The influence of OH groups on laser performance in phosphate glasses

Because of the influence of OH groups in phosphate glasses on the radiation of rare-earth ions, the laser performance is degraded. The laser efficiency and the small signal gain experiment of several phosphate glass samples have been done, the concentration of OH groups in glasses was calculated from the measured absorption coefficient at 3.47 μm. It is shown that the concentration of OH groups in phosphate glasses can seriously influence the laser output characteristics, and the OH groups have worse influence on the laser amplifier than laser oscillator.

Statistiques de pêche en Lagune Aby (Côte d'Ivoire): la pêche a l'epervier (1988)

Cast net fishing is a relatively important socio-economíc activity in Aby lagoon. About 516 fishermen practice this activity for an annual total production estimated at 336 millions CFA, which represents 54,000 CFA per month. The catches are essentially composed of Cichlidae (88,7 %) and Mugilidae (2,8 %). The annual production represents 15 % of that of other types of gears used (beach seines, syndicat seines and gill nets).

导模法生长晶体研究进展

导模法是一种极具应用潜力的晶体生长方法,具有生长速度快,加工成本低的优点,广泛用于生长各种形状的晶体。对导模法的原理、特点和发展历史进行了简单介绍,着重论述了导模法在生长有形蓝宝石和硅晶体中的发展和应用,对目前导模法生长晶体过程中存在的问题做了简单的介绍。

Effects of CO2 laser conditioning of the antireflection Y2O3/SiO2 coatings at 351 nm

Y2O3/SiO2 coatings were deposited on fused silica by electron beam evaporation. A continuous wave CO2 laser was used to condition parts of the prepared samples at different scanning speeds in the air. LAMBDA 900 spectrometer was used to investigate the changes of the transmittance and residual reflection spectrum. A Nomarski microscope under dark field was used to examine the changes of the micro defect density. The changes of the surface roughness and the microstructure of the film before and after conditioning were investigated by AFM and X-ray diffraction, respectively. We found that laser-induced damage threshold (LIDT) of the films conditioning at 30 mm/s scanning speed was increased by more than a factor of 3 over the thresholds of the as-deposited films. The conditioning effect was correlated with an irradiation-induced decrease of the defect density and absorption of the films. (c) 2005 Elsevier B.V. All rights reserved.

Soluciones pragmáticas en el campo privado para la cobertura de dependencia en España

336 p.

"Construcción estética de la realidad". El problema de la constancia cromatica y percepción del color.

640 p.

HfO2的纯度对紫外多层膜反射率的影响

用辉光放电质谱法和二次离子质谱仪测定了两种HfO2材料及它们相应的单层膜中的杂质含量，结果发现，无论是在体材料中还是在用电子束蒸发技术沉积的材料单层薄膜中，ZrO2都是这两种HfO2材料中最主要的杂质。而且，这两种HfO2材料中Zr含量的差别远远大于Ti、Fe含量的差别，这说明Zr含量的差别正是引起两种HfO2膜层光学性能差别的原因。用这两种不同纯度的HfO2材料与同一纯度的SiO2材料组合，沉积形成266nm的紫外反射镜，实验结果表明这两种反射镜的反射率分别在99.85% 和 99.15%左右。这个结果与依据单层膜得出的光学常数所设计的结果符合的很好。

Variations in eastern North Pacific demersal fish biomass based on the U.S. west coast groundfish bottom trawl survey (2003–2010)

In response to declining biomass of Northeast Pacific groundfish in the late 1990s and to improve the scientific basis for management of the fishery, the Northwest Fisheries Science Center standardized and enhanced their annual bottom trawl survey in 2003. The survey was expanded to include the entire area along the U.S. west coast at depths of 55–1280 m. Coast-wide biomass and species richness significantly decreased during the first eight years (2003–10) of this fishery-independent survey. We observed an overall tendency toward declining biomass for 62 dominant taxa combined (fishery target and nontarget species) and four of seven subgroups (including cartilaginous fish, flatfishes, shelf rockfishes, and other shelf species), despite increasing or variable biomass trends in individual species. These decreases occurred during a period of reduced catch for groundfish along the shelf and upper slope regions relative to historical rates. We used information from multiple stock assessments to aggregate species into three groups: 1) with strong recruitment, 2) without strong recruitment in 1999, and 3) with unknown recruitment level. For each group, we evaluated whether declining biomass was primarily related to depletion (using year as a proxy) or environmental factors (i.e., variation in the Pacific Decadal Oscillation). According to Akaike’s information criterion, changes in aggregate biomass for species with strong recruitment were more closely related to year, whereas those with no strong recruitment were more closely related to climate. The significant decline in biomass for species without strong recruitment confirms that factors other than depletion of the exceptional 1999 year class may be responsible for the observed decrease in biomass along the U.S. west coast.