智能定标器的设计与实现

介绍使用现代EDA手段设计定标器的原理和实现方法。新的定标器利用FPGA技术实现对系统中大量电路进行集成，结合AT89C51单片机进行控制和处理，并增加数据存储功能和RS232接口，简化了系统结构。     

暗房中央控制系统的应用

介绍了采用AT89C51单片机作为控制芯片的多功能暗房中央控制系统的硬件和软件的设计及其在普通物理实验中的应用。     

基于单片机的迈克耳孙干涉仪自动计数装置

选用AT89C51单片机,为迈克耳孙干涉仪设计了干涉条纹自动计数装置．用程序来控制计数和步进电动机的运行;用光电转换器使明暗变化的条纹转化成脉冲电流,作为计数脉冲信号;用步进电动机带动迈克耳孙干涉仪的微调手轮,使其慢速可控转动,完成脉冲信号采样;并用数码管直接显示计数结果．     

基于单片机的声脉冲信号发生器设计

声脉冲法是近代现场隔声测试和吸声测试技术的主要方法之一,但声脉冲信号的产生是阻碍其应用的一个难点。本文以AT89C52单片机和DAC0832模∕数芯片为核心,设计一种声脉冲信号发生器,具有结构简单,成本低廉,使用方便的特点。经过测试,给出了该声脉冲信号发生器所产生声脉冲信号的时频域波形图。     

基于单片机的温度控制系统的设计

针对单片机温度控制系统采用传统控制方法容易出现响应速度慢、振荡剧烈、控制精度低等问题,对单片机温度控制系统的硬件电路、控制精度、控制算法等方面进行了设计研究。基于以AT89C51单片机为核心运用DS18B20温度传感器的温度控制系统,提出了变论域模糊PID控制算法,将变论域模糊控制和PID控制相结合,结合生猪猪舍温度控制系统对传统PID控制算法以及变论域模糊PID控制进行对比分析。实验结果表明,设计的温度控制系统采用了变论域模糊PID控制算法,提高了控制精度,加快了系统的响应速度,从而增强了温度控制系统的实用性,产生了重要的实际工程意义。     

基于单片机的全固态激光器电控系统

利用AT89C55单片机,将激光器多路控制信号整合在一起,设计并制作完成了一套结构紧凑,使用方便,操作智能,运行稳定的全固态激光器综合电控系统.     

基于AT89C51数控电流源的设计

系统以AT89C51单片机为主控制器,由电流源、DA转换、AD转换和LED数码管等模块组成。利用电流负反馈和键盘设置,实现数控直流电流源,并能将预设的电流值与实际值在数码管上交替显示,通过检测证明本系统输出电流稳定。     

自动控温混水阀的设计与制作

以AT89C51单片机系统为核心,DS18B20芯片为温度传感器,步进电机为温度调控动力装置的自动控温混水阀能够实现对水温的自动调节、温度显示和声光报警等功能.基于Proteus进行电路设计和仿真,仿真结果表明本设计能够实现水温检测与显示、声光报警和自动控温控制等预期功能;实物化后,测试结果表明系统具有较高的可靠性,实现了预期目标.     

基于STC89C51的新型液氮低温微创冷冻控制系统设计

设计了一种新型液氮低温微创冷冻控制系统,详述了系统的控制原理及各功能模块的实现.采用热流平衡原理、PID技术与STC89C51单片机及外围控制电路对冷冻冻结面范围、液氮瓶压力及冷刀刀头温度进行实时控制和显示.应用结果表明:该系统运行稳定,可靠性高,操作简单.     

CCD自动调光设计

介绍一种在89C51单片机的智能控制系统中,用A/D536等器件组成的真有效值电路作为CCD视频信号的检测电路,采取程序控制方式对天空背景下的目标进行自动调光控制.     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.     

A stereo matching algorithm using multi-peak candidate matches and geometric constraints

Gray cross correlation matching technique is adopted to extract candidate matches with gray cross correla- tion coefficients less than some certain range of maximal correlation coefficient called multi-peak candidate matches. Multi-peak candidates are extracted corresponding to three closest feature points at first. The corresponding multi-peak candidate matches are used to construct the model polygon. Correspondence is determined based on the local geometric relations between the three feature points and the multi-peak candidates. The disparity test and the global consistency checkout are applied to eliminate the remaining ambiguous matches that are not removed by the local geometric relational test. Experimental results show that the proposed algorithm is feasible and accurate.     

Fiber Modal Index Measurements Based on Fiber Gratings

A novel method based on fiber gratings for measuring the effective indices of fiber modes is proposed. The effective index difference between the core mode and a cladding mode was obtained by analyzing the interference fringe of a pair of cascaded long-period fiber gratings. In order to extract the core mode index from the measured index difference, an index matching oil immersion method is proposed. By analyzing the interaction between the cladding mode and the oil applied on the cladding surface, the mode order and the effective index of the involved cladding mode might be calculated. Experimental results about the interference fringe shifts induced by the oil index and the oil-applied length are also presented.     

Optical Pulse Compression Schemes That Use Nonlinear Bragg Gratings

Nonlinear optical pulse compression of picosecond pulses typically requires long lengths of optical fiber and multiple components. Periodic structures, such as fiber Bragg gratings, are highly dispersive at wavelengths outside of the photonic bandgap. This implies that such gratings can be used as very short all-fiber compressors. In this paper a number of such compression schemes are reviewed involving uniform and nonuniform fiber Bragg gratings, relying on both soliton and nonsoliton compression principles. Experimental results supporting the corresponding underlying theory are also presented. Finally, an extension of one of the compression schemes is shown, which allows the generation of adjustable high-repetition rate soliton trains.