Journals >Acta Photonica Sinica
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2012
Volume: 41 Issue 7
24 Article(s)
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Research Article
Slight Zoomed Conformal Optical System Design Using Freeform Surface
SUN Jinxia, PAN Guoqing, and SUN Qiang
In order to find unvignetted target in the large field of regard in gimbaled conformal seeker, a freeform corrector and slight zoomed catadioptric real imaging system are used to balance and correct dynamic aberrations. The RMS spot diameter of the slight zoomed conformal optical system is near or smaller than the pixIn order to find unvignetted target in the large field of regard in gimbaled conformal seeker, a freeform corrector and slight zoomed catadioptric real imaging system are used to balance and correct dynamic aberrations. The RMS spot diameter of the slight zoomed conformal optical system is near or smaller than the pixel size in all field of regard. Besides, the system achieves near diffraction limited performance even in big field of regard..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 757 (2012)
Design of K Mirror for Altaz Telescope
WANG Zhichen, ZHAO Yongzhi, and ZHOU Chao
Stars in the image field are rotating around image center when altaz telescope tracks celestial targets, which increases difficulty to real time target identification and image processing based on multiframe images. The K mirror with large aperture is designed to compensate image rotation for the Coude optical path oStars in the image field are rotating around image center when altaz telescope tracks celestial targets, which increases difficulty to real time target identification and image processing based on multiframe images. The K mirror with large aperture is designed to compensate image rotation for the Coude optical path of altaz telescope in the paper. K mirror is composed of three reflecting mirrors, and its aperture is 42 mm. The angle between reflecting mirror 1 and reflecting mirror 3 is 120 degrees, and K mirror can be used in all spectral ranges. If incoming vector rotates a certain angle, and K mirror rotates half the angle that incoming vector rotated, then output vector does not rotate any angle. The reflecting mirror 1 and reflecting mirror 3 are made of plane mirrors and fixed on a metal triangle, substituting reflector which is made of triangular prism. Every reflecting mirror is assembled by using photoelectric autocollimator and fine rotating platform, so it can be sure that the light axis of K mirror and the rotating axis of K mirror are in one line. The K mirror is directly drived by DC toque motor for the reason of fast response speed, and Renishaw angle encoder which angle resolution can be reach 0.072 arcsec by interpolation is adopted..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 762 (2012)
A Novel MicroLCD Backlighting Design Technology
JIN Shiwei, and YANG Xinjun
Aiming at the problem that the current microLCD brightness can not meet the brightness requirements of airborne helmetmounted displgy, a novel backlighting structure form and design principle were proposed, and the optical system was designed using the CODEV software. The light distribution effect of the backlight moAiming at the problem that the current microLCD brightness can not meet the brightness requirements of airborne helmetmounted displgy, a novel backlighting structure form and design principle were proposed, and the optical system was designed using the CODEV software. The light distribution effect of the backlight module was simulated using the LIGHTOOLS software. The results show that, when taking 85 lm green LUXEON Rebel LEDS as the light source, its output brightness is close to 160 000 cd/m2, uniformity is greater than 85%, and power consumption is only 1.25 W, which meets the requirements of the airborne helmetmounted display..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 766 (2012)
Fatigue Study for Processing of Space Optical Remotesensor Primary Mirror
YU Shanmeng, LIU Ju, JIANG Fan, YANG Jinsong, GUAN Fengwei, and CUI Kang
During the primary mirror of space optical remotesensor processing, grinding disc and the primary mirror moving back and forth which operation caused the flexible support structure fatigue life issue. Through the establishment of the primary mirror assembly finite element model, fatigue life of components was analyzedDuring the primary mirror of space optical remotesensor processing, grinding disc and the primary mirror moving back and forth which operation caused the flexible support structure fatigue life issue. Through the establishment of the primary mirror assembly finite element model, fatigue life of components was analyzed by MSC.Fatigue software with stresslife (SN) method, the weak position of support structure was identified. Simulation error analysis was carried out, and factors affecting the simulation results were discussed. It is verified that the processing and design parameters of flexible support structure are rational through comparing the surface accuracy data of the primary mirror surface which collected before and after the thermal vacuum experiment and dynamic components test. The fatigue life simulation can predict the fatigue condition in the process of optical structure processing, and provide a theoretical basis for design and manufacturing..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 771 (2012)
Design and Analysis of Optical System for Solar Extremeultraviolet Imaging Spectrometer
LIU Zhuang, and GONG Yan
A kind of optical system of solar extreme ultraviolet imaging spectrometer is designed aiming at solar extreme ultraviolet imaging spectrometer′s application objective and working environment. The optical system consists of a telescope, a scanning mirror, a slit, a grating and a detector. Wolter typeⅡ configuration is A kind of optical system of solar extreme ultraviolet imaging spectrometer is designed aiming at solar extreme ultraviolet imaging spectrometer′s application objective and working environment. The optical system consists of a telescope, a scanning mirror, a slit, a grating and a detector. Wolter typeⅡ configuration is chosen for the telescope, light enter the system by grazing incident, so it has wide working band, and is highly stable, practicable to withstand the rigors of spaceflight. A plane mirror is chosen for scanning mirror, so the imaging quality would not change with scanning angle. A toroidal variedlinespace grating which is 3 600 lines/mm is chosen for dispersion. Compared with toroidal uniformlinespace grating, it superiors in imaging quality, spectral resolution and shortening system length. The working band of the optical system is 17.0~21.0 nm which could meet the probe of the quiet corona in the temperature region 5.8≤log T≤6.3. The field of view is 1228″× 0.8″, the spatial resolution is 0.8 arc sec/pixel, the spectral resolution is about 0.001 98 nm/pixel, the total length is under 2.5 m. The telescope system′s effective area is calculated, and the telescope′s imaging quality and real field of view are given. The imaging quality of whole system, the smile and keystone of grating can satisfy the application demand..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 776 (2012)
Reverse Calculation of Optical Parameters of Scattering Medium Based on Fast Monte Carlo Simulation
ZHANG Mei, LIN Lin, GAO Yingjun, and LUO Yunhan
A method of coherent measuring optical parameters of scattering medium is presented based on Monte Carlo simulation. The condensed scaling method is introduced to accelerating process of calculation. A trilayer structure BPartificial neural network is developed for reverse calculation of scattering and absorption coeA method of coherent measuring optical parameters of scattering medium is presented based on Monte Carlo simulation. The condensed scaling method is introduced to accelerating process of calculation. A trilayer structure BPartificial neural network is developed for reverse calculation of scattering and absorption coefficients of medium. Fat emulsion and stain mixture of IntralipidTM and India ink are taken as scattering and absorbing sample for coherent measurement by fiber Michelson interferometer. Results of experiments show the linear relation between scattering or absorption coefficients and concentration of IntralipidTM or India ink. The method is helpful to nondestructive testing components of turbid material..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 781 (2012)
Second Harmonic Generation with Broadened Band Width in Onedimensional Nonlinear Photonic Crystal at the Oblique Incidence of Light
WANG Aihua, and ZHAO Jing
The onedimensional nonlinear photonic crystals containing defects that are embedded in air are investigated. However, attributed that the reflective second harmonic wave is so strong that it can not be ignored, the slowly varying amplitude approximation is not applicable to such a system. The paper presents a general The onedimensional nonlinear photonic crystals containing defects that are embedded in air are investigated. However, attributed that the reflective second harmonic wave is so strong that it can not be ignored, the slowly varying amplitude approximation is not applicable to such a system. The paper presents a general solution of second harmonic generation without adopting the slowly varying approximation when the incident light is obliquely launched upon the onedimensional inhomogeneous systems. The result shows that the wavelengthes corresponding to the defect modes shift to the shortwavelength with the increasing angle of incidence. The broadened band width second harmonic generation with high conversion efficiency can be achieved by modulating the angle of incidence of fundamental wave. Furthermore, this method can be applicable to any onedimensional inhomogeneous systems and the conversion efficiency of second harmonic generation can be easily and conveniently calculated..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 786 (2012)
PLMapping of the Epitaxial Wafer System Based on LabVIEW
CUI Linzhe, LI Shuping, and KANG Junyong
A set of semiconductors photoluminescence scanning(PLMapping)system using LabVIEW8 is summarized. In consideration of the spectra collected distortion originate from excessive weak fluorescent signal of epitaxial wafers, inhomogeneous background illumination noises and then the inaccurate physical parameters in spectrA set of semiconductors photoluminescence scanning(PLMapping)system using LabVIEW8 is summarized. In consideration of the spectra collected distortion originate from excessive weak fluorescent signal of epitaxial wafers, inhomogeneous background illumination noises and then the inaccurate physical parameters in spectra analysis and others, methods for optimizing system such as backlight deduction, sample isolation, Gaussian fitting are developed. The communication and control with the spectrometer and motorized is realized with the help of strong ability of instrument control such as calling DLL and ActiveX in LabVIEW. Owing to the same wonderful ability in data analysis and display, the process of measuring, read, analysis and realtime display is easily integrated into an interface, hence the optical property of sample on spatial discrimination is obtained effectively and efficiently. Finally luminance uniformity of epitaxial wafer is preliminary analyzed. Wavelengths agree with temperatures distribution, which affirm the importance of maintaining consistent temperature in growth chamber. It is a system friendly interfaced, easy to use, high realtime and built simply, which offers researcher accurate and rapid measurement..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 790 (2012)
Design and Simulation of Planar 4×4 Electrooptic Switches Based Ferroelectric Inverted Domains
LU Zhiyong, WAN Lingyu, and CHAO Liangfang
An integrated 4×4 planar electrooptic switch is designed based on the electrooptic effect in ferroelectric inverted domains. It integrated four minute halfparabola shaped and four parabola shaped deflectors with the same configurations in a ferroelectric wafer. To optimize the design of the parabola shaped deflAn integrated 4×4 planar electrooptic switch is designed based on the electrooptic effect in ferroelectric inverted domains. It integrated four minute halfparabola shaped and four parabola shaped deflectors with the same configurations in a ferroelectric wafer. To optimize the design of the parabola shaped deflectors, an appropriate electrooptic switch is provided. Its properties of switch and exchange are analyzed using the beam propagation method (BPM). Simulation results show that the 4×4 planar electrooptic switch is feasible and the beam deflection errors can be compensated in practice by adjusting applied electricfield. The size of the optical switch is 48 mm×2.2 mm×0.5 mm and its maximum applied electricfield is about 13.73 V/μm. It has potential applications in highspeed optical exchange systems..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 794 (2012)
A Method to Extract Carrierwave Speckle Pattern Fringe Skeletons Based on Modulation Direction
LIN Zhenheng
Fringe center method is an important demodulation method for electronic speckle pattern interferometry fringe. The precondition of this method is to obtain fringe skeletons with high precision. Based on the analysis of carrierwave electronic interferometry fringe characteristics, a fringe skeletons extracting method bFringe center method is an important demodulation method for electronic speckle pattern interferometry fringe. The precondition of this method is to obtain fringe skeletons with high precision. Based on the analysis of carrierwave electronic interferometry fringe characteristics, a fringe skeletons extracting method based on modulation direction was proposed. Firstly, a homomorphic filtering was used to filter the high frequency multiplicative speckle pattern noise effectively and pick out carrierwave fringes. Then a fringe skeletons extracting algorithm based on modulation direction was applied to confirm the dots of gray scale extremum and make binarization processing. In order to get whole fringe skeletons map, the mending methods based on skeletons curve fitting or based on the fringe separation were adopted to compensate the edge fringe skeletons. Experimental results show that this method is simple and reliable. It can extract the consecutive fringe skeletons quickly and accurately..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 800 (2012)
Turbulence Characteristics Optical Test Contrast
JING Wenbo, ZHAO Si, FU Qiang, WANG Xiaoman, and JIANG Huilin
During the temperature difference of 10℃~230℃, three kinds of ShackHartman measuring methods are used to contrast atmospheric coherence length r0 with quadrant detector(QD), and ShackHartman(SH) and photomultiplier tube(PMT) respectively are applied to contrast refractive index structure parameter C2n with scintillatDuring the temperature difference of 10℃~230℃, three kinds of ShackHartman measuring methods are used to contrast atmospheric coherence length r0 with quadrant detector(QD), and ShackHartman(SH) and photomultiplier tube(PMT) respectively are applied to contrast refractive index structure parameter C2n with scintillation power spectrum. The experimental results show that: for r0 , the stability of QD decreases more obviously than SH when there is strong turbulence, and for three ShackHartman methods, DIMM overcomes problems such as device jitter but brings in problem of inconsistency in direction which wave front method can avoid; for C2n, SH is more precise than PMT which fitting correlation coefficient is up to 0.96; for scintillation power spectrum, the maximum frequency SH tested is 15 Hz higher than that of PMT when it is 200℃ influenced by noise; through the analysis of ShackHartman subaperture scintillation power spectrum, the scintillation power spectrum is not able to be measured precisely and different subapertures accomplish the measurement turbulence uniformity when the same subaperture incident intensity is not in the CCD response linear interval. The results will provide an optimal test method and theoretical basis for turbulence cell..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 805 (2012)
Observations of Atmospheric CO2 Concentration Profiles over Hefei Area with Raman Lidar
YU Haili, HU Shunxing, YUAN Kee, WU Xiaoqing, CAO Kaifa, MENG Xiangqian, HUANG Jian, SHAO Shisheng, and XU Zhihai
Raman lidar is used as an effective tool for detection of the atmospheric compositions and characteristics. A complicated Raman lidar system was developed by Anhui Institute of Optics and Fine Mechanics of Chinese Academy of Sciences for measuring the lowtropospheric temporal and spatial distribution of CO2 in the atmRaman lidar is used as an effective tool for detection of the atmospheric compositions and characteristics. A complicated Raman lidar system was developed by Anhui Institute of Optics and Fine Mechanics of Chinese Academy of Sciences for measuring the lowtropospheric temporal and spatial distribution of CO2 in the atmosphere. And a series of observations and comparative analysis were performed. A wavelength of 355 nm UV laser was applied as the light resource in this system and the N2 and CO2 Raman backscattering signals were acquired by a dualchannel photoncounting card. Li7500 H2O/CO2 analyzer was employed to compare with the detection results to make system calibration and then to retrieve the atmospheric CO2 volume mixing ratio in the horizontal and vertical direction. And the spatial temporal variation of a whole night atmospheric boundary layer CO2 profile was measured at Hefei area. The observations have a good agreement in the trend of change with the Li7500 H2O/CO2 analyzer. The results show that atmospheric CO2 has relatively homogeneous concentration and the Raman lidar is capable of continuous measuring efficiently the temporal and spatial distribution of CO2 in the atmosphere..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 812 (2012)
Propagation Properties of HermiteGaussian Beams in NonKolmogorov Turbulence
HUANG Yongping, and ZENG Anping
Based on the extended HuygensFresnel principle and nonKolmogorov spectrum, analytical expressions for the beam width, angular spread and M2factor of HermiteGaussian (HG) beams through nonKolmogorov turbulence are derived. The results show that at a sufficiently long propagation distance(such as z≥3 km), the beam Based on the extended HuygensFresnel principle and nonKolmogorov spectrum, analytical expressions for the beam width, angular spread and M2factor of HermiteGaussian (HG) beams through nonKolmogorov turbulence are derived. The results show that at a sufficiently long propagation distance(such as z≥3 km), the beam width, angular spread and the M2factor of HG beams through nonKolmogorov turbulence all increase with the increasing outer scale L0(3.6<α<4)and decreasing inner scale l0, and increase with the increasing exponent parameter α until it reaches its maximum value at α=3.11, then decrease with increasing α. However, the beam width and M2factor of HG beams hardly vary with increasing outer scale L0 in the region 3<α<3.6..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 818 (2012)
Comparing and Analysis of Calculation Methods of Longperiod Fiber Gratings Transmission Spectra
YANG Ying, and GU Zhengtian
Many methods are considered for calculating longperiod fiber gratings (LPFGs) transmission spectra such as integral method, formula method and transfer matrix method. In this paper, these methods are analyzed based on the coupledmode theory and their characteristics and the conditions of application are pointed out. Many methods are considered for calculating longperiod fiber gratings (LPFGs) transmission spectra such as integral method, formula method and transfer matrix method. In this paper, these methods are analyzed based on the coupledmode theory and their characteristics and the conditions of application are pointed out. Exact solution for multimode transmission spectra can be obtained directly by integral method in a wide wavelength range, however, the computation process of integral method is complicated. The formula method is convenient for calculating and expressing, but it can only solve single mode transmission spectra directly in a narrow wavelength range. The transfer matrix method is suitable for calculating some transmission spectra of nonuniform fiber gratings, it is simple to implement, almost always sufficiently accurate, and general the fastest. Through the analysis and compare of the three methods, a best method with high precision and simple calculation is provided for longperiod fiber gratings transmission spectra in theory, which is important for the research and application of LPFGs..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 824 (2012)
High Precision Temperature Calculation Method of Fiberoptic Distributed Temperature Sensing System Based on Iteration Technique
XIA Tao, LI Xiaobing, GUO Jiangtao, ZHANG Rui, and MAO Xin
A high precision temperature calculation method of fiberoptic distributed temperature sensing system based on iteration technique is introduced. Compared with the traditional calculation methods, this iterationbased method further corrects the attenuation coefficient difference of the Raman antistokes wavelength andA high precision temperature calculation method of fiberoptic distributed temperature sensing system based on iteration technique is introduced. Compared with the traditional calculation methods, this iterationbased method further corrects the attenuation coefficient difference of the Raman antistokes wavelength and stokes wavelength in optical fiber which is temperaturesensitive, thus increases the precision of temperature measurement. It especially works well with the measurements of normaldistance, complex temperature distribution fields. The iterative formula is established by theoretical analysis, the corresponding fiber parameters are premeasured, by programming on data processing module of the sensing system. The result shows great accordance between calculation and actual temperature distribution within the range from 0 to 90℃ along a whole fiber of 5 km..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 831 (2012)
A New Demodulated System of Distributed FBG Based on Temperature Characteristics of AWG
QIAN Cuiping, PENG Baojin, WAN Xu, YANG Liu, ZHU Jianchengwu, XU Fei, DONG Yue, and YE Neng
A set of using arrayed waveguide grating (AWG) for distributed fiber Bragg grating (FBG) wide variation of center wavelength demodulation method is presented. According to the characteristics that AWG center wavelength of each channel can change with the chip′s temperature changes, a voltage control circuit was designeA set of using arrayed waveguide grating (AWG) for distributed fiber Bragg grating (FBG) wide variation of center wavelength demodulation method is presented. According to the characteristics that AWG center wavelength of each channel can change with the chip′s temperature changes, a voltage control circuit was designed, and the chip′s temperature can vary from 30℃ to 90℃ periodically, several minutes per period. Simultaneously, the data of the channels of AWG can be collected in high speed by a computer. Then the chip′s temperature can be found responding to the maximum of each channel. Finally, the computer can report central wavelength of FBG according the relationship of wavelength and temperature. The experiment demodulating system was established. The experiment results prove that the system can effectively resolve the problem of measurement range. The system can report the central wavelength of FGB in 0.6 nm each channel (40 channels in total) in less than 10 minutes, but also measurement error is less than 2 percent..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 836 (2012)
Experimentally Study on Highsensitivity Fiberoptic Refractometers Based on MachZehnder Interference
ZHOU Yingwu
A high sensitivity fiberoptic refractive index sensor based on MachZehnder interferometer is proposed and fabricated. The relationship between the resonance wavelength shifts to the refractive index is studied with NaCl and glycerin solution. The experimental results show that the resonance wavelength shifts to longeA high sensitivity fiberoptic refractive index sensor based on MachZehnder interferometer is proposed and fabricated. The relationship between the resonance wavelength shifts to the refractive index is studied with NaCl and glycerin solution. The experimental results show that the resonance wavelength shifts to longer wavelength with the increase of the refractive index of the surrounding media, and the wavelength shift is nearly linear to the refractive index with a sensitivity is of 4 086 nm/refractiveindex as the refractive index ranges from 1.333 to 1.356. The sensor is easy to fabricate, compact, and will be usefull in chemical and biotechnological industry..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 841 (2012)
Strain Demodulation Method Based on Matched Fiber Bragg Grating FabryPerot Interferometer
HUANG Zhao, ZHAO Jianlin, JIANG Biqiang, and QIN Chuan
A novel demodulation method based on matched Fiber Bragg grating FabryPerot interferometer (FBGFPI) for strain measurement is proposed and demonstrated, which combines the advantages of fiber FabryPerot interferometry and matched fiber Bragg grating filtering technique. In order to solve the mismatch problem and keeA novel demodulation method based on matched Fiber Bragg grating FabryPerot interferometer (FBGFPI) for strain measurement is proposed and demonstrated, which combines the advantages of fiber FabryPerot interferometry and matched fiber Bragg grating filtering technique. In order to solve the mismatch problem and keep the static working point at the best matching position, the strain and temperature of the matched FBGFPI are adjusted by a closedloop control system consisted of the semiconductor refrigeration and piezoelectric ceramic. Meanwhile, the system is immune to the surrounding temperature. Experimental results show that the system can respond to the input signal with the frequency range of 50~800 Hz, is insensitive to the temperature fluctuation, and the strain resolution is up to 0.4 nε/Hz1/2. Therefore, this method has a higher practicality for dynamic strain monitoring and vibration measurement..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 845 (2012)
Brain Tumor Segmentation Based on Spatialfrequency Domain Image Enhancement
HUANG Jing, and YANG Feng
In view of the problems that the target border always appears too fuzzy to be detected, a novel method of brain tumor segmentation is proposed based on spatialfrequency domain image enhancement. The method is composed of the spatial and frequency domain enhancing process and the detecting process. In the enhancing proIn view of the problems that the target border always appears too fuzzy to be detected, a novel method of brain tumor segmentation is proposed based on spatialfrequency domain image enhancement. The method is composed of the spatial and frequency domain enhancing process and the detecting process. In the enhancing process, the directional filter band, neighborhood and histogram equalization are combined to overcome the defect of contrast reduction caused by directional filter and the defect of details vagueness caused by histogram equalization. Then in the detecting process, a method of image segmentation is applied to find the area of the brain tumor. The experiment results show that the enhancing process strengthens the features of tumor greatly, and improves the contrast and definition of the image..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 850 (2012)
An Improved Brenner Algorithm for Image Definition Criterion
WANG Jian, CHEN Hongbin, ZHOU Guozhong, and AN Tao
The image definition criterion is one of basic problems in passive autofocusing technique based on digital image.The traditional Brenner Algorithm has a fast calculation speed,but the accuracy of evaluation result depends on the threshold value,and the Algorithm sensitivity is low. For this issue, an improved AlgorithThe image definition criterion is one of basic problems in passive autofocusing technique based on digital image.The traditional Brenner Algorithm has a fast calculation speed,but the accuracy of evaluation result depends on the threshold value,and the Algorithm sensitivity is low. For this issue, an improved Algorithm is proposed. The improved function uses high pass filter and bandpass filter to evaluate the image, and overcomes the limitation of traditional Brenner Algorithm depending on the threshold value.In order to evaluate the improved Algorithm performance, the parameters of unimodality, accuracy, sensitivity, calculating cost are compared and analyzed.Compared with the traditional Brenner Algorithm, the experiments and analysis show that the improved Algorithm can meet unimodality, accuracy, and improve sensitivity and reduce calculating cost..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 855 (2012)
A Selfembedding Image Watermarking Scheme with Dual Purpose
YE Tianyu
An image watermarking scheme with dual purpose is proposed by introducing the selfembedding technology, which can achieve both copyright protection and content authentication. At the embedding side, an original image is split into nonoverlapping blocks, and the m least significant bits of every pixel in each block arAn image watermarking scheme with dual purpose is proposed by introducing the selfembedding technology, which can achieve both copyright protection and content authentication. At the embedding side, an original image is split into nonoverlapping blocks, and the m least significant bits of every pixel in each block are set to be zero. Then each block is conducted with singular value decomposition, and an original robust feature watermark is derived from judging the parity of the first digit of singular value′s norm from each block. Finally, a watermarked image is produced by selfembedding the original robust feature watermark into the m least significant bits of every pixel in each block. At the detection side, robust feature watermark′s extraction from an attacked watermarked image is similar to its production at the embedding end. Copyright identification is accomplished by calculating the normalized correlation between the extracted robust feature watermark and the original robust feature watermark. Content authentication is accomplished by tamper detection through judging the consistency between the extracted robust feature watermark and the m least significant bits of every pixel in each block of attacked image. Both theoretic analysis and experimental results illustrate that it has perfect invisibility. Experimental results also show that it not only has strong robustness towards attacks such as adding noise, cropping, JPEG compression, smoothing, resampling and geometric attacks like random row removal, right shifting and downward shifting, but also can accurately locate the tampered region and distinguish tamper type. Therefore, it can achieve dual purpose containing copyright protection and content authentication..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 859 (2012)
Morphological Characteristics of Maize Seed Extraction and Identification Based on the Hyperspectral Image
HUANG Min, ZHU Xiao, ZHU Qibing, and FENG Zhaoli
Morphological characteristic of maize seed is an important factor in identifying maize varieties. Hyperspectral images of 432 maize seeds including nine varieties were acquired using hyperspectral imaging system. The images were corrected and preprocessed, and then shape features of each sample were extracted in the rMorphological characteristic of maize seed is an important factor in identifying maize varieties. Hyperspectral images of 432 maize seeds including nine varieties were acquired using hyperspectral imaging system. The images were corrected and preprocessed, and then shape features of each sample were extracted in the range of 563.6~911.4 nm including 55 wavelengths. The classification models were developed using the shape features of maize seeds from singlewavelength, multiwavelengths and full wavelengths coupled with partial least squares discriminant analysis (PLSDA), respectively. Simulation results indicate that the average correct identification rate of training set and testing set with full wavelengths is 98.31% and 93.98%, which are better than singlewavelength and multiwavelengths. Therefore, that is the accurate mean for identifying maize varieties using the feature information of visible and nearinfrared region from hyperspectral images..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 868 (2012)
Influence of Formative Native Oxide Layer on Mechanical Polished Cu Surface on Fluorescence Spectrum
DONG Jun, ZHAO Jiuqiang, LI Xuqiang, Chen Jia, and ZHENG Hairong
The enhanced fluorescence effect of Rh6G molecules deposited on physically polished copper surface was studied. The result shows that the formation of oxidation film on the metal surface plays an important role in the fluorescence emission. The quench and enhanced surface fluorescence effect from the physically polisheThe enhanced fluorescence effect of Rh6G molecules deposited on physically polished copper surface was studied. The result shows that the formation of oxidation film on the metal surface plays an important role in the fluorescence emission. The quench and enhanced surface fluorescence effect from the physically polished rough copper surface with/without oxide layer were experimentally observed. The formative oxidation film was helpful to decrease the efficiency of the noradiative energy transfer from the fluorophore to the metal surface, and enhanced fluorescence intensity will be obtained with the properly controlling of the spacer layer between the molecules and metal surface. The experimental observation was analyzed with the local field of surface enhanced fluorescence..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 874 (2012)
A Novel Apodization Function of Single Sided Interferogram
ZHANG Peng, and ZHANG Zhihui
A novel apodization function is proposed. The new apodization function multiplied by zerocrossing single sided interferogram can average the product of twiddle factor and intensity of two points having the same optical path difference, and reduce the error due to the data around zero optical path difference used twiceA novel apodization function is proposed. The new apodization function multiplied by zerocrossing single sided interferogram can average the product of twiddle factor and intensity of two points having the same optical path difference, and reduce the error due to the data around zero optical path difference used twice. The simulation results show that the new apodization function fits better in some serious unsymmetrical interferograms than the Mertz apodization function and can minish the spectral distortion. Moreover, the computational complexity can be reduced significantly. The new apodization function can be widely applied to zerocrossing single sided interferogram data processing of fourier transform spectrometer..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 878 (2012)
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