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HfO_2/SiO_2高反膜、增透膜及偏振膜的1064nm激光损伤特性 总被引:2,自引:0,他引:2
高反膜、增透膜和偏振膜是Nd∶YAG激光器中的关键薄膜元件 ,其抗激光损伤能力直接影响到激光器的输出能量和功率。由于优异的物理化学性能 ,高功率Nd∶YAG激光器的光学薄膜一般采用HfO2 /SiO2 膜料组合镀制 ,因而用此膜料镀制的光学薄膜的激光损伤特性是薄膜工作者重点关注的问题。对光学中心APS15 0 4镀膜机镀制的HfO2 /SiO2 高反膜、增透膜和偏振膜等开展了 10 64nm的激光损伤实验研究 ,用 2 0 0倍的Normaski显微镜详细分析了高反 ,增透和偏振膜的激光损伤图貌 ,发现对于脉宽为 10ns波长的 10 64nm的激光而言 ,高反膜基本表现为孔洞和等离子体烧蚀疤痕 ,孔洞是由薄膜中的节瘤 (nodular)缺陷的激光损伤引起的 ,损伤的能流密度较低 ,为薄膜的零损伤阈值密度。疤痕为薄膜的激光等离子体烧伤引起的 ,尺寸大小与激光能量密度成近似正比。增透膜一般为双面镀 ,分前后膜堆两种情况 ,前膜堆表现为孔洞和疤痕 ,与高反膜相似 ;后膜堆为孔洞型的小圆麻点聚积 ,麻点处的薄膜完全剥落 ,没有疤痕等烧伤痕迹 ,是激光在基片之间形成的驻波电场损毁 ,损伤阈值比前膜堆低 1 5倍 ,决定着增透膜的损伤阈值。偏振膜的低能量密度损伤与增透膜后膜堆相似 ,表现为孔洞型小麻点聚积 ,损伤处未见疤痕等烧蚀痕迹。对薄膜小尺度损? 相似文献
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A new high-T_c (HT_c) rf SQUID working at around 1.3GHz has been developed to avoid electromagnetic interference such as growing mobile communication jamming. This new system works in a frequency range from 1.23 to 1.42GHz (centred at 1.3GHz), which is not occupied by commercial communication. The sensor used in the 1.3GHz rf SQUID is made of a HT_c coplanar superconducting resonator and a large-area HT_c superconducting film concentrator. We have achieved in the 1.3GHz HT_c rf SQUID system a minimal flux noise of 2.5×10^{-5}Φ_0/\sqrt{Hz} and a magnetic field sensitivity of 38fT/\sqrt{Hz} in white noise range, respectively. The effective area of the concentrator fabricated on a 15×15mm^2 substrate is 1.35mm^2. It is shown that the 1.3GHz rf SQUID system has a high field sensitivity. Design and implementation of 1.3GHz HT_c rf SQUID offers a promising direction of rf SQUID development for higher working frequency ranges. 相似文献
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翡翠为一种珍贵的玉石。不同品级的翡翠价值差异巨大,翡翠经充填、染色等处理以提高外观质量,并冒充天然翡翠。鉴别翡翠就显得非常必要。全面收集了市场上常见的A,B,C,不同颜色B+C货翡翠样品,在常规宝石学特征描述的基础上, 进行了三维荧光光谱测试。三维荧光光谱技术是近年发展起来的一门新的荧光分析技术,该技术在宝石学方面还未得到广泛应用。目前主要依赖红外光谱对经充胶处理的宝石进行无损检测,其测试结果会受到样品表面抛光程度及样品透明度的影响,三维荧光光谱技术对样品抛光程度及透明度要求不高,在一定程度上能避免红外光谱由于抛光程度、透明度对测试结果的影响,采用三维荧光光谱技术对市场上不同处理类型翡翠样品的三维荧光光谱特征进行分析, 结果显示:除A货翡翠没有荧光反应外, B货翡翠荧光中心多集中在380 nm(λex)/440 nm(λem),在长波紫外灯下具有中强蓝白色荧光。C货翡翠荧光中心集中在365 nm(λex)/443 nm(λem),在长波紫外光下呈弱紫色荧光,B+C紫色翡翠荧光中心集中在365(λex)/443 nm(λem), 长波紫外光下具有蓝紫色荧光。B+C绿色翡翠荧光峰值主要集中在290(λex)/308 nm(λem),短波紫外光下具有弱蓝白色荧光。B+C黄色翡翠荧光峰值集中在335(λex)/377 nm(λem), 长波紫外光下具有弱绿色荧光。B+C红色翡翠荧光峰值为290(λex)/308 nm(λem),长波紫外光下具有弱绿色荧光。在255 nm激发光源下时,不同处理类型翡翠发光范围集中在紫-蓝区域,发光中心波长呈B+C绿色翡翠>B货翡翠>C货翡翠,在365 nm的激发光源下,翡翠样品的荧光明显强于短波,不同处理类型翡翠发光范围集中在紫-绿区域,发光中心波长呈B+C黄色翡翠>B+C绿色翡翠>B+C紫色翡翠>C货翡翠>B货翡翠的大小关系。三维荧光光谱有助于表征树脂,有机染料及金属染剂, 它能快速有效鉴别不同方法处理的翡翠类型。 相似文献
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试验了一种能够在含水的岩层、土壤甚至海水中建立起无线通信的系统和方法.该系统的关键部件,高灵敏接收前端和接收机使用的是商品级高温超导量子干涉仪(high critical temperature superconducting quantum interference device,HTcSQUID)磁强计和商用高速、高精度数据采集处理系统.目前在从30 Hz到100 kHz频段内,商品级HTcSQUID磁强计可以提供优于100 fT/Hz1/2的内秉磁场噪声谱密度,同时商用数据采集处理系统可通过软件实现对传输信息的调制、采集、解调和分析.利用低频电磁波在导电介质中有较大穿透深度以及HTcSQUID磁强计低频磁场灵敏度高、体积小的特点,对于一种能在地下(岩石和土壤)和水下(海水)环境中使用的可移动式低频无线电通讯系统实现的可行性,进行了初步讨论.使用面积等于1 m2的方形线圈作为测试信号的辐射体(发射天线),将SQUID磁强计的传感器封闭在一个能对超低频测试信号提供较大衰减的电磁屏蔽体中,成功地接收到了发射线圈辐射的99 Hz调幅信号.因此证明,采用HTcSQUID技术,可以在地面与数百米深的地下建立起有实用价值的无线电通信. 相似文献
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Subsurface defect characterization and laser-induced damage performance of fused silica optics polished with colloidal silica and ceria 下载免费PDF全文
This paper mainly focuses on the influence of colloidal silica polishing on the damage performance of fused silica optics. In this paper, nanometer sized colloidal silica and micron sized ceria are used to polish fused silica optics. The colloidal silica polished samples and ceria polished samples exhibit that the root-mean-squared(RMS) average surface roughness values are 0.7 nm and 1.0 nm, respectively. The subsurface defects and damage performance of the polished optics are analyzed and discussed. It is revealed that colloidal silica polishing will introduce much fewer absorptive contaminant elements and subsurface damages especially no trailing indentation fracture. The 355-nm laser damage test reveals that each of the fused silica samples polished with colloidal silica has a much higher damage threshold and lower damage density than ceria polished samples. Colloidal silica polishing is potential in manufacturing high power laser optics. 相似文献
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We present the theoretical investigation of spontaneous magnetization of a coupled 2×2 πring array. It is indicated by free energy calculation that the system has the lowest energy when the four π rings have the full antiparallel configuration. Furthermore, the numerical evaluation results show that the system which favours full antiparallel spontaneous magnetization is a quantum effect deriving from the phase cohering of the superconducting quantum wavefunctions in the four superconducting rings through the shared Josephson junctions. 相似文献
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