小型波长检测型表面等离子体共振分析仪的设计与研制

小型波长检测型表面等离子体共振(SPR)分析仪采用固定光的入射角,监测共振波长变化的测量模式,可进行多波长同时测量.设计并组装了SPR分析仪中的微型光纤光谱仪,采用光导纤维输入被测光,固定全息衍射光栅分光,线阵CCD光电传感器检测,可检测的波长范围是500～900 nm,分辨率0.23 nm.自行编制了控制传感器数据采...     

Nanocrystalline ZnO coated fiber optic sensor for ammonia gas detection

A cladding modified fiber optic sensor coated with nanocrystalline ZnO is proposed for ammonia gas detection. As-prepared and annealed zinc oxide (500 and 1200 °C) samples are used as the gas sensing media. The spectral characteristics of the fiber optic gas sensor are studied for various concentrations of ammonia (0–500 ppm). The sensor exhibits linear variation in the spectral peak intensity with the ammonia concentration. The characteristics of the sensor when exposed to ethanol and methanol gases are also studied for gas selectivity. The time response characteristics of the sensor are reported.     

Investigation of cladding and coating stripping methods for specialty optical fibers

Fiber optic sensing technology is used extensively in several engineering fields, including smart structures, health and usage monitoring, non-destructive testing, minimum invasive sensing, safety monitoring, and other advanced measurement fields. A general optical fiber consists of a core, cladding, and coating layers. Many sensing principles require that the cladding or coating layer should be removed or modified. In addition, since different sensing systems are needed for different types of optical fibers, it is very important to find and sort out the suitable cladding or coating removal method for a particular fiber. This study focuses on finding the cladding and coating stripping methods for four recent specialty optical fibers, namely: hard polymer-clad fiber, graded-index plastic optical fiber, copper/carbon-coated optical fiber, and aluminum-coated optical fiber. Several methods, including novel laser stripping and conventional chemical and mechanical stripping, were tried to determine the most suitable and efficient technique. Microscopic investigation of the fiber surfaces was used to visually evaluate the mechanical reliability. Optical time domain reflectometric signals of the successful removal cases were investigated to further examine the optical reliability. Based on our results, we describe and summarize the successful and unsuccessful methods.     

Influence of l-alanine doping on crystalline perfection, SHG efficiency, optical and mechanical properties of KDP single crystals

Pure and l-alanine (LA) doped single crystals of potassium dihydrogen orthophosphate (KDP) were grown by slow evaporation solution technique (SEST) in aqueous solution at ambient temperature. Powder X-ray diffraction study was done to confirm the crystal system and lattice parameters of KDP. No additional phases were observed at all doping concentrations (1-7.5 mol%), which was further confirmed by FT-Raman spectroscopy analysis. The influence of LA doping on the crystalline perfection was assessed by high-resolution X-ray diffractometry (HRXRD) analysis. HRXRD studies revealed that the grown crystals could accommodate LA at the interstitial positions in the crystalline matrix of KDP up to some critical concentration without any deterioration in the crystalline perfection. Above this concentration, very low angle structural grain boundaries were developed and it seems that the excess LA above the critical concentration was segregated along the grain boundaries. The SHG efficiency was measured using the Kurtz powder technique. The relative SHG efficiency of the crystals was found to be increased with doping concentration up to 5 mol% and above this it decreases. Optical transmission study also revealed the same behavior with enhancement up to 5 mol% concentration and later decreased. The hardness values were found to be increased by increasing the doping concentration.     

基于集成光学的ICF脉冲整形系统

本文对基于集成光学的激光约束核聚变（ＩＣＦ）脉冲整形进行了系统研究,分析了这种新型脉冲整形技术与以往技术相比所具有的优越性能及所包含的关键技术成分,并指出了脉冲整形系统性能的影响因素     

凝固浴温度对纤维素中空纤维膜结构及气体渗透分离性能影响研究

利用新型溶解工艺,在不同的凝固浴温度(0～60℃)下制备了纤维素中空纤维膜,考察了凝固浴温度对纤维素中空纤维膜结晶结构、机械性能和气体渗透分离性能的影响.扫描电镜表征表明凝固浴温度的升高使得纤维素中空纤维膜更加疏松,并且内侧的指状孔变大变多;膜的机械性能随凝固浴温度的升高而变差;XRD谱图显示凝固浴温度对纤维素中空纤维...     

Enumeration of subgroups in the fundamental groups of orientable circle bundles over surfaces

The aim of this paper is to count subgroups of a given index in the fundamental group of an orientable S ¹-bundle over a compact surface. The number of subgroups of index n turns out to be independent of the orientability of the base surface 𝔣, closed or bordered, and is expressed as a linear combination of the numbers of surface subgroups of indices m = n/l l∣n. For a closed base surface of characteristic χ the respective coefficients are equal to l ^–χm+2 or vanish depending on l,n and the Euler number of the S ¹ -bundle.     

Nonlinear optical properties of a Woods–Saxon quantum dot under an electric field

A theoretical study of the effect of the confining potential on the nonlinear optical properties of two dimensional quantum dots is performed. A three-parameter Woods–Saxon potential is used within the density matrix formalism. The control of confinement by three parameters and an applied electric field gives one quite an advantage in studying their effects on the nonlinear properties. The coefficients investigated include the optical rectification, second and third-harmonic generation and the change in the refractive index. Their dependence on the electric field values, dot size and the energy of the incoming photons is studied extensively.It is shown that the Woods–Saxon potential can be used to model the confinement in quantum dots with considerable success.     

原子干涉陀螺仪关键技术与研究进展

从使用需求出发,简单介绍了不同种类陀螺在惯性导航领域可能的发展趋势。从原理上比较原子干涉与光学干涉的异同,阐明了原子干涉高精度测量的优势,并预测原子干涉陀螺仪是下一代超高精度陀螺仪的发展方向。最后对原子陀螺的组成进行了描述,介绍了国际上原子陀螺工程化样机研制的最新进展。     

基于DSP＋POS的机载稳定平台控制系统设计

为消除机栽姿态角扰动对航空遥感的影响,设计了由横滚和方位组成的两轴稳定平台,该平台通过减振器与载机固联隔离高频扰动,通过伺服控制系统隔离低频扰动,并实时跟踪当地水平面和飞行航线。系统以TMS320F2812为核心微处理器,对POS中MEMS陀螺和欧拉角进行采样,将其采样结果经超前一滞后控制算法输出PWM给直流伺服电机,对平台进行实时控制;针对光轴偏移的问题,提出控制模式切换法,即瞬态工作域采用单闭环速度环控制和稳态工作域采用双闭环位置,速度控制消除了光轴漂移现象。最后给出系统仿真及试飞试验结果,结果表明该平台具有良好的抗扰能力和较强的跟踪能力,满足系统的要求。