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22nd Congress of the International Commission for Optics - Light for the development of the World

作者： Alieva, Tatiana Camara, Alejandro Bastiaans, Martin J. Univ Complutense Madrid Fac Ciencias Fis Ciudad Univ S-N E-28040 Madrid Spain Eindhoven Univ Technol Dept Elect Engn NL-5600 MB Eindhoven Netherlands

ISBN: (纸本)9780819485854

Representation of two-dimensional optical signals on the orbital angular Poincare sphere is useful for beam analysis, synthesis and comparison. This mapping is based on the measurement of the second-order moments, which are widely used for beam characterization. It is well known that two second-order moments invariants allow dividing two-dimensional signals into two classes: isotropic and anisotropic. Using the modified Iwasawa decomposition of the ray transformation matrix and bringing the second-order moments matrix to its diagonalized form, we are able to associate the anisotropic signal with a certain point on the sphere. The latitude of this point describes the vorticity of the signal, while its longitude corresponds to the orientation of the beam's principal axes. Apart from that, the beam's scaling and its curvature can be defined. Before beam comparison, it is thus appropriate to perform first its normalization and mapping on the Poincare sphere. There are many very different beams associated with the same point and therefore this procedure makes sense for fine analysis of beams whose intensity distributions have similar forms. Moreover, every point on the sphere is associated with an orthonormal set of Hermite-Laguerre-Gaussian modes, which can be used for the corresponding beam decomposition that is important for its synthesis and analysis. The developed algorithm for the beam mapping is demonstrated on several examples.

关键词： Beam analyzers Poincaré sphere Optical spheres Beam propagation method Transformers algorithm development Phase modulation Phase shift keying Signal processing Technetium

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LED Spectrum Measurement via Low Cost Spectrum Sensor On-a-Chip

LED Spectrum Measurement via Low Cost Spectrum Sensor On-a-C...

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Conference on Optical Sensors and Biophotonics II

作者： Chang, Cheng-Chun Chen, Chien-Chou Lin, Nan-Ting Kurokawa, Umpei Choi, Byung I. Natl Taipei Univ Technol Dept Elect Engn Taipei 106 Taiwan Nanolambda Inc Pittsburgh PA 15238 USA

ISBN: (纸本)9780819485588

Miniature spectrometers with desirable properties such as being small in size, light weight and non-fragile provide solutions to a variety of promising application. In this work, through the developed algorithms, a low-cost chip-scale spectrometer is demonstrated in particular for LED spectrum sensing, as the market of LED lights has been booming and low-cost solution for testing and monitoring LEDs spectral characteristics become essential. The developed algorithms are in two forms, namely algebraic approach and training approach. For the algebraic approach, non-negative least square method is reported useful for spectrum reconstruction of narrowband LED spectra. For the training approach, FWHM measurement and peak wavelength measurement, the two major parameters for specifying monotonic LED spectra, are reported with accuracy within 1nm.

关键词： Light emitting diodes Sensors Spectrometers Light sources algorithm development LED lighting Ocean optics Reconstruction algorithms Transmittance Optics manufacturing

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Real-time generation of fully optimized holograms for optical trapping applications

Real-time generation of fully optimized holograms for optica...

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Conference on Optical Trapping and Optical Micromanipulation VIII

作者： Persson, Martin Engstrom, David Goksor, Mattias Univ Gothenburg Dept Phys SE-41296 Gothenburg Sweden

ISBN: (纸本)9780819487070

We have implemented several algorithms for hologram generation, aimed for holographic optical tweezers applications, using the parallel computing architecture CUDA. We compare required computation time for different implementations of the Gerchberg-Saxton algorithm and provide guidelines for choosing the best suited version with respect to the application. We also show that additional calculations, compensating for limitations in the used spatial light modulator and optical system, can be included in the hologram generating software with little or no loss in computational speed.

关键词： Holograms Spatial light modulators Optical tweezers Diffraction Holography applications LabVIEW Wavefront distortions algorithm development Graphics processing units Wavefronts

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Can AlgoTutor Change Attitudes toward algorithms? 11

Can AlgoTutor Change Attitudes toward Algorithms?

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42nd ACM Technical Symposium on Computer Science Education

作者： Yoo, Jungsoon Yoo, Sung Seo, Suk Pettey, Chrisila Middle Tennessee State Univ Dept Comp Sci Murfreesboro TN 37132 USA

ISBN: (纸本)9781450305006

The ability to design an algorithm is one of the most important learning outcomes of a computer science program. Unfortunately, not only is learning how to design algorithms a challenging task, but many students believe that algorithm design is not an important part of problem solving. To address this challenge and hopefully change student attitudes, we developed AlgoTutor, a web-based algorithm development tutoring system. AlgoTutor's primary components are the algorithm composer and the algorithm tracer. A third component, ProgramPad, was added to show the connection between algorithms and code. This paper presents the results of experiments that assessed AlgoTutor's effectiveness in changing student attitudes about algorithm development. The results show that students who used AlgoTutor in CS-I were more likely to realize the importance of algorithm design in problem solving and to have confidence in their own algorithm development abilities.

关键词： algorithm development learning environment

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Helical x-ray differential phase contrast computed tomography

Helical x-ray differential phase contrast computed tomograph...

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Conference on Medical Imaging 2011 - Physics of Medical Imaging

作者： Qi, Zhihua Theriault-Lauzier, Pascal Bevins, Nicholas Zambelli, Joseph Li, Ke Chen, Guang-Hong Univ Wisconsin Dept Med Phys Madison WI 53705 USA

ISBN: (纸本)9780819485038

Helical computed tomography revolutionized the field of x-ray computed tomography two decades ago. The simultaneous translation of an image object with a standard computed tomography acquisition allows for fast volumetric scan for long image objects. X-ray phase sensitive imaging methods have been studied over the past few decades to provide new contrast mechanisms for imaging an object. A Talbot-Lau grating interferometer based differential phase contrast imaging method has recently demonstrated its pontential for implentation in clinical and industrial applications. In this work, the principles of helical computed tomography are extended to differential phase contrast imaging to produce volumetric reconstructions based on fan-beam data. The method demonstrates the potential for helical differential phase contrast CT to scan long objects with relatively small detector coverage in the axial direction.

关键词： Phase contrast Reconstruction algorithms Sensors Computed tomography Absorption X-rays Fluctuations and noise X-ray computed tomography Zinc algorithm development

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Uncooled infrared development for small unmanned aerial vehicles

Uncooled infrared development for small unmanned aerial vehi...

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Conference on Infrared Technology and Applications XXXVI

作者： Pitt, Timothy S. Wood, Sam B. Waddle, Caleb E. Edwards, William D. Yeske, Ben S. USA Aviat & Missile Res Dev & Engn Ctr Redstone Arsenal AL USA Dynetics Inc Huntsville AL USA

ISBN: (纸本)9780819481245

The US Army Aviation and Missile Research, development, and Engineering Center (AMRDEC) is developing a micro-uncooled infrared (IR) capability for small unmanned aerial systems (SUAS). In 2007, AMRDEC procured several uncooled microbolometers for lab and field test evaluations, and static tower tests involving specific target sets confirmed initial modeling and simulation predictions. With these promising results, AMRDEC procured two captive flight test (CFT) vehicles and, in 2008, completed numerous captive flights to capture imagery with the micro-uncooled infrared sensors. Several test configurations were used to build a comprehensive data set. These configurations included variations in look-down angles, fields of view (FOV), environments, altitudes, and target scenarios. Data collected during these field tests is also being used to develop human tracking algorithms and image stabilization software by other AMRDEC personnel. Details of these ongoing efforts will be presented in this paper and will include: 1) onboard digital data recording capabilities;2) analog data links for visual verification of imagery;3) sensor packaging and design;which include both infrared and visible cameras;4) field test and data collection results;5) future plans;6) potential applications. Finally, AMRDEC has recently acquired a 17 mu m pitch detector array. The paper will include plans to test both 17 mu m and 25 mu m microbolometer technologies simultaneously in a side-by-side captive flight comparison.

关键词： Cameras Sensors Infrared radiation Systems modeling algorithm development Computing systems Infrared sensors Microbolometers Neodymium NVThermIP

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Digital Filter Design Using Computer Algebra Systems

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CIRCUITS SYSTEMS AND SIGNAL PROCESSING 2010年第1期29卷 51-64页

作者： Lutovac, Miroslav D. Certic, Jelena D. Milic, Ljiljana D. Univ Belgrade Sch Elect Engn Belgrade 11000 Serbia State Univ Novi Pazar Novi Pazar 36300 Serbia

Digital filter design can be performed very efficiently using modern computer tools. The drawback of the numeric-based tools is that they usually generate a tremendous amount of numeric data, and the user might easily lose insight into the phenomenon being investigated. The computer algebra systems successfully overcome some problems encountered in the traditional numeric-only approach. In this paper, we introduce an original approach to algorithm development and digital filter design using a computer algebra system. The main result of the paper is the development of an algorithm for an infinite impulse response (IIR) filter design that, theoretically, is impossible to be implemented using the traditional approach. We present a step-by-step procedure which includes derivations of closed-form expressions for (1) the transfer functions of the implemented digital filter which contains the algebraic loop;(2) the closed-form expression for computing the number of requested iteration steps;and (3) the error function representing the difference of the output sample values of the new filter and that of the conventional filter. We demonstrate how one can use some already-known multiplierless digital filter as a start-up filter to design a new digital filter whose passband edge frequency can be simply moved by using a single parameter. As a result, we obtain a multiplierless IIR filter, which belongs to the family of low-power digital filters where multipliers are replaced with a small number of adders and shifters.

关键词： Symbolic signal processing Algebraic loop algorithm development Modeling Implementation Multiplierless IIR filter

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Satellite remote sensing of harmful algal blooms: A new multi-algorithm method for detecting the Florida Red Tide (Karenia brevis)

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HARMFUL ALGAE 2010年第5期9卷 440-448页

作者： Carvalho, Gustavo A. Minnett, Peter J. Fleming, Lora E. Banzon, Viva F. Baringer, Warner Univ Miami Rosenstiel Sch Marine & Atmospher Sci Div Meteorol & Phys Oceanog Miami FL 33149 USA Univ Miami Rosenstiel Sch Marine & Atmospher Sci NSF NIEHS Oceans & Human Hlth Ctr Miami FL 33149 USA Univ Miami Miller Sch Med Dept Epidemiol & Publ Hlth Miami FL 33149 USA NOAA NESDIS Remote Sensing & Applicat Div Natl Climat Data Ctr Asheville NC USA

In a continuing effort to develop suitable methods for the surveillance of harmful algal blooms (HABs) of Karenia brevis using satellite radiometers, a new multi-algorithm method was developed to explore whether improvements in the remote-sensing detection of the Florida Red Tide was possible. A Hybrid Scheme was introduced that sequentially applies the optimized versions of two pre-existing satellite-based algorithms: an Empirical Approach (using water-leaving radiance as a function of chlorophyll concentration) and a Bio-optical Technique (using particulate backscatter along with chlorophyll concentration). The long-term evaluation of the new multi-algorithm method was performed using a multi-year MODIS dataset (2002-2006;during the boreal Summer-Fall periods - July-December) along the Central West Florida Shelf between 25.75 degrees N and 28.25 degrees N. algorithm validation was done with in situ measurements of the abundances of K. brevis: cell counts >= 1.5 x 10(4) cells I-1 defined a detectable HAB. Encouraging statistical results were derived when either or both algorithms correctly flagged known samples. The majority of the valid match-ups were correctly identified (similar to 80% of both HABs and non-blooming conditions) and few false negatives or false positives were produced (similar to 20% of each). Additionally, most of the HAB-positive identifications in the satellite data were indeed HAB samples (positive predictive value: similar to 70%) and those classified as HAB-negative were almost all non-bloom cases (negative predictive value: similar to 86%). These results demonstrate an excellent detection capability, on average similar to 10% more accurate than the individual algorithms used separately. Thus, the new Hybrid Scheme could become a powerful tool for environmental monitoring of K. brevis blooms, with valuable consequences including leading to the more rapid and efficient use of ships to make in situ measurements of HABs. (C) 2010 Elsevier B.V.

关键词： algorithm development Central West Florida Shelf (Gulf of Mexico) Detection Florida Red Tide (Karenia brevis) Harmful algal bloom (HAB) Hybrid Scheme Ocean color (MODIS-Aqua) Satellite remote sensing

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The JPDAF in Practical Systems: Approximations

The JPDAF in Practical Systems: Approximations

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Conference on Signal and Data Processing of Small Targets 2010

作者： Romeo, Kevin Crouse, David F. Bar-Shalom, Yaakov Willett, Peter Univ Connecticut Dept Elect & Comp Engn Storrs CT 06269 USA

ISBN: (纸本)9780819481627

In this paper we look at various algorithms for approximating the target-measurement association probabilities of the Joint Probabilistic Data Association Filter (JPDAF). We consider their computational complexity and compare their performance with respect to the Mean Optimal Subpattern Assignment (MOSPA) statistic in a scenario involving closely-spaced targets.

关键词： Detection and tracking algorithms Target detection Monte Carlo methods Computer simulations Error analysis Time metrology algorithm development Computing systems Data processing Signal processing

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A new approach to limited angle tomography using the compressed sensing framework

A new approach to limited angle tomography using the compres...

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Conference on Medical Imaging - Physics of Medical Imaging

作者： Ritschl, Ludwig Bergner, Frank Kachelriess, Marc Univ Erlangen Nurnberg IMP D-91052 Erlangen Germany

ISBN: (纸本)9780819480231

The limited angle problem is a well-known problem in computed tomography. It is caused by missing data over a certain angle interval, which make an inverse Radon transform impossible. In daily routine this problem can arise for example in tomosynthesis, C-arm CT or dental CT. In the last years there has been a big development in the field of compressed sensing algorithms in computed tomography, which deal very good with incomplete data. The most popular way is to integrate a minimal total variation norm in form of a cost function into the iteration process. To find an exact solution of such a constrained minimization problem, computationally very demanding higher order algorithms should be used. Due to the non perfect sparsity of the total variation representation, reconstructions often show the so called staircase effect. The method proposed here uses the solutions of the iteration process as an estimation for the missing angle data. Compared to a pure compressed sensing-based algorithm we reached much better results within the same number of iterations and could eliminate the staircase effect. The algorithm is evaluated using measured clinical datasets.

关键词： Image segmentation Reconstruction algorithms Image processing algorithms and systems Compressed sensing Computed tomography Data analysis Tomography algorithm development Radon transform Bone

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