2011
2011
-
Record 421 of
Title:Research of transparent object by means of LED-based digital holography
Author(s):Liu, Xianglian(1,2); Qin, Yi(3)Source: Proceedings of 2011 International Conference on Electronic and Mechanical Engineering and Information Technology, EMEIT 2011 Volume: 6 Issue: DOI: 10.1109/EMEIT.2011.6023750 Published: 2011Abstract:In this paper, a new interferometer is proposed and employed to investigate transparent object by means of LED(light emitting diode)-based digital holography. The interferometer combines the advantages of Mach-Zehder interferometer and Michelson interferometer, it enable us to adjust the optical path difference of the two beams interference on a Mach-Zehder interferometer. Thus the interference fringe patterns of LED could be observed quickly and conveniently. First the principle of the new interferometer is stated and then it is compared with other interferometers. Secondly, LED-based phase-shifting digital holography is carried out to investigate transparent object. Both theory ant experiment results are presented. ? 2011 IEEE.Accession Number: 20114014403656 -
Record 422 of
Title:Discrete complex amplitude filter for ultra long optical tube
Author(s):Wang, Jiming(1,2); Liu, Qingliang(1); Liu, Youwen(1); Chen, Weibin(3); Zhan, Qiwen(3)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8097 Issue: DOI: 10.1117/12.893756 Published: 2011Abstract:We proposed a discrete complex amplitude filter to create a focused hollow field with ultra long depth of focus. As for a high numerical aperture lens (NA=0.95), the focused field in the focal region can be engineered into a field like a long "tube" with flat wall through manipulating the distribution of the transmitted amplitude and phase at the pupil plane. This complex amplitude filter at the pupil plane can be discretized into multiple annular zones with different radius, transmittances and phase delays. A focused tube field with long depth of focus(～9λ) has been created as an example through separating and averaging of the projected pupil radiation pattern of magnetic dipole array in the focal region. Imperfections of the designed filter will influence the quality of the generated optical tube field and tolerance deviation of the radius, transmittance and phase delay in each zone is discussed. For the optical trapping, this created tube field can expand the manipulated distance and increase the trapped particles' numbers. ? 2011 SPIE.Accession Number: 20114214439558 -
Record 423 of
Title:Micro/Nano displacement measurement using sub-pixel DSCM
Author(s):Li, Xin-Zhong(1); Tai, Yu-Ping(2); Nie, Zhao-Gang(3); Zhang, Li-Ping(1); Wang, Ya-Jun(4)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8192 Issue: DOI: 10.1117/12.899580 Published: 2011Abstract:A selection method of subset size in sub-pixel displacement registration is proposed. The algorithm principle of interpolation, fitting of distribution of the correlation coefficients and gradient-based methods are introduced. Using computer-simulated speckle images, their precision and efficiency depending on the subset size are studied. The optimal method and subset size are presented in various measurement ranges, which offer measuring bases for sub-pixel in DSCM. ? 2011 SPIE.Accession Number: 20113714320208 -
Record 424 of
Title:Modulation instability of low-amplitude quasi-plane-wave optical beams in biased photorefractive crystals
Author(s):Zhang, Xianfeng(1); Lu, Keqing(1); Tian, Ning(1); Miao, Changyun(1); Li, Hongqiang(1); Wang, Sasa(1); Li, Kehao(2)Source: 2011 International Conference on Control, Automation and Systems Engineering, CASE 2011 Volume: Issue: DOI: 10.1109/ICCASE.2011.5997527 Published: 2011Abstract:We present a study of the modulation instability of low-amplitude broad optical beams in biased photorefractive crystals under steady-state conditions. The modulation instability growth rate can be obtained provided that E 0 is positive quantity, where E0 is the field constant correlated with terms in the space-charge field. Our analysis indicates that the growth rates depend on E0 and the ratio of the optical beam's intensity to that of the dark irradiance, and the maximum modulation instability gain as well as the corresponding spatial-frequency increase with increasing E0 and the ratio of the optical beam's intensity to that of the dark irradiance. Relevant examples are provided where the photorefractive crystal is assumed to be of strontium barium niobate type. ? 2011 IEEE.Accession Number: 20113814348363 -
Record 425 of
Title:Zernike-moment-based image super resolution
Author(s):Gao, Xinbo(1); Wang, Qian(1); Li, Xuelong(2); Tao, Dacheng(3); Zhang, Kaibing(1)Source: IEEE Transactions on Image Processing Volume: 20 Issue: 10 DOI: 10.1109/TIP.2011.2134859 Published: October 2011Abstract:Multiframe super-resolution (SR) reconstruction aims to produce a high-resolution (HR) image using a set of low-resolution (LR) images. In the process of reconstruction, fuzzy registration usually plays a critical role. It mainly focuses on the correlation between pixels of the candidate and the reference images to reconstruct each pixel by averaging all its neighboring pixels. Therefore, the fuzzy-registration-based SR performs well and has been widely applied in practice. However, if some objects appear or disappear among LR images or different angle rotations exist among them, the correlation between corresponding pixels becomes weak. Thus, it will be difficult to use LR images effectively in the process of SR reconstruction. Moreover, if the LR images are noised, the reconstruction quality will be affected seriously. To address or at least reduce these problems, this paper presents a novel SR method based on the Zernike moment, to make the most of possible details in each LR image for high-quality SR reconstruction. Experimental results show that the proposed method outperforms existing methods in terms of robustness and visual effects. ? 2011 IEEE.Accession Number: 20113814351126 -
Record 426 of
Title:Image quality evaluation of light field photography
Author(s):Fu, Qiang(1); Zhou, Zhiliang(2); Yuan, Yan(3); Xiangli, Bin(4)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 7867 Issue: DOI: 10.1117/12.872486 Published: 2011Abstract:Light field photography captures 4D radiance information of a scene. Digital refocusing and digital correction of aberrations could be done after the photograph is taken. However, capturing 4D light field is costly and tradeoffs between different image quality metrics should be made and evaluated. This paper explores the effects of light field photography on image quality by quantitatively evaluating some basic criteria for an imaging system. A simulation approach was first developed by ray-tracing a designed light field camera. A standard testing chart followed by ISO 12233 was provided as the input scene. A sequence of light field raw images were acquired and processed by light field rendering methods afterwards. Through-focus visual resolution and MTF were calculated and analyzed. As a comparison, the same tests were taken for the same main lens system as the results of conventional photography. An experimental light field system was built up and its performance was tested. This work helps better understanding the pros and cons of light field photography in contrast with conventional imaging methods and perceiving the way to optimize the joint digital-optical design of the system. ? 2011 SPIE-IS&T.Accession Number: 20110813694137 -
Record 427 of
Title:Phase-shifting Zernike phase contrast microscopy for quantitative phase measurement
Author(s):Gao, Peng(1,2,3); Yao, Baoli(1); Harder, Irina(1); Lindlein, Norbert(1); Torcal-Milla, Francisco Jose(1)Source: Optics Letters Volume: 36 Issue: 21 DOI: 10.1364/OL.36.004305 Published: November 1, 2011Abstract:Zernike phase contrast microscopy is extended and combined with a phase-shifting mechanism to perform quantitative phase measurements of microscopic objects. Dozens of discrete point light sources on a ring are constructed for illumination. For each point light source, three different levels of point-like phase steps are designed, which are alternatively located along a ring on a silica plate to perform phase retardation on the undiffracted (dc) component of the object waves. These three levels of the phase steps are respectively selected by rotating the silica plate. Thus, quantitative evaluation of phase specimens can be performed via phase-shifting mechanism. The proposed method has low "halo" and "shade-off" effects, low coherent noise level, and high lateral resolution due to the improved illumination scheme. ? 2011 Optical Society of America.Accession Number: 20114514500340