness measurement of the softer materials. By analysis on the effects of substrate material on nanohardness and elastic modulus, it can be known that the substrate has great influence on the mechanical characteristic of the film when the thickness of film is less than 5 to 10 times the peak depth. Nanohardness increases with a decrease in the indentation depth, which indicates a strong size effect, but there is no significant effect on the elastic modulus based the load-displacement curves.Keywords：atomic force microscope;nanohardness;nanoindentation;TriboIndenter- 45
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Published：2020-08-12 -
Analysis and design of input torque of spherical 3-DOF manipulator
Abstract：The torque balance equations of a spherical 3-DOF manipulator was derived in closed forms by analyzing the relationship of its input and output torques, then the torque input stability evaluation index and the global torque input stability evaluation index were defined and discussed based on the torque balance equation in detail. Finally, using the physical model technique, the parameters of the spherical 3-DOF manipulator were optimized based upon the global torque input stability evaluation index. Moreover, the integrated design scheme of spherical 3-DOF manipulator was confirmed to provide theoretical base for the applications of the spherical 3-DOF manipulator when satisfied the assembly conditions. Experimental results show that the spherical 3-DOF manipulator can be used as the waist, wrist and the precision platform to meet the requirements for high stiffness, high accuracy and good technological efficiency.Keywords：spherical 3-DOF manipulator;performance evaluation index;parameter optimization- 47
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Published：2020-08-12 -
Fabrication of nickel soft contact microprobe based on UV-LIGA
Abstract：Fabrication method and its key process points of the micro probes used in ICs or semiconductors were analyzed. The processes of nickel soft contact microprobes produced by UV-LIGA were introduced. By analyzing on its fabricating keys and optimizing the experimental process parameters of some key fabrication steps,a kind of nickel soft contact microprobe was fabricated. The experimental results show that nickel soft contact microprobe has total length of 4 mm, width of 80 μm, and height of 100 μm. Radius of curvature of the tip is less than 5 μm and the high-to wide ratio(100 μm∶20 μm) of spring is 5. The micro probes with appropriate dimensional accuracy, good appearance quality and less drawbacks can be fabricated relatively economically based on the optimized process conditions (before-exposure bake: 60 ℃, 120 min, 90 ℃,120 min; exposure: high level of exposure energy; post-exposure bake: 65 ℃,10 min,95 ℃,45 min; accessorial measurements: ultrasonic stirring developing, placing in air, cooling resist with stove closed) of UV- LIGA.Keywords：UV-LIGA;soft contact microprobe;SU-8 resist;photography;electroforming- 51
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Published：2020-08-12 -
Design and experiment of tracking and detecting system for azimuth
Abstract：A system for tracking and detecting flying object rapidly and exactly is designed and the accurate azimuth of the flying object is obtained synchronously. In this system, the azimuth error signal from detecting devices drives a servo running flat with detecting devices and an H-type bipolar PWM project is used in driving subsystem to drive DC motor in the servo running flat to improre response speed. A speed-detected motor is used to get speed feedback signal for better stability. A high precision encoder is adopted to get azimuth signal of flying object for higher measure precision. For analysis on system dynamic transfer function, the dynamic curve is emulated and dynamic parameter is calculated, also switch frequency and delay time are given. Displacement curve and speed curve of step response and other results of the system are obtained by experiment. The results indicate that the system can meet the technique requirements,it shows the excellent parameter in dynamic precision of 0.1°, max tracking velocity of 38.3 (°)/s and max tracking acceleration of 23.5 (°)/s2.Keywords：photoelectric tracking;azimuth measurement;PWM circuit;switch frequency;delay- 35
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Published：2020-08-12 -
Investigation on integral method of pendulous gyroscope
Abstract：An improved integral measuring method of pendulous gyroscope is developed to shorten the north seeking time and improve the measuring precision. On the rough north seeking stage, a step move method that is to consume the mechanical energy of gyroscopic pendulum by the outer action is used to realize the fast north seeking, and then, on the precise north seeking stage, a double photoelectric integral method is adopted to get the intersecting angle between the meridian plane and the reference axis of gyro. The double photoelectric integral method gets the equilibrium position of gyro swing by one and a half periods integral calculating of measuring data and then makes use of the formula to compute the intersecting angle. The experimental results show that the double photoelectric integral method can effectively improve the measuring precision and decrease the integral error of measuring period variety; the integral error is less than one of tenth that in the traditional photoelectric integral method; and the scheme satisfies the engineering requirement of accuracy and speediness basically.Keywords：pendulous gyroscope;north seeking;step move method;double photoelectric integral method- 32
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Published：2020-08-12 -
Correction algorithm of restriction of linear phase-shift error in complex spectral OCT system
Abstract：The conventional phase-shift methods in acquiring initial phase under the impact of linear-shift error are analyzed,and the ability of a fixed step algorithm to restrict the linear phase-shift error is researched by frequency domain and spatial domain analysis methods. The emalation model of a Complex Spectral Optical Coherence Tomography(CSOCT) spatial analysis for linear phase-shift is established, and the results are given in accordance with emulation in spatial domain and experiment. The analysis indicates that five frame phase-shift method impacts real structures of the sample in a least degree, restricts mirror image best and obtains images of the sample in 100% range.Keywords：linear phase-shift error;spatial analysis;phase-shift algorithm;complex spectral OCT(CSOCT)- 51
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Published：2020-08-12 -
A oxygen content magnetomotive analyzer
Abstract：Research is done on the measuring cell, light path and data acquisition system of a magnetomotive oxygen measuring instrument. Base on the magnetic performance of gas,the moment of rotation of a dumbbell is derived when it is in a nonuniform magnetic field. A design of the measuring cell is proposed,a rotary resistance for the dumbbell ball is implemented by a silver-coated erosion approach,and the techinque requirements are analyzed for the nonuniform gradient magnetic field. The light path and the CCD data acquisition system are introduced. To meet the requirements for instrumental scaling,temperature compensation and correction, five functional keys are set up,and their function are explained by list. The correction programme of the instrument and test data is given later on.Experiments results show that the precision of the instrument is above 0.2% at different temperature, the performance of temperature compensation,the precision and stability of the instrument satisfy the design requirements.Keywords：magnetomotive;oxygen conten analyser;Linear array CCD;correction- 43
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Published：2020-08-12 -
Restoration of motion-blurred images
Abstract：A new algorithm based on one-dimensional Wiener Filter (1DWF) is proposed to restore the image degraded in a deterministic way by motion-blurred and in a stochastic way by additive white noise. From the theoretical derivation of the new algorithm, this paper shows that it is possible to restore the two-dimensional images with 1 DWF, and the computational requirements of the 1DWF method are just one third of the old Wiener filter's. The experiment result of the 1DWF method shows that 1DWF can restore test images, 512×512 size and quantized in 8 bits, in 36 ms with Intel Pentium 4 3.0 GHz CPU. It means that the 1DWF method can reach speeds of restoration in 25 frames per second just with one CPU. And the experiment result also reveals that the quali ty of the images restored is no noticeable difference between the 1DWF method and the old Wiener filter.Keywords：motion-blurred;Wiener filter;image restoration;real-time restoration;fast algorithm- 41
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Published：2020-08-12 -
Application of wavelet neural network for identification of drifts errors in fiber optical gyroscope
Abstract：A wavelet de-noise model and wavelet neural network model are presented to predict drift errors of FOG and to enhance identification precision. The method utilizes wavelet analysis to remove high frequency noise and to improve its signal-to-noise ratio. De-noise signal is looked on as the desired output. Then, the network is trained and the weight matrices of neural network are modified by the recursive least square method with forgetting factor. This algorithm without any matrix operation can reduce the computation time and greatly improve real-time performance at fast convergence speed and high precision. The simulation results show that the identification error is within 1.5%. The method establishes the foundations for identification and compensation of the drift error effectively and accurately in inertial navigation systems.Keywords：fiber optical gyroscope;neural network;wavelet analysis;identification;drift- 56
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Published：2020-08-12 -
Elimination of impulse noise by auto-adapted weight filter
Abstract：An auto-adapted weight filtering method is put forward. The validity of the pixel is analyzed with a Rank-order Absolute Difference (ROAD) method, if the pixel is noise, the pixel will be reconstructed by the neighbor pixels with different weights, and the weight of the neighbor pixel is correlative with its validity. At last, not only the impulse noise is restrained, but also the detail of the image is reserved. Experiments show that when using the auto-adapted weight filtering to get rid of the impulse noise, an evident improvement is found compared with the general method, both in visual image quality and quantitative measures of signal restoration. When the impulse noise occupies 35% in image, the effect of data recovery by this method can be increased by 10 dB compared with conventional median filter.Keywords：image denoising;impulse noise;rank-order absolute difference;auto-adapted weight filter- 43
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Published：2020-08-12 -
Improved TennenGrad function for microscopic coarse autofocuing
Abstract：An improved TennenGrad criterion function and an improved Laplace criterion function are proposed for microscopic coarse autofocusing, which use Sobel operators and Laplacian operators to convolve and add together the absolute values of matrix pixels for a image. Several different existed criterion functions in microscope autofocusing are compared and analyzed. To judge the efficiencies of criterion functions, function criteria are analysed with smoothness, efficiency and robustness as the main criteria. In the CCD camera microscope experiment system, a micro accelerometer is used as the measured object. Three autofocusing strategies are proposed and compared, and the n-pixel grey level method is preferred for microscopic autofocusing. Coarse autofocusing results show that the improved TennenGrad function has the best performance, autofocusing range is 210 μm, and autofocusing resolution is 7 μm. Image results show that autofocusing curve becomes smoother, and the number of extremums reduce from 5 to 0.Keywords：microscopy;autofocusing;coarse adjustment;focusing criteria function;focusing strategy- 48
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Published：2020-08-12 -
Secure data hiding algorithm based on simulated annealing
Abstract：Taking the Average Relative Entropy(ARE) of DCT coefficients distribution before and after data hiding as the measures of security and the security optimization object, a optimal adjustment variables in the quantization embedding algorithm are chosen in simulated annealing. The experimental results based on the five standard test images show that comparing with other four algorithms the capacity is improved by 1.86 times in average, and the ARE object is decreased by 38% in average. And they also show that the proposed method can decrease the statistical distribution changes of DCT coefficients to keep the security in statistical sense with larger steganographic capacity.Keywords：data hiding;steganography;statistical security;Simulated annealing- 55
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Published：2020-08-12 -
Improved directional-distance filter
Abstract：Based on psychological distance, a spatial-distance weighting function is presented to quantify the influence of spatial distances on filtering effect. Combining this formula with the traditional Directional-Distance Filter(DDF), a new filter, Adaptive spatial Distance-weighted Directional-distance Filter (ADWDDF), is proposed. The experimental results show that the new filter, compared with the traditional DDF and several other representative vector filters, provides better performance and filtering effect on noise attenuation, chromaticity retention, and edge or detail preservation. In particular, when the contaminated rate is not larger than 10%, the proposed algorithm provides a significant performance improvement with a decrease of about 1/3 in Normalized Mean Square Error(NMSE) and a decrease of more than 50% in Normalized Color Difference(NCD) averagely, compared with the traditional DDF.Keywords：directional-distance filter;spatial distance weighting;impulsive noise;color image;adaptive technique- 27
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Published：2020-08-12
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