2-nm narrow band pass filter in standard configuration evaporate coating machine

High sophisticated optical monitoring systems like the OMS 5000 from Leyboldoptics are commonly used in vacuum coating system to improve the capabilities and reliability of production processes concerning optical performance and repeatability optics. This letter describes a method to perform high end optical filters with additional backside blocking over a wide spectral range. The direct monitoring with intermittent measurement on a large area rotating substrate holder is used to facilitate a narrow band pass filter of 2-nm half bandwidth at 532 nm and high transmittance together with a complex blocking filter to retard disturbing radiation from the ultraviolet （UV） range to the near infrared range. The machine is an ARES 1350 coating system with basically standard configuration.     

窄带高温超导滤波器的研制

介绍了S波段窄带高温超导滤波器的设计过程,采用仿真建模和拓扑结构优化关键技术,在不需调谐的情况下,研制成功中心频率2.1GHz,带宽6MHz,群延时起伏在4.3MHz(71.7%带宽)内达到了18.321ns,插入损耗小于0.5dB,带边陡度大于17dB/MHz,驻波比优于1.5的高温超导滤波器,有利于器件的工程化应用。     

窄带集成声光可调谐滤波器的研制

利用模式耦合理论分析了声光模式转换,并对声光可调谐滤波器的滤波带宽、调谐范围、驱动功率等性能参数进行分析计算。设计并制作出窄带集成声光可调谐滤波器(IAOTF)样品,搭建相应的IAOTF测试平台,得到中心波长在1.55μm,滤波带宽达到0.85 nm,波长调谐范围达到80 nm,驱动功率低于40mW的IAOTF。并对进一步压缩滤波带宽和旁瓣效应提出了解决途径。     

基于超透射现象的带通滤光膜潜在失效模式分析

文章在理论方面利用亚波长孔阵结构透射峰位关系公式,针对光谱探测器件所需要的具备单峰窄带透射特性的介质-金属-介质的三层结构"双玻孔阵"结构模型的窄带单峰透射结果,基于现有的加工工艺对较常出现的上沿过刻、孔底残留和孔底过刻三种实验误差进行了潜在失效模式分析,与标准双玻孔阵模型对比结果,分析得到加工误差对窄带单峰透射的各种...     

带通滤波器对能见度测量不确定度的影响

在能见度测量中,为了抑制环境光变化对测量不确定度的影响,在光发射端对探测光束进行调制,在接收端对探测到的光电信号进行带通滤波。带通滤波器的特性参数受到工作环境温度变化的影响,导致频响函数变化,从而引入能见度测量的不确定度。以二阶有源带通滤波器为例,从传输函数入手分析了带通滤波器频响幅度随温度变化的规律,实验测定了频响幅度随温度变化的关系。结果表明:在高能见度天气状况下,在15 ℃~40 ℃温度范围内,环境温度每变化1 ℃,带通滤波器将贡献约4.5%的不确定度;低能见度时,带通滤波器的影响比高能见度时小得多。     

无调谐窄带超导陷波器研制技术

报道了一种用于信息装备上的相对带宽为1.2%窄带超导陷波器,并对其仿真、设计技术进行了分析,在无需调谐的情况下,实测的结果实现了50dB以上的陷波深度,并与仿真结果吻合非常好。     

A very narrow spectral band

The power spectrum of the variablez in the Lorenz equations with =10,b=8/3, andr=200 appeared in previous work to contain a line superposed on a continuum. Analysis of an extended solution into consecutive segments with rather similar initial states, each segment spanning at least seven maxima ofz, shows that the apparent line is actually a narrow band. Solutions spanning at least 14000 maxima ofz would be needed to resolve the band by standard computation procedures. Multiplication of the right side of each equation by the same function can convert the band to a line, while leaving the points of the attractor unchanged. It is proposed that the spectrum of a completely coupled autonomous flow is, in a certain sense, unlikely to contain a superposition of lines and a continuum.     

橡皮筋滞后特性的实验分析

利用约利弹簧秤对橡皮筋的力的滞后特性进行了实验分析，并由此说明了不能用橡皮筋做测力计的物理机理，为检验弹簧的质量提供了一种实验途径及理论依据．     

短波通滤光片膜系设计

详细介绍用等效折射率概念设计短波通滤光片的原理和计算方法。根据原理和方法，选择二氧化钛（TiO2）作为高折射率材料、二氧化硅（SiO2）作为低折射率材料。首先从理论上计算出用这2种材料设计的波长λ=950～1150nm的短波通滤光片所需要的周期数，然后给出短波通滤光片的主膜系和光谱曲线。由于据此周期数设计出的膜系光谱曲线在750～810nm处的透过率不符合要求，因此对该膜系进行了改进。依照改进的设计进行多次制备，最终制备出了符合要求的短波通滤光片，找到了最佳制备工艺和方法。最后，对制备出来的短波通滤光片薄膜进行了各种环境实验。实验结果表明，膜层的各项指标符合设计要求。     

矩形波宽带通滤光膜研究

对矩形波宽带通滤光片进行了深入研究,提出了一种设计、制备矩形波宽带通滤光片的方法。使用该方法设计并制备了400 nm～1 100 nm波段,中心波长λ₀=515 nm,透射带λ=λ₀±25 nm,透射带平均透射率■≥92%,截止带λ=400 nm～475 nm、λ=555 nm～1 100 nm,截止带透射率小于0.1%的矩形波宽带通OD3-A滤光片。对样片光谱进行了测试,结果满足需求。该方法设计、制备矩形波宽带通滤光片克服了F-P型窄带滤光膜监控精度要求高、通带宽带窄、成本高以及传统长、短波截止膜组合方式膜层总厚度过大、通带透过率低、波形矩形度差的缺点。     

A narrow band pattern-matching model of vowel perception

The purpose of this paper is to propose and evaluate a new model of vowel perception which assumes that vowel identity is recognized by a template-matching process involving the comparison of narrow band input spectra with a set of smoothed spectral-shape templates that are learned through ordinary exposure to speech. In the present simulation of this process, the input spectra are computed over a sufficiently long window to resolve individual harmonics of voiced speech. Prior to template creation and pattern matching, the narrow band spectra are amplitude equalized by a spectrum-level normalization process, and the information-bearing spectral peaks are enhanced by a "flooring" procedure that zeroes out spectral values below a threshold function consisting of a center-weighted running average of spectral amplitudes. Templates for each vowel category are created simply by averaging the narrow band spectra of like vowels spoken by a panel of talkers. In the present implementation, separate templates are used for men, women, and children. The pattern matching is implemented with a simple city-block distance measure given by the sum of the channel-by-channel differences between the narrow band input spectrum (level-equalized and floored) and each vowel template. Spectral movement is taken into account by computing the distance measure at several points throughout the course of the vowel. The input spectrum is assigned to the vowel template that results in the smallest difference accumulated over the sequence of spectral slices. The model was evaluated using a large database consisting of 12 vowels in /hVd/ context spoken by 45 men, 48 women, and 46 children. The narrow band model classified vowels in this database with a degree of accuracy (91.4%) approaching that of human listeners.     

A nonuniform narrow band correlated-k approximation using the k-moment method

Narrow band k-moment (NBKM) formulations of the transmission function for nonuniform gaseous paths are developed. One of them, called the scaled variance (SV) approximation, is based on the assumption of correlated absorption coefficients. Theoretical derivations are properly detailed and several test cases taken from the literature are provided to assess the approximate modeling results against LBL reference calculations. In most cases representative of combustion configurations, it is shown that the scaled variance approximation is more accurate than the Curtis–Godson one for CO₂ but not for H₂O.     

A simple model for the effect of pressure on the properties of narrow band metallic paramagnets

It is shown that the effect of pressure on the resistivity of α-Ce can be qualitatively explained by a simple band model for spin fluctuations in narrow band metallic paramagnets.     

A photonic-crystal polarizer integrated with the functions of narrow bandpass and narrow transmission-angle filtering

Through the transfer matrix method, we demonstrated a special polarizer integrated with the functions of narrow bandpass (NBP) and narrow transmission-angle (NTA) filtering at normal incidence in a stack of two one-dimensional defective photonic crystals (PCs). One of the PCs is made of an isotropic dielectric media, while the other PC is made of anisotropic media. The key point in designing the stack is to set the central frequencies of the defect modes of the two sub-PCs to be the same for one polarization at normal incidence, but different for oblique incidence or for other polarizations, so that the stack structure could have the functions of three elements: a polarizer, an NBP filter, and an NTA filter. PACS 42.79.Ci; 42.70.Qs; 41.20.Jb     

Polarization-independent narrow bandpass filter and narrow transmission-angle filter based on photonic heterostructures composed of single-negative materials

We propose a photonic heterostructure consisting of two substructures composed of single-negative materials. Calculating the transmission spectra, we find that only the electromagnetic wave within a narrow bandpass and a narrow range of incident directions can be transmitted through this structure. Such structure can be used as a polarization-independent frequency filter integrated with a direction filter.     

The narrow band THz filter in metallic photonic crystal slab framework: Design and investigation

A band pass THz filter has been presented by the aid of coupling between the waveguides and ring resonator based on metallic photonic crystal slab. The rows of rods are missed and remaining rods in the rows play as a reflector then the position of central rods are rearranged as a ring, the radius of reflector rods and ring resonator is modified in order to optimize the resonance frequency and Q-factor. In addition, 3D-FDTD method is used for simulation results. One of the predominant features of the proposed structure for THz filter is its capability of obtaining a Q-factor of about 333 in the 1 THz resonance frequency with the normalized peak transmission of higher than 0.7, because of high Q-factor cavity based on ring resonator.     

On the validity of the narrow band approximation

The accuracy of the narrow band approximation is estimated. It is shown that, in order to assess the accuracy of the approximation, not only the form of the source function but also the form of the integrand is required. The accuracy is improved when the integrand is symmetric.     

一种双反射壁型二维光子晶体窄带滤波器

提出了一种基于双反射壁型结构的光子晶体窄带滤波器, 该滤波器由一个单模谐振腔和两个反射壁构成. 通过调节谐振腔与反射壁之间的距离可以改变滤波谱线的带宽. 利用时域有限差分法进行仿真分析, 结果表明, 该滤波器的工作频率在193.40 THz附近, 带宽小于5.9 GHz, 峰值透射率高达94%, 工作区域长度仅有9 μm. 该器件可应用于密集波分复用系统.