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Record 1 of
Title:Approach for differential phase contrast imaging in x-ray microscopy
Author(s):Liu, Zhenwei(1,2); Lin, Danying(2); Huang, Jianheng(2); Niu, Hanben(1,2)
Source: Optics Letters Volume: 38 Issue: 11 DOI: 10.1364/OL.38.001990 Published: June 1, 2013
Abstract:We propose a differential phase contrast imaging method in x-ray microscopy by utilizing a biased derivative filter, which is structurally similar to that used in visible optics, except that phase changes by the filter cannot be ignored in the x-ray range. However, it is demonstrated that the filter's phase retardation does not disturb its function of phase contrast imaging, and even enhances the signals to some extent. Theoretical formulations and corresponding numerical simulations show that the approach is capable of performing characteristic differential microscopic phase imaging with nanometer-scale resolution. Manageable parameters are also examined in detail for pursuing a high image quality. ? 2013 Optical Society of America.
Accession Number: 20132416413136
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Record 2 of
Title:Design of optical window thickness and influence of its deformation on multi-spectral camera's optical performance
Author(s):Fang, Yu(1,2); Xiangli, Bin(3); Lü, Qunbo(3); Jing, Juanjuan(1)
Source: Guangxue Xuebao/Acta Optica Sinica Volume: 33 Issue: 4 DOI: 10.3788/AOS201333.0422007 Published: April 2013
Abstract:Based on the fracture mechanics analysis, the glass thickness of the optical window of an airborne multi-spectral camera is designed in detail. Correlation analyses solve the engineering design problems of the optical window thickness and ensure the design more reasonable and reliable. Considering the complex environment, steady-state temperature field is calculated by means of finite element method. Linking temperature load to generalized force load, the deformation of optical window under the structure-thermal coupling condition is calculated. Optical window surface after deformation are derived by fitting the final deformation value using Zernike polynomial fitting. Fitting coefficients as the input of Zemax, the impact of the deformation of the optical window on the optical performance of multi-spectral camera is analyzed by means of wavefront error and modulaiton transfer function (MTF) as a measurement of imaging quality. The result shows that based on the known operational environment, the impact on imaging quality of optical system is negligible.
Accession Number: 20132116362355
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Record 3 of
Title:Application of norm theory in the wake bubble screen parameter study
Author(s):Xu, Rui-Hua(1,2); Lv, Pei(1); Zhao, Juan-Ning(2)
Source: Guangdianzi Jiguang/Journal of Optoelectronics Laser Volume: 24 Issue: 7 DOI: Published: July 2013
Abstract:Through researching the parameters of bubbly screen in the ship wake, the bubble movement characteristics can be found out. Also, the research and realization of the ship wake self-guide torpedo are based upon this characteristic. Currently, the wake research shortcomings include the measuring is complex, the measured value is susceptible to be impacted by the external environment, etc. From a new point of view, the norm theory is applied to measure the parameters of the ship wake bubble. A slice imaging system based on light sheet is used to acquire the ship wake bubble screen images in the experiment. We utilize the norm algorithm and the diameter size of the bubble to acquire the bubble density, uniformity distribution and the volume density of the bubble screen. According to the above parameters, the related information of the target ship can be analyzed and judged. The norm algorithm has many advantages compared with the conventional one, such as the less known information is needed, the algorithm is simple, the information obtained is informative, the judgement of the ships condition is accurate, and so on. This algorithm is expected to be used in acquiring the parameters of bubbly screen in the ship wake, and will have significant applications in the ship wake bubble screen research.
Accession Number: 20133216587637
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Record 4 of
Title:Effects of laser propagation through atmospheric turbulence on imaging quality in Fourier telescopy
Author(s):Li, Yang(1,2); Xiang, Libin(3); Zhang, Wenxi(2,3)
Source: Qiangjiguang Yu Lizishu/High Power Laser and Particle Beams Volume: 25 Issue: 2 DOI: 10.3788/HPLPB20132502.0292 Published: February 2013
Abstract:In order to determine the imaging quality degradation caused by the laser propagation through atmospheric turbulence in the Fourier telescopy system, the effects of turbulence on beam propagation characteristics are analyzed. We pointed out that the degradation in the quality of imaging is mainly from the beam wander and beam spreading induced by atmospheric turbulence that arises the pointing error. The mechanism of the pointing error affecting imaging process is analyzed. The pointing errors caused by turbulence of the entire uplink are calculated and imaging results are simulated under different atmospheric conditions. It is concluded that in weak and moderate turbulence (the refractive index structure constant of atmospheric turbulence is less than 10-14 m-2/3), the random pointing error is small (the random pointing offset proportion is less than 0.06) while the reconstructed image has good recognizability. However, in strong turbulence, imaging quality suffers severe decline. Thus the Fourier telescopy should be selected to avoid the strong turbulence location and time.
Accession Number: 20130615999525
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Record 5 of
Title:Speckle noise suppression of reconstructed image based on dual-tree complex wavelet and anisotropic diffusion
Author(s):Wu, Yiquan(1,2); Ye, Zhilong(1); Wan, Hong(1)
Source: Zhongguo Jiguang/Chinese Journal of Lasers Volume: 40 Issue: 4 DOI: 10.3788/CJL201340.0409002 Published: April 2013
Abstract:In order to suppress the speckle noise of reconstructed image in digital holography effectively and to further improve the quality of reconstructed image, a speckle noise suppression method of reconstructed image in digital holography based on dual-tree complex wavelet transform (DT-CWT) and anisotropic diffusion is proposed. The reconstructed image is decomposed through DT-CWT. Then, the low-frequency components and the high-frequency components in six directions are processed through P_Laplace diffusion and Laplacian pyramid-based nonlinear diffusion (LPND), respectively. The new reconstructed image is synthesized through inverse dual-tree complex wavelet transform (IDT-CWT). The experimental results are given, and a subjective visual comparison is made with the method of wavelet threshold shrinkage and total variation (TV) diffusion, the method of LPND, and the method combining contourlet transform with TV and adaptive contrast diffusion. While the results are evaluated quantitatively according to peak signal to noise ratio (PSNR), correlation coefficient (COR) and running time. Experimental results show that the proposed method has a better performance in speckle noise suppression and preserves the detail and textural features of original reconstructed image more efficiently.
Accession Number: 20132216376028
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Record 6 of
Title:Calibration and correction of the CCD spectral response nonuniformity for Fourier transform imaging spectrometer
Author(s):Dalian, Shi(1,2); Xuebin, Liu(1); Shuang, Wang(1,2); Juanjuan, Jing(3); Desheng, Wen(1); Qinglan, Bai(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8910 Issue: DOI: 10.1117/12.2034271 Published: 2013
Abstract:Due to the manufacturing technique, some kinds of CCD, such as the back illuminated CCD, have the problem of spectral response nonuniformity. The near infrared light passing through the substrate and gates and is reflected back into the substrate for a second pass resulting in increased response. For the Fourier transform imaging spectrometer, it adds stripe pattern error to the interferogram and distorts the reconstructed spectrum. The nonuniform response is wavelength dependent due to changes in reflectivity of metal and the cavity formed by silicon and metal with transparent dielectric, so it adds difficulty to the correction of the error of the reconstructed spectrum. In order to reduce the error of the reconstructed spectrum, in this paper, a calibration method and a correction method to correct the error caused by the CCD spectral response nonuniformity was developed, basing on analysis of the property of the CCD spectral response nonuniformity. Firstly, a calibrated monochromater was used to measure the CCD spectral response nonuniformity and the property and affect of the CCD spectral response nonuniformity were analyzed. Method to correct the error of the reconstructed spectrum caused by the stripe pattern error was developed. Secondly, to calibrate the CCD spectral response nonuniformity, the spectral response coefficient and the spatial response nonuniformity coefficient was measured and computed. Finally, we took data with a Fourier transform imaging spectrometer, and got the correction results of the reconstructed spectrums. The results showed that the distortion of recovered spectrum was evidently reduced and the effect of the calibration and correction method was proved. ? 2013 SPIE.
Accession Number: 20141317516389
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Record 7 of
Title:Target velocity acquisition from signals received by Fourier telescopy
Author(s):Li, Yang(1,2); Xiang, Libin(3); Zhang, Wenxi(2,3)
Source: Qiangjiguang Yu Lizishu/High Power Laser and Particle Beams Volume: 25 Issue: 9 DOI: 10.3788/HPLPB20132509.2193 Published: September 2013
Abstract:The signals received by Fourier telescopy are analyzed and demonstrated to contain not only image information but also two-dimensional velocity information of the measured target. The velocities on each component can be calculated by the periodic signal frequencies that can be extracted from received signals. Then the two-dimension velocity is composited. The frequency of the signal is extracted by fast Fourier transform analysis for coarse frequency estimate, and by ratio frequency correction algorithms using Hanning window for precise frequency correction. Simulation is made to measure the flight velocity of the missile by Fourier telescopy. The result shows that the target velocity acquired by this method has almost no error without noise, while it has relatively high precision with noise when SNR is higher than 5 dB. The velocity acquisition method from receiving signal of Fourier telescopy is demonstrated to have high precision, a good anti-noise property and to be theoretically feasible.
Accession Number: 20134116842453
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Record 8 of
Title:A level set with shape priors using moment-based alignment and locality preserving projections
Author(s):Wang, Bin(1); Gao, Xinbo(1); Li, Jie(1); Li, Xuelong(2); Tao, Dacheng(3)
Source: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) Volume: 8261 LNCS Issue: DOI: 10.1007/978-3-642-42057-3-88 Published: 2013
Abstract:A novel level set method (LSM) with shape priors is proposed to implement a shape-driven image segmentation. By using image moments, we deprive the shape priors of position, scale and angle information, consequently obtain the aligned shape priors. Considering that the shape priors sparsely distribute into the observation space, we utilize the locality preserving projections (LPP) to map them into a low dimensional subspace in which the probability distribution is predicted by using kernel density estimation. Finally, a new energy functional with shape priors is developed by combining the negative log-probability of shape priors with other data-driven energy items. We assess the proposed LSM on the synthetic, medical and natural images. The experimental results show that it is superior to the pure data-driven LSMs and the representative LSM with shape priors. ? 2013 Springer-Verlag Berlin Heidelberg.
Accession Number: 20140517246456
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Record 9 of
Title:Saliency detection by multiple-instance learning
Author(s):Wang, Qi(1); Yuan, Yuan(1); Yan, Pingkun(1); Li, Xuelong(1)
Source: IEEE Transactions on Cybernetics Volume: 43 Issue: 2 DOI: 10.1109/TSMCB.2012.2214210 Published: April 2013
Abstract:Saliency detection has been a hot topic in recent years. Its popularity is mainly because of its theoretical meaning for explaining human attention and applicable aims in segmentation, recognition, etc. Nevertheless, traditional algorithms are mostly based on unsupervised techniques, which have limited learning ability. The obtained saliency map is also inconsistent with many properties of human behavior. In order to overcome the challenges of inability and inconsistency, this paper presents a framework based on multiple-instance learning. Low-, mid-, and high-level features are incorporated in the detection procedure, and the learning ability enables it robust to noise. Experiments on a data set containing 1000 images demonstrate the effectiveness of the proposed framework. Its applicability is shown in the context of a seam carving application. ? 2012 IEEE.
Accession Number: 20135117116106
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Record 10 of
Title:Design and fabrication of cyclic-olefin copolymer based terahertz hollow-core photonic crystal fiber
Author(s):Chen, Qi(1,2); Zhang, Yi-Xia(1); He, Xiao-Yang(1); Kong, De-Peng(3); Zhang, Jian(1,2)
Source: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz Volume: Issue: DOI: 10.1109/IRMMW-THz.2013.6665663 Published: 2013
Abstract:In this paper a kind of hollow-core terahertz photonic crystal fiber made of Cyclic-olefin Copolymer with low absorption loss is designed. Results show these fibers are much better than metallic waveguides for their fine transmission properties in terahertz band. Along with the fine flexibility to bend, they are of great importance in application. ? 2013 IEEE.
Accession Number: 20140617284718
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Record 11 of
Title:Interferogram filtering method based on empirical mode decomposition
Author(s):Jing, Juanjuan(1,2); Xiangli, Bin(2); Li, Ran(1); Shi, Dalian(1)
Source: Guangxue Xuebao/Acta Optica Sinica Volume: 33 Issue: 10 DOI: 10.3788/AOS201333.1007001 Published: October 2013
Abstract:Interferogram filtering is a key technique in the process of spectral recovery of imaging Fourier transform spectrometer. Differential filtering and polynomial filtering are usually used, but differential filtering cannot filter the noise completely, and polynomial filtering, which needs the noise type when filtering, produces big bias at both ends of the interferograms. Empirical mode decomposition (EMD), a new signal processing method in linearity and stationary spectral analysis, is now widely used in many aspects. EMD technique is applied to interferogram filtering. It can avoid the disadvantages of differential filtering and polynomial filtering, and it is more reasonable to extract the background noise. The data acquired in the laboratory are used to analyze the precision of different filtering methods. The result indicates that the precisions of differential filtering, polynomial filtering and EMD are 0.0079, 0.0073, 0.0068, respectively. EMD is the optimum filtering method, followed by the polynomial filtering and differential filtering.
Accession Number: 20134817030479
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Record 12 of
Title:Multi-shape infrared target detection algorithm based on Markov Random Field
Author(s):Xue, Yong-Hong(1,2); Zhang, Tao(2); Chen, Rong-Li(3); An, Wei(1); Zhang, Yin-Sheng(2)
Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 42 Issue: 10 DOI: 10.3788/gzxb20134210.1231 Published: October 2013
Abstract:The problem of shape target detection was formulated as a binary classification problem of each pixel under Markov Random Field (MRF)theoretical framework and the adaptive neighborhood system of MRF was introduced. Firstly, the factors that cause the changing of target shapes were analyzed and classic target shapes presented on obtained infrared images were concluded. Secondly, the classic shapes were used as templates while establishing the new neighborhood system of MRF. Thirdly, to achieve the optimal detection performance, a criterion function for adaptively selecting the proper neighborhood for each pixel was proposed and at last a new potential function using finite difference operator was proposed for the classification of target and background at each pixel. For the usage of adaptive neighborhood system, the proposed algorithm has following advantages: further reduction of the threshold crossing rate of target detection in single image frame while maintaining the target detection rate and better preservation of target shape details than algorithms using classic neighborhood system of MRF. By simulations and experiments, the results show that the proposed algorithm can optimally detect targets under various image Signal-to-clutter ratios, and perfectly protect target shape details.
Accession Number: 20135117103927
