960 resultados para applied optics


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The basic elements of Bragg-Fresnel multilayer optics are multilayer gratings. In this paper, the fabrication process for the simplest Bragg-Fresnel multilayer optics is given; the diffraction measurements at 8-keV x rays of multilayer gratings are presented; and the measurement results in the diffraction spectrum are analyzed and discussed in detail. (C) 1996 Society of Photo-Optical Instrumentation Engineers.

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We describe a nonpolarizing filter design at oblique incidence and a polarizing filter design at normal incidence that use a uniaxially anisotropic layer. The phase thicknesses and the optical admittances of 14 the layers are compensated for by the birefringent properties of a thin film at oblique incidence. This concept can be applied to the design of nonpolarizing bandpass and edge filters at oblique incidence and of polarizing beam splitters at normal incidence. Besides, the dependence of narrow-bandpass filters on normal incidence is discussed. (c) 2005 Optical Society of America.

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A novel design for dielectric anisotropic mirrors with birefringent thin films for normal incidence is presented. This mirror consists of a stack of quarter-wave biaxial layers. The biaxial anisotropic layers can be fabricated by oblique deposition. The reflectance is different for two linear polarizations of light incidence on the mirrors. As a numerical example, the design is carried out on glass with TiO2 and ZrO2. These thin films could be applied to anisotropic reflective devices for lasers.

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采用Berreman特征矩阵方法,通过数值计算研究了双折射薄膜的反射、透射等光谱响应特性。依据电磁场理论的电场分量、磁场分量的界面连续条件,推导了光波在各向异性双轴薄膜中的Berreman转移矩阵,用以分析含有各向异性介质层的复杂薄膜系统的光学性质。这些矩阵递推关系包含了界面处的多点反射,适用于一般的各向异性的多层膜系统,包括入射媒质或基底为各向异性的情况。在文中给出了各向同性入射媒质双轴各向异性膜层一各向同性基底薄膜系统的计算结果,验证了该计算方法的可行性,以此作为进一步研究各向异性薄膜和相关光学薄膜器

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A method for the design of an all-dielectric nonpolarizing prism beam splitter utilizing the principle of frustrated total internal reflection is reported. The nonpolarizing condition for a prism beam splitter is discussed, and some single layer design examples are elaborated. The concept can be applied to a wide range of wavelengths and arbitrary transmittance values, and with the help of a computer design program examples of 400-700 nm, T-p = T-p = 0.5 +/- 0.01, with incident angles of 45 degrees and 62 degrees are given. In addition, the sensitivity and application of the design are also discussed. (c) 2006 Optical Society of America.

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A method for the control of polarization for a broadband dichroic filter was reported and some design examples were elaborated. This method could be applied over a wide range of wavelengths and a wide range of polarizations in the transmission region. A nonpolaiizing broadband dichroic filter and a broadband dichroic filter with certain polarization were designed and fabricated by electron beam evaporation with ion beam assisted deposition. The experimental spectral performances showed good agreement with their theoretical curves. In addition, the application of the method was discussed. (c) 2007 Optical Society of America

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A generalized Bayesian population dynamics model was developed for analysis of historical mark-recapture studies. The Bayesian approach builds upon existing maximum likelihood methods and is useful when substantial uncertainties exist in the data or little information is available about auxiliary parameters such as tag loss and reporting rates. Movement rates are obtained through Markov-chain Monte-Carlo (MCMC) simulation, which are suitable for use as input in subsequent stock assessment analysis. The mark-recapture model was applied to English sole (Parophrys vetulus) off the west coast of the United States and Canada and migration rates were estimated to be 2% per month to the north and 4% per month to the south. These posterior parameter distributions and the Bayesian framework for comparing hypotheses can guide fishery scientists in structuring the spatial and temporal complexity of future analyses of this kind. This approach could be easily generalized for application to other species and more data-rich fishery analyses.

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Background: In contrast with the recommendations of clinical practice guidelines, the most common treatment for anxiety and depressive disorders in primary care is pharmacological. The aim of this study is to assess the efficacy of a cognitive-behavioural psychological intervention, delivered by primary care psychologists in patients with mixed anxiety-depressive disorder compared to usual care. Methods/Design: This is an open-label, multicentre, randomized, and controlled study with two parallel groups. A random sample of 246 patients will be recruited with mild-to-moderate mixed anxiety-depressive disorder, from the target population on the lists of 41 primary care doctors. Patients will be randomly assigned to the intervention group, who will receive standardised cognitive-behavioural therapy delivered by psychologists together with usual care, or to a control group, who will receive usual care alone. The cognitive-behavioural therapy intervention is composed of eight individual 60-minute face-to face sessions conducted in eight consecutive weeks. A follow-up session will be conducted over the telephone, for reinforcement or referral as appropriate, 6 months after the intervention, as required. The primary outcome variable will be the change in scores on the Short Form-36 General Health Survey. We will also measure the change in the frequency and intensity of anxiety symptoms (State-Trait Anxiety Inventory) and depression (Beck Depression Inventory) at baseline, and 3, 6 and 12 months later. Additionally, we will collect information on the use of drugs and health care services. Discussion: The aim of this study is to assess the efficacy of a primary care-based cognitive-behavioural psychological intervention in patients with mixed anxiety-depressive disorder. The international scientific evidence has demonstrated the need for psychologists in primary care. However, given the differences between health policies and health services, it is important to test the effect of these psychological interventions in our geographical setting.

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Formal decision analysis was applied to the management of loco (Concholepas concholepas, Fam. Muricidae) in Chile, 29-35 degrees S. Four interested groups were considered "Fishers", "Scientists", "Buyers" and the "State", along with three fishing effort levels and four subobjectives. The method was found to encourage the emergence of a consensus (here: halving of effort), and is recommended for use in other fisheries.

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Video technology has been used as a tool in research for many years. However, its widespread use as a fisheries management tool has been limited due to its relatively high cost. This is changing as video technology becomes a household commodity now widely available throughout the world.