波分复用薄膜干涉窄带滤光片的设计

总结了波分复用薄膜干涉窄带滤光片的几种设计方法,在此基础上用计算机进行规整系自动设计的方法设计出了50GHz的滤光片,并计算出了它的群延迟.     

波分复用薄膜干涉窄带滤光片的设计

总结了波分复用薄膜干涉窄带滤光片的几种设计方法,在此基础上用计算机进行规整系自动设计的方法设计出了50GHz的滤光片,并计算出了它的群延迟.     

导纳轨迹图解方法在诱导透射滤光片设计中的应用

诱导透射滤光片设计中,金属层厚度的选择是很重要的环节。应用导纳轨迹图解方法,可以确定能诱导出滤光片最大透射率的金属层厚度。与用势透射率概念设计方法相比,采用该方法确定的金属层厚度,可使所设计制作的诱导透射滤光片的峰值透射率更高。实际设计中,可以以此厚度为基础进行调整,使膜系满足设计要求。     

微型低温远红外带通滤光片的研制

论述了微型低温远红外带通滤光片的设计和研制。介绍了该滤光片不同于一般远红外滤光片的研制工艺。测试出了低温下该滤光片中心波长漂移参数，并给出和分折了校准后的测试结果。     

超宽超窄矩形带通滤光片的设计

回顾了带通滤光片的研究应用现状 ,得出要设计超宽超窄的带通滤光片必须采用多腔串置的结构。引入了影响带通滤光片性能的参数 ,并对这些参数进行了分析。设计出了两类性能完全不同的带通滤光片 ,并对它们的特性做了一定的分析。     

超宽超窄矩形带通滤光片的设计

回顾了带通滤光片的研究应用现状,得出要设计超宽超窄的带通滤光片必须采用多腔串置的结构.引入了影响带通滤光片性能的参数,并对这些参数进行了分析.设计出了两类性能完全不同的带通滤光片,并对它们的特性做了一定的分析.     

超宽超窄矩形带通滤光片的设计

回顾了带通滤光片的研究应用现状,得出要设计超宽超窄的带通滤光片必须采用多腔串置的结构.引入了影响带通滤光片性能的参数,并对这些参数进行了分析.设计出了两类性能完全不同的带通滤光片,并对它们的特性做了一定的分析.     

薄膜干涉滤光片单色性的研究与应用

研究了薄膜干涉滤光片的单色性对生化仪和光谱分析仪实现高信噪比的重要性。通过对薄膜干涉滤光片单色性的数学分析,结合实际应用,设计和制作出的高信噪比薄膜干涉滤光片能完全符合生化检测的要求,能正确地反映出不同被检样品的特性。     

红外地球敏感器用高截止度宽带红外滤光片研制

高截止度宽带红外滤光片是新型红外地球敏感器的关键件之一.介绍了高截止度宽带红外滤光片的设计方法和镀膜的工艺技术,给出了膜系设计和研制的结果,并与国内外同类滤光片的光学特性进行了比较,试验表明这种红外滤光片的膜系设计是成功的.     

红外地球敏感器用高截止度宽带红外滤光片研制

高截止度宽带红外滤光片是新型红外地球敏感器的关键件之一。介绍了高截止度宽带红外滤光片的设计方法和镀膜的工艺技术 ,给出了膜系设计和研制的结果 ,并与国内外同类滤光片的光学特性进行了比较 ,试验表明这种红外滤光片的膜系设计是成功的     

滚动轴承振动速度测量中的滤波器设计

借助组合小波,介绍了数字化滤波器设计,用于滚动轴承振动速度信号的低、中、高频段测量。所设计的带通滤波器具有过渡带窄、带通平稳和线性相位特点。并详细地说明了滤波器设计参数和滤波特性,列举了滚动轴承振动速度测量的实例,其有效性在计算机测量中得到证实。     

稳定的窄带干涉滤光片

滤光片通带中心波长λ０ 的稳定性,是使用过程中最重要的性能参数。该文从薄膜材料的“微孔度”出发,实验筛选出两种“微孔度”最小的膜料,用以组成窄带干涉滤光片。研配一种新的完全中性的光学胶,它不与滤光片膜层发生任何化学反应。再辅以其它工艺措施,成功制作出高稳定度的滤光片。滤光片存放３ 年,其λ０ 未发生漂移。这些滤光片已用于激光测距等多种军事工程,它们的长期稳定性在战备环境中得到了进一步验证。此外,该文还提出了一种新的膜厚监控方法。     

椭圆滤波器边带优化设计方法研究

给出了椭圆函数滤波器边带特性优化设计的一种新方法。该方法把椭圆函数滤波器的边带选择性作为一个设计参数进行优化处理,充分利用函数逼近阶数的计算余量,通过相应的算法调整归一化的阻带角频率使边带选择特性最大化,可以在不增加阶数的前提下获得更好的衰减特性,有效地减小过渡带宽。文中给出了计算方法和实例分析。     

基于谱峭度的滚动轴承包络分析

介绍了一种基于谱峭度和复平移Morlet小波的滚动轴承诊断包络分析法,该方法可根据谱峭度值自适应确定共振解调所用的带通滤波中心频率及带宽,使包络分析得到简化,但存在计算量大的不足.对此提出了一种改进的计算方法,该方法利用相邻不同级滤波器组中具有交叠频带的滤波器滤波和谱峭度计算结果的相关性,有效减少了实际需要构建的小波带通滤波器数量和相应的带通滤波、包络提取及谱峭度计算,降低了计算量,使该方法更适合于工程应用,仿真和实际测试验证了该方法的有效性.     

基于Hilbert-Huang变换与理想带通滤波器的系统识别

针对经验模态分解存在模态混叠现象,提出基于Hilbert-Huang变换与理想带通滤波器的系统识别方法。该方法利用傅里叶变换得到结构加速度响应频响函数,粗略估计固有频率范围,通过半功率带宽法设计理想带通滤波器,定量化确定通带带宽,使信号在经过滤波器后频域内零相移,同时不改变其幅值谱。结构响应通过指定频带的理想带通滤波器产生若干窄带信号,利用经验模态分解获取结构模态响应,经Hilbert变换构造模态响应解析信号,并通过线性最小二乘拟合提取结构模态参数与物理参数。结果表明:半功率带宽法可实现带通滤波器频带的定量化设计,理想带通滤波器的零相移特点较好契合Hilbert-Huang变换用于系统识别的要求,两者结合可有效地解决模态混叠现象,减少虚假模态,大大提高结构系统识别精度。     

一种立方棱镜带通滤光片的设计

提出了低偏振分离的立方棱镜带通滤光片的设计方法。为减小光在立方棱镜中s、p偏振光的偏振分离,采用三种材料来构成带通滤光片的反射镜,并采用不同折射率排列的反射镜结构构成嵌入式的多个带通滤光片,既提高了s、p偏振光的通带透射率,又减小了s、p偏振光在通带中的偏振分离和偏振位相差。通过改变反射镜的基本周期数和滤光片的周期数,可以调节滤光片的通带宽度和截止度,经膜厚优化,得到满意的设计结果。     

Cat Swarm Optimization algorithm for optimal linear phase FIR filter design

In this paper a new meta-heuristic search method, called Cat Swarm Optimization (CSO) algorithm is applied to determine the best optimal impulse response coefficients of FIR low pass, high pass, band pass and band stop filters, trying to meet the respective ideal frequency response characteristics. CSO is generated by observing the behaviour of cats and composed of two sub-models. In CSO, one can decide how many cats are used in the iteration. Every cat has its′ own position composed of M dimensions, velocities for each dimension, a fitness value which represents the accommodation of the cat to the fitness function, and a flag to identify whether the cat is in seeking mode or tracing mode. The final solution would be the best position of one of the cats. CSO keeps the best solution until it reaches the end of the iteration. The results of the proposed CSO based approach have been compared to those of other well-known optimization methods such as Real Coded Genetic Algorithm (RGA), standard Particle Swarm Optimization (PSO) and Differential Evolution (DE). The CSO based results confirm the superiority of the proposed CSO for solving FIR filter design problems. The performances of the CSO based designed FIR filters have proven to be superior as compared to those obtained by RGA, conventional PSO and DE. The simulation results also demonstrate that the CSO is the best optimizer among other relevant techniques, not only in the convergence speed but also in the optimal performances of the designed filters.     

Error analysis on measurement temperature by means dual-color thermography technique

Dual color thermography is a non-contact measurement temperature technique used mainly when the emissivity of surface is unknown; it is based on ratio of monochromatic emissive power calculated by means Planck’s radiation equation and allows measuring the temperature of gray body surface objects without being assigned their emissivity and without approximations.For real surfaces, the emissivity varies with the temperature of surface as well as the wavelength and the direction of radiation. In this case, the dual color thermometry is executed by equipping the IR camera of two narrow band pass filters, so as to consider the surface emissivity of a quite constant value. This allows calculating the ratio between the radiative fluxes of the two different emission wavelengths that is almost independent to the surface emissivity.One of the crucial factor in this technique is the choice of the two narrow filter wavelengths. In fact the measurement errors depends directly on the two wavelengths and the variation of spectral emissivity related to the wavelength chosen and it also depends inversely on distance between central value of filters.In this paper, the authors have developed and validated a mathematical model of experimental setup to measure object surface temperature by means IR thermo-camera. This mathematical model was used to quantify the temperature measurement error in the dual-color technique. A novel correlation to estimate temperature measurement error was provided.     

Digital processing of mechanical transient response signals—Digital filter approach

The primary aim of this paper is to bring to the attention of shock and vibration engineers the advantages of using digital filters for processing transient response signals. Specifically, the development of reliable high pass digital filters to remove the low frequency components in the acquired acceleration signals so as to obtain valid velocity and displacement-time records, is presented. It is concluded that the non-recursive filters are well suited for mechanical engineering transient response applications. The viability of the non-recursive digital filters for the intended application is established with the use of acceleration signals obtained from a laboratory shock test. Also as a part of this investigation, a set of user-friendly, computer programs for filter design and filtering are developed and implemented.