用5种不同的电子光学软件对微波管电子枪进行模拟计算

 对TWTCAD微机版、工作站版本、EGUN，CAMEO以及Orprogr电子光学软件背景和特点作了一个简单介绍，并利用其模拟计算了11支不同结构的电子枪。将计算得到的导流系数、射程和注腰半径与实验数据列表对比，结果表明：不同电子光学软件计算不同类型电子枪其计算精度也不一样。在导流系数方面，EGUN和Orprogr的计算精度较高，绝对平均误差分别为7.18%和7.4%；在射程方面，TWTCAD的计算精度最高，绝对平均误差为5.69%；在注腰半径方面，Orprogr与实验值偏差较大，绝对平均误差为47.43%，而工作站版本的计算精度最高，绝对误差仅为2.29%。     

Non-contact optical fibre phased array generation of ultrasound for non-destructive evaluation of materials and processes

The use of non-contact laser techniques for the generation of ultrasound has extended the limits of the application of traditional ultrasonic techniques. This paper focusses on the use of one such non-contact laser technique, known as ‘optical fibre array’, to generate shear and surface waves. The shear wave experimental directivity pattern results are presented and compared with the theoretical results of a single source and an array source. The experimental directivity results for the surface wave are also presented, and compared with the theoretical results. The data show that the array enhances signal generation in the forward direction for both shear and surface waves. The array gain is also discussed. The receiver for the directivity measurements was a contact piezoelectric transducer.     

Design and development of a fiber-optic immunosensor utilizing near-infrared fluorophores

The design and application of a fluorescent fiber-optic immunosensor (FFOI) are reported. The FFOI is utilized for the detection of antibody/antigen binding within the near-infrared (NIR) spectral region. The technique is developed through the combined use of fiber-optic, semiconductor laser-excitation, fluorescence detection, NIR dye, and immunochemical techniques. The antibody is immobilized on the FFOI and utilized as a recognition component for trace amounts of specific antigen. The FFOI is constructed to utilize an antibody sandwich technique. The assay involves the immobilization of the capture antibody on the sensing tip of the FFOI followed by the exposure of the immobilized sensing tip to the antigen. The antigen-coated FFOI is then introduced to a second antibody previously labeled with the NIR dye. Typical measurements are performed in about 15 min. A semiconductor laser provides the excitation (780 nm) of the immune complex. The resulting emission is detected by a silicon photodiode detector (820 nm). The intensity of the resulting fluorescence is directly proportional to the concentration of the antigen. The sensitivity of the analysis reaches 10 ng/ml and the response time is 10–15 min.     

超短光脉冲作用下的二能级原子

考虑到光场的振幅随时间分布的影响时,我们重新研究了光场与二能级原子相互作用的跃迁几率问题。在强光信号作用下,经过一定的数学代换后,上能级几率的求解可归结为类希尔方程求解;在弱光信号作用下,利用转动波近似(RWA),给出了二能级原子跃迁几率的解析表达式,并讨论了几种典型脉冲光场的分布。     

一种多波长窄线宽环形掺铒光纤激光器

本文提出了一种利用多个光纤光栅串接来实现环形掺铒光纤多波长,窄线宽激光器的新颖方法,并在实验中验证了这一设计的合理性,得到了稳定的双波长输出。     

Evidence for pinning by (Sr,Ca)2CuOy particles in partial-melting processed bulk Bi2Sr2CaCu2O8+δ ceramics

Flux distributions of partial-melting processed Bi₂Sr₂CaCu₂O_8+δ ceramics are obtained using magneto-optic imaging. In remanent states (μ₀H_a=0 T), large amounts of trapped flux are observed along (Sr,Ca)₂CuO_y particles embedded in the Bi₂Sr₂CaCu₂O_8+δ matrix. Despite the relatively large size of these particles (up to 30 μm), the pinning effect is similar to that of Y₂BaCuO₅ particles in melt-processed YBa₂Cu₃O_7−δ. Furthermore, we discuss how the pinning capability of non-superconducting particles of different sizes and densities will show up in magneto-optic images.     

Self-mode-locking in a Q-switched Nd: doped silica fibre laser

Operating characteristics of a Q-switched Nd³⁺: doped single-mode silica fibre with a mechanical chopper as a Q-switching device are presented. Peak powers as high as 16 W with pulse duration of 146 ns are demonstrated. Self-mode-locking in Nd³⁺:doped fibre is also reported. An output power of 312 W with a centre pulse duration of 4 ns is observed.     

Cryogenic radiometer based absolute spectral power responsivity calibration of integrating sphere radiometer to be used in power measurements at optical fiber communication wavelengths

This paper covers the absolute spectral power responsivity calibration of spectralon-coated Integrating Sphere Radiometer (ISR) equipped with 3 mm diameter InGaAs photodiode to be used as a transfer standard in fiber optic power measurements against Electrical Substitution Cryogenic Radiometer (ESCR) in Optics Laboratory of National Metrology Institute (TUBITAK UME) of Turkey. The initial uncertainty arising from the use of the Electrically Calibrated Pyroelectric Radiometer (ECPR) as a transfer standard in radiometric scale is 0.5% (k=2), which particularly comes from irregularity in the surface homogeneity of ECPR. In order to eliminate the ECPR step as well as its initial uncertainty contribution in fiber optic power measurements, the calibration application herein was carried out. Moreover power stabilization measurements of DFB laser sources at both 1309.1 nm and 1549.0 nm, the beam size determinations, and spectral analyses of these laser sources as well as spatial and angular dependence of spectral responsivities of the ISR were presented in this paper. The total expanded uncertainties were calculated as 0.283% and 0.315% in the determination of absolute spectral power responsivities of the ISR for 1309.1 nm and 1549.0 nm wavelengths respectively (k=2).     

Comparative study of spectroscopic properties of Er^3＋／Yb^3＋-codoped tellurite glass and fibres under 980nm excitation＊

A tellurite fibre of TeO_{2}－ZnO－La_{2}O_{3}－Li_{2}O glass codoped with 20000 ppm ytterbium and 5000 ppm erbium was fabricated by the suction casting and rod-in-tube technologies. The absorption spectrum of Er^{3+}/Yb^{3+} -codoped bulk glass has been measured. From the Judd－Ofelt intensity parameters, the spontaneous emission probability and radiative lifetime τ_{rad} of Er^{3+}:{}^{4}I_{13/2}→{}^{4}I_{15/2} transition for the bulk glass have been calculated. The emission fluorescence spectra and lifetimes around 1.5μm, and subsequent upconversion fluorescence in the range of 500－700nm were measured in fibres and compared with those in bulk glass. The changes in amplified spontaneous emission with fibre length and pumping power was also measured. It was found that the emission spectrum from erbium in fibres is almost twice as broad as the corresponding spectrum in bulk glass when pumped at 980nm.     

光学非球面凹面零件仿形加工方法的修正

从圆锥体靠模仿形法加工非球面光学零件的基本原理出发,指出加工凸非球面时无原理误差,但加工凹非球面时,只能用圆弧包络法加工。用实心圆锥体靠模时,必然存在误差。解决方法是减小工具的曲率半径,或增加一维数控进行补偿,或使用空心圆锥体仿形。实际应用中前两种方法只能减小误差,不能消除。而采用凹模仿形时,则不存在原理误差。