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IEEE International Conference on Robotics, Biomimetics, and Intelligent Computational Systems (ROBIONETICS)

作者： Keum-Shik Hong Hendrik Santosa School of Mechanical Engineering Pusan National University Busan Korea Department of Cogno-Mechatronics Engineering Pusan National University Busan Korea

Various neuroimaging modalities have appeared to acquire brain signals for developing a brain-computer interface (BCI). In this article, we review studies on different modalities including both invasive and non-invasive techniques for the implementation of BCIs, for brain signals detection, decoding, feature extraction, and classification. We discuss their advantages, disadvantages, and implementation issues to design of BCIs. Finally, we focus on fundamental principles, recent developments, and applications by using optical imaging as a promising modality for BCI applications.

关键词： Wavelength measurement Feature extraction Electroencephalography Magnetic resonance imaging Motion measurement Detectors Artificial neural networks

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design and implementation of multi-layer and multi-bit micro holographic optical data storage employing blue lasers

Design and implementation of multi-layer and multi-bit micro...

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Conference on current developments in Lens design and optical engineering Xiii

作者： Takashima, Yuzuru Hesselink, Lambertus Univ Arizona Coll Opt Sci Tucson AZ 85721 USA

ISBN: (纸本)9780819492036

A zoom objective lens for a multi-layer optical recording has been designed. A newly proposed optical power arrangement enables varying back focal length while focal length invariant by a linear movement of single zooming component. The zoom lens is implemented into multi-layer and multi-bit holographic recording system employing 405 nm blue lasers.

关键词： Objectives optical design Holography Aspheric lenses Lens design optical storage Zoom lenses Distance measurement optical components optical recording

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Efficiency-Droop Suppression by Using Large-Bandgap AlGaInN Thin Barrier Layers in InGaN Quantum-Well Light-Emitting Diodes

IEEE PHOTONICS JOURNAL

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IEEE PHOTONICS JOURNAL 2013年第2期5卷

作者： Liu, Guangyu Zhang, Jing Tan, Chee-Keong Tansu, Nelson Lehigh Univ Dept Elect & Comp Engn Ctr Photon & Nanoelect Bethlehem PA 18015 USA

The electrical and optical characteristics of InGaN quantum-well light-emitting diodes with large-bandgap AlGaInN thin barriers were analyzed with the consideration of carrier transport effect for efficiency droop suppression. The lattice-matched AlGaInN quaternary alloys with different compositions, thicknesses, and positions were employed as thin barrier layers (1-2 nm) surrounding the InGaN QW in LED structures. The increased effective barrier heights of AlGaInN thin barrier led to suppression of carrier leakage as compared to conventional InGaN QW LEDs with GaN barrier only. The current work provides a comprehensive simulation taking into consideration the carrier transport in self-consistent manner, and the finding indicated the use of thin layers of AlGaInN or AlInN barriers as sufficient for suppressing the droop in InGaN-based QW LEDs. The efficiency of InGaN QW LED with the insertion of lattice-matched Al0.82In0.18N thin barrier layers showed the least droop phenomenon at high current density among the investigated LEDs. The thickness study indicated that a thin layer (< 2 nm) of large-bandgap material in the barrier region was sufficient for efficiency droop suppression.

关键词： Efficiency droop light-emitting diodes (LEDs) internal quantum efficiency (IQE) iii-nitride InGaN quantum wells (QWs) thin barrier design

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design and fabrication of imaging optical systems with freeform surfaces

Design and fabrication of imaging optical systems with freef...

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Conference on current developments in Lens design and optical engineering Xiii

作者： Zhang Xin Zheng Ligong He Xin Wang Lingjie Zhang Feng Yu Shuqin Shi Guangwei Zhang Binzhi Liu Qiang Wang Tongtong Changchun Inst Opt Key Lab Opt Syst Adv Mfg Technol Changchun 130033 Peoples R China

ISBN: (纸本)9780819492036

Freeform surfaces provide more degrees of freedom for design of optical systems, and enhance the ability of compensation and correction aberrations. Freeform surfaces are of advantage to balance the unsymmetrical aberrations, especially for the wide-field off-axis optical systems. This paper focus on an off-axis reflective optical system, which focal length is 550mm, F# is 6.5 and field of view (FOV) is 76 degrees. The system adopts some freeform surfaces. We discuss the problems we noticed in processes of design, manufacture, measurement and alignment, and the solutions. At last, the periodical research result and the expected performance are given.

关键词： Freeform surfaces aberrations correction off-axis reflective optical system wide FOV

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Gain in optical Coatings

Gain in Optical Coatings

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Conference on current developments in Lens design and optical engineering Xiii

作者： Macleod, Angus Clark, Christopher Thin Film Ctr Inc Tucson AZ 85716 USA

ISBN: (纸本)9780819492036

The introduction of gain into an optical medium is most easily accomplished by reversing the sign of the extinction coefficient. The theoretical expression for reflectance at a simple boundary between a dielectric, lossless incident medium and a medium with a finite extinction coefficient, however, takes no account of the sign of the extinction coefficient In such an arrangement, therefore, can the presence of gain possibly result in an enhanced reflectance? Opinions in the literature differ but tend to find enhancement beyond the critical angle and none below. This study examines both cases and shows that all results are in fact correct but they are not necessarily stable and it is their stability, or lack of it, that leads to the different results.

关键词： Gain in optical coatings optical coating theory admittance loci with gain

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Finding starting points analytically for optical system optimization

Finding starting points analytically for optical system opti...

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Conference on current developments in Lens design and optical engineering Xiii

作者： Bociort, F. van Grol, P. Delft Univ Technol Opt Res Grp NL-2628 CJ Delft Netherlands

ISBN: (纸本)9780819492036

Understanding the structure of the design space in optical system optimization is difficult, because common human intuition fails when it encounters the challenge of high dimensionality, resulting from the many optimization parameters of lens systems. However, a deep mathematical idea, that critical points structure the properties of the space around them, is fruitful in lens design as well. Here we discuss simple systems, triplets with curvatures as variables, for which the design space is still simple enough to be studied in detail, but complex enough to be non-trivial. A one-to-one correspondence between the possible design shapes and the critical points resulting from a simplified model based on third-order spherical aberration within the framework of thin-lens theory could lead in the future to a new way to determine good starting points for subsequent local optimization.

关键词： saddle point critical point global optimization optical system design

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Novel global optimization algorithms: binary construction and the saddle-point method

Novel global optimization algorithms: binary construction an...

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Conference on current developments in Lens design and optical engineering Xiii

作者： Dilworth, Donald C. Optical Systems Design Inc. (United States)

ISBN: (纸本)9780819492036

This paper describes our experience with global lens optimization using algorithms that can modify an existing lens construction in an optimal way or create an entirely new construction. The binary-search method assembles lens elements according to the bits in a binary number, ensuring that all combinations of power are tested, while the saddle-point method can either add elements to a starting lens or start from scratch. The latter algorithm also naturally leads to a method of removing an element in an optimum way, which can sometimes simplify a lens with no loss of quality.

关键词： Global optimization lens design saddle-point lens optimization PSD algorithm

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Graphically selecting optical components and housing material for color correction and passive athermalization

Graphically selecting optical components and housing materia...

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Conference on current developments in Lens design and optical engineering Xiii

作者： Schwertz, Katie Dillon, Dan Sparrold, Scott Edmund Opt Tucson AZ USA

ISBN: (纸本)9780819492036

This paper will demonstrate a graphical method for selecting a pair of optical components to simultaneously achromatize and passively athermalize an imaging lens for use in a housing with a particular coefficient of thermal expansion. The effort will be presented for a generic spectrum, so readers may apply the method to whatever waveband and set of materials that are of interest. The term "component" is used in place of "material" since this paper will explore combinations of refractive and diffractive optics. The method for creating an achromat with two refractive materials will be reviewed. To create an athermal doublet, or lens that does not change focus under temperature changes, the same color equations are used with a slight modification to include housing thermal effects. The paper will culminate by demonstrating how a set of two materials can be used to both color correct and passively athermalize a single lens;these materials can be quickly chosen to match a particular housing material via nomograph. A sample chart for a common waveband will be demonstrated.

关键词： lens design optical design passively athermal thermal defocus achromatic graphic solution

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Color mixing collimating lamp based on RGB LEDs

Color mixing collimating lamp based on RGB LEDs

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Conference on current developments in Lens design and optical engineering Xiii

作者： Lo, Yi-Chien Moreno, Ivan Chiu, Bo-Chun Chien, Wei-Ting Cai, Jhih-You Chang, Yu-Yu Sun, Ching-Cherng Natl Cent Univ Inst Lighting & Display Sci Dept Opt & Photon Chungli 320 Taiwan

ISBN: (纸本)9780819492036

A novel light luminaire is proposed and experimentally analyzed, which efficiently mixes and projects the tunable light from red, green and blue (RGB) light-emitting diodes (LEDs). Simultaneous light collimation and color mixing is a challenging task because most collimators separate colors, and most color mixers spread the light beam. We performed an experimental study to find a balance between optical efficiency and color uniformity by changing light recycling and color mixing.

关键词： LED color mixing color uniformity optical efficiency luminaire

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design and Fabrication of Nano-pyramid GaAs Solar Cell

Design and Fabrication of Nano-pyramid GaAs Solar Cell

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IEEE Photovoltaic Specialists Conference

作者： Yangsen Kang Dong Liang Yijie Huo Anjia Gu Shuang Li Yusi Chen James Harris Department of Electrical Engineering Stanford University Department of Physics Stanford University Department of Applied Physics Stanford University

ISBN: (纸本)9781479933006

We demonstrate a genetic method to fabricate large-area nano-structure iii-V solar cells with conformal epitaxial growth on pre-patterned substrate. The design, simulation, fabrication, and characterization of a nano-structure gallium arsenide (GaAs) solar cell device are presented. The optical simulation illustrates that the nano-pyramid array is able to suppress the reflection and enhance the absorption in a wide spectrum range. The IV characterization shows that the short circuit current of the nano-pyramid GaAs solar cell with 200 nm thick junction is as high as 18.5 mA/cm~2, which is more than triple of the planar cell. Our results suggest this nano-structure thin film absorber could significantly reduce epitaxial growth cost and increase yield, thus provides a pathway towards high-efficiency and low-cost solar cells.

关键词： Gallium arsenide Photovoltaic cells Thin film nano-structures Light trapping Semiconductor growth

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