共查询到20条相似文献,搜索用时 31 毫秒
1.
This work designs a type of line-defect photonic crystal waveguide (PCW) called hypoellipse PCW (HPCW) that considers two conflicting issues: group index and bandwidth. To do so, the recent multi objective framework called MoMIR is employed. A wide range of designs obtained demonstrates the advantage of considering group index and bandwidth simultaneously when designing HPCWs. Comparison of the proposed HPCW with the current best PCWs shows a nearly 7% improvement over the latter in terms of normalized delay-bandwidth product (NDBP). Analysis of the results reveals some of the physical rules about the structure of the HPCW. Finally, optical pulse propagation in obtained HPCWs and the process of designing an optical buffer by using an obtained design are explained. 相似文献
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不同病害胁迫下大豆的光谱特征及识别研究 总被引:3,自引:0,他引:3
在英国诺丁汉大学Sutton Bonington校区(52.8°N, 1.2°W)实测感染锈病与普通花叶病大豆的单叶光谱数据,利用连续统去除法对原始光谱数据进行处理,筛选对病害及锈病严重度敏感的波段,构建植被指数对感染锈病与普通花叶病及不同严重度锈病的大豆进行识别研究。研究发现普通花叶病胁迫下的大豆光谱反射率在可见光区域均大于健康大豆的,而锈病胁迫的大豆光谱反射率在绿光区随病情严重度增加而减小,在红光区随病情严重增强而增大。根据大豆光谱变化特征设计了一个植被指数R500×R550/R680对大豆病害进行识别,通过计算不同病害及不同严重度之间的J-M距离对指数识别病害能力进行检验,结果表明指数R500×R550/R680能够较好的识别出大豆锈病与普通花叶病,且该指数在识别大豆锈病严重度方面也有较强的能力。研究结果对农作物病害遥感监测与防治具有重要的理论价值与实际应用意义。 相似文献
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We present a concept of a wide-angle, lightweight, optical see-through head-mounted display (HMD) using free-form optics tiling. Free-form optics tiling can potentially address several critical problems in existing tiled HMD designs that use rotationally symmetric optics. The optical design of our tiled optical see-through HMD achieves a field of view (FOV) of 56° × 45° and an angular resolution of 3.2 arcmin with two display channels. We demonstrate a proof-of-concept prototype and present some of its manufacturing details. The FOV can be further enlarged by tiling more display channels together at their bottom and side surfaces. 相似文献
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We describe a method of optical refocusing for high numerical aperture (NA) systems that is particularly relevant for confocal and multiphoton microscopy. This method avoids the spherical aberration that is common to other optical refocusing systems. We show that aberration-free images can be obtained over an axial scan range of 70 mum for a 1.4 NA objective lens. As refocusing is implemented remotely from the specimen, this method will enable high axial scan speeds without mechanical interference between the objective lens and the specimen. 相似文献
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本文基于ybar-y图, 建立了计算光学系统一阶结构的数学模型, 并利用粒子群优化算法对模型进行了求解, 可以自动优化出各种光学系统的一阶结构. 编写了一套含图形用户界面(GUI)的软件, 将光学系统的基本设计要求进行处理后导入GUI, 求解之后利用商用光学设计软件如ZEMAX等, 将一阶结构转换为实际透镜结构, 然后经过透镜优化, 就可以设计出满足要求的光学系统. 根据本文所提出的光学结构计算方法, 首先进行了1300万像素手机摄像物镜的设计, 该物镜使用了4片非球面, 各项性能指标能够满足设计要求. 然后设计出一套头盔显示光学系统的目镜, 使用了两片非球面透镜实现了90°的视场角, 其他的性能指标也都满足要求. 两类光学系统的设计实例验证了该方法是一种可靠的光学系统一阶结构获取方法. 相似文献
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Through researching and validating, a set of optical designs using a diffractive optical element (DOE) and optimization process has been derived in this paper. We put forward a set of theories to solve the numerous quality issues in imaging and applied it to an optical design. For an optical design to be successful, it must comply with the standards of the optical system. Optical designers must also take into consideration imaging quality, wherein the most influential aspects are chromatic aberration and monochromatic aberration. We complied with systemic standards such as effective focal length and total system length. Diffractive Optical Element, based on the theory of wave phase difference, takes advantage of negative Abbe number, which might significantly eliminate chromatic aberrations of optics. Following the advanced technology applied to micro lens and etching process, precisely made micro DOE element now is possible to be manufactured in a large number. A 350× zoom lens with DOE is demonstrated in the proposal. The results show that regardless of whether chromatic aberration is axial or longitudinal, issues concerning the optical lens's chromatic aberration could be significantly reduced. 相似文献
7.
Zentgraf T Dorfmüller J Rockstuhl C Etrich C Vogelgesang R Kern K Pertsch T Lederer F Giessen H 《Optics letters》2008,33(8):848-850
We investigate the local optical response of split-ring resonator-(SRR)-based metamaterials with an apertureless scanning near-field optical microscope. By mapping the near fields of suitably resonant micrometer-sized SRRs in the near-infrared spectral region with an uncoated silicon tip, we obtain a spatial resolution of better than lambda/50. The experimental results confirm numerical predictions of the near-field excitations of SRRs. Combining experimental near-field optical studies with near- and far-field optical simulations provides a detailed understanding of resonance mechanisms in subwavelength structures and will facilitate an efficient approach to improved designs. 相似文献
8.
The need for increasingly high-speed digital optical systems and optical processors demands ultra-fast all-optical logic and arithmetic units. In this paper, we combine the attractive and powerful parallelism property of the modified signed-digit (MSD) number representation with the ultra-fast all-optical switching property of the semiconductor optical amplifier and Mach-Zehnder interferometer (SOA-MZI) to design and implement all-optical MSD adder/subtracter circuits. Non-minimized and minimized techniques are presented to design and realize efficient circuits to perform arithmetic operations. Several all-optical circuits’ designs are proposed with the objective to minimize the number of the SOA-MZI switches, the time delay units in the adders, and other optical elements. To use the switching property of the SOA-MZI structure, two bits per digit binary encoding for each of the trinary MSD digits are used. The proposed optical circuits will be very helpful in developing hardware modules for optical digital computing processors. 相似文献
9.
During the design process of Blu-ray disc optical pick-up (BD OPU), the optical system and the collimator lens design is especially important. This paper designs an optical system and some lenses for the BD OPU, including collimator lens, beam shaping lens for laser beam shaping, and cylinder lens for signal detecting. In this OPU, we use a triplet lens to collimate the laser beam. At the same time, we build a series of assembly jigs to make sure that each lens can be put into the OPU basement properly. At last, we get the reading spot image and S-curve photo of OPU, which can be used to read Blu-ray disc (BD). 相似文献
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Trapping force of an optical tweezers system with an oil immersion objective is calculated with a ray-optics model. Results indicate that the trapping force will be decreased as a result of the introduction of spherical aberration, which is caused by the refractive mismatch between objective oil and water, when the sample manipulated is suspended in a water solution. The effect of spherical aberration will be serious when the detection depth of the optical tweezers is enhanced. 相似文献
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New designs for gas cells are presented that incorporate transmissive or reflective optical diffusers. These components offer
simple alignment and can disrupt the formation of optical etalons. We analyse the performance–limiting effects in these cells
of random laser speckle (both objective and subjective speckle), interferometric speckle and self-mixing interference, and
show how designs can be optimised. A simple, single pass transmissive gas cell has been studied using wavelength modulation
spectroscopy to measure methane at 1651 nm. We have demonstrated a short-term noise equivalent absorbance (NEA, 1σ) of 2×10−5, but longer term drift of up to 3×10−4 over 22 hours. 相似文献
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Design optimization of broadband extreme ultraviolet polarizer in high-dimensional objective space 下载免费PDF全文
Shang-Qi Kuang 《中国物理 B》2022,31(7):77802-077802
With the purpose of designing the extreme ultraviolet polarizer with many objectives, a combined application of multi-objective genetic algorithms is theoretically proposed. Owing to the multi-objective genetic algorithm, the relationships between different designing objectives of extreme ultraviolet polarizer have been obtained by analyzing the distribution of nondominated solutions in the four-dimensional objective space, and the optimized multilayer design can be obtained by guiding the searching in the desired region based on the multi-objective genetic algorithm with reference direction. Compared with the conventional method of multilayer design, our method has a higher probability of achieving the optimal multilayer design. Our work should be the first research in optimizing the optical multilayer designs in the high-dimensional objective space, and our results demonstrate a potential application of our method in the designs of optical thin films. 相似文献
16.
This paper reviews recent progress in the nascent field of semiconductor optical fibres, from the fundamentals through to device demonstration. The incorporation of semiconductor materials into both the step‐index and microstructured fibre geometries provides a route to introducing new optoelectronic functionality into existing glass fibre technologies. Herein, the various fabrication methods that have been developed as of to date are described, and their compatibility with the different semiconductor materials and fibre designs discussed. Results will be presented on the optical transmission properties of several fibre types, with particular attention being paid to the observation of nonlinear propagation in silicon core fibres. Finally, some speculation regarding the future prospects and applications of this new class of fibre will be provided. 相似文献
17.
In this paper, we present improved all-optical circuits that implement ultra-fast adders based on the carry-free property of the modified signed-digit (MSD) number representation. The all-optical realizations are based on semiconductor optical amplifier (SOA) and Mach-Zehnder interferometer (MZI) switches, which represent one of the most promising solutions due to their compact size, thermal stability and low power operation. Several all-optical circuit designs are proposed with the objective to minimize the number of the SOA-MZI switches, the time delay in the adders and some other optical elements. The proposed circuits are more efficient comparing to previously published ones in terms of the number of optical components (less by 50%) as well as the operational speed (faster by 50%). 相似文献
18.
Y. Zhang T. M. Benson P. Sewell A. Vukovic D. Zhang W. J. Pan A Loni D. Furniss A. B. Seddon 《Optical and Quantum Electronics》2006,38(1-3):97-110
This paper presents our recent simulation results and novel designs of single mode large cross-section glass-based waveguides for photonic integrated circuits (PICs). Simulations were performed using an in-house Finite Difference (FD) based mode solver and the FD Beam propagation Method (FD-BPM). Our simulation results show that this innovative technology could provide a simplified means to couple optical energy efficiently between optical components in a single chip. This would provide the base for the future large-scale integration of optical components in PICs. The novel idea of using single mode large cross-section glass-based waveguides as an optical integration platform is an evolutionary innovative solution for the monolithic integration of optical components, in which the glass-based structures act both as waveguides and as an optical bench for integration. This allows easy and efficient optical coupling between optical components and optical fibres, removing costly and tedious alignment problems and considerably reducing optical coupling losses in PICs. We expect that the glass-based waveguide PICs technology will enable the emergence of a new generation of compact, reliable, high speed, and multifunctional devices. 相似文献
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