微光学陀螺仪系统结构的研究

介绍了谐振型和干涉型两种微光学陀螺仪的分辨率计算公式,并在光纤仿真装置上,分别进行了系统结构的实验研究.在谐振型装置中,作为光源采用了具有 Bragg 光栅的窄线宽激光二极管.在干涉型装置中,为了保证双向光束在Sagnac 效应敏感环 (SSR) 中可以循环传播,采用了大功率的超辐射发光二极管(SLD)作为光源.为了保持双向光束在 SSR 中循环传播多圈,需要在 SSR 中插入一个光放大器,以补偿光束在传播中的各种损耗.研究结果表明,所建议的系统结构对于开发中等精度的微光学陀螺仪产品具有可行性.     

集成光学角速度传感器系统方案的研究

本文研究了谐振型和干涉型两类集成光学角速度传器（Ｒ－ ＩＯＲＳ 和Ｉ－ ＩＯＲＳ） 的系统方案,设计了两种Ｒ－ ＩＯＲＳ 的光纤仿真实验装置：反射式和透射式,并介绍了对它们的实验研究结果。文中还提出了一种再入式Ｉ－ ＩＯＲＳ的系统方案,并进行了理论分析。     

激光干涉测速中信号光纤色散测量

为对激光干涉测速系统(VISAR)中信号光纤的色散特性进行快速测量,搭建了一种基于时域法的 多模光纤色散测量装置。该装置由532nm 的皮秒激光器、快响应光电探测器以及宽带数字示波器组成,通 过对输入光纤前后的光脉冲时间宽度进行测量,来获得光纤的脉冲响应3dB脉宽(即色散时间)。利用该装 置分别对一根长度为123m 的国产梯度折射率光纤以及一根10m 长的阶跃折射率光纤在532nm 波长附近 的色散特性进行了测量。测得的梯度折射率光纤色散时间为(68316)ps,对应3dB频响带宽为646MHz; 阶跃折射率光纤色散时间为(163114)ps,对应频响带宽为271MHz。对实验结果进行了测量不确定度分 析,并与理论计算值进行了比较,获得了较好的一致性。研究表明,利用该实验装置,可对激光干涉测速应用 中信号光纤的色散特性进行迅速、准确的测量,从而为实验中信号光纤类型、长度等的合理选用提供参考。     

循环干涉型光纤陀螺及其光源

介绍了一种新型光纤陀螺及其关键器件。包括：（1）循环干涉型光纤陀螺的系统方案；（2）大功率超辐射发光二极管；（3）多功能光学发收模块，它们是国内光纤陀螺研制中急待解决的关键技术。采用模块化结构和微光电机系统（MOEMS）是国外光纤陀螺的发展方向。     

测量炸药旁侧爆轰波速度的啁啾光纤布拉格光栅传感器技术

提出了一种适用于啁啾光纤布拉格光栅CFBG(chirped fiber Bragg grating)传感器测量爆轰波速度的实验公式,该公式考虑了ASE(amplified spontaneous emission)光源的光谱、CFBG的平坦度对测量的影响;研究了CFBG的反射谱线宽与长度的理论关系,并设计了测量CFBG反射谱线宽的实验装置,从而可计算出CFBG长度。搭建了测量CFBG传感器系统常数的实验装置,并利用实验数据拟合了系统常数;用CFBG传感器测量了RDX/TNT(60/40)的旁侧爆轰波速度,与其爆速有3.4%的差异。     

光纤位移干涉仪在爆轰加载飞片速度测量中的应用

利用光学多普勒效应和外差方法搭建了一台光纤位移干涉仪。装置采用光通信行业中已经发展成熟的器件,主要由带尾纤的半导体激光器、三端口环形器、光纤探头、宽带探测器以及宽带高采样率示波器等构成。整个装置结构简单,价格便宜,采用了信号光和参考光同轴结构,实现了任意反射面的速度测量,克服了偏振模式色散的影响,能够实现长量程测量,量程达到20 mm。利用该装置进行了爆轰加载下飞片速度测量,测量最高速度达到1 300 m/s,工作距离达到20 mm,同时利用VISAR对飞片速度进行了对比测量,结果表明用两种不同方法所测得的速度曲线吻合很好。     

消息与动态

WZD-3型光测弹性仪北京科学仪器厂对该厂60年代老产品WZD-2型光测弹性仪(即409-2型)进行更新换代,从光学、机械、电器等方面作了较大的改进,试制成WZD-3型光测弹性仪,于1984年12月初通过鉴定。经样机实测,光学系统分辨率达到每毫米15对线,照度强,放大倍数达到10倍,成象清晰;机械结构合理,使用方便;电器系统部件单元性好,便于部件更换。会议同意设计定型,投入小批试生产,并提出几点改进意见:(1) 加载系统功能要多样化;(2) 改进结构,能一人同步操纵进行测量;(3) 今后改型时,应向一机多用发展。     

消息与动态(34)

WZD-3型光测弹性仪北京科学仪器厂对该厂60年代老产品WZD-2型光测弹性仪(即409-2型)进行更新换代,从光学、机械、电器等方面作了较大的改进,试制成WZD-3型光测弹性仪,于1984年12月初通过鉴定。经样机实测,光学系统分辨率达到每毫米15对线,照度强,放大倍数达到10倍,成象清晰;机械结构合理,使用方便;电器系统部件单元性好,便于部件更换。会议同意设计定型,投入小批试生产,并提出几点改进意见:(1) 加载系统功能要多样化;(2) 改进结构,能一人同步操纵进行测量;(3) 今后改型时,应向一机多用发展。     

消息与动态(34)

WZD-3型光测弹性仪北京科学仪器厂对该厂60年代老产品WZD-2型光测弹性仪(即409-2型)进行更新换代,从光学、机械、电器等方面作了较大的改进,试制成WZD-3型光测弹性仪,于1984年12月初通过鉴定。经样机实测,光学系统分辨率达到每毫米15对线,照度强,放大倍数达到10倍,成象清晰;机械结构合理,使用方便;电器系统部件单元性好,便于部件更换。会议同意设计定型,投入小批试生产,并提出几点改进意见:(1) 加载系统功能要多样化;(2) 改进结构,能一人同步操纵进行测量;(3) 今后改型时,应向一机多用发展。     

菲涅耳反射光强抑制及光隔离器测试系统设计

分析了菲涅耳反射光强对光纤陀螺的影响,提出了采用光纤研磨与折射率匹配相结合的方法抑制菲涅耳反射光,并进行了实验,实验结果表明该方案可成功的将反射光强从一百多微瓦降至万分之一纳瓦以下,消除了菲涅耳反射光强对陀螺信号的干扰;针对陀螺系统中采用光隔离器来隔离反射光对光源的影响,提出了一种使用很少仪器和元器件并能实现参数准确测量的光隔离器测试系统,实际测试了一款双级型光隔离器的主要性能参数并对测量结果与误差做了进一步的分析和讨论。     

激光器光谱线宽对布里渊光纤谐振腔谐振特性的影响

针对激光器光谱线宽不可能严格为零的问题,在激光相干理论的基础上,采用光波场叠加的方法计算了布里渊光纤谐振腔的循环光强,详细分析了激光器光谱线宽对布里渊光纤谐振腔谐振谱线宽度和精细度的影响,并进一步分析了光谱线宽对谐振腔受激布里渊散射阈值的影响,最后,引入了线宽压缩的概念分析了布里渊光纤陀螺的灵敏度。分析表明,除了耦合器插入损耗外,激光器光谱线宽也是影响精细度的重要因素,具体影响程度与激光器光谱线宽及谐振腔本征谱线宽度间的相对大小有关,受激布里渊散射阈值随激光器线宽的增加而近似线性增加,另外在其他参数相同的情况下,布里渊光纤陀螺的灵敏度比谐振式光纤陀螺高大约三个数量级。本文为布里渊光纤陀螺的光源选择及光路参数的优化设计过程提供了理论依据。     

An experimental study of dynamic delamination of thick fiber reinforced polymeric matrix composites

Dynamic delamination of thick fiber reinforced polymeric matrix composite laminates is investigated using optical techniques and high-speed photography. The laminates used in this work are graphite/epoxy fiber reinforced, 65 percent fiber volume fraction, composite plates consisting of 48 plies (6 mm plate thickness). Two different laminate layups are tested: a quasi-isotropic arrangement and a unidirectional arrangement. The experimental setup consists of 152 mm×152 mm square plates impact loaded in an outof-plane configuration using a high-speed gas gun. Impact speeds range from 1 m/s to 30 m/s. Real-time imaging of the laminate out-of-pane displacement is performed using the lateral shearing interferometer of coherent gradient sensing (CGS) in conjunction with high-speed photography. Onset of dynamic delamination can be observed, and quantities such as delamination speeds (in some cases up to 1800 m/s) are measured and reported. A brief comparison is made with dynamic fracture experiments of the same material conducted in a separate study.     

含脱层损伤复合材料层合梁冲击动力响应实验研究

对纤维增强复合材料层合梁在受轴向冲击时的动力响应问题进行了实验研究。实验以单向玻璃纤维布和环氧树脂材料制作试件,在层间预埋薄铜箔模拟脱层损伤。采用激光测速仪测量子弹速度,动态应变仪和TDS420A数字示波器记录应变时程曲线进行动力响应分析。实验结果表明铺层角度是决定材料性能的主要原因,脱层损伤的存在及大小对动力响应和发生动力屈曲有重要影响。此外,初始缺陷的影响也是不可忽视的重要因素。     

多次循环干涉型光纤陀螺仪的实验研究

详细介绍了循环干涉型光纤陀螺仪的实验装置及测试结果，给出了无源和有源补偿的两种敏感环结构下陀蛇分辨率公式。在实验装置中采用了大功率光源和低耦合比输入耦合器，以提高光波在敏感环中的循环次数。实验结果表明：光束在敏感环中循环了2－3次，并达到了较好的零偏稳定性。     

Mechanical Fatigue Measurement via a Vibrating Cantilever Beam for Self-Supported Thin Solid Films

In this paper, we develop a novel experimental apparatus, referred to as the resonant frequency device, and establish methodology to measure the fatigue properties of thin solid films. Arranging thin-film strips of our specimens into the mechanical setting of a cantilever beam and using state-of-the-art piezo actuators to generate oscillation at the clamp of the cantilever, we create a system suitable for studying the material properties of the cantilever, such as Young's modulus, fatigue and possibly, loss tangent. Deformation of the cantilever is our controlled variable in the present study, and measured with fiber-optic probes pointed at the specimen and at the piezo driver. Stress is calculated from relative deformation of the cantilever specimen with respect to the piezo actuator via a photograph of the cantilever under vibration with a curve fitting method. A LabView computer program is developed for the fatigue tests to accurately count number of cycles applied on the specimens, and a feedback mechanism is adopted to maintain displacement during the tests. Here, we present our experimental setup, procedure and theoretical models for material-property extraction. For small displacement, the two-dimensional Euler–Bernoulli beam theory is adopted. With large displacement, the system behaves as the Duffing oscillator due to geometrical nonlinearity. In addition, some experimental observations of the piezo actuators and fiber optics are reported. The method is applied to evaluate the fatigue properties of nanolayered copper-niobium composites and significant increase in the fatigue endurance limit compared to the constituent materials in the bulk form is noted.     

Design of multi-layered porous fibrous metals for optimal sound absorption in the low frequency range

We present a design method for calculating and optimizing sound absorption coefficient of multi-layered porous fibrous metals(PFM) in the low frequency range. PFM is simplified as an equivalent idealized sheet with all metallic fibers aligned in one direction and distributed in periodic hexagonal patterns. We use a phenomenological model in the literature to investigate the effects of pore geometrical parameters(fiber diameter and gap) on sound absorption performance. The sound absorption coefficient of multilayered PFMs is calculated using impedance translation theorem. To demonstrate the validity of the present model, we compare the predicted results with the experimental data. With the average sound absorption(low frequency range) as the objective function and the fiber gaps as the design variables,an optimization method for multi-layered fibrous metals is proposed. A new fibrous layout with given porosity of multi-layered fibrous metals is suggested to achieve optimal low frequency sound absorption.The sound absorption coefficient of the optimal multi-layered fibrous metal is higher than the singlelayered fibrous metal, and a significant effect of the fibrous material on sound absorption is found due to the surface porosity of the multi-layered fibrous.     

Non-linear vibrations of free-edge thin spherical shells: Experiments on a 1:1:2 internal resonance

This study is devoted to the experimental validation of a theoretical model of large amplitude vibrations of thin spherical shells described in a previous study by the same authors. A modal analysis of the structure is first detailed. Then, a specific mode coupling due to a 1:1:2 internal resonance between an axisymmetric mode and two companion asymmetric modes is especially addressed. The structure is forced with a simple-harmonic signal of frequency close to the natural frequency of the axisymmetric mode. The experimental setup, which allows precise measurements of the vibration amplitudes of the three involved modes, is presented. Experimental frequency response curves showing the amplitude of the modes as functions of the driving frequency are compared to the theoretical ones. A good qualitative agreement is obtained with the predictions given by in the model. Some quantitative discrepancies are observed and discussed, and improvements of the model are proposed.