强辐射传热节能的多功能炉衬

采用强辐射传热节能技术构成了多功能炉衬工业炉,多功能炉衬是实施强辐射传热节能技术的“载体”。多功能炉衬组成的核心是工业标准黑体,其发射率为0．96。“多功能”是：①节能率为20％～30％;②炉温均匀性显著改善;③炉衬寿命延长一倍以上;④炉子增产10％～20％;⑤具有环保效应。强辐射传热的多功能炉衬是节能技术的突破性进展,具有国际竞争力。     

镜面反射目标激光雷达截面的估算方法

为了解决镜面反射目标激光雷达截面的工程计算问题,本文从激光雷达截面的定义出发,在具体分析镜面反射目标激光散射特性的基础上,提出了一种简便的适用于镜面反射目标的激光雷达截面的工程估算方法,该方法仅利用目标有效照射面积、散射光束发散角和目标后向反射比就可以估算得到镜面反射目标的激光雷达截面.本文还将该方法应用于两类典型的镜面反射目标,即激光角反射器目标和"猫眼"目标,得到了相应的激光雷达截面估算公式.该法计算结果与实测一致,可用于镜面反射目标激光雷达截面的工程计算.     

单向激励源在TD-BPM中的应用

把单向激励源应用到隐式时域光束传播方法(TD- BPM)中,结合交替方向隐式方法(ADIM)及Grank- Nicho-son差分原理,给出了单向激励源在隐式TD- BPM中的具体实现方法.通过该方法可以方便地得到各种有反射结构的反射场和总场,在模拟计算不连续界面的反射、透射问题中有重要的作用.通过几个基本问题得到了该方法的各种计算结果,验证了该方法的有效性     

对交联型极化聚合物交联温度的实时测量

交联型聚合物要取得良好的极化效果,要求尽量保证极化取向过程与交联过程的同时进行。准确界定交联过程发生的温度段对于极化效果至关重要,为此提出了一种实时测量交联型极化聚合物交联温度的方法。实验利用基于衰减全反射原理制作的CCD监控系统,监控了交联型聚合物聚氨酯升温过程中薄膜厚度以及折射率的变化。发现在80℃附近以及130℃附近,由于聚氨酯发生交联反应所带来的影响,厚度以及折射率曲线斜率均发生突变,由此得出聚氨酯的交联温度范围即最佳极化温度范围为80℃-130℃。界定交联过程的温度范围,有助于优化交联型聚合物材料的极化条件。     

地形对基于波瓣分裂的米波雷达测高方法的影响

针对基于波瓣分裂的米波雷达“比相比幅”测高方法,研究地形对米波雷达测高的影响。说明不同介质的平坦地面反射系数,分析影响粗糙地面反射系数的各种因素,讨论不同地面反射系数对高度测量精度的影响。阐述地面几何反射点的计算方法,解释地面有效反射区的范围及其在测高中的应用,探讨漫反射信号产生原因及其对基于波瓣分裂测高方法的影响。     

Fabry-Perot Temperature Sensor for Quasi-Distributed Measurement Utilizing OTDR

A quasi-distributed Fabry-Perot fiber optic temperature sensor array using optical time domain reflectometry （OTDR） technique is presented. The F-P sensor is made by two face to face single-mode optical fibers and their surfaces have been polished. Due to the low reflectivity of the fiber surfaces, the sensor is described as low Fresnel Fabry-Perot interferometer （FPI）. The working principle is analyzed using twobeam optical interference approximation. To measure the temperature, a certain temperature sensitive material is filled in the cavity. The slight changes of the reflective intensity which is induced by the refractive index of the material was caught by OTDR. The length of the cavity is obtained by monitoring the interference spectrum which is used for the setting of the sensor static characteristics within the quasi-linear range. Based on our design, a three point sensor array are fabricated and characterized. The experimental results show that with the temperature increasing from -30℃ to 80℃, the reflectivity increase in a good linear manner. The sensitivity was approximate 0.074 dB℃. For the low transmission loss, more sensors can be integrated.     

External Optical Feedback Induced Noise in DFB Fiber Laser Sensor System

External optical feedback effects due to reflection, Rayleigh backscattering and coherent Rayleigh backseattering in fiber distributed feedback （DFB） fiber laser sensor system have been investigated. If the feedback intensity exceeds critical amount, excess noise would be induced in the demodulator. The maximum tolerable intensity back-reflection coefficient Rc and backscattering coefficient Sc into a fiber DFB laser with lead fiber length from I m to 37.5 km before the onset of instabilities are shown. Rc is found to decrease with increasing lead fiber length while Sc was relatively invariable with varying fiber length. The coherent Rayleigh backscattering （CRBS） would induce neglectable noise with a lead fiber exceeding 13.5 kin. To eliminate these noises, one or two isolators should be incorporated in the system.     

高功率激光辐射近场鬼点反射对激光器损伤及抑制方法研究

高功率固体激光系统中的光学透镜对激光束的残余反射,可形成能量较大的鬼光束,极易对元器件及激光器造成损害,研究了高功率激光装置中的鬼点反射及其带来的破坏影响,给出了避开鬼点反射损伤的方法,可为高功率激光装置中透镜的设计提供参考．     

Design of objective lens with reflective spherical Fresnel zone plate

An objective lens composed of a spherical Fresnel zone plate mirror and aspheric mirrors is designed.The Fresnel zone plate with a spherical shape is analyzed, and the method to approximately replace the aspherical mirror with spherical Fresnel zone plate is deduced. The objective lens is designed with a single spherical Fresnel zone plate mirror and three aspherical mirrors. Under the condition of 100 × magnification,2.5 Fresnel number and 120° field angle, the modulation transfer function can reach above 40% at 0.6 line pairs/mm on the magnification side, and the distortion is less than 2.2%. This method can provide a reference for the application of Fresnel zone plate in visible light imaging, and has a bright future with the continuous development of the fabrication technique of Fresnel devices.     

Structural Analysis of CdTe Hetero-epitaxy on (211) Si

X-ray diffraction full-width at half-maximum (XRD FWHM), reflection high-energy electron diffraction (RHEED), and atomic force microscopy (AFM) indicate a mosaic structure for molecular-beam epitaxy (MBE) (211)B CdTe/Si. AFM measurements indicate long, thin, small-angle-disoriented grains for CdTe/Si epilayers. These disoriented grains are ~1 μm in the [] direction and are ~40 nm in the [] direction. The RHEED pattern in the [] direction depicts nearly ideal single-crystal periodicity. The RHEED pattern in the [] direction is indicative of small-angle-disoriented crystalline grains. Scanning electron microscopy (SEM), AFM, and XRD measurements all indicate an approximate factor of 10 increase in the Everson etch pit density (EPD) over standard Nomarski microscopy Everson EPD determination.