Journals >Acta Photonica Sinica
Contents
2015
Volume: 44 Issue 5
35 Article(s)
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Research Article
Analysis on Molecular Number Density Distribution in the Middle Atmosphere with 16 Years′ Lidar Data in Hefei
CHEN Feng, SHI Dong-feng, HUANG Jian, YUAN Ke-e, CAO Kai-fa, and HU Shun-xing
The structure of L625 Rayleigh lidar system, principles of atmospheric density measurement which is based on the Rayleigh scattering theory and iterative method to retrieve middle atmosphere density profiles were described respectively. In order to prove the effectiveness of iterative algorithm, simulation analysis wasThe structure of L625 Rayleigh lidar system, principles of atmospheric density measurement which is based on the Rayleigh scattering theory and iterative method to retrieve middle atmosphere density profiles were described respectively. In order to prove the effectiveness of iterative algorithm, simulation analysis was made. Error analysis indicated that contributions to the uncertainty of the retrieved molecular number density mainly derived from signal to noise ratio of the return signals and molecular number density at the reference point. Meanwhile, main error sources of the return signals and method to determine the reference point were given. Finally, according to 16 years’ routine observations of L625 Rayleigh lidar, monthly distribution and annual average of molecular number density from 1997 to 2004 and 2006 to 2012 in the middle atmosphere were presented. Results show that molecule number density distribution is sparse in winter and it becomes thick in summer. The yearly distribution of molecular number density seems to be relatively stable. Comparison with the model density which is obtained from 1976 USA standard atmospheric model indicates that density ratio profile of L625 Rayleigh lidar to the model density fluctuates between 1.05 and 1.13..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 501001 (2015)
Distance Estimation Method Based on Photon Counting LIDAR
YIN Wen-ye, SHI Feng, HE Wei-ji, GU Guo-hua, and CHEN Qian
In order to solve the certain randomness in the signal received of photon counting. Light detection and ranging a method of Markov techniques based on the Bayesian inference was proposed to extract the peak position, peak amplitude and the noise of the present sampling data, so that the accurate distance was easily gotIn order to solve the certain randomness in the signal received of photon counting. Light detection and ranging a method of Markov techniques based on the Bayesian inference was proposed to extract the peak position, peak amplitude and the noise of the present sampling data, so that the accurate distance was easily got. In Bayesian inference, the posterior distribution can be adopted to describe the prior distribution as approximately, which could effectively improve the exploration of the parameter spaces. During processing, the updated parameter and other parameters constituted a global approximate solution, and the Bayesian inference was used for the optimal solution in the global approximation solutions. Experiments demonstrated show that the parameters can be estimated to a high degree of accuracy and the method is robust..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 501002 (2015)
Fine Adjustable Non-glued Fiber Optic Taper Array Coupled Digital X-ray Detector
ZHAO Zhi-gang, WANG Ru, LEI Yao-hu, GUO Jin-chuan, YANG Qin-lao, and NIU Han-ben
Fiber Optic Taper(FOT) array coupled digital X-ray detector is an efficient way for large-area high-resolution X-ray imaging applications, but the coupling method between the small ends of FOT array and the corresponding image sensors is commonly tightly glued coupling at present. To avoid the disadvantages in the convFiber Optic Taper(FOT) array coupled digital X-ray detector is an efficient way for large-area high-resolution X-ray imaging applications, but the coupling method between the small ends of FOT array and the corresponding image sensors is commonly tightly glued coupling at present. To avoid the disadvantages in the conventional glued coupling method, a fine adjustable non-glued 2×2 FOT array coupled digital X-ray detector was designed and implemented. The proposed X-ray detector scheme can realize multi-dimensional adjustment of the four data acquisition boards on the same adjusting layer through the novel horizontal and vertical adjusting mechanisms, with the restriction of the limited adjusting space formed by the structure of the FOT array and the sizes of the printed circuit boards, and especially under the condition of the distance between the boards was only 40 mm in the vertical direction. According to the fact that the four data acquisition boards and the data transmission board are separated, an embedded Ethernet data acquisition system for multiple CMOS image sensors based on one ARM chip and four FPGA chips was implemented. Tested results showed that the implemented X-ray detector with the imaging area of as large as 100mm×100mm, can realize fine adjustable non-glued coupling and data acquisition of multiple CMOS image sensors, which could be a new way for multipurpose use in large-area high-resolution digital X-ray imaging applications for scientific researches..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 504001 (2015)
Tunable Narrow Bandpass Vacuum Ultraviolet Photon Detector for Inverse Photoemission Spectroscopy
LIU Shu-hu, HONG Cai-hao, ZHAO Yi-dong, GENG Dong-ping, ZHENG Lei, ZHAO Xiao-liang, and LI Hua-peng
This paper presents a novel Vacuum Ultraviolet (VUV) bandpass photon-counting detector which was designed to count photons with energies approximately 9.70 eV for inverse photoemission spectroscopy experiments. The performance was analyzed to improve the signal-to-noise ratio and resolution of the spectrum. The geometrThis paper presents a novel Vacuum Ultraviolet (VUV) bandpass photon-counting detector which was designed to count photons with energies approximately 9.70 eV for inverse photoemission spectroscopy experiments. The performance was analyzed to improve the signal-to-noise ratio and resolution of the spectrum. The geometric structure of this detector is similar to a special Geiger-Müller tube. It is filled with a dilute mixture of acetone vapor and argon gas. The proportion was investigated and ascertained to be close to 1 to 20. A SrF2 crystal was used as the input window to cut off high-energy photons with energies greater than 9.7 eV. Acetone vapor was selected as the functional gas to capture photons. Moreover, it can prevent low energy photons from being detected. The optical bandpass width is less than 100 meV and can be tuned continuously by cooling the SrF2 window. The temperature is controlled by a self-developed cryogenic system with accuracy of±0.2 K. The relationship between the detector bandpass width and the SrF2 window temperature is calibrated using a deuterium lamp and a grating monochromator..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 504002 (2015)
Distribution of Reciprocal Vectors Based on Diffraction Patterns of Superlattice Structures
MA Bo-qin, SHI Jian-hua, and TIAN Shao-hua
A experimental method was provided, in which the distribution of reciprocal vectors can be easily obtained by their diffraction patterns. First, the diffraction pattern of square periodic superlattice as a reference grating was gotten. The value of the reciprocal vector according to the Fourier optics was calculated, aA experimental method was provided, in which the distribution of reciprocal vectors can be easily obtained by their diffraction patterns. First, the diffraction pattern of square periodic superlattice as a reference grating was gotten. The value of the reciprocal vector according to the Fourier optics was calculated, and the scale relation with the geometric length in the pattern was built. By introducing the rectangular superlattice structure, this method was proved to be right in the periodic superlattices. Secondly, the diffraction patterns of the H-shape and Sierpinski fractal superlattice structures were realized and made a comparison with the square structure. The reciprocal vectors in two structures could be calculated based on the obtained geometric length ratio. Then by quantitative relation between the reciprocal vectors and fundamental wavelengths in quasi-phase matching processes, the harmonic wavelengths were calculated. Finally, the LiNbO3 nonlinear photonic crystals with fractal superlattice structures were fabricated experimentally. It can be gotten that the experimental quasi-phase matching harmonic wavelengths agree with the calculated ones. Especially, for Sierpinski fractal superlattice, by calculation, the effective second harmonic of 1.352 μm can be realized. And the corresponding results can be accomplished by experiments..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 506001 (2015)
Slow-light Effect in Microfiber Double-knot Resonator with a Parallel Structure
XU Yi-ping, REN Li-yong, WANG Ying-li, KONG Xu-dong, LIANG Jian, JU Hai-juan, and QIAO Dun
In order to study the slow-light effect in the microfiber based resonator,a microfiber double-knot resonator with a parallel structure was designed and fabricated.Based on the theories of the ring resonator and the direction coupler,the theoretical model of the microfiber double-knot resonator with a parallel structureIn order to study the slow-light effect in the microfiber based resonator,a microfiber double-knot resonator with a parallel structure was designed and fabricated.Based on the theories of the ring resonator and the direction coupler,the theoretical model of the microfiber double-knot resonator with a parallel structure was proposed,the direction of the light-field propagation and coupling in the resonator was analyzed,the mathematic expression between the output light and the input one in the resonator was deduced,and the expression of the group delay time was also obtained.By numerical simulating method,the spectra of the transmission and the group delay time were given,the corresponding relationship between group delays and resonant wavelengths of the transmission spectrum in the resonator was analyzed.The numerical result indicates that a large group delay can be obtained at the resonant wavelength with a large extinction ratio in the resonator.In experimental,a microfiber double-knot resonator with a parallel structure was fabricated,the transmission spectrum of the fabricated resonator was well consistent with the theoretical simulation, indicating that the theoretical analysis is correct.Employing the pulse-delay method in the Oscilloscope,a measuring system of the slow-light delay in the resonator was set up.A group delay of about 75 ps in the fabricated resonator is achieved,which is larger than the reported value.The resonator could be beneficial to applicating in data delay lines,optical switches and optical memories,etc..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 506002 (2015)
Refractive Index Sensing Based on the Modal Interference of U-shape Bending Fiber
TANG Jie-yuan, ZHANG Quan-quan, ZENG Yang-fu, LUO Yun-han, CHEN Zhe, YU Jian-hui, LU Hui-hui, and ZHANG Jun
To develop a kind of easy-fabrication and stable optical fiber sensor, a new method for fabricating the fiber sensors was proposed, and the sensing performance of a U-shape bending single mode fiber was investigated. A section of SM-28 single mode fiber was bent into U-shaped structure with variety of radii of curvaturTo develop a kind of easy-fabrication and stable optical fiber sensor, a new method for fabricating the fiber sensors was proposed, and the sensing performance of a U-shape bending single mode fiber was investigated. A section of SM-28 single mode fiber was bent into U-shaped structure with variety of radii of curvature, and then the U-shaped structure is fixed. After that, the U-shaped portion of the fiber was immersed in liquid with different refractive indices respectively. Meanwhile, the transmission spectrum of the U-shaped optical fiber was recorded. The modal interference theoretical analysis shows that the core guiding mode and the cladding mode, which propagate independently in the bending section, interferes each other in the straight region, and that the interference wavelengths depend on the bending radius and surrounding refractive index. Obvious interference spectra can be clearly observed on the U-shape bending fiber with radius ranging from 2.5 mm to 5.0 mm. The interference wavelengths red-shift as the surrounding refractive index increases from 1.30 to 1.43RIU. Higher sensitivity could be achieved when the bending fiber has a lager bending radius. In the case of the bending radius being 5.0 mm, the sensitivity reaches to 207nm/RIU and 1 220 nm/RIU in the SRI region of 1.30~1.40 RIU and 1.40~1.42RIU. The characteristics of the interference dip, such as full width at half maximum, contrast are determined by the ratio of core guiding mode and cladding mode. The narrowest full width at half maximum was achieved when the bending radius was 4.5 mm of U-bend single mode fiber were discussed. A low cost and easy making sensor was proposed. The figure of merit, which integrates the sensitivity and the full width at half maximum, reach the maximal value of 43.1 RIU-1 and 191.2 RIU-1 in the surrounding refractive index region of 1.30~1.40 RIU and 1.40~1.42 RIU, when the bending radius is 4.5 mm. This sensor is fabricated with a common single mode fiber with simply bending process, and shows potential in the fiber sensing application with the features of low cost and high mechanical strength..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 506003 (2015)
Nonlinearity of Dispersion Characteristics of Nano-core Fiber Based on the Selective Filling Method
WANG Guan-jun, TAN Xu-xiang, and WANG Zhi-bin
For improving the nonlinearity and dispersion properties of nan-core fiber, the idea of enlarging the nonlinearity and improving the dispersion characteristics of the present nano-core fiber by nonlinear fluid filling method is proposed. The special impact of selective fluid filling method on the fiber nonlinearity andFor improving the nonlinearity and dispersion properties of nan-core fiber, the idea of enlarging the nonlinearity and improving the dispersion characteristics of the present nano-core fiber by nonlinear fluid filling method is proposed. The special impact of selective fluid filling method on the fiber nonlinearity and dispersion is analyzed too. Calculation results show that the appropriate structure parameters and the specific selective filling method could help to enhance the nonlinearity and improve the fiber dispersion characteristics..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 506004 (2015)
Effects of Doping and Structureon Brillouin Frequency Shift and Scattering Efficiency of Depolarized Guided Acoustic Wave in Fibers
ZHANG Wen-yu, HOU Shang-lin, LIU Yan-jun, LEI Jing-li, LI Xiao-xiao, WANG Dao-bin, WU Gang, and XU Yong-zhao
The effects of the doping material, concentration and fiber structure on the frequency shift and Brillouin scattering efficiency of depolarized guided acoustic wave Brillouin scattering in single mode fiber and photonic crystal fiber are investigated by the all-vector finite element method. The results show that the BrThe effects of the doping material, concentration and fiber structure on the frequency shift and Brillouin scattering efficiency of depolarized guided acoustic wave Brillouin scattering in single mode fiber and photonic crystal fiber are investigated by the all-vector finite element method. The results show that the Brillouin frequency shift of the two kinds of fibers decrease and scattering efficiency of the single mode fiber increase with the increase of doped F concentrationin the cladding and doped GeO2concentrationin the core. The Brillouin frequency shift decreases with the increasing number of air holes rings at the given doped F concentration in photonic crystal fiber. The Brillouin frequency shift of TR2,3 mode increases, but that of TR2,7 modedecreases with the increasing number of air holes rings at a given doped GeO2concentration in fiber core..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 506005 (2015)
Temperature Calibration of Distributed Optical Fiber Temperature Sensor Based on Raman Scattering
TANG Yu-quan, SUN Miao, LI Jun, YANG Shuang, Brian Culshaw, and DONG Feng-zhong
The main causes of the temperature measurement error of Raman distributed optical fiber temperature sensor was researched and discussed based upon the Raman scatting principle and temperature demodulation algorithm. A method to address the effects caused by the attenuation differences between Stokes and anti-Stokes ligThe main causes of the temperature measurement error of Raman distributed optical fiber temperature sensor was researched and discussed based upon the Raman scatting principle and temperature demodulation algorithm. A method to address the effects caused by the attenuation differences between Stokes and anti-Stokes light, additional attenaution of fiber bending, stress and environment changes was proposed. Furthermore, the measurement error caused by dark current produced by the detector was also reduced by using nonlinear equations with three different temperature signals acquired along the same-fiber section location. The experimental results demonstrate that the aritmatic mean error of calibrated system has reduced from 8.0℃ to 0.37℃ with the fiber location found at 900 m. Overall, a temperature arithmatic mean error better than 0.6℃ is achieved..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 506006 (2015)
Fiber Fabry-Perot Sensor for Partial Discharges Based on Tunable Lasers
GUO Shao-peng, HAN Li, YIN Bo-hua, and JU Yu
A fiber fabry-perot sensor for partial discharges measurement was studied on getting stable working points. The parameters of the sensor were optimized to achieve higher sensitivities. The working points could be stabilized illuminated by a tunable laser. For a senor, the cavity length of the sensor was determined by tA fiber fabry-perot sensor for partial discharges measurement was studied on getting stable working points. The parameters of the sensor were optimized to achieve higher sensitivities. The working points could be stabilized illuminated by a tunable laser. For a senor, the cavity length of the sensor was determined by the tuning range of the tunable laser. Then, the reflectivity of the silica film was set to 1. Finally, the reflectivity of the fiber end was optimized by numerical simulations according to Gaussian beams and multi-beam interference theory. In experiments, a sensor was made with 28nm-FSR, 43μm-cavity length, the reflectivity of the silica film is above 0.97, and the reflectivity of the fiber end is 0.52. The losses of the cavity are 10 percent of the total energy. The fringe contrasts of the sensors arrive to 1. The sensor operates steadily illuminated by a tunable laser with 1530nm to 1565nm tuning range. The minimum detectable acoustic-pressure is about 1Pa. The performances of the sensor meet the demand of practical applications..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 506007 (2015)
Compensation of the Non-common Path Aberrations in an Adaptive Optics System with a Wavefront Processor
WANG Liang, CHEN Tao, LIU Xin-yue, JIA Jian-lu, LIN Xu-dong, and WEI Pei-feng
Non-Common Path Aberrations (NCPA) often exist in adaptive optics system, due to the discrepancy between sensing path and imaging path. A method for correcting NCPA was presented, which is very suitable for wavefront processors in forms of hardware. First, causes of NCPA were analyzed and NCPA examination with phase diNon-Common Path Aberrations (NCPA) often exist in adaptive optics system, due to the discrepancy between sensing path and imaging path. A method for correcting NCPA was presented, which is very suitable for wavefront processors in forms of hardware. First, causes of NCPA were analyzed and NCPA examination with phase diversity was discussed. Then, according to the working process of wavefront processors, an algorithm which converts NCPA to reference spot shifts of the wavefront sensor was deduced, and a software module in main controller computer was programmed for implementing this algorithm. Finally, an experiment with a light source as a target was conducted in the optical path of a telescope. Experiment results show that energy concentration of the target image is increased by 17.6% approximately after NCPA correction with this method. The experiment proves that this method is capable of NCPA correction for adaptive optics system..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 511001 (2015)
Application Informal Phase Closure about Image Reconstruction Algorithm Based on Fourier Telescopy
YU Shu-hai, WANG Jian-li, DONG Lei, LIU Xin-yue, WANG Liang, LI Hong-zhuang, and LIU Jie
To apply Fourier Telescopy (FT) based on T type laser transmitter array to detect remote targets of dim, weak and small in high resolution, a new image reconstruction algorithm is proposed. The image reconstruction algorithm of dot-plane type laser transmitter array is used for reference proposes a concept which is namTo apply Fourier Telescopy (FT) based on T type laser transmitter array to detect remote targets of dim, weak and small in high resolution, a new image reconstruction algorithm is proposed. The image reconstruction algorithm of dot-plane type laser transmitter array is used for reference proposes a concept which is named informal phase closure (IPC). The least mean square (LMS) reconstruction method and weighted noise Wiener filter algorithm (Wiener) are obtained perfect the FT system imaging quality of T-type laser transmitter configuration. The image reconstruction algorithm will lay the technical foundation for the implementation of practical engineering system. By the numerical simulation the overall system under different signal to noise ratios (SNR) of imaging conditions, imaging quality is improved, when the imaging SNR is low, such as SNR is 50, compared to directly inverse Fourier Transform method, the Strehl Ratios (SR) of reconstruction images of using the LMS and Wiener algorithms are respectively increased by 7% and 8.4%. The simulation confirms the feasibility and validity of the LMS and Wiener algorithms..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 511002 (2015)
LINS Initial Alignment Algorithm Based on the Attitude Tracking Approach for a Rocking Base
LI Han-zhou, PAN Quan, WANG Xiao-xu, ZHANG Juan-ni, and DENG Lin
In order to improve the accuracy, a high precision alignment of laser inertial navigation system was proposed based on the attitude tracking approach for a rocking base. The low frequency changes of the attitude angle could be considered as a useful signal that reflects the true motion of the base, which should not be In order to improve the accuracy, a high precision alignment of laser inertial navigation system was proposed based on the attitude tracking approach for a rocking base. The low frequency changes of the attitude angle could be considered as a useful signal that reflects the true motion of the base, which should not be removed, but should be tracked. The coarse alignment was carried out in the inertial coordinate system, which was sensitive to attitude change and could track the attitude swaying. The alignment errors were ensured to be a small value after the coarse alignment. The standard Kalman filter was employed in fine alignment to avoid to use the complex nonlinear algorithm. Two horizontal accelerations were added into the measurement vector besides of two level velocities, which can improve the tracking capability of Kalman filter. The alignment accuracy was checked by the repetitiveness of the final alignment results with the alignment from different starting time to the same end time. A high precision laser strapdown inertial navigtion system was used to verify the algorithm. It is shown that the alignment precision is about 0.04° by the alignment experiment on rocking vehicle, and the alignment time needs 180 s, the level position error is 770 m/h, and the proposed algorithm can satisfy with need of the high precision laser inertial navigation alignment..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 512001 (2015)
The Attitude Angle Estimation-based Distance Measurement of Tank Target in Monocular Image
XU Chao, GAO Min, and CAO Huan
To overcome the traditional image ranging algorithm dependent on camera attitude and parallax, an attitude angle estimation-based ranging method of tank target, in monocular image cathched by observe control and launch system charge coupled device, is proposed. Firstly, multistage scale invariant feature transform matcTo overcome the traditional image ranging algorithm dependent on camera attitude and parallax, an attitude angle estimation-based ranging method of tank target, in monocular image cathched by observe control and launch system charge coupled device, is proposed. Firstly, multistage scale invariant feature transform matching method is applied to obtain the template with minor error comparing with current target by fast attitude angle estimation. Secondly, the template and current target are used to form a novel monocular range model, without camera attitude and parallax between two images. In such a model, the features points matching the tank target image of the template are projected to the approximated 2D world coordinate with the assumption of far distance and tiny error of the attitude. Thus we set up the mapping relationship between the image points and target points, and then external parameters of camera are achieved by monocular camera calibration to calculate the distance of the camera center from target center. Series of targets range from 200 m to 2 500 m are adopted to verify the effectiveness of the proposed algorithm. Sequentially, the alteration of error along with distance increasing is analyzed, and the comparison between measurement error and the maximal tolerance of middle-to-terminal guidance under various ranges is executed. The results indicates that the proposed algorithm do not need to capture the accurate position and angle of camera, resulting in fast and far distance measurement of individual anti-tank missile system in field. Meanwhile, the maximal relative error is 4.9% and the maximal absolute error is 87.7 m, which satisfy the demand of the biggest tolerance errors in the whole range of missile..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 512002 (2015)
Light Propagation and Localization Properties of Edge States in Diatomic Square Lattice
WANG Dao-bin, YUAN Li-hua, LEI Jing-li, LI Xiao-xiao, and HOU Shang-lin
Utilizing the plane wave expansion method, it is found that there are two types of edge states existing on the surface termination along the ΓM direction of a diatomic photonic crystal. Through analying the surface mode band structure and the field distribution, the effect of the edge parameter on the waveguiding propeUtilizing the plane wave expansion method, it is found that there are two types of edge states existing on the surface termination along the ΓM direction of a diatomic photonic crystal. Through analying the surface mode band structure and the field distribution, the effect of the edge parameter on the waveguiding properties of these edge states were investigated. The group index and group velocity dispersion parameter were calculated according to the dispersion curves. The results demonstrate that the variation of the edge parameter has a very slight effect on the light propagation properties of first type of edge state. Its average group index is always around 5.0. The second edge state is obviously different with the first state and the variation of edge parameters can control the propagation performance of this mode efficiently. The maximal average group index of this edge state can achieve 178. The finite difference time domain methods was used to record the electric field distributions and amplitudes near the surface at different times. From the obtained results, it is found that these edge states can be confined in the area near the surface termination and propagate forward. The group velocity extracted from the finite difference time domain method is consistent with the result from the plane wave expansion method..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 516001 (2015)
Luminescence, Concentration Quenching and Thermal Stability of Ca9Al(PO4)7: Eu2+
WANG Di, MENG Xiang-yu, ZHAO Jia-wei, WANG Ying-bin, ZHANG Yue-dong, WANG Zhi-jun, GAO Shao-jie, ZHANG Kun, and LI Pan-lai
Ca9Al(PO4)7: Eu2+ blue emitting phosphor was synthesized by high temperature solid state method. Luminescence, concentration quenching and thermal stability of Ca9Al(PO4)7: Eu2+ were investigated. Excitation spectrum of Ca9Al(PO4)7: Eu2+ extended from 200 nm to 350 nm. Under an ultraviolet excitation, Ca9Al(PO4)7: Eu2+Ca9Al(PO4)7: Eu2+ blue emitting phosphor was synthesized by high temperature solid state method. Luminescence, concentration quenching and thermal stability of Ca9Al(PO4)7: Eu2+ were investigated. Excitation spectrum of Ca9Al(PO4)7: Eu2+ extended from 200 nm to 350 nm. Under an ultraviolet excitation, Ca9Al(PO4)7: Eu2+ showed a broad emission band with a maximum at 445 nm, which corresponded to 4f65d1→4f7 transition of Eu2+. Emission intensities of Ca9Al(PO4)7: Eu2+ were influenced by Eu2+ concentration, and they enhanced with increasing Eu2+ concentration, and reached a maximum value at 0.01 Eu2+, then decreased with further increasing Eu2+ concentration because of concentration quenching effect. The concentration quenching mechanism was verified to be dipole-dipole interaction. According to crystal structure data, critical distance can be obtained to be 2.297 nm. The emission intensity of Ca9Al(PO4)7: Eu2+ as a function of temperature was explored. When temperature turned up to 150 ℃, the emission intensity of Ca9Al(PO4)7: Eu2+ was 81.0% of the initial value at 25 ℃, and the corresponding activation energy was calculated to be 0.268 eV, which could prove the thermal stability of Ca9Al(PO4)7: Eu2+..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 516002 (2015)
Aberration Analysis on the Central Deviation of Corrective Lens on Hyperopic Amblyopia
LI Xin-hua, GAO Zhi-shan, and OUYANG Yong-bin
The +6.00 m-1 hypermetropia models and correction models were built by changing axial length and corneal curvature of the anterior surface using optical design program Zemax. Based on the correction models, the aberrations which were due to the central deviation of corrective lens were analyzed. For the +6.00 m-1 axialThe +6.00 m-1 hypermetropia models and correction models were built by changing axial length and corneal curvature of the anterior surface using optical design program Zemax. Based on the correction models, the aberrations which were due to the central deviation of corrective lens were analyzed. For the +6.00 m-1 axial hypermetropia, when the lens offset is more than 4mm, the spherical aberration, astigmatism and distortion are beginning to affect vision. Because of the central deviation of corrective lens, the spherical aberration is obvious in the model which is high percentage of axis changing, while the distortion and astigmatism are no significant difference in various models. These aberrations will reduce the treatment of amblyopia. During the correction of the hyperopic amblyopia, it is necessary to measure the anterior surface radius of cornea and the eye axial length. According to the composition proportion of the refractive error, aspheric lens is designed individually for the hyperopic amblyopia in order to ensure the treatment of amblyopia..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 517001 (2015)
Analysis of Iterative Denoising Method in Sparse Computed Tomography Reconstruction
LI Hong-xiao, CHEN Xiao-dong, LI Jun-wei, WANG Yi, and YU Dao-yin
The iterative denoising models and their solving algorithms in the sparse computed tomoyraphy reconstruction were researched. The theoretical derivations and simulation experiments demonstrate that the Algebraic Reconstruction Technique (ART) have the denoising ability. Two models for the sparse computed tomoyraphy denThe iterative denoising models and their solving algorithms in the sparse computed tomoyraphy reconstruction were researched. The theoretical derivations and simulation experiments demonstrate that the Algebraic Reconstruction Technique (ART) have the denoising ability. Two models for the sparse computed tomoyraphy denoise were proposed. One is based on the Euclidean norm inequality constraint, and the other is based on the infinity norm inequality constraint. Inspaired by the iterative method in ART, we use projection onto convex sets method to solve these two denoising models. The algorithm derivation is provided. The results indicate that the Euclidean norm based denoise model is better than the infinity norm based denoise model, and the ART method has the ability of denoising..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 517002 (2015)
Effect of Extremely Low Frequency Pulsed Electric Field on Delayed Biophoton Emission of Cells in Maize Seedling Root under Osmotic Stress
HE Rui-rui, XI Gang, LIU Kai, and ZHAO Yan-yan
Extremely low frequency pulsed electric field could arouse a comparatively intense reaction on physiological characteristics of plant cells, so the effect of the extremely low frequency pulsed electric field on crops drought resistance is very worthy to be studied. The delayed biophoton emission of cells, as a kind of Extremely low frequency pulsed electric field could arouse a comparatively intense reaction on physiological characteristics of plant cells, so the effect of the extremely low frequency pulsed electric field on crops drought resistance is very worthy to be studied. The delayed biophoton emission of cells, as a kind of life information, can reflect the changes of cellular physiological state. In order to study the influence of the extremely low frequency pulsed electric field on drought resistance of plants seedlings and its mechanism, the PEG-6000 solution with the osmotic potential of -0.1 MPa was used to simulate drought conditions, the germinating maize was treated by the extremely low frequency pulsed electric field at 100 kV/m, frequency 1 Hz and pulse width 80 ms, the changes of the delayed biophoton emission from maize seedling roots under osmotic stress were discussed. The results show that the changes of the kinetic parameters about delayed biophoton emission such as the initial photon number I0, coherence time τ and decay factor β decrease volatility. The changes of the kinetic parameters about delayed biophoton emission of maize seedling root treated by extremely low frequency pulsed electric field are the same, but, the value of these parameter increase significantly in comparison with the control. The analysis indicates that the extremely low frequency pulsed electric field treatment can raise the level of the metabolic level of cell and improve tissue order, the interactions between functional molecules in cells is enhanced. The results of this paper provide a reference for explaining clearly the effect of extremely low frequency pulsed electric field on drought resistance of plants seedlings and its mechanism..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 517003 (2015)
Optical Design of Space-based UV Panoramic Sounder for Nadir and Limb Viewing
XUE Qing-sheng, LI Yang, and DUAN Min-zheng
Space-based atmospheric remote sensing urgently require UV panoramic imager. The research objective is sounding nadir and limb atmosphere simultaneously. Based on this research objective, a new optical system construction of UV panoramic imager is proposed, in which, the nadir Field of View (FOV) and limb FOV use a comSpace-based atmospheric remote sensing urgently require UV panoramic imager. The research objective is sounding nadir and limb atmosphere simultaneously. Based on this research objective, a new optical system construction of UV panoramic imager is proposed, in which, the nadir Field of View (FOV) and limb FOV use a common image plane. An optical system of panoramic imager is designed, the central wavelength is 360nm, the bandwidth is 10nm, the nadir FOV is 10°, the limb FOV is 360°×(70.31°～72.71°), the focal length is 5mm, an the relative aperture is 1: 3.3. The energy of margin FOV is increased by using the distortion of the optical system, and the image irradiance is increased by using the effective aberration vignetting caused by pupil aberration. The relative illumination of margin FOV is more than 98% of that of central FOV. The multi-configuration is established with the optical paths of nadir FOV and limb FOV. The optical paths of nadir FOV and limb FOV is optimized by using multi-configuration optimization function of ZEMAX-EE software. The design result shows that the MTF of nadir and limb FOV are both more than 0.6@38.5lp/mm, The design requirements are satisfied. The volume of the panoramic imager is small, and is suitable for appplication in space..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 522001 (2015)
Design the Diffractive Optical Element with Large Diffraction Angle Based on Rayleigh-Sommerfeld Integral
PANG Hui, MAN Zhang, DENG Qi-ling, QIU Qi, and DU Chun-lei
A novel method is presented for designing the diffractive optical element with large diffraction angle based on the Rayleigh-Sommerfeld Integral. In the design, the target intensity distribution is firstly modified with coordinate transformation and intensity adjustment. Thereafter the modified Gerchberg-Saxton algoritA novel method is presented for designing the diffractive optical element with large diffraction angle based on the Rayleigh-Sommerfeld Integral. In the design, the target intensity distribution is firstly modified with coordinate transformation and intensity adjustment. Thereafter the modified Gerchberg-Saxton algorithm is adopted to optimize the phase distribution of the diffractive optical element. Our method and the original method, which adopts Frauhofer diffraction integral to calculate the diffraction, are used to design the diffractive optical element to reconstruct a structured light and a square pattern with different diffraction angle. And the result shows that the original method can work well only the diffraction angle below 25°. When the diffraction angle gets larger the reconstructed light field shows significant pillow distortion and uneven intensity distribution. In contrast, our method can achieve the exact diffraction angle and even intensity distribution at all the angle..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 522002 (2015)
The Research of the Light Source for Star Simulator with Automatic Calibration and Adjustable Spectrum
LI Xiao-ni, WU Cui-gang, ZHAO Xin, LU Zhen-hua, and XIE Lai-yun
In order to obtain the star simulator sources system of the adjustable spectrum with more color temperatures and more magnitudes and it can be calibrated automatically in a wide range of spectral bands. Embarking from the amplitude and colorimetry, This paper realize the automatic calibrating multispectral light star sIn order to obtain the star simulator sources system of the adjustable spectrum with more color temperatures and more magnitudes and it can be calibrated automatically in a wide range of spectral bands. Embarking from the amplitude and colorimetry, This paper realize the automatic calibrating multispectral light star simulator system which the color temperature is continuous adjustable from 3 900 K to 6 500 K and the magnitudes is 1 MV adjustable in -1 MV~+6 MV with double integrating spheres in 400 nm~900 nm spectral range,The light system is based on the least squares method and the white LED are treated as the main body, a variety of different peak wavelength and narrow-band spectrum LEDs to compensate the objective spectrum.Finally,the source system and star simulator are completed and debugged in the laboratory,and the results are compared with the theoretical simulation values and standard visual magnitudes. The results show that the star simulator spectrum simulation error and magnitude error are within the range of ±10% and ±10% respectively and meet the stage star sensor needs, At the same time ,In ensuring the stability of the control circuit,magnitude error can be within the range of ±5%..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 522003 (2015)
Design of a Focus-tunable Capsule Endoscope System
GUO Xin, ZHANG Wei, SU Jin-hui, YANG Bo, and WAN Xin-jun
To solve the problem of constraint between resolution and depth of field in capsule endoscope system, a single-liquid, electron-controlled, focus-tunable len was applied into the design of capsule endoscope system. By using of liquid lens, the depth of field of system was enlarged with the required resolution. The initTo solve the problem of constraint between resolution and depth of field in capsule endoscope system, a single-liquid, electron-controlled, focus-tunable len was applied into the design of capsule endoscope system. By using of liquid lens, the depth of field of system was enlarged with the required resolution. The initial system was set up by the optical design software CODE V. The liquid lens model was built according to its structure restriction. The liquid volume of the lens was constant,while the radius, the aperture and the thickness of the lens were changed during the focal length changing process. At different depth of field, the appropriate radius,aperture and thickness of the liquid lens were calculated by MATLAB, and the calculation result was imported into CODE V. The optimizing process was designed. After the optimization, in 3~100 mm depth of field, clear images can be obtained. The field of view is more than 110°, and the modulation transfer function of the system is larger than 0.3 in all field of view at 40 lp/mm..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 522004 (2015)
Thermal Design for the Optical-structure System of High Resolution High-altitude Camera
SHI Kui, YANG Hong-tao, CHEN Wei-ning, FAN Zhe-yuan, ZHANG Gao-peng, and WU Deng-shan
To guarantee the image quality of a high-altitude camera in extreme low temperatures, thermal design for camera optical system was done by combined passive thermal control with active thermal control. Polyimide insulation material is used for passive thermal control, increasing the camera's thermal resistance betweTo guarantee the image quality of a high-altitude camera in extreme low temperatures, thermal design for camera optical system was done by combined passive thermal control with active thermal control. Polyimide insulation material is used for passive thermal control, increasing the camera's thermal resistance between internal structures and external environment, and decreasing the influence of the external cryogenic environment on the temperatures of camera lens. The method of using electric heating film to heat camera lens was adopted as an active thermal control means. The heat transfer model of the lens in the optical system was built in the WorkBench finite element software with heating power loads, thermal convection loads and thermal radiation loads considered, and steady-state thermal analysis was carried out. It turned out that, the temperature of the camera optical system was controlled in the range of 18℃~22℃ when the heating power of six heating zones was 12、17、22、17、10、13 W, and the thermal control result meted the design requirements..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 522005 (2015)
The Frequency Hopping Bandpass Microwave Photonic Filter with High Q-factor
ZHANG Ai-ling, HUANG Cong, PAN Hong-gang, CAO Ye, and LIU Ce
A frequency hopping bandpass microwave photonic filter based on Lyot-sagnac filter and cascaded structure was proposed. In the filtering system, a continuous optical source with variable wavelength separation is achieved by using broadband source and Loyt-sagnac filter. The first order filter is composed of a phase modA frequency hopping bandpass microwave photonic filter based on Lyot-sagnac filter and cascaded structure was proposed. In the filtering system, a continuous optical source with variable wavelength separation is achieved by using broadband source and Loyt-sagnac filter. The first order filter is composed of a phase modulator and a signal mode fiber. A ring resonator is cascaded to be the second order filtering structure. A frequency hopping single-bandpass microwave photonic filter with high Q-factor is achieved by cascading the two filters. In the case of choosing three sections of polarization maintaining fiber, the central frequency of the filter is hopped among 1.012 1 GHz, 1.214 5 GHz, 1.416 9 GHz, 1.619 3 GHz and 1.821 7 GHz by adjusting the polarization state of polarization controller. Since a cascaded structure is used in this article, the implementation of the filter inherited advantage of both filters. So the filter has good frequency response. The highest Q-factor is 13 155.69. Main side lobe suppression radio varies from 18 dB to 25.51 dB. Besides, the device has simple structure and is easy to control..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 523001 (2015)
All-Optical Serial-to-Parallel Converter based on Semiconductor Laser Amplifer in Loop Mirrors
LIAO Li-dan, LING Yun, HE Bin-bin, SHEN Su-qi, QIU Kun, and ZHENG Mian
In order to reduce the bitrate of high-speed optical signal, a novel all-optical serial-to-parallel converter is proposed, which is based on the cascaded Semiconductor Laser Amplifier in a Loop Mirror(SLALOM), to be used to convert high speed serial optical signal to multi-output low-speed parallel optical signal. The In order to reduce the bitrate of high-speed optical signal, a novel all-optical serial-to-parallel converter is proposed, which is based on the cascaded Semiconductor Laser Amplifier in a Loop Mirror(SLALOM), to be used to convert high speed serial optical signal to multi-output low-speed parallel optical signal. The converter adopts the structure of the cascaded SLALOMs, the output of the previous SLALOM connects to the input of the next one with the optical propagation delay time between them equaling to the bit period of the input optical pulse signal. Morever, the particular timing of optical control and signal pulses is designed to guarantee appropriate outputs. The feasibility is verified by converting 80 Gb/s serial optical signal to ten 8 Gb/s parallel outputs by using the designed 1×10 all-optical serial-to-parallel converter. The device parameters are optimized including the optical power of control / signal pulse and the time offset of them. The difference of the receive sensitivity values of all output ports is less than 10 dB. Comparing with the traditional parrallel structure, the proposed converter has the advantage of lower optical power loss, and it′s easier to extend parallel port numbers, which is available for the applications including high-speed demultiplexing, optical information processing and optical switching system..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 523002 (2015)
Temperature Dependence of Garnet-type Polarization-modulation
NGUYEN Truong-giang, JIAO Xin-bing, CHEN Lin, and GAO Jun
The influence of temperature on the garnet-type polarization modulation was investigated. The garnet-type polarization modulation was prepared by magnetron sputtering method, the polarization properties and optical spots of laserbeam through garent and garnet-type polarization modulation were examined by Stokes polarimThe influence of temperature on the garnet-type polarization modulation was investigated. The garnet-type polarization modulation was prepared by magnetron sputtering method, the polarization properties and optical spots of laserbeam through garent and garnet-type polarization modulation were examined by Stokes polarimeter and CCD. The experimental results show that the Stokes parameters of the laser beam passing through different materials present different trends, while the degree of polarization, degree of linear polarization and degree of circular polarization are nearly unchanged as the ellipticity angle does not change, when changing the temperature from 25 to 75 °C..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 523003 (2015)
Electro-optical Composite Logic Gates Based on Periodically Poled Lithium Niobate Crystal
ZHONG Dong-zhou, and JI Yong-qiang
According to the coupling-wave theory of quasi-phase-matched linear electro-optic effect, the logical calculation methods of the AND and OR gates with electro-optical composite were proposed based on a single periodically poled lithium niobate. And those of the exclusive-OR gate, half-adder and half-subtractor were furAccording to the coupling-wave theory of quasi-phase-matched linear electro-optic effect, the logical calculation methods of the AND and OR gates with electro-optical composite were proposed based on a single periodically poled lithium niobate. And those of the exclusive-OR gate, half-adder and half-subtractor were further explored based on cascading periodically poled lithium niobate crystal. With the applied electric field fixed at 0.184 KV/mm and 0.368 KV/mm , the influences of the wavelength, the azimuth and the polar angle of light, as well as the temperature of the crystal on the logic output were discussed. It is found that the logical calculation of the above-mentioned basic logic gates can be performed successfully. However, the logical calculation is very sensitive to the temperature, the azimuth and the polar angle. The slight varization of these parameters will lead to the change of the logic output. The calculation scheme can be generalized to applications of more complex basic logic gate, and the various basic logic gates of more than three logic inputs and outputs..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 523004 (2015)
Study on Theory and Technology of Low Voltage Variable-focus Double Liquid Lens
WEI Mao-wei, PENG Run-ling, TANG Zheng-yang, and CHEN Jia-bi
In this paper, theoretical analysis of the cylindrical double-liquid lens model with single-layer dielectric film, tells us that the thickness and uniformity of the dielectric film have great influence on the performance of variable-focus double liquid lens. The relation curve between focal length of liquid lens and drIn this paper, theoretical analysis of the cylindrical double-liquid lens model with single-layer dielectric film, tells us that the thickness and uniformity of the dielectric film have great influence on the performance of variable-focus double liquid lens. The relation curve between focal length of liquid lens and driving voltage is drawn. On this basis, parylene is chosen as the dielectric film of low voltage variable-focus double liquid lens to reduce the driving voltage. The parylene film inside the cylindrical chamber with suitable thickness is coated by vacuum evaporation, and the surface appearance and the thickness of the film are also measured. In the experiment, the conducting liquid of potassium chloride and insulating liquid of silicone oil are chosen, with centrifugal degasification processing before used. At last, a sample of liquid lens is produced. The sample has excellent property with focal range ±20 V under the maximum driving voltage 30 V. The friction term is introduced into Yong′s equation and a reasonable explanation is given for the phnomenon of variable-focus hysteresis..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 523005 (2015)
Theoretical Analysis on Optical Parallelism of Pentaprism
WANG Qiu-shi, LI Ming, LIAO Ke-liang, YANG Fu-gui, and SHENG Wei-fan
By using matrix optics method, expressions of two types of optical parallelism in pentaprism were obtained. An relationship between optical parallelism and normal vector of working surface was analysed. An experiment device based on Agilent laser interferometer and DHC 3D rotation platform was established. With angularBy using matrix optics method, expressions of two types of optical parallelism in pentaprism were obtained. An relationship between optical parallelism and normal vector of working surface was analysed. An experiment device based on Agilent laser interferometer and DHC 3D rotation platform was established. With angular measurement function provided by the device, optical parallelism of a pentaprism made by Thorlabs were measured. The experimental results are consisten with the calculation of analytical expressions, whose deviation is no more than 4%. Conclusion indicates that changes of roll angle and yaw angle in practical application are equivalent to alteration of optical parallelism. It means that the jitter errors of online measurement and fabrication errors can be in-situ calibrated simultaneously by coordinates transformation. The study is useful for manufacturing, adjusting and pre-calibrating a pentaprism in optical system, and the conclusions above can be a good help in high-precision optical surface profiler metrology in practice..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 523006 (2015)
The Effect of Sample Temperature on the Laser-induced Plasma Radiation Characteristics
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In order to investigate the influence of sample temperature on the radiation characteristic of laser induced plasma, the target prepared from the national standard soil samples was ablated in air by a Nd∶YAG nanosecond pulse laser with wavelength 1 064 nm under different temperatures (TS≤350 ℃). The line intensity and In order to investigate the influence of sample temperature on the radiation characteristic of laser induced plasma, the target prepared from the national standard soil samples was ablated in air by a Nd∶YAG nanosecond pulse laser with wavelength 1 064 nm under different temperatures (TS≤350 ℃). The line intensity and signal-to-noise ratio of spectrum were measured, the detection limit of analytical spectroscopy and the accuracy of signal measurement were calculated. The experimental results show that, with the increase of sample temperature under the condition of laser energy for 200 mJ, plasma radiation increases and reaches the maximum at the sample temperature of 300 ℃. Calculations show that compared with that of the room temperature, the spectrum line intensities of Al, Mg, Ba and Fe increased by 67%, 58%, 61% and 52% respectively, and the spectral signal-to- noise ratios increased by 41%, 51%, 28% and 38% respectively. The detection limit of analytical elements and the stability of spectral signal were improved. Obviously, the rise of the sample temperature can effectively enhance the quality of the laser spectrum..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 530001 (2015)
Determination of Optical Constants and Thickness of Online Low-E Glass in Visible-near Infrared Region by Ellipsometry
JI Bei, HUANG Shui-ping, and ZHOU Jun
Based on the optical mechanism of online Low-E glass,the optical constants of functional layer and transition layer of online Low-E glass in visible-near infrared region were analyzed by the spectroscopic ellipsometry.The ellipsometric data of the sample at three different angles of incidence were measured at first,theBased on the optical mechanism of online Low-E glass,the optical constants of functional layer and transition layer of online Low-E glass in visible-near infrared region were analyzed by the spectroscopic ellipsometry.The ellipsometric data of the sample at three different angles of incidence were measured at first,then the Lorentz two-oscillator model and Cauchy model were used to characterize the dispersion characteristics of functional layer and transition layer of online Low-E glass ,respectively.The optical constants and the thickness of each layer of online Low-E glass were obtained by fitting the measured ellipsometric data.Moreover,the Scanning Electron Microscope (SEM) were used to investigate the film thickness of the sample.The fitting results suggest that Lorentz two-oscillator model and Cauchy model can explain the optical properties of online Low-E glass well.Meanwhile,the ellipsometry also provides a reliable method for the determination of optical constants and thickness of the multilayer film systems..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 531001 (2015)
Contrast Enhancement Method for Transparent Pattern of Indium Tin Oxide Conductive Film
CHEN Fang-han, ZHAO Guang-yu, JIANG Shi-long, and PENG Wen-da
ITO conductive layer is the absolute location components in touch display technology. It is necessary to inspect the surface defects of ITO layer for guaranteeing the sensitivity and accuracy of touch operation. According to the issue existing in inspecting transparent area of ITO layer automatically based on machine vITO conductive layer is the absolute location components in touch display technology. It is necessary to inspect the surface defects of ITO layer for guaranteeing the sensitivity and accuracy of touch operation. According to the issue existing in inspecting transparent area of ITO layer automatically based on machine vision technology, a method used for enhancing contrast of pattern on ITO layer is presented in paper. The method exploited the spectral property of ITO and its interaction with light, and a NIR coaxial light was designed to illuminate. The optical method improved the contrast of ITO pattern from 0 to 4.5%. Based on the fundamental contribution of illumination, nonlinear enhancement performed by wavelet transform was further applied. The contrast eventually increased to 16%, which provides a good reliability to analyze and recognize ITO layer defects..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 531002 (2015)
Finite Element Analysis of Temperature Rising in VO2 Thin Films Under Irradiation of CO2 Pulse Laser
XU Kai, LU Yuan, LING Yong-shun, and QIAO Ya
In order to know the influence of parameter of pulse laser on the temperature filed in the researches of protection to high power pulse laser, the change of temperature filed of the films was analyzed by thermal analysis module of ANSYS. The influence of laser facula radius, power density, pulse width and repetition frIn order to know the influence of parameter of pulse laser on the temperature filed in the researches of protection to high power pulse laser, the change of temperature filed of the films was analyzed by thermal analysis module of ANSYS. The influence of laser facula radius, power density, pulse width and repetition frequency on the time and area size of the VO2 thin films phase transition was analyzed in the module. The results of analysis show that, the four parameters effect the transition reaching time of thin films together. The time can be shortened by amplifying laser facula radius and power density, but the proportion of area radius to laser facula radius can’t be effected directly. Amplifying pulse width or repetition frequency can shorten the transition reaching time, while the former is better to amplifying the heat production by one pulse than the latter..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 5, 531003 (2015)
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