Contents
2013
Volume: 33 Issue 8
51 Article(s)
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Atmospheric Optics and Oceanic Optics
Measurement and Analysis of Wide-Wave Band Sky Background Radiance
Xu Wenqing, Zhan Jie, and Xu Qingshan
A measurement program of wide-wave band based DTL-1 sky brightness meter is developed to gain the real time sky background radiance fast. The principle for measuring the integral radiance in wave range from visible to near-infrared (400~1000 nm) is analyzed. Furthermore, the response coefficient and luminous efficiencyA measurement program of wide-wave band based DTL-1 sky brightness meter is developed to gain the real time sky background radiance fast. The principle for measuring the integral radiance in wave range from visible to near-infrared (400~1000 nm) is analyzed. Furthermore, the response coefficient and luminous efficiency are calculated, and an error analysis for the measurement results is made. The linearity checking of the DTL-1 and the data are carried out using spectrometer. The relative error is below 10%, which indicates the credibility of the instrument. The precision of the instrument can satisfy the requirement on real application. The all sky radiances in Hefei and Southwest districts are measured by using DTL-1, and the measurement data in the two districts are analyzed in brief..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 801001 (2013)
Measurement of Atmospheric Water Vapor Column Density with Passive Differential Optical Absorption Spectroscopy Technology
Liu Jin, Si Fuqi, Zhou Haijin, Zhao Minjie, Dou Ke, and Liu Wenqing
A measurement method of atmospheric water vapor column density by passive differential optical absorption spectroscopy (DOAS) technology is developed. The solar spectrum at the top of atmosphere can be considered as the reference spectrum and the total slant column densities of water vapor and O4 can be retrieved simulA measurement method of atmospheric water vapor column density by passive differential optical absorption spectroscopy (DOAS) technology is developed. The solar spectrum at the top of atmosphere can be considered as the reference spectrum and the total slant column densities of water vapor and O4 can be retrieved simultaneously from the measurement spectrum by DOAS algorithm. To convert the slant column density to the vertical column density, the relationship of air mass factors (AMFs) of water vapor and O4 is analyzed. The vertical column density of water vapor is resolved with the AMF of O4. The saturated absorption problem of water vapor affects the retrieval precision of DOAS, so a numerical simulation method is developed to revise the water vapor density. The water vapor measurement result of DOAS is compared with those obtained with sun photometer and GOME-2 satellite. Good correlation is shown, and thus the feasibility of the method is verified..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 801002 (2013)
Vertical Distribution of Aerosol Extinction Coefficient Detection in Boundary Layer Using CCD Lidar
Meng Xiangqian, Hu Shunxing, Wang Zhenzhu, Hu Huanling, and Wang Yingjian
A method for the retrieval of the aerosol scattering coefficient profiles in boundary layer is presented. A bistatic lidar system (CCD Lidar) with charge coupled device (CCD) as the detector and laser as transmitter is constructed. Aerosol scattering images of a horizontal laser beam and a vertical laser beam from grouA method for the retrieval of the aerosol scattering coefficient profiles in boundary layer is presented. A bistatic lidar system (CCD Lidar) with charge coupled device (CCD) as the detector and laser as transmitter is constructed. Aerosol scattering images of a horizontal laser beam and a vertical laser beam from ground to 1.2 km are imaged based on the CCD lidar system. The relative atmospheric scattering phase function (SPF) can be obtained by the aerosol scattering image of the horizontal laser beam, and the aerosol extinction coefficient (AEC) profile is inverted using the relative SPF. The AEC measured by CCD lidar has shown good agreement with that measured by double wavelength polarization lidar (DWPL) in 400 m and 600 m. Four nighttime AEC profile contours observed in Hefei are given. CCD lidar needs no overlap correction, it has a high spatial resolution of 0.032 m/pixel, and is expected as a potential technique of aerosol detection in boundary layer..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 801003 (2013)
Energy Design of Fourier Telescope System in the Atmospheric Environment
Luo Xiujuan, Zhang Yu, Sun Xin, Cao Bei, Zeng Zhihong, Xia Aili, Li Libo, and Zhu Shaolan
Energy design technology is one of the key techniques of Fourier telescope. Laser propagation in the atmosphere and its impact on the energy of the laser beams are analyzed. According to the uplink and downlink transmission of energy, a total laser energy calculation method of Fourier telescope system is derived, and tEnergy design technology is one of the key techniques of Fourier telescope. Laser propagation in the atmosphere and its impact on the energy of the laser beams are analyzed. According to the uplink and downlink transmission of energy, a total laser energy calculation method of Fourier telescope system is derived, and the corresponding applicable conditions are given. Meanwhile, based on radiation theory, a fast energy estimation method is proposed by which the required total transmitter energy of a Fourier telescope for 1000 km low-orbit objects is estimated. The effects of transmitter energy imbalance on the image quality are pointed out and simulated. It can be concluded that the intensity differences among laser beams of transmitter array must be less than 5%. From the atmospheric transmittance, laser emitting aperture, beam collimation, transmitting scheme, speckle effect, receiving technologies, image reconstruction techniques and other aspects, the design ideas and measurements to reduce energy loss are put forward..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 801004 (2013)
Fiber Optics and Optical Communications
Study on Delay and Dispersion Characteristics of the Fiber Bragg Grating Fabry-Perot Cavity
Qu Li, Meng Yu, Zhuo Zhongchang, Guo Xiuzhen, and Su Xuemei
Based on the fiber Bragg grating Fabry-Perot (F-P) cavity with identical grating parameters at two ends, using the transfer matrix method and numerical simulation method, the influence of various parameters of fiber Bragg grating F-P cavity on its transmission spectrum features is analyzed, and the delay and dispersionBased on the fiber Bragg grating Fabry-Perot (F-P) cavity with identical grating parameters at two ends, using the transfer matrix method and numerical simulation method, the influence of various parameters of fiber Bragg grating F-P cavity on its transmission spectrum features is analyzed, and the delay and dispersion characteristics of the fiber Bragg grating F-P cavity are discussed in detail. Finally, when its cavity length of fiber Bragg grating F-P cavity is changed, the influence on its slow light characteristics is analyzed. The results of this study can be useful for designing Bragg grating F-P cavity, which are also meaningful to actual experiments and applications in using fiber Bragg grating F-P cavity on the slow light and dispersion compensation..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 806001 (2013)
Fiber Fabry-Pérot Accelerometer Based on SU-8 Photoresist
You Jingjing, Wang Ming, Rong Hua, and Dai Lihua
A beams-mass structure, which is sensitive to the acceleration, is designed based on the SU-8 photoresist′s high aspect ratio imaging feature. Theoretical expressions are deduced for analyzing the relationships between acceleration and the deflection of the beams-mass structure, acceleration and the light intensity of A beams-mass structure, which is sensitive to the acceleration, is designed based on the SU-8 photoresist′s high aspect ratio imaging feature. Theoretical expressions are deduced for analyzing the relationships between acceleration and the deflection of the beams-mass structure, acceleration and the light intensity of Fabry-Pérot interference. Simplified calculation formulas are obtained and major influences such as the sensitivity and the natural frequency are discussed. The new beams-mass structure with the “卍” form is presented, and its parameters are analyzed and determined. The results show that the new SU-8 photoresist Fabry-Pérot acceleration sensor with “卍” structure improves the sensitivity vastly and has a good detection mode. The simulation results match to the theoretical analysis, which confirms that the designed structure can be applied in acceleration monitoring based on Fabry-Pérot interference theory..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 806002 (2013)
Path Design of Clos Network Based on Device Constraint in Large Capacity Optical Switches
Zhou Yumeng, Qiu Kun, Xu Bo, Cui Zhanqi, Ling Yun, and Chen Xilian
Optical switching architecture based on fast tunable laser and arrayed waveguide grating is an ideal choice to realize optical switches with large capacity. However, the fast tuning requirement of the fast tunable laser makes it necessary for the fast tunable laser to keep seeding light even under idle state without daOptical switching architecture based on fast tunable laser and arrayed waveguide grating is an ideal choice to realize optical switches with large capacity. However, the fast tuning requirement of the fast tunable laser makes it necessary for the fast tunable laser to keep seeding light even under idle state without data, and the optical light from the idle fast tunable laser may introduce significant interference to a valid optical signal if they are routed to the same receiver. In order to solve the influence of the fast tunable laser constraint, a method is proposed to use the invalid demands to fill idle time slots so that the valid demands and invalid demands have different output ports and no longer interfere with each other. Two different methods to generate the invalid demands are proposed, namely the random strategy and the sequential strategy, and the performances of the two strategies with different traffic loads are studied and compared through simulations. Meanwhile, in order to reduce the number of rearrangement in the scheduling algorithm, a threshold-based strategy to find the path for an invalid demand is proposed. The simulation results show that this threshold-based method can greatly reduce the number of rearrangement, and improve the computation efficiency of the scheduling algorithm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 806003 (2013)
Simulation and Analysis of Single Mode-Multimode-Single Mode Fiber Structure under Condition of Unweak-Guidance
Hong Songchong, Chen Yaofei, Jiang Junfeng, Kim Chol, Kim Wonphil, and Li Hyomin
Aiming at theoretical analysis of single mode-multimode-single mode(SMS) fiber under unweak-guidance condition, a simple and accuracy simulation method is studied. Propagation characteristics and transmission efficiency of all the modes of mutimode fiber segment in SMS fiber under unweak-guidance condition are analyzedAiming at theoretical analysis of single mode-multimode-single mode(SMS) fiber under unweak-guidance condition, a simple and accuracy simulation method is studied. Propagation characteristics and transmission efficiency of all the modes of mutimode fiber segment in SMS fiber under unweak-guidance condition are analyzed using Taylor′s series expansion of input light field and vector mode expansion of electromagnetic field in multimode fiber. Based on analysis of mode characteristic equations, the smallest mode numbers contributing to multimode interference in the single mode-mutimode-single mode fiber are reasonably selected and transmission efficiency of every mode is calculated and compared with experimental results. It is proved that the light field in the multimode fiber can be expanded only by the linearly polarized radial function, zero-order Bessel function(scalar model) to obtain the good simulation results under condition that the single mode fiber and multimode fiber are well concentric. This work can simplity complexity of theoretical research in this field effectively..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 806004 (2013)
Numerical Investigation of a Ultra-Broadband Low-Dispersion Holey Fiber
Wang Dan, and Zheng Yi
Using the finite element method, the dispersion property, mode area and nonlinear coefficient are numerically simulated by artificially choosing the parameters of the proposed novel holey fiber. The results show that the novel fiber not only has a relatively simple structure, but also has better dispersion property. ByUsing the finite element method, the dispersion property, mode area and nonlinear coefficient are numerically simulated by artificially choosing the parameters of the proposed novel holey fiber. The results show that the novel fiber not only has a relatively simple structure, but also has better dispersion property. By optimizing the structure parameters, a flattened dispersion holey fiber with three zero-dispersion wavelengths (λ=1.0 μm, λ=1.53 μm, λ=1.81 μm) in the 900 nm wavelength range has been designed. These results can be used to guide the design of novel holey fiber..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 806005 (2013)
Holography
Suppressing Methods for Oblique Stripe Noise in the Image of Marine Microorganism
Liu Yucui, and Tang Chunming
The holographic camera system for research and analysis on marine microorganisms and particles has a wide application prospect. Because of the special imaging technique (the holographic imaging technology) and the special imaging environment (seabed), there are a variety of different oblique stripe noises in the hologrThe holographic camera system for research and analysis on marine microorganisms and particles has a wide application prospect. Because of the special imaging technique (the holographic imaging technology) and the special imaging environment (seabed), there are a variety of different oblique stripe noises in the holograms. The existence of oblique stripe noises seriously affect quality of reconstructed image of the marine biological hologram and further processing, and the present methods for common stripe noise are no longer suitable. An effective method is proposed to deal with the oblique stripe noises. For the periodic oblique stripe noise, the local threshold method is adopted to find out the frequency center of the noise, and the Gaussian notch filter is utilized to eliminate the noise. For the aperiodic oblique stripe noise, the linear equation is used to simulate the bright line of the noise in the frequency domain, and the partial notch filter is exploited to depress the noise. Simulation results illustrate that the proposed method can filter out the periodic oblique stripe noise completely as well as the aperiodic oblique stripe noise mostly, and the useful information of the holograms can be kept..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 809001 (2013)
Imaging Systems
Numerical Simulation of Fourier Telescopy Based on Non-Uniform Sampling
Yu Shuhai, Wang Jianli, Dong Lei, Liu Xinyue, and Wang Guocong
In order to apply Fourier telescopy (FT) to the detection of synchronous geostationary orbit and low-earth orbit motion satellite and fulfill high-resolution imaging, a new method is proposed based on non-uniform sampling technology to achieve low sampling frequency for the high frequency information processing. Non-unIn order to apply Fourier telescopy (FT) to the detection of synchronous geostationary orbit and low-earth orbit motion satellite and fulfill high-resolution imaging, a new method is proposed based on non-uniform sampling technology to achieve low sampling frequency for the high frequency information processing. Non-uniform sampling is made for the time domain returned signal into digital signal and the non-uniform discrete Fourier transform (NUDFT) is used. Amplitude damping is done to all the signals except the low-frequency signal and then the low frequency component information can be accurately extracted by the use of NUDFT. Amplitude damping and NUDFT are repeated until all the frequency information is extracted. The target can be constructed with phase closure techniques and traditional reconstruction method. This method reduces the sampling frequency, overcomes the spectral noise of the NUDFT method and avoids the influence of high-frequency noise on the imaging quality. It has bright application prospect, especially in low orbit multi-beam Fourier telescope imaging area. The feasibility of the method is verified by numerical simulation. Comparative researches are done for reconstruction image with the traditional uniform sampling result under different signal-to-noise ratios (SNRs). The method is consistent on the noise sensitivity with traditional methods..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 811001 (2013)
Near-Infrared Microscopic Image Segmentation Based on W2DPCA-FCM
Yang Xiukun, Zhong Mingliang, Jing Xiaojun, and Yue Xinqi
Segmentation of near-infrared (NIR) microscopic image by feature extraction and clustering analysis methods can be used for efficient extraction of chemical information. Due to the high computational complexity of principal component analysis (PCA) in extracting features, we propose a weighted two-dimensional PCA (W2DPSegmentation of near-infrared (NIR) microscopic image by feature extraction and clustering analysis methods can be used for efficient extraction of chemical information. Due to the high computational complexity of principal component analysis (PCA) in extracting features, we propose a weighted two-dimensional PCA (W2DPCA) spectral feature extraction scheme in this paper, which is combined with fuzzy C-mean (FCM) algorithm to extract the chemical information of NIR microscopic image. The feasibility and effectiveness of the proposed algorithm are verified by simulation experiments performed on NIR microscopic image of tablets. Experimental results show that W2DPCA-FCM is an effective infrared microscopy image analysis method since it can reduce the computation time and improve the clustering accuracy..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 811002 (2013)
Dynamic Imaging Detection and Target Recognition for Cat-Eye Effect Echo
Wu Dongsheng, Bai Tingzhu, Liu Bingqi, Zhou Bin, and Hu Wengang
In order to realize dynamic imaging detection and target recognition for cat-eye effect echo in complex background，the imaging detection system is constructed and the detection methods are discussed according to the imaging characteristics of the cat-eye effect echo, background and noises. The detection mode is proposeIn order to realize dynamic imaging detection and target recognition for cat-eye effect echo in complex background，the imaging detection system is constructed and the detection methods are discussed according to the imaging characteristics of the cat-eye effect echo, background and noises. The detection mode is proposed that the timing is modulated synchronously and the field of view is controlled synchronously for the laser irradiation and imaging detection. Based on it, the target recognition algorithm is researched. The background interference can be removed by the method of frame difference. The method of regional grayscale average is put forward to suppress noises. The target can be recognized through adaptive thresholds of target discrimination and recognition. The detection experiments for 500 m and 2500 m targets are carried out with built imaging detection system. The results show that, utilizing imaging detection method and target recognition algorithm, the false alarm probability is 0.3×10-12 and the detection probability is one in the detection distance of 2500 m, which eliminates the effect of background and noise in target recognition process..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 811003 (2013)
Efficient Segmentation of SAR Images Using Markov Random Field Models with Edge Penalties and an Adaptive Weighting Parameter
He Feiyue, Tian Zheng, Fu Huijing, and Yan Weidong
An efficient synthetic aperture radar (SAR) image segmentation approach using a Markov random field (MRF) model with edge penalties and an adaptive weighting parameter is proposed. The edge penalty and the adaptive weighting parameter are introduced into the energy function of MRF segmentation model. As a result, the eAn efficient synthetic aperture radar (SAR) image segmentation approach using a Markov random field (MRF) model with edge penalties and an adaptive weighting parameter is proposed. The edge penalty and the adaptive weighting parameter are introduced into the energy function of MRF segmentation model. As a result, the edge fuzzy is reduced with the introduction of edge penalty. The adaptive weighting parameter can adjust adaptively the weights of the data modeling factor in the energy function according to the stages of iteration and the heterogeneity of local scenes, which is in favor to get smoother results for homogeneous regions and preserve edges and important image details for heterogeneous regions. An efficient optimization algorithm called heterogeneous point tracking algorithm is presented in terms of the characteristics of the energy function. Experiments with simulated data and real SAR images show that the proposed algorithm improves the segmentation accuracy and reduces the running time..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 811004 (2013)
Telescope Primary Mirror Seeing and Air Knife Effect Analysis Based on Theoretical Calculation of Temperature Field
Zhang Jun, Xian Hao, Zhang Cheng, Tang Jinlong, and Li Cheng
The theoretical model in temperature field based on primary mirror of ground based telescope with the condition of non-linear ambient temperature and forced air flow upon the optical surface is analyzed. The analytical solution is gotten by separation of variables and Green function method. Take 4-m primary mirror as aThe theoretical model in temperature field based on primary mirror of ground based telescope with the condition of non-linear ambient temperature and forced air flow upon the optical surface is analyzed. The analytical solution is gotten by separation of variables and Green function method. Take 4-m primary mirror as an example, the value of mirror seeing is caculated and anylised by using analytical solution of temperature field theory model. The effect of air flow upon the primany mirror seeing is discussed. The relationship between mirror seeing and air flow velocity upon the primary mirror is studied. Primary mirror seeing is analyzed with different ratios of mirror′s diameter to thickness. The temperature field of primary mirror of 4-m diameter is also studied by finite element method. The analytical solution is highly consistent with the solution of finite element method. The analytical solution of temperature field model has universal application value in designing telescope primary mirror..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 811005 (2013)
Image Restoration for Catadioptric Defocus Blur Based on Omni-Total Variation Minimization
Li Yongle, Lou Jingtao, Zhang Maojun, Wang Wei, and Xiong Zhihui
Combined with the characteristics of catadioptric omnidirectional imaging, the method of image restoration for catadioptric defocus blur based on omni-total variation minimization is proposed. The problem of catadioptric omnidirectional imaging defocus blur, which is caused by lens aperture and mirror curvature, becomeCombined with the characteristics of catadioptric omnidirectional imaging, the method of image restoration for catadioptric defocus blur based on omni-total variation minimization is proposed. The problem of catadioptric omnidirectional imaging defocus blur, which is caused by lens aperture and mirror curvature, becomes more severe when high resolution sensors and large apertures are applied. In the catadioptric omnidirectional image, the two points near each other do not have the relation in true scene. So the traditional gradient computation cannot fit catadioptric omnidirectional image processing. The omni-gradient computing method combined with the characteristics of omnidirectional imaging is proposed. Then, the omni-total variation minimization is used as the condition of deconvolution regularization, which is used for the defocus blur omnidirectional image restoration to obtain all sharp omnidirectional images..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 811006 (2013)
Instrumentation, Measurement and Metrology
Interpolation Error Correction of Moiré Fringe Photoelectric Signals in the Approximate Form of Triangle Wave
Feng Yingqiao, Wan Qiuhua, Sun Ying, Yang Shouwang, and Zhao Changhai
To improve the precision of small photoelectric encoders, a lot of research is conducted on the interpolation error correction method of moiré fringe photoelectric signals. A parameter equation of single channel signal waveform is built firstly, and then Fourier transform is performed on sampled signals to get theTo improve the precision of small photoelectric encoders, a lot of research is conducted on the interpolation error correction method of moiré fringe photoelectric signals. A parameter equation of single channel signal waveform is built firstly, and then Fourier transform is performed on sampled signals to get the waveform parameters. The high spatial harmonics in the signal waveform are transformed into higher order components using the multiple angle formula, and photoelectric signals are corrected to standard sine and cosine ones using the Newton iteration method. After that, a phase error correction model of the sine and cosine signals is built, phase error correction parameters are then solved using the least squares fitting method, and finally the phase error correction of the photoelectric signals are realized. The interpolation error correction of a 16-bit small photoelectrical encoder is carried out. The result demonstrates that, it can effectively reduce interpolation error and improve the precision, which is important in the development of small and high-precision photoelectrical encoders..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 812001 (2013)
Filter Optimization Design for Photoelectric Integral Light Source Color Illumination Instrument
Yuan Kun, Yan Huimin, Jin Shangzhong, and Wang Cong
Filter optimization design method of photoelectric integral light source color illumination instruments is introduced. The design error is caused by the beam oblique incidence which leads to the filter spectral transmittance different from that under of normal incidence. The diffuse incident colored glass transmittanceFilter optimization design method of photoelectric integral light source color illumination instruments is introduced. The design error is caused by the beam oblique incidence which leads to the filter spectral transmittance different from that under of normal incidence. The diffuse incident colored glass transmittance correction model is established. The model is applied to the color illuminance measurement instrument design. Experiments are designed to verify the matching results, and the experimental results demonstrate that the correction model reduces the design error effectively..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 812002 (2013)
Point Cloud Data Processing Method of Cavity 3D Laser Scanner
Chen Kai, Zhang Da, and Zhang Yuansheng
The traditional cavity monitoring measures have many shortcomings, including of obtaining little of data, being difficult to monitor the unmanned cavity, and not calculating the volume of the cavity accurately. The three-dimensional (3D) laser scanner for cavity can scan the cavity to obtain the 3D point cloud data effThe traditional cavity monitoring measures have many shortcomings, including of obtaining little of data, being difficult to monitor the unmanned cavity, and not calculating the volume of the cavity accurately. The three-dimensional (3D) laser scanner for cavity can scan the cavity to obtain the 3D point cloud data effectively and roundly, but it is trouble to use these point clouds which will exist a lot of noise that is formed by the dusty, moisture and the 3D laser scanner, and the first point cloud and the second point cloud will be misaligned because the ground may have the emergence of deformation. To solve these problems, this paper puts forward the point cloud denoising algorithm based on KD Tree and registration algorithm based on characteristics of point cloud. The experiments show that these algorithms are effective to remove the noise in the point cloud and realize the registration of point cloud, the point cloud will provide the data basic for mine to use in the future..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 812003 (2013)
Research on System Level Calibration Method of Multi-Band Filter Radiometer
Zhang Yanna, Zheng Xiaobing, Li Jianjun, and Zhang Wei
To meet the requirement of high-precision radiation calibration for remote sensor and to achieve the radiance transfer chain “cryogenic radiometer→ multi-band filter radiometer→ integrating sphere → remote sensor”, a calibration method of multi-band filter radiometer is developed. In this method, the uniform, stable anTo meet the requirement of high-precision radiation calibration for remote sensor and to achieve the radiance transfer chain “cryogenic radiometer→ multi-band filter radiometer→ integrating sphere → remote sensor”, a calibration method of multi-band filter radiometer is developed. In this method, the uniform, stable and unpolarized surface source is acquired from the tunable laser-illuminated integrating sphere, and the standard radiance detector that is traced from the cryogenic absolute radiometer is used as transferring standard, and the absolute spectral radiance responsibility of a multi-band filter radiometer is obtained at 753, 865, 900 and 1030 nm by the system level calibration, and the calibration uncertainty is below 0.58%. The multi-band filter radiometer and the solar radiometer CIMEL CE318 which is traced from blackbody radiation in France are used to measure radiance of integrating sphere respectively, and the results show that the differences of the four calibration bands are -0.216%, -2.564%, -4.248% and 2.226%, which validate the rationality of the calibration method..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 812004 (2013)
Research on Dual-Channel Detection Technology of Bio-Aerosols with Intrinsic Fluorescence Measurement
Xu Ao, Xiong Chao, Zhang Pei, Liao Xiaoqing, Yang Wei, Zhao Yongkai, and Huang Huijie
Real-time detection of bio-aerosol has become the focus of research in recent years. Based on the existing technology, the dual-channel bio-aerosol detection method which includes 280 nm and 365 nm channel is developed. With the dual-channel bio-aerosol detection system, the intrinsic fluorescence spectra and intensityReal-time detection of bio-aerosol has become the focus of research in recent years. Based on the existing technology, the dual-channel bio-aerosol detection method which includes 280 nm and 365 nm channel is developed. With the dual-channel bio-aerosol detection system, the intrinsic fluorescence spectra and intensity of tryptophan and nicotinamide adenine dinucleotide (NADH) are detected respectively by deploying the ultraviolet source at 280 nm and 365 nm. On the basis of the result, the calibration method is determined, and then the analysis of bull serum albumin (BSA) and cigarette particles′ results are researched. The results demonstrate that it can improve the accuracy of particles pre-discrimination by using the dual-channel bio-aerosol detection technology. The technology has strong application value and development space..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 812005 (2013)
Lasers and Laser Optics
Study on Separate LCP from RCP Based on Multioscillator Ring Laser Gyroscope with Optical Signal Processing
Yu Wendong, Lü Wancheng, Chen Linfeng, Han Zonghu, and Li Long
In order to improve precision of multioscillator ring laser gyroscope (MRLG), the separation left-handed circular polarization (LCP) from right-handed circular polarization (RCP) based on MRLG with optical signal processing is studied both theoretically and experimentally. Considering that the polarizations of optical In order to improve precision of multioscillator ring laser gyroscope (MRLG), the separation left-handed circular polarization (LCP) from right-handed circular polarization (RCP) based on MRLG with optical signal processing is studied both theoretically and experimentally. Considering that the polarizations of optical modes which are exported from MRLG influence the separation LCP from RCP, mechanism of influence is analyzed. After the separation, defining the signal-to-noise ratio（SNR） of the LCP or RCP, the value of the influence is derived. The higher of SNR, the smaller of the influence. Based on the study of theory and experimentation, the relationship between SNR and angle of sheet polarizer which is installed in the system of optical signle processing is presented. It is found that the SNR can be enhanced by adjusting the angle of sheet polarizer efficiently. A new method of separation LCP from RCP named “eliminating” is advanced by optimization installation of sheet polarizer. Compared with the earlier method named “extracting”, the new method is better than the earlier one. The result is proved both by theory and experiment..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 814001 (2013)
Residual Wavefront Aberration of High-Power Laser Facility
Guo Ailin, Zhu Haidong, Tang Shiwang, Xie Xinglong, and Zhu Jianqiang
The core of adaptive optics wavefront control of the high-power laser facility is to pre-correct the dynamic wavefront aberration of the high-energy laser accurately. Based on the experimental data of closed-loop pre-correction and using the wavefront propagation model of the SG-II updated laser facility, the deviationThe core of adaptive optics wavefront control of the high-power laser facility is to pre-correct the dynamic wavefront aberration of the high-energy laser accurately. Based on the experimental data of closed-loop pre-correction and using the wavefront propagation model of the SG-II updated laser facility, the deviation of the pre-corrected dynamic wavefront aberration is calculated, and the more accurate deformed-shape of the deformable mirror is obtained. Then using the deformable mirror control algorithm that based on the phase correction at the actuator position to correct the driving voltage of the deformable mirror, so that the accuracy of the pre-corrected dynamic wavefront aberration is improved, and the residual wavefront aberration of the output high-energy laser shot is reduced. Comparing with the traditional technology that based on the closed-loop pre-correction of the dynamic wavefront aberration, this technology has a better control effect in the SG-II updated laser facility, so that the high-energy laser beam can pass through the filtering hole smoothly, the safety of the laser facility is ensured, the wavefront quality of the output laser is improved obviously, and the success rate of the high-energy laser emission experiment is increased..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 814002 (2013)
Influence of Transmitting Fiber Length on SBS Threshold of Continuous-Wave Single-Frequency All Fiber Amplifier
Hao Liyun, Qi Yunfeng, Su Cen, Liu Chi, and Zhou Jun
Stimulated Brillouin scattering (SBS) is an important factor that affects the increase of output power of single-frequency fiber amplifier. The impactions of length of transmitting fiber on the SBS threshold power of continuous-wave single-frequency all fiber amplifier are experimentally studied. Two stage continuous-wStimulated Brillouin scattering (SBS) is an important factor that affects the increase of output power of single-frequency fiber amplifier. The impactions of length of transmitting fiber on the SBS threshold power of continuous-wave single-frequency all fiber amplifier are experimentally studied. Two stage continuous-wave all fiber amplifier is set up with the seed line-width of 2.35 kHz. By changing the length of the transmitting fiber between the gain fiber and the output isolator, the power feedback and spectral feedback of amplifier as a function of output power are measured, and the impactions of the length of transmitting on SBS characteristics of all fiber single-frequency laser are analyzed. The experimental results match very well with the theoretically calculated results..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 814003 (2013)
Machine Vision
3D Point Cloud Simplification Algorithm Based on Fuzzy Entropy Iteration
Chen Zhangwen, and Da Feipeng
A novel algorithm based on fuzzy entropy iteration is proposed to simplify point cloud data. Better detail features of the streamlined point cloud model are retained while the algorithm′s operating efficiency is improved. To retain the boundary characteristics, X-Y boundary of all point cloud data is extracted quickly.A novel algorithm based on fuzzy entropy iteration is proposed to simplify point cloud data. Better detail features of the streamlined point cloud model are retained while the algorithm′s operating efficiency is improved. To retain the boundary characteristics, X-Y boundary of all point cloud data is extracted quickly. Curvature of each data point is calculated. Data points except boundary points are grouped according to the curvatures. Then the number of data points and the average of the curvatures in each group are computed. Fuzzy sets of point cloud model are constructed according to the curvatures. Then the minimum fuzzy entropy is calculated to obtain the curvature threshold, so that the data points can be divided best. The data points are diluted when their curvatures are less than the threshold. The dilution ratio depends on the iteration number. When satisfying the requirements of number, the data points are processed when their curvatures are bigger than the threshold. In this iteration process, new minimum fuzzy entropy and new curvature threshold are obtained. If not satisfying the requirements of number, the data points whose curvatures are bigger than the threshold are retained. The experimental results show that the proposed algorithm approximates the point cloud model and has a satisfactory computing efficiency..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 815001 (2013)
Materials
Influence of Temperature on the Transition of Stark Sublevels of Er3+ Doped ZBLAN Glass
Feng Zhijun, Zhang Xiaosong, Zhou Yongliang, Ling Zhi, Li Mengzhen, Sun Jian, and Li Lan
Er3+-doped 53ZrF4-20BaF2-4LaF3-3AlF3-20NaF-2.4PbF2 (ZBLAN) fluoride transparent glasses are prepared by the melt quenching method. The fluorescence spectra are measured for the transition of Er3+ Stark sublevels 4S3/2(1)→4I15/2 and 4S3/2(2)→4I15/2 (λ1=542 nm, λ2=548 nm) with in the temperature range of 10 K~540 K. The Er3+-doped 53ZrF4-20BaF2-4LaF3-3AlF3-20NaF-2.4PbF2 (ZBLAN) fluoride transparent glasses are prepared by the melt quenching method. The fluorescence spectra are measured for the transition of Er3+ Stark sublevels 4S3/2(1)→4I15/2 and 4S3/2(2)→4I15/2 (λ1=542 nm, λ2=548 nm) with in the temperature range of 10 K~540 K. The results show a rapid decrease in emission intensity and an obvious difference in decay rate with the temperature increase. According to the configurational coordinate, the mechanism is proposed to involve the difference of thermal quenching rate from the fitted activation energy (ΔE) of 0.078 eV and 0.049 eV for two sublevels of 4S3/2(1) and 4S3/2(2), respectively. The calculated fluorescence intensity ratio (FIR), which is corresponding to the transition of Er3+ stark sublevels 4S3/2(1)→4I15/2 and 4S3/2(2)→4I15/2, shows a linearly increase with temperature rise and then tends to flatten at high temperature region. The temperature sensitivity of sample is obtained for the maximum value of 0.0011 K-1 at the temperature of 90 K. The features in temperature sensitivity would be an application of optical temperature sensor..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 816001 (2013)
Synthesis and Luminescence Properties of Copolymer of Fluorene and Bithiophene
Wang Jin, Hai Jiefeng, Zhang Fujun, and Tang Weihua
A novel conductive polymer poly{2,7-(9,9-didodecyl-fluorene)-alt-[3,3′-p-di(dicyanide-vinylidene-phenyl)-bithiophene]}(PFC12Th-DCN) is synthesized by Suzuki cross-coupling reaction. The photoluminescence (PL) spectra, ultraviolet-visible absorption spectra and excited spectra of PFC12Th-DCN thin films are investigated A novel conductive polymer poly{2,7-(9,9-didodecyl-fluorene)-alt-[3,3′-p-di(dicyanide-vinylidene-phenyl)-bithiophene]}(PFC12Th-DCN) is synthesized by Suzuki cross-coupling reaction. The photoluminescence (PL) spectra, ultraviolet-visible absorption spectra and excited spectra of PFC12Th-DCN thin films are investigated in detail. The experimental results show that the conductive polymer has strong absorption from 300 nm to 450 nm and an absorption peak at 375 nm. Excited by 375 nm light, the PL spectrum of PFC12Th-DCN has a peak emission at about 625 nm, showing that it is an orange-yellow luminescent material. The electroluminescence (EL) device: ITO/PEDOTPSS/PFC12Th-DCN/Al is prepared. The turn-on voltage of the device is 5 V. The peak emission wavelength is about 649 nm and the chromaticity coordinate locates at (0.62, 0.36). Compared with its PL spectrum, the EL spectrum shows a red shift of about 25 nm. Based on the experimental results, the emission red shift is attributed to the PFC12Th-DCN molecules aggregation induced emission..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 816002 (2013)
Preparation and Photoluminescence Property of ZnWO4:Eu3+ Nanorods
Fan Ting, and Lü Jiantao
Monodisperse ZnWO4 and Eu3+-doped ZnWO4 nanorods are prepared via a simple hydrothermal method. The structure and morphology are characterized through X-ray diffraction pattern and transmission electron microscope. The nanorods are pure wolframite and Eu3+ ions completely enter into the lattice. The diameters of ZnWO4:Monodisperse ZnWO4 and Eu3+-doped ZnWO4 nanorods are prepared via a simple hydrothermal method. The structure and morphology are characterized through X-ray diffraction pattern and transmission electron microscope. The nanorods are pure wolframite and Eu3+ ions completely enter into the lattice. The diameters of ZnWO4:Eu3+ nanorods are about 20~40 nm and the lengths are about 50~70 nm. The excited and photoluminescence spectra of ZnWO4 and Eu3+-doped ZnWO4 nanorods indicate an energy transfer from WO2-4 groups to Eu3+ ions. Electric dipole transition 5D0-7F0 of Eu3+ ion is weak, while electric dipole transition 5D0-7F2 is very strong, which indicates that Eu3+ ions are in C2 symmetry points of the lattice..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 816003 (2013)
Effect of Red Shift in Rutile TiO2 Caused by Nonmetallic Impurity C, N, S Co-Doping
Tian Yun, Feng Qing, Din Shoubing, Liu Tong, Gao Jiemei, and Wu Fang
Recently, through nonmetallic impurity doping rutile TiO2 to change its optical properties and expand the application in the fields of photocatalysis and photoelectric conversion is a hot research topic. The electronic properties and optical properties of rutile TiO2 super cell with nonmetallic impurity doped (includinRecently, through nonmetallic impurity doping rutile TiO2 to change its optical properties and expand the application in the fields of photocatalysis and photoelectric conversion is a hot research topic. The electronic properties and optical properties of rutile TiO2 super cell with nonmetallic impurity doped (including C,N,S,C-N,C-S,N-S) are calculated by plane wave pseudopotential method based on the density functional theory, such as the band structure, density of states, dielectric constant, absorption spectroscopy and reflection spectroscopy, etc. Nonmetallic elements doping makes TiO2 band gap decrease, and the absorption spectrum and reflection spectra exhibit red shift. To a certain extent, nonmetallic impurity doping improves the TiO2 utilization of visible light, but visible light utilization rate of co-doped TiO2 is higher than that of single-doped TiO2. The research results show that in the visible light high energy area from 400 nm to 575 nm, C-doped rutile TiO2 performs much better than others in absorptivity and reflectivity. In the visible light low energy area from 575 nm to 760 nm, absorptivity and reflectivity of N-doped rutile TiO2 are much better than others. Therefore, the visible light utilization in C-N co-doped TiO2 is better than those of other nonmetallic doped systems..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 816004 (2013)
Medical Optics and Biotechnology
Measurement of Enamel Mineral Density by Optical Coherence Tomography
Li Jianghua, Huang Hai, Tang Zhilie, and Liu Songhao
The measurement on the mineral density (MD) of human tooth enamel with optical coherence tomography (OCT) is done, which is based on the linear relationship between the optical attenuation coefficient (OAC) and MD. Synthetic calcium hydroxyapatite discs (the key component of enamel) with different densities ranging froThe measurement on the mineral density (MD) of human tooth enamel with optical coherence tomography (OCT) is done, which is based on the linear relationship between the optical attenuation coefficient (OAC) and MD. Synthetic calcium hydroxyapatite discs (the key component of enamel) with different densities ranging from 1.28 g/cm3 to 1.9 g/cm3 are scanned with OCT, OACs are fitted from OCT images, and MD versus OAC curve as a calibration curve is developed; then the OACs within OCT images of human teeth are obtained; the MD is determined according to the calibration curve of OAC and MD. The MD of sound enamel is found to be 2.5~3.1 g/cm3, which is in agreement with literature values; while the MD of white spot lesions is around 2.0 g/cm3. This non-destructive method has the potential to be used in quantitative determination of demineralization and remineralization of enamel and clinic..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 817001 (2013)
Optical Design and Fabrication
Design of Wide Band and Large Relative Aperture Star Sensor Optical System with Asphere
Gong Dun, Tian Tieyin, and Wang Hong
The star sensor is composed of an optical system and a photoelectric sensor, and the former is the most important part. The star sensor optical system requires high imaging quality and good technical indexes, and its volume and weight are strictly limited, so that the corresponding optical design is difficult. In the pThe star sensor is composed of an optical system and a photoelectric sensor, and the former is the most important part. The star sensor optical system requires high imaging quality and good technical indexes, and its volume and weight are strictly limited, so that the corresponding optical design is difficult. In the premise of meeting volume requirements, the best system structure is selected, and the focal power is reasonably distributed to reduce distortion and high order aberration. At the same time, the system is made as a telecentric light path. Special dispersion glass is adopted to correct chromatic aberration of wide band range, and the asphere is adopted to improve imaging quality. The results show that the measured modulation transfer function (MTF) of each field is more than 0.344 (at Nquist frequency), the laboratory static MTF is more than 0.2 (at Nquist frequency), 80% of the imaging dispersion spot energy is focused inside 23 μm, and the relative distortion is less than 0.1%. The technical indexes and the imaging quality requirements are satisfied..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 822001 (2013)
Restraint of Mid-Spatial-Frequency Error Aspheric Surface by Small-Tool Adaptive Polishing
Zhang Jian, Dai Lei, Wang Fei, and Wang Lipeng
A method is proposed to restrain mid-spatial-frequency errors (MSFE) by iterative small tool polishing, which is based on the research of restraint methods of MSFE, as well as the characteristics of polishing tools for high-accuracy aspheres. An asphere with obvious MSFE after fine grinding is prepared for pre-polishinA method is proposed to restrain mid-spatial-frequency errors (MSFE) by iterative small tool polishing, which is based on the research of restraint methods of MSFE, as well as the characteristics of polishing tools for high-accuracy aspheres. An asphere with obvious MSFE after fine grinding is prepared for pre-polishing in order to remove sub-surface damage as well as to control the figure accuracy. Then the aspheric surface is corrected to higher accuracy by bonnet polishing method, which is followed by the restraint of MSFE in the surface using self-made dual-flexible adaptive polishing tool. The restraint of MSFE is not finished until Zernike residual does not converge through CGH testing. An asphere with a diameter of 150 mm and a maximum departure of 0.344 mm from best fit sphere are successfully polished through 3 runs.The form is improved to achieves 4.5 nm RMS from 76 nm RMS and Zernike residual converged from 22.72 nm RMS to 3.46 nm RMS. Results show that the proposed method is useful to realize fast and valid restraint of MSFE for aspheres..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 822002 (2013)
Optical Devices
Narrow Bandpass Angular Filter Based on Anisotropic Photonic Band Gap
Liu Yanhong, Dong Lijuan, Liu Lixiang, and Shi Yunlong
A narrow bandpass optical angular filter is proposed based on the band gaps of one-dimensional aniosotropic photonic crystal. The angle photonic band gap structures and the angle defect modes of doped anisotropic stuctures are caculated by the electromagnetic finite element method. Numerical simulations show that thereA narrow bandpass optical angular filter is proposed based on the band gaps of one-dimensional aniosotropic photonic crystal. The angle photonic band gap structures and the angle defect modes of doped anisotropic stuctures are caculated by the electromagnetic finite element method. Numerical simulations show that there is a strong correlation between the photonic band gap and the incident angle, as well as the defect modes are tunable based on the incident angles. Unique properties of this systems emerging from doped anisotropic strucstures can realize a narrow band angle filtering which can be used as a good optical device in the future..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 823001 (2013)
Global Dimming Algorithm Based on Image Classification
He Huijie, Feng Qibin, Zhang Lei, Zhang Xitiao, and Lü Guoqiang
To tackle the problems of low power efficiency and low contrast of liquid crystal display, a global dimming algorithm based on image classification is proposed. As brightness and contrast are two important display parameters, the paper takes use of these two parameters to classify the input images. Backlight dimming leTo tackle the problems of low power efficiency and low contrast of liquid crystal display, a global dimming algorithm based on image classification is proposed. As brightness and contrast are two important display parameters, the paper takes use of these two parameters to classify the input images. Backlight dimming level is determined by image category, the average luminance and the difference between the average and maximum grayscales of all subpixels. The S-shaped curve is generated based on the characteristic value and the image category of input image to compensate liquid crystal pixels. For 60 images, the simulation results show that the average backlight power consumption is reduced by 19% and the static contrast ratio is improved by 143%. The prototype is developed based on the dimming algorithm. Compared with the LCD TV without applying the dimming algorithm, the practical results show that the average power consumption is reduced by 12.9% and the static contrast ratio is improved by 43.18%..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 823002 (2013)
Designment of a Novel Optical Streak Camera with Ultrahigh Temporal Resolution
Wei Huiyue, Xu Tao, Wang Feng, Peng Xiaoshi, Wei Xin, and Liu Shenye
For more precise measurements of the temporal evolution of plasma in the study of inertial confinement fusion (ICF), a novel optical streak camera with ultrahigh temporal resolution is proposed. Based on the photo-generated carrier effects, waveguide transmission and prism dispersion principle, this all-optical device For more precise measurements of the temporal evolution of plasma in the study of inertial confinement fusion (ICF), a novel optical streak camera with ultrahigh temporal resolution is proposed. Based on the photo-generated carrier effects, waveguide transmission and prism dispersion principle, this all-optical device can avoid the influence of the space charge effect. Then the key component in the camera, the optical scanning module, is designed and simulated through an emulator aiming at 1 ps time resolution capability. Results show that this module can deflect the signal light and transform the information it contains from time domain into space domain, which verifies the feasibility of such system and its benefits for the following experiments..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 823003 (2013)
Study on All-Inorganic Light Emitting Devices Based on ZnO Nanorods with Modification of SiO2
Ge Lin, Xu Jianping, Zhang Xiaosong, Luo Chengyuan, Wang Lishi, Li Mengzhen, Ren Zhirui, Chen Yipeng, Wang Youwei, Shi Qingliang, Zhu Mingxue, and Li Lan
ZnO nanorods are synthesised by the chemical solution method on indium tin oxide (ITO) substrate. The all-inorganic light emitting devices, with the structure of ITO/ZnO/ZnO nanorods/SiO2/Al, are obtained with various amount of SiO2 by different spin-coating speeds. According to energy dispersive spectrum (EDS) and absZnO nanorods are synthesised by the chemical solution method on indium tin oxide (ITO) substrate. The all-inorganic light emitting devices, with the structure of ITO/ZnO/ZnO nanorods/SiO2/Al, are obtained with various amount of SiO2 by different spin-coating speeds. According to energy dispersive spectrum (EDS) and absorption spectrum, the modification amount of SiO2 shows a gradual increase when the casting speed is reduced from 3000 r/min to 500 r/min. The electroluminescent (EL) spectra of devices, influenced by the casting speed, are measured and compared. For each spin coating speed, the EL intensity of devices shows obvious enhancement in the ultraviolet (UV) range with the applied voltage increasing ,whick is weakened simultaneously in visible region. The luminescent intensity in UV range enhances obviously when the casting speed increases to 1000 r/min and then declines gradually. At the same time, the visible emission disappears. The I-V curves reveal that the additional SiO2 modification drives up the turn-on voltage of the device monotonically and leads to a decline of maximum operating current. The discussion based on photolumine-scence (PL) spectra and the energy level diagram suggests that, besides surface passivation of ZnO nanorods by SiO2, the high barrier between ZnO and SiO2 induces electron accumulation and suppresses non-radiative recombination at ZnO layer. And the SiO2 on the surface of ZnO nanorods helps to improve the electron density and then the recombination rate at the higher levels of ZnO..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 823004 (2013)
Thermal Analysis for LED Chip on Board Package Based on Plastic Radiator without Substrate
Chen Yingcong, Wen Shangsheng, and Wu Yuxiang
A novel method of LED chip on board (COB) package based on plastic radiator without substrate is proposed. The thermal properties of tradition COB package and this new structure are simulated by using finite element analysis software Ansys. The simulation results show that, by mounting the LED chips on the plastic radiA novel method of LED chip on board (COB) package based on plastic radiator without substrate is proposed. The thermal properties of tradition COB package and this new structure are simulated by using finite element analysis software Ansys. The simulation results show that, by mounting the LED chips on the plastic radiator with thermal conductivity of 20 W/(m·K), the method of LED COB package can provide a much lower temperature than the metal substrate COB package, and is similar to the ceramic substrate COB package. By further simulations, it is found that the thermal resistance is the minimum when the thickness of the plastic radiator is 3.9 mm. Moreover, with the thermal conductivity and the convection coefficient increasing, the thermal resistance reduces in different degrees. Because of the easy preparation process and colorful luster of the plastic, this new method of LED COB package has a broad application prospect..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 823005 (2013)
Physical Optics
Refractive Index Compensation to Fix the Error of Electromagnetic Field Simulation by Boundary Element Method
Shu Fangjie, Hu Pinglin, and Li Jiancong
The boundary element method is a highly efficient algorithm for numerical solution of partial differential equations, which is widely used in solving electromagnetic field problems in micro- and nano-optics. The complex resonance frequency of circular cavity with different numbers of boundary elements is obtained, and The boundary element method is a highly efficient algorithm for numerical solution of partial differential equations, which is widely used in solving electromagnetic field problems in micro- and nano-optics. The complex resonance frequency of circular cavity with different numbers of boundary elements is obtained, and its error is discussed. Major error can be regarded as absorption or amplification of electromagnetic waves by microcavity, which is concluded from the analysis of the quality factor. Then refractive index compensation method for fixing the error introduced by discrete process of boundary integral equation is proposed. The accuracy of the boundary element method is improved at least an order of magnitude after the amendment. Moreover, the correction amount obtained by a center frequency is valid, when it is used in a wide range of frequency around the central frequency. Therefore, the refractive index compensation method makes the calculation accurate and the computing speed significantly improved, the time and memory consumption sharply dropped. At the same time, correcting the simulation error from the physical point of view can be extended to other numerical methods..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 826001 (2013)
Visualization of Polarization State and Its Imaging Method
Tang Peijun, Chen Feihu, and Tang Zhilie
A new polarization imaging method, based on polarization state, is developed to obtain the spatial distribution of polarization state of object. A measurable physical quantity, called polarized-chromatic value, is introduced to describe the polarization state. The Stokes parameters employed to describe the polarizationA new polarization imaging method, based on polarization state, is developed to obtain the spatial distribution of polarization state of object. A measurable physical quantity, called polarized-chromatic value, is introduced to describe the polarization state. The Stokes parameters employed to describe the polarization state are converted to three basic colors RGB, then the chromatic value of the RGB is used to describe the polarization state, therefore there is a one-to-one relationship between the polarized-chromatic value and the polarization state, and the polarized-chromatic value and the pixels. On this basis, the Stokes parameters measurement method is used for object point measurement to obtain the spatial distribution of Stokes parameters of the object. Then through the distribution of polarized-chromatic value, space distribution of the polarization state of the object is characterized, and thus the polarization imaging is realized. The experimental results show that the polarizaion state imaging method not only can measure the distribution of the stress size, but also measure the distribution of the stress direction..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 826002 (2013)
Quantum Optics
General Non-Markov Effect of Open Cavity System Coupled to a Reservoir
Liu Zhiquan, Yan Kezhu, and Wang Jisuo
Non-Markov dynamics for open systems of a microcavity coupled to a general resonator with Lorentzian form are studied. Using the exact master equation of the reduced density operator, the propagating (retarded) Green function and correlation Green function which the non-Markov dynamics are completely determined by are Non-Markov dynamics for open systems of a microcavity coupled to a general resonator with Lorentzian form are studied. Using the exact master equation of the reduced density operator, the propagating (retarded) Green function and correlation Green function which the non-Markov dynamics are completely determined by are solved analytically. The state and dissipation dynamics of the cavity are studied by numerically solving the Green function, and the evolution of them with time under different half-widths of the spectral density and detuning is discussed. It shows that the stronger the coherence is, the longer time of the non-Markov effect becomes..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 827001 (2013)
Remote Sensing and Sensors
Destriping of Remote Sensing Images with Applications to Push-Broom-Type Cameras
Guo Lingling, Wu Zepeng, Zhang Liguo, Zhang Xingxiang, and Ren Jianyue
Stripe noise is common to most push-broom-type imagers and it perturbs both image quality analysis and the posterior processing. Based on the analysis of the the characteristics of the stripe noise, a new destriping method is proposed. By taking a quasi-homogeneous region as a reference, ideal data of the striped area Stripe noise is common to most push-broom-type imagers and it perturbs both image quality analysis and the posterior processing. Based on the analysis of the the characteristics of the stripe noise, a new destriping method is proposed. By taking a quasi-homogeneous region as a reference, ideal data of the striped area can be estimated and be used to compute correction parameters. The cross-track edge information is extracted and processed using morphological techniques. Experiments carried out on real remote sensing data demonstrate that the proposed method can bring peak signal-to-noise ratio from 32 dB up to 48 dB. Compared to the existing typical algorithms, this destriping method can achieve lower image distortion, higher inverse coefficient of variation and peak signal-to-noise ratio. By reducing stripe noise and reserving useful details, the image quality is improved effectively..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 828001 (2013)
Modified Linear-Prediction Based Band Selection for Hyperspectral Image
Zhou Yang, Li Xiaorun, and Zhao Liaoying
Band selection can greatly increase the efficiency of classification and unmixing of hyperspectral image. Two modified linear-prediction (LP) band selection methods based on similarity are proposed, which measure the information amount of bands through Skewness or Kurtosis and measure the similarity of bands through muBand selection can greatly increase the efficiency of classification and unmixing of hyperspectral image. Two modified linear-prediction (LP) band selection methods based on similarity are proposed, which measure the information amount of bands through Skewness or Kurtosis and measure the similarity of bands through mutual information (MI) or K-L (Kullback-Leibler) divergence. The least similar two bands with large information amount are selected as the initial two bands, and the rest bands are selected by modified linear prediction. However, the existence of noise bands will affect the result of band selection, making the accuracy of classification or unmixing lower than expected. In order to weaken the adverse effect of noise bands, further efforts are made to estimate the noise of every band through wavelet entropy and remove the bands with considerable noise before band selection. The experiments of classification and unmixing after band selection for real hyperspectral images indicate that linear prediction based band selection can greatly increase the accuracy and efficiency of classification and unmixing , and it is an effective dimensionality reduction method for hyperspectral image..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 828002 (2013)
Methods to Simultaneously Achieve Radiometric and Polarimetric Accuracy for Multichannel Ultra-Wide-Angle Polarimetric Camera
Qiu Zhenwei, Hong Jin, Li Shuang, and Sun Liang
Multichannel ultra-wide-angle polarimetric camera is a fine solution for polarimetric remote sensing by achieving multispectral, multiangle, and polarimetric information in target detection. By analyzing the optical system of Directional Polarimetric Camera, which belongs to this type, it is shown that the different asMultichannel ultra-wide-angle polarimetric camera is a fine solution for polarimetric remote sensing by achieving multispectral, multiangle, and polarimetric information in target detection. By analyzing the optical system of Directional Polarimetric Camera, which belongs to this type, it is shown that the different aspects of the polarization properties of ultra-wide-angle lens (linear diattenuation and retardance) bring different effects on radiometric and polarimetric accuracies so that they can hardly be satisfied simultaneously. Based on the original design of Directional Polarimetric Camera, a method, which includes improved lens design, better optical coating design and modified polarimetric calibration is developed, to satisfy the accuracy specifications. After comparison between these two designs, the result shows that the improved method reduces the above so-called difference effectively. The method can work as a reference for accuracy design of other multichannel ultra-wide-angle polarimetric cameras..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 828003 (2013)
Scattering
Impact of Different Mixing Ways of Black Carbon and Non-Absorbing Aerosols on the Optical Properties
Zhou Chen, Zhang Hua, and Wang Zhili
In order to study the impact of mixing ways of aerosols on their optical properties, one typical external mixing model plus three different internal mixing models of aerosols are introduced. The optical properties of mixed aerosol particles formed by black carbon, sulfate and organic carbon at 550 nm wavelength are calIn order to study the impact of mixing ways of aerosols on their optical properties, one typical external mixing model plus three different internal mixing models of aerosols are introduced. The optical properties of mixed aerosol particles formed by black carbon, sulfate and organic carbon at 550 nm wavelength are calculated. The results show that there are great differences in optical properties of mixing particles and particle groups obtained by these models except Maxwell-Garnett model and Bruggeman model (difference less than 2%). Compared with externally mixed particle groups, the mass absorption factors of internally mixed particle groups are increased by about 20%, while the mass scattering factors of the particle groups are decreased by 10%~15% in most cases. The internal mixing models make a large enhancement of the mass extinction factors of mixed particle groups by 25% for maximum. Furthermore, the reduction of single scattering albedo is significant. In particular, the reduction of the scattering albedo of the mixed particle groups can be larger than 20% under circumstances that the volume ratio of black carbon is below 30% and the relative humidity is above 70%. In addition, optical properties of mixed particles, except the asymmetry parameter, are distinctly related to the change of volume ratio or relative humidity..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 829001 (2013)
Confirm of Scattering Direction and Comparison of Two Modes in Monte Carlo Photons Tracking
Du Yongcheng, and Yang Li
A method is designed for acquiring the explicit cumulative probability distribution function (CPDF) based on curve fitting with a user defined function. By comparing and analyzing the efficiencies of two photons tracking modes named event method and weight method respectively, the relationship between sample size and cA method is designed for acquiring the explicit cumulative probability distribution function (CPDF) based on curve fitting with a user defined function. By comparing and analyzing the efficiencies of two photons tracking modes named event method and weight method respectively, the relationship between sample size and calculation time in the two modes is found to be linear. The calculation speed of event method is faster than that of weight method, but the convergence of weight method is better than that of event method obviously. To achieve the same convergence standard, the sample size of weight method required can even be 1~2 orders of magnitudes less than that of event method. The influence of threshold value on the calculation accuracy and time of weight method always happens when the threshold value is larger than one spercent of the computing object, and generally speaking, the calculation efficiencies of weight method are better than that of event method..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 829002 (2013)
Spectroscopy
Experimental Study of the Photochemical Reaction in the Smog Chamber Using a Chernin Multipass Cell
Cheng Yue, Zhao Weixiong, Hu Changjin, Gu Xuejun, Pei Shixin, Huang Wei, and Zhang Weijun
A Chernin multipass absorption spectroscopy system is combined with the photochemical simulation smog chamber and applied to the detection of trace gases in the smog chamber. The system accuracy and reliability are proved with NO2 detection. The NO2 measurements of the system and the results of Thermo 42i NO-NO2-NOx anA Chernin multipass absorption spectroscopy system is combined with the photochemical simulation smog chamber and applied to the detection of trace gases in the smog chamber. The system accuracy and reliability are proved with NO2 detection. The NO2 measurements of the system and the results of Thermo 42i NO-NO2-NOx analyzer have a good linear relationship. The system is applied to online detection of SO2 during β-pinene/O3/SO2 system chemical reaction in the smog chamber and with 36 m absorption path length, the SO2 detection limit of the system is 22.2×10-9. The result demonstrates that the Chernin multipass absorption spectroscopy system has the capability of quantitative measurement and can be used in online detection of trace gases during photochemical reactions in the smog chamber..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 830001 (2013)
Plasma Emission Spectra During Laser Dressing of Bronze-Bonded Diamond Wheel
Deng Hui, Chen Genyu, Zhang Ling, Xu Jianbo, and Zhou Xingcai
The spatial evolution of the plasma emission spectra in the wavelength range of 490~600 nm during pulsed fiber laser dressing of bronze-bonded diamond grinding wheel under different laser conditions are studied. Under the assumption of local thermodynamic equilibrium, the electron temperature is determined from the BolThe spatial evolution of the plasma emission spectra in the wavelength range of 490~600 nm during pulsed fiber laser dressing of bronze-bonded diamond grinding wheel under different laser conditions are studied. Under the assumption of local thermodynamic equilibrium, the electron temperature is determined from the Boltzmann plot method whereas the electron number density is calculated from the Stark broadened profiles according to the experimentally observed line profiles of neutral copper. Besides, the variations of the electron temperature and the electron number density as a function of the single-pulse laser energy at different distances along the direction of propagation of the plasma are studied. The results show that the electron temperature and density take on the Lorentz distribution as the distances increases, and they increase exponentially as the single-pulse laser energy increases. In addition, the behavior of the inverse bremsstrahlung absorption coefficient with the detecting distance and the single-pulse laser energy is also discussed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 830002 (2013)
Multiple Beam Interferential Spectral Imaging Technology
Du Shusong, Wang Yongmei, and Tao Ran
Fabry-Perot (F-P) interferometer is a kind of multiple beam interferometer. It has very high spectral resolution, and can be used to research fine structure of the matter. The application of F-P interferometer is limited by the free spectral range. The fine structure of the matter will not be got when the bandwidth of Fabry-Perot (F-P) interferometer is a kind of multiple beam interferometer. It has very high spectral resolution, and can be used to research fine structure of the matter. The application of F-P interferometer is limited by the free spectral range. The fine structure of the matter will not be got when the bandwidth of the light surpass the free spectral range. Based on the F-P interferometer, we describe the relationship between the interference pattern and the spectral curve as equation sequence. The equation sequence is solved by the singular value decomposition, and the wide bandwidth spectral curve will be got. By this way F-P interferometer can be used as a spectral imaging instrument. But the algorithm is sensitivity to the noise of the interference pattern. After some simulation work, we find the noise of the interference pattern should be less than 0.2%..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 830003 (2013)
Thin Films
Diffractive Characteristics of Optically Transparent Frequency Selective Surface
Yu Miao, Gao Jinsong, and Xu Nianxi
Optically transparent frequency selective surface (FSS) is designed on metallic mesh. When it is loaded on the optical window of combined guidance radome, the diffractive effect to infrared will interfere with the quality of imaging system. For reducing the interference in the design procedure of optically transparent Optically transparent frequency selective surface (FSS) is designed on metallic mesh. When it is loaded on the optical window of combined guidance radome, the diffractive effect to infrared will interfere with the quality of imaging system. For reducing the interference in the design procedure of optically transparent FSS, this paper specifically studies the influence of structural parameters of optically transparent FSS on the diffractive characteristics based on Fraunhofer diffractive theory. It is found that when the period of metallic mesh increases or the line width decreases, the intensity of diffractive light increases but distribution remains constant and the period has more notable influence on intensity. As the slit width and length of cross FSS unit increase separately, the diffractive light has rising intensity and unchanged distribution. Moreover, when the wavelength of incident light increases, the integral transmittance of optically transparent FSS increases. These show a good agreement with experimental results. The analysis mentioned above will have an important guiding significance in the process of designing optically transparent FSS..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 831001 (2013)
Slow Light Phenomenon and Its Theory in Thin Film Media
Lü Yi, Wu Jiuhui, and Li Lili
Aiming at slow light phenomenon in the thin film, the mechanism of slow light and its influence factors are investigated. Because the thickness of the thin film is extremely small, an assumption that the component of the magnetic field in the thickness direction is independent of the thickness is proposed. Then the disAiming at slow light phenomenon in the thin film, the mechanism of slow light and its influence factors are investigated. Because the thickness of the thin film is extremely small, an assumption that the component of the magnetic field in the thickness direction is independent of the thickness is proposed. Then the dispersion relation in the thin film media is obtained. The expression of the group velocity of the light in the thin film media is deduced. Then the influences of the frequency of the light, the refractive index of the thin film media and the thickness of the thin film media on the group velocity are analyzed. The influence curves of the group velocity in the thin film media are acquired. The research shows that speed of the light in the thin film media can be greatly reduced by selecting the appropriate influence factors. It provides a theoretical basis for the slow light technology in thin film media..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 831002 (2013)
A Structure Design of the Amorphous Silicon Single-Junction Jhin-Film Solar Cells for Increasing Sunlight Absorption
Lu Huidong, Shen Hongjun, Li Lei, and Yan Wenjie
A kind of amorphous silicon(a-Si) thin film solar cell structure, which has an antireflection (AR) coating and a back reflector, is presented. The AR coating consists of four dielectric materials with refractive index from low to high. The back reflector consists of a triangle dielectric diffraction grating and a one-dA kind of amorphous silicon(a-Si) thin film solar cell structure, which has an antireflection (AR) coating and a back reflector, is presented. The AR coating consists of four dielectric materials with refractive index from low to high. The back reflector consists of a triangle dielectric diffraction grating and a one-dimensional photonic crystal structure. The parameters of the dielectric layers and the grating are optimized by rigorous coupled wave analysis and plane wave theory method. The reflection efficiency of the AR coating and back reflector with incident angle range of 0°～60° are calculated numerically. The results show that the AR coating has high transmission within the wavelength range of 300～750 nm and the back reflector has high reflection within the wavelength range of 600～750 nm. For the a-Si thin film solar cell with 700-nm-thick active layer, with incident wave of TM polarization and incident angle which is less than 75°, the solar cell has an average absorptance of 95% after optimizing in wavelength range of 300～750 nm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue 8, 831003 (2013)
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