Journals >Chinese Optics Letters
Contents
2007
Volume: 5 Issue 3
18 Article(s)
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Research Article
Effect of the reflection of underlying surface on sky radiance distribution
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Sky radiance might be influenced by the multiple reflectance between the earth's albedo surface and the atmosphere. Based on the Lambert's law and the radiative transfer equation (RTE), a model is developed to calculate the additional sky radiance at wavelengths of 0.4-3 microns due to the reflectance contributSky radiance might be influenced by the multiple reflectance between the earth's albedo surface and the atmosphere. Based on the Lambert's law and the radiative transfer equation (RTE), a model is developed to calculate the additional sky radiance at wavelengths of 0.4-3 microns due to the reflectance contribution of the underlying surface. The iterative method is used to calculate sky radiance without the reflectance from underlying surface. The hybrid modified delta-Eddington approximation is used to compute the atmospheric reflection of the radiation from the earth's surface. An interaction factor is introduced to deal with the multiple reflectance between the atmosphere and the underlying surface. The sky radiance increment is evaluated for some different albedos of the earth's surface. The results show that the sky radiance increment rises rapidly while viewing zenith angle is near to 90 deg., and the larger the albedo of the earth's surface is, the more obvious this effect appears..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 3, 125 (2007)
Reduction of interference fringes in absorption imaging of cold atom cloud using eigenface method
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Eigenface method used in face recognition is introduced to reduce the pattern of interference fringes appearing in the absorption image of cold rubidium atom cloud trapped by an atom chip. The standard method for processing the absorption image is proposed, and the origin of the interference fringes is analyzed. ComparEigenface method used in face recognition is introduced to reduce the pattern of interference fringes appearing in the absorption image of cold rubidium atom cloud trapped by an atom chip. The standard method for processing the absorption image is proposed, and the origin of the interference fringes is analyzed. Compared with the standard processing method which uses only one reference image, we take advantage of fifty reference images and reconstruct a new reference image which is more similar to the absorption image than all of the fifty original reference images. Then obvious reduction of interference fringes can be obtained..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 3, 128 (2007)
Characteristics of holey fibers fabricated at different drawing speeds
Faramarz E. Seraji, Mahnaz Rashidi, and Maryam Karimi
The effects of high drawing speeds on parameters of holey fibers are presented. A holey fiber preform structure was made by using tube-in-tube method and was drawn at high speeds with an aim of mass production to meet the demand of next generation communication systems. Transmission parameters such as numerical aperturThe effects of high drawing speeds on parameters of holey fibers are presented. A holey fiber preform structure was made by using tube-in-tube method and was drawn at high speeds with an aim of mass production to meet the demand of next generation communication systems. Transmission parameters such as numerical aperture and normalized frequency of the fabricated holey fibers have been measured and compared with theoretical values based on effective index method. Although the fabricated holey fibers were not of high quality, the analyses of the parameters have shown promising outlook for fabrication of such fibers..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 3, 131 (2007)
Multiplexed reflective-matched optical fiber grating interrogation technique
[in Chinese], [in Chinese], and [in Chinese]
The multiplexed-reflective matched fiber grating interrogation technique was presented in this paper. The interrogation technique was based on the use of two (or more) wavelength-matched fiber Bragg gratings (FBGs) to receive the reflected signal from the sensing FBG. The two (or more) matched gratings were arranged paThe multiplexed-reflective matched fiber grating interrogation technique was presented in this paper. The interrogation technique was based on the use of two (or more) wavelength-matched fiber Bragg gratings (FBGs) to receive the reflected signal from the sensing FBG. The two (or more) matched gratings were arranged parallelly and used as filters to convert wavelength into intensity encoded information for interrogation. Theoretical and experimental results demonstrated that the interrogation system is immune to the source fluctuation and cross-sensitivity effect between temperature and strain, and also can enlarge the dynamic range..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 3, 135 (2007)
Feature analysis of the scale factor variation on a constant rate biased ring laser gyro
[in Chinese], [in Chinese], and [in Chinese]
Scale factor of a constant rate biased ring laser gyro (RLG) is studied both theoretically and experimentally. By analyzing experimental data, we find that there are three main terms contributing to the scale factor deviation. One of them is independent of time, the second varies linearly with time and the third variesScale factor of a constant rate biased ring laser gyro (RLG) is studied both theoretically and experimentally. By analyzing experimental data, we find that there are three main terms contributing to the scale factor deviation. One of them is independent of time, the second varies linearly with time and the third varies exponentially with time. Theoretical analyses show that the first term is caused by experimental setup, the second and the third are caused by un-uniform thermal expension and cavity loss variation of the RLG..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 3, 138 (2007)
Recovery schemes for different distributed connection management in generalized multi-protocol label switching networks
[in Chinese], and [in Chinese]
As the wavelength division multiplexing (WDM) technology matures and the demands for bandwidth increase, survivability becomes more and more important in generalized multi-protocol label switching (GMPLS) controlled intelligent optical networks (IONs). There are great interests to study the performance of restorabilityAs the wavelength division multiplexing (WDM) technology matures and the demands for bandwidth increase, survivability becomes more and more important in generalized multi-protocol label switching (GMPLS) controlled intelligent optical networks (IONs). There are great interests to study the performance of restorability under one certain connection management strategy. And studies in the problem of providing recovery from link failures under two different resource reservation schemes, forward reservation protocols (FRPs) and backward reservation protocols (BRPs), are presented. They are examined from the point of view of connection blocking probability, restorability and average recovery time. The two different connection management schemes and the survey of different recovery schemes are first presented. The performance of these recovery strategies is analyzed and compared both through theoretical analysis and simulation results. The main stressed idea is that using BRPs gives the best performance in terms of restorability and blocking probability in restorable GMPLS networks..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 3, 142 (2007)
Analysis of eccentric photorefraction by Fourier optics
[in Chinese], and [in Chinese]
Eccentric photorefraction usually is used as early eyesight diagnostic test of infants and small children. Unlike currently approved geometrical optical model of eccentric photorefractometer, the crescent formation and the light-intensity distribution in the pupil image of a myopic eye are analyzed by Fourier optics wiEccentric photorefraction usually is used as early eyesight diagnostic test of infants and small children. Unlike currently approved geometrical optical model of eccentric photorefractometer, the crescent formation and the light-intensity distribution in the pupil image of a myopic eye are analyzed by Fourier optics with the assumption of an isotropic scattering retina. In the case of little circular light source and rectangular slit, the simulation results of different myopic diopters are obtained by geometrical optical theory and Fourier optics respectively. It is found that the simulation results by Fourier optics are similar as those obtained by geometrical optics, and all simulations are almost corresponding to the experimental result. The result demonstrates that the new method presented here is feasible..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 3, 146 (2007)
Fast regularized image interpolation method
[in Chinese], [in Chinese], and [in Chinese]
The regularized image interpolation method is widely used based on the vector interpolation model in which down-sampling matrix has very large dimension and needs large storage consumption and higher computation complexity. In this paper, a fast algorithm for image interpolation based on the tensor product of matrices The regularized image interpolation method is widely used based on the vector interpolation model in which down-sampling matrix has very large dimension and needs large storage consumption and higher computation complexity. In this paper, a fast algorithm for image interpolation based on the tensor product of matrices is presented, which transforms the vector interpolation model to matrix form. The proposed algorithm can extremely reduce the storage requirement and time consumption. The simulation results verify their validity..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 3, 149 (2007)
SFCVQ and EZW coding method based on Karhunen-Loeve transformation and integer wavelet transformation
[in Chinese], and [in Chinese]
A new hyperspectral image compression method of spectral feature classification vector quantization (SFCVQ) and embedded zero-tree of wavelet (EZW) based on Karhunen-Loeve transformation (KLT) and integer wavelet transformation is represented. In comparison with the other methods, this method not only keeps the charactA new hyperspectral image compression method of spectral feature classification vector quantization (SFCVQ) and embedded zero-tree of wavelet (EZW) based on Karhunen-Loeve transformation (KLT) and integer wavelet transformation is represented. In comparison with the other methods, this method not only keeps the characteristics of high compression ratio and easy real-time transmission, but also has the advantage of high computation speed. After lifting based integer wavelet and SFCVQ coding are introduced, a system of nearly lossless compression of hyperspectral images is designed. KLT is used to remove the correlation of spectral redundancy as one-dimensional (1D) linear transform, and SFCVQ coding is applied to enhance compression ratio. The two-dimensional (2D) integer wavelet transformation is adopted for the decorrelation of 2D spatial redundancy. EZW coding method is applied to compress data in wavelet domain. Experimental results show that in comparison with the method of wavelet SFCVQ (WSFCVQ), the method of improved BiBlock zero tree coding (IBBZTC) and the method of feature spectral vector quantization (FSVQ), the peak signal-to-noise ratio (PSNR) of this method can enhance over 9 dB, and the total compression performance is improved greatly..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 3, 153 (2007)
Image denoising exploiting inter- and intra-scale dependency in complex wavelet domain
[in Chinese], and [in Chinese]
A new locally adaptive image denoising method, which exploits the intra-scale and inter-scale dependency in the dual-tree complex wavelet domain, is presented. Firstly, a recently emerged bivariate shrinkage rule is extended to a complex coefficient and its neighborhood, the corresponding nonlinear threshold functions A new locally adaptive image denoising method, which exploits the intra-scale and inter-scale dependency in the dual-tree complex wavelet domain, is presented. Firstly, a recently emerged bivariate shrinkage rule is extended to a complex coefficient and its neighborhood, the corresponding nonlinear threshold functions are derived from the models using Bayesian estimation theory. Secondly, an adaptive weight, which is able to capture the inter-scale dependency of the complex wavelet coefficients, is combined to the obtained bishrink threshold. The experimental results demonstrate an improved denoising performance over related earlier techniques both in peak signal-to-noise ratio (PSNR) and visual effect..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 3, 156 (2007)
Finger crease pattern recognition using Legendre moments and principal component analysis
[in Chinese], and [in Chinese]
The finger joint lines defined as finger creases and its distribution can identify a person. In this paper, we propose a new finger crease pattern recognition method based on Legendre moments and principal component analysis (PCA). After obtaining the region of interest (ROI) for each finger image in the pre-processingThe finger joint lines defined as finger creases and its distribution can identify a person. In this paper, we propose a new finger crease pattern recognition method based on Legendre moments and principal component analysis (PCA). After obtaining the region of interest (ROI) for each finger image in the pre-processing stage, Legendre moments under Radon transform are applied to construct a moment feature matrix from the ROI, which greatly decreases the dimensionality of ROI and can represent principal components of the finger creases quite well. Then, an approach to finger crease pattern recognition is designed based on Karhunen-Loeve (K-L) transform. The method applies PCA to a moment feature matrix rather than the original image matrix to achieve the feature vector. The proposed method has been tested on a database of 824 images from 103 individuals using the nearest neighbor classifier. The accuracy up to 98.584% has been obtained when using 4 samples per class for training. The experimental results demonstrate that our proposed approach is feasible and effective in biometrics..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 3, 160 (2007)
Sinusoidal phase-modulating laser diode interferometer for real-time surface profile measurement
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A sinusoidal phase-modulating (SPM) laser diode (LD) interferometer for real-time surface profile measurement is proposed and its principle is analyzed. The phase signal of the surface profile is detected from the sinusoidal phase-modulating interference signal using a real-time phase detection circuit. For 60*60 measuA sinusoidal phase-modulating (SPM) laser diode (LD) interferometer for real-time surface profile measurement is proposed and its principle is analyzed. The phase signal of the surface profile is detected from the sinusoidal phase-modulating interference signal using a real-time phase detection circuit. For 60*60 measurement points of the surface profile, the measuring time is 10 ms. A root mean square (RMS) measurement repeatability of 3.93 nm is realized, and the measurement resolution reaches 0.19 nm..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 3, 164 (2007)
Design of multi-spectrum BRDF measurement system
[in Chinese], [in Chinese], and [in Chinese]
A multi-spectrum bidirectional reflectance distribution function (BRDF) measurement system was developed with the adoption of single reference standard measurement method. An arm-adjustable corner device was designed for the BRDF system. Changing the distance to the sample by moving the detector arm made the device appA multi-spectrum bidirectional reflectance distribution function (BRDF) measurement system was developed with the adoption of single reference standard measurement method. An arm-adjustable corner device was designed for the BRDF system. Changing the distance to the sample by moving the detector arm made the device applicable to different wavelengths. The system could be used for the spectrum range from visible light (0.6328 microns) to mid-far infrared (10.6 microns), the facular size between 0.8-3 cm. The rotating limit of detector arm was +-180 deg., the rotation range of sample holding table was 360 deg., and the angle resolution was 0.036 deg.. A silicon carbide sample was measured using this system with reflectance zenith from -55 to +55 deg.. According to the error analysis, the measurement uncertainty of this device was about 6.42%..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 3, 168 (2007)
Diode-pumped efficient laser action of Yb3+:LYSO crystal
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Effective diode-pumped continuous wave (CW) tunable laser action of a new alloyed crystal Yb:LYSO is demonstrated. The alloyed LYSO crystal possesses the desirable physical and laser performance of La2SiO5 (LSO), as well as the favorable growth properties and costs of Y2SiO5 (YSO) in the same time. With a 5 at.-% Yb:LYEffective diode-pumped continuous wave (CW) tunable laser action of a new alloyed crystal Yb:LYSO is demonstrated. The alloyed LYSO crystal possesses the desirable physical and laser performance of La2SiO5 (LSO), as well as the favorable growth properties and costs of Y2SiO5 (YSO) in the same time. With a 5 at.-% Yb:LYSO sample, the output power of 2.84 W at 1085 nm and an optical-to-optical conversion efficiency of 54.5% are achieved. Its laser wavelength can be tuned over a broad range of 81 nm, from 1030 to 1111 nm..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 3, 172 (2007)
Study on optical characteristics of Nd:YVO4/YVO4 composite crystal laser
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Thermal effect in crystals is the main obstacle blocking diode-pumped solid state laser to get high and stable output power. Diffusion bonding crystal has been demonstrated to be an effective method to relieve the thermal lensing theoretically based on the numerical heat analysis to the end-pumped anisotropic laser cryThermal effect in crystals is the main obstacle blocking diode-pumped solid state laser to get high and stable output power. Diffusion bonding crystal has been demonstrated to be an effective method to relieve the thermal lensing theoretically based on the numerical heat analysis to the end-pumped anisotropic laser crystal. The temperature distributions in Nd:YVO4/YVO4 composite crystal and conventional crystal were analyzed and compared. The end-pumped Nd:YVO4/YVO4 composite crystal laser was designed and set up with z-cavity. The maximum output powers of 9.87 W at 1064 nm and 6.14 W at 532 nm were obtained at the incident pump power of 16.5 W. The highest optical-optical conversion efficiencies were up to 59.8% at 1064 nm and 37.2% at 532 nm respectively..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 3, 175 (2007)
Theoretical analysis of thermal effects in fiber laser from the moment when pump is turned on to steady-state
[in Chinese], [in Chinese], and [in Chinese]
A theoretical analysis of the pump-induced temperature change and associated thermal phase shift occurring in a fiber laser is presented. The temperature rise and thermal phase shift from the moment when pump is turned on to steady-state in fiber lasers, such as Yb-doped fiber laser, are numerical calculated. With the A theoretical analysis of the pump-induced temperature change and associated thermal phase shift occurring in a fiber laser is presented. The temperature rise and thermal phase shift from the moment when pump is turned on to steady-state in fiber lasers, such as Yb-doped fiber laser, are numerical calculated. With the same parameters, the numerical solution is in good agreement with the finite-element (ANSYS software) simulation..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 3, 178 (2007)
Determination of human skin optical properties in vivo from reflectance spectroscopic measurements
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A novel approach has been proved to quickly and non-invasively determine the optical properties of human skin in vivo. It is based on the diffuse reflectance approximation model and subjected to the well established library of absorption spectra of water and hemoglobin. Under the nonlinear least-square algorithm, fittiA novel approach has been proved to quickly and non-invasively determine the optical properties of human skin in vivo. It is based on the diffuse reflectance approximation model and subjected to the well established library of absorption spectra of water and hemoglobin. Under the nonlinear least-square algorithm, fitting the measured spectra in the range of 400-1000 nm to the diffusion approximation model, the reduced scattering coefficient and absorption coefficient of skin tissue can be quickly determined in vivo. The results show that this method is convenient and suitable for the real-time clinical application..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 3, 181 (2007)
Ultrafast blue light emission from SiC nanowires
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Cubic silicon carbide (SiC) nanowires are synthesized in a catalyst-assisted process. The nanowires with diameter of ~40 nm exhibit strong blue light emission at room temperature under ultraviolet (UV) femtosecond laser excitation. The photon energy of peak emission is higher than the energy bandgap of cubic SiC which Cubic silicon carbide (SiC) nanowires are synthesized in a catalyst-assisted process. The nanowires with diameter of ~40 nm exhibit strong blue light emission at room temperature under ultraviolet (UV) femtosecond laser excitation. The photon energy of peak emission is higher than the energy bandgap of cubic SiC which shows involvement of quantum conf inement ef fect. The ultrafast f luorescence is deconvoluted by Monte-Carlo method. The results show two ultrafast decay processes whose lifetimes are about 26 and 567 ps respectively. The mechanisms of such ultrafast processes are discussed..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 3, 184 (2007)
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