激光与透明类非金属材料相互作用的实验研究

实验验证了激光在透明类材料内部聚焦并进行切割的可行性 ,得出了激光参数与扫描速度匹配的一般性原则。本文的结果在工艺品制作等方面可以开拓激光的应用范围     

An Alternative Method to Analyze Field Distribution in Curved Dielectric Waveguides

A simple and effective method is proposed to analyze the field distribution of a curved dielectric waveguide with rectangular cross-section. Numerical results are compared with the measured values. It is shown that the present approach is effective and reliable.     

Analysis of the time response of multiconductor transmission lineswith frequency-dependent losses by the method ofconvolution-characteristics

A new method for analysis of the time response of multiconductor transmission lines with frequency-dependent losses is presented. This method can solve the time response of various kinds of transmission lines with arbitrary terminal networks. Particularly, it can analyze nonuniform lines with frequency-dependent losses, for which no effective method for analyzing their time response exists. This method starts from the frequency-domain telegrapher's equations. After decoupling and inversely Fourier transforming, then a set of decoupled time-domain equations including convolutions are given. These equations can be solved with the characteristic method. The results obtained with this method are stable and accurate. Two examples are given to illustrate the application of this method to various multiconductor transmission lines     

金刚石薄膜的红外增透性

以 CH_3COCH_3/H_2为工作气体,用 HFCVD 方法,制备出适用于红外光学的金刚石薄膜。用 SEM 观察到了所制备膜的表面晶形。讨论了金刚石薄膜的红外增透性。     

内磁校正FCRT扇形失真方案实验报告

本文介绍了扁平CRT扇形失真内磁校的两个方案,通过在高真空动态系统内的实验来研究方案的可行性和有效性,并对比了两个方案的优劣,提出了改进和优良的方向。     

气象环境监测远程数据采集系统

针对小区域范围气象环境监测问题,设计了一种气象环境检测远程数据采集系统。该系统以MSP430单片机为控制核心,利用多种气象环境传感器采集相关信息参数,并通过NRF24L01无线收发模块和GSM通信模块实现了对所测气象环境数据的远程无线传输。实验结果表明,该采集系统实现了小区域气象环境参数的实时无线监测,测量精度高,稳定性好。     

定向凝固镍基高温合金的塑性变形与γ′相中的位错结构

本文利用透射电镜观察了定向凝固高温合金DS Rene80在拉伸及蠕变时的位错亚结构。试验结果表明:在低于760℃拉伸时,切割γ′粒子的是在{111}面上夹有APB的(1/2)〈110〉位错对。在不低于760℃拉伸时,切割γ′粒子的是在{111}面上夹有超点阵内禀层错(SISF)γ(1/3)〈112〉不全位错;这些不全位错在大应力的作用下于{111}面上将分解为一根(1/2)〈110〉螺位错和一根(1/6)〈112〉刃位错,并在其间夹有一个APB。在760℃,618MPa条件下蠕变时,切割γ′粒子的是在{111}面上夹有SISF的(1/3)〈112〉不全位错;这些不全位错此时不分解。与此同时,亦有(1/2)〈110〉位错对切割γ粒子。在980℃,190MPa条件下蠕变时,则无γ′粒子被切割的现象。在760℃,618MPa及980℃,190MPa条件下蠕变至第二阶段时,在γ/γ′界面上都形成了二维位错网络墙,墙上位错的攀移是合金形变的控制因素。第二阶段蠕变速率(ε)与立方γ′粒子的尺寸(α)和体积分数(V_f)的关系符合ε∝α/V_f~(2/3)     

Mode excitation theory and experiment of single-mode fiber directional coupler with strong coupling

The mode excitation theory is presented to analyze single-mode optical fiber directional couplers with transverse strong coupling, which either the weakly coupling theory or the ray theory fails to expound. By using the equivalence between the waveguides with square and circular cross sections, regarding the coupling zone of the coupler as a single waveguide, the excitation coefficients of the propagation modes in the coupling zone excited by the modes in the input waveguide have been evaluated. The theoretical coupling amount and insertion loss have been studied. Using a special monitoring technique to control the coupling length, several couplers with various coupling amounts have been made by the polishing method. The spectral characteristic of the coupling amount has been measured and compared with the theoretically inferred result. The two are found to agree with each other. The offset effect on the coupling amount has also been measured and it is different from that of the weak coupling device-the Stanford coupler.     

Switchable multiwavelength erbium-doped fiber laser with cascadedfiber grating cavities

We propose a new concept to produce switchable multiwavelength oscillations with a cascaded fiber Bragg grating overlapping cavity erbium-doped fiber laser. The laser can be designed to operate in multiwavelength or in wavelength switching modes. The different lines have different thresholds. For three-wavelength oscillation, the output powers are linear or piecewise linear functions of the input pump power. An output with a variation of only 1.5 dB has been achieved with an input pump power of 100 mW. For wavelength switching, three single-wavelength and two dual-wavelength operation regions have been obtained toy adjusting the input pump levels     

Performance of a large liquid argon shower detector used at Fermilab

Details of the construction and operation of a lead, liquid argon electromagnetic calorimeter used in Fermilab experiment E515 are presented. The system had an active projected area of 1.2×2.4 m². Its performance in low intensity electron beams and in exposure to intense, high multiplicity 200 GeV/c π^? Be interactions are described.