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Measurement of Sub-micrometer Features Based on The Topographic Contrast Using Reflection Confocal Microscopy

Journal of the Optical Society of Korea 2005年第1期9卷 26-31页

作者： SeungWoo Lee DongKyun Kang HongKi Yoo TaeJoong Kim Dae-Gab Gweon Suk-Won Lee Kwang-Soo Kim Dept. of Mechanical Eng KAIST Micro Nano System Technology R/D LAB Samsung Electronics Co. Ltd

We describe the design and the implementation of video-rate reflection confocal scanning microscopy (CSM) using an acousto-optical deflector (AOD) for the fast horizontal scan and a galvanometer mirror (GM) for the slow vertical scan. Design parameters of the optical system are determined for optimal resolution and contrast. The OSLO simulations show that the performances of CSM are not changed with deflection angle and the wavefront errors of the system are less than 0.012λ. To evaluate the performances of designed CSM, we do a series of tests, measuring lateral and axial resolution, real time image acquisition. Due to a higher axial resolution compared with conventional microscopy, CSM can detect the surface of sub-micrometer features. We detect 138㎚ line shape pattern with a video-rate (30 frm/sec). And 10㎚ axial resolution is archived. The lateral resolution of the topographic images will be further enhanced by differential confocal microscopy (DCM) method and computational algorithms.

关键词： Acoustooptical deflectors computation methods Confocal microscopy Line shapes Microscopy Reflection

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Efficient coupling into and out of high-Q resonators

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION 2004年第8期21卷 1512-1517页

作者： Harbers, R Moll, N Erni, D Bona, GL Bächtold, W Swiss Fed Inst Technol Lab Electromagnet Fields & Microwave Elect CH-8092 Zurich Switzerland IBM Res Corp Zurich Res Lab CH-8803 Ruschlikon Switzerland

The temporal-coupled-mode theory is directly applied to the design of devices that feature a resonator with a high quality factor. For the temporal-coupled-mode theory we calculate the decay rate of the resonator to determine the transmission properties of the device. The analysis using the decay rates requires little computational effort, and therefore the optimum device properties can be determined quickly. Two examples, a wavelength filter and a resonator crossing, are presented to illustrate the use of the analysis. (C) 2004 Optical Society of America.

关键词： computation methods Optical resonators Photonic crystals Refractive index Transmission coefficient Wavelength filtering devices

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Color constancy through inverse-intensity chromaticity space

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION 2004年第3期21卷 321-334页

作者： Tan, RT Nishino, K Ikeuchi, K Univ Tokyo Dept Comp Sci Meguro Ku Tokyo 1538505 Japan Columbia Univ Dept Comp Sci New York NY 10027 USA

Existing color constancy methods cannot handle both uniformly colored surfaces and highly textured surfaces in a single integrated framework. Statistics-based methods require many surface colors and become error prone when there are only a few surface colors. In contrast, dichromatic-based methods can successfully handle uniformly colored surfaces but cannot be applied to highly textured surfaces;since they require precise color segmentation. We present a single integrated method to estimate illumination chromaticity from single-colored and multicolored surfaces. Unlike existing dichromatic-based methods, the proposed method requires only rough highlight regions without segmenting the colors inside them. We show that, by analyzing highlights, a direct correlation between illumination chromaticity and image chromaticity can be obtained. This correlation is clearly described in "inverse-intensity chromaticity space," a novel two-dimensional space that we introduce. In addition, when Hough transform and histogram analysis is utilized in this space, illumination chromaticity can be estimated robustly, even for a highly textured surface. (C) 2004 Optical Society of America.

关键词： Color constancy Color reproduction computation methods Fresnel reflection Machine vision Nonlinear correlation

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Gridding-based direct Fourier inversion of the three-dimensional ray transform

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION 2004年第4期21卷 499-509页

作者： Penczek, PA Renka, R Schomberg, H Univ Texas Sch Med Dept Biochem & Mol Biol Houston TX 77030 USA Univ N Texas Dept Comp Sci Denton TX 76203 USA Philips Res Hamburg D-22335 Hamburg Germany

We describe a fast and accurate direct Fourier method for reconstructing a function f of three variables from a. number of its parallel beam projections. The main application of our method is in single particle analysis, where the goal is to reconstruct the mass density of a biological macromolecule. Typically, the number of projections is extremely large, and each projection is extremely noisy. The projection directions are random and initially unknown. However, it is possible to determine both the directions and f by an iterative procedure;during each stage of the iteration, one has to solve a reconstruction problem of the type considered here. Our reconstruction algorithm is distinguished from other direct Fourier methods by the use of gridding techniques that provide an efficient means to compute a uniformly sampled version of a function g from a nominiformly sampled version of Fg, the Fourier transform of g, or vice versa. We apply the two-dimensional reverse gridding method to each available projection of f, the function to be reconstructed, in order to obtain Ff on a special sphericalgrid. Then we use the three-dimensional gridding method to reconstruct f from this sampled version of Ff. This stage requires a proper weighting of the samples of Ff to compensate for their nonuniform distribution. We use a fast method for computing appropriate weights that exploits the special properties of the spherical sampling grid for Ff and involves the computation of a Voronoi diagram on the unit sphere. We demonstrate the excellent speed and accuracy of our method by using simulated data. (C) 2004 Optical Society of America.

关键词： computation methods Discrete Fourier transforms Fourier transforms Image processing Image reconstruction Reconstruction algorithms

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Fractional finite Fourier transform

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION 2004年第7期21卷 1179-1185页

作者： Khare, K George, N Univ Rochester Inst Opt Rochester NY 14627 USA

We show that a fractional version of the finite Fourier transform may be defined by using prolate spheroidal wave functions of order zero. The transform is linear and additive in its index and asymptotically goes over to Namias's definition of the fractional Fourier transform. As a special case of this definition, it is shown that the finite Fourier transform may be inverted by using information over a finite range of frequencies in Fourier space, the inversion being sensitive to noise. Numerical illustrations for both forward (fractional) and inverse finite transforms are provided. (C) 2004 Optical Society of America.

关键词： computation methods Fourier transforms Fractional Fourier transforms Fresnel diffraction Inverse problems Transforms

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Analysis of circular fibers with an arbitrary index profile by the Galerkin method

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OPTICS LETTERS 2004年第1期29卷 32-34页

作者： Guo, SP Wu, F Ikram, K Albin, S Old Dominion Univ Dept Elect & Comp Engn Photon Lab Norfolk VA 23529 USA

We propose a full-vectorial Galerkin method for the analysis of circular symmetric fibers with arbitrary index profiles. A set of orthogonal Laguerre-Gauss functions is used to calculate the dispersion relation and mode fields of TE and TM modes. Examples are given for both standard step-index fibers and Bragg fibers. For standard step-index fiber with low or high index contrast, the Galerkin method agrees well with the analytical results. In the case of the TE mode of a Bragg fiber it agrees well with the asymptotic results. (C) 2004 Optical Society of America.

关键词： computation methods Microstructured fibers Refractive index Step index fibers Total internal reflection Waveguide modes

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Limited possibility for quantifying mean particle size by logarithmic light-scattering spectroscopy

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APPLIED OPTICS 2003年第16期42卷 2968-2971页

作者： Johns, M Liu, HL Univ Texas Dept Biomed Engn Arlington TX 76019 USA

Recent studies have shown that the slope of logarithmic scattering spectroscopy of a turbid medium is related to the sizes of the scattering particles within the turbid medium. Mie theory can be used to generate a logarithmic plot of the reduced-scattering coefficient versus wavelength. According to Nilsson et al. [Appl. Opt. 37, 1256 (1998)], the slope value of a linear fit of the logarithmic scattering spectroscopy between 600 and 1050 nm can be used for direct determination of particle size. We performed similar calculations using the Rayleigh-Gans approximation and obtained an analogous overall shape with additional sinusoidal features. Our calculations indicate a possible relationship between the slope and the particle size when the size is used to calculate the slope, namely, in the forward calculation. However, because of the sinusoidal pattern, the inverse calculation to obtain the particle size from the slope may be applied only for particles with a radius of <0.13 mum in combination with 650-1050-nm light. Caution should be exercised when inverse calculation is performed to determine the scattering particle sizes in the range of radii >0.13 mum, with the slope of logarithmic scattering spectroscopy within 650-1050 nm. (C) 2003 Optical Society of America.

关键词： computation methods Mie theory Particle scattering Scattering Scattering measurement Turbid media

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Efficient light-scattering calculations for aggregates of large spheres

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APPLIED OPTICS 2003年第15期42卷 2785-2793页

作者： Saija, R Iatì, MA Denti, P Borghese, F Giusto, A Sindoni, OI Univ Messina Dipartimento Fis Mat & Tecnol Fis Avanzate I-98166 Messina Italy Univ Messina Ist Nazl Fis Mat Unita Messina I-98166 Messina Italy Edgewood Chem Biol Ctr Gunpowder Branch Aberdeen Proving Ground MD 21010 USA

Calculation of the scattering pattern from aggregates of spheres through the T-matrix approach yields high-precision results but at a high-computational cost, especially when the aggregate concerned is large or is composed of large-size spheres. With reference to a specific but representative aggregate, we discuss how and to what extent the computational effort can be reduced but still preserve the qualitative features of the signature of the aggregate concerned. (C) 2003 Optical Society of America.

关键词： computation methods In field scattering Mie theory Optical properties Particle scattering Scattering

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Spectral estimation theory: beyond linear but before Bayesian

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION 2003年第7期20卷 1261-1270页

作者： DiCarlo, JM Wandell, BA Stanford Univ Dept Elect Engn Stanford CA 94305 USA

Most color-acquisition devices capture spectral signals by acquiring only three samples, critically undersampling the spectral information. We analyze the problem of estimating high-dimensional spectral signals from low-dimensional device responses. We begin with the theory and geometry of linear estimation methods. These methods use linear models to characterize the likely input signals and reduce the number of estimation parameters. Next, we introduce two submanifold estimation methods. These methods are based on the observation that for many data sets the deviation between the signal and the linear estimate is systematic;the methods incorporate knowledge of these systematic deviations to improve upon linear estimation methods. We describe the geometric intuition of these methods and evaluate the submanifold method on hyperspectral image data. (C) 2003 Optical Society of America.

关键词： Charge coupled devices Color reproduction computation methods Hyperspectral imaging Image sensors Visual system

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Numerical evaluation of Hankel transforms for oscillating functions

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION 2003年第4期20卷 621-630页

作者： Markham, J Conchello, JA Washington Univ Sch Med Mallinckrodt Inst Radiol St Louis MO 63110 USA Washington Univ Sch Med Dept Anat & Neurobiol St Louis MO 63110 USA

Six methods for the numerical calculation of zero-order Hankel transforms of oscillating functions were evaluated. One method based on Filon quadrature philosophy, two published projection-slice methods, and a third projection-slice method based on a new approach to computation of the Abel transform were implemented;alternative versions of two of the projection-slice methods were derived for more accurate approximations in the projection step. These six algorithms were tested with an oscillating sweep signal and with the calculation of a three-dimensional diffraction-limited point-spread function of a fluorescence microscope. We found that the Filon quadrature method is highly accurate but also computationally demanding. The projection-slice methods, in particular the new one that we derived, offer an excellent compromise between accuracy and computational efficiency. (C) 2003 Optical Society of America.

关键词： Blind deconvolution computation methods Deconvolution Fluorescence microscopy Fourier transforms Transforms

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