共查询到17条相似文献,搜索用时 728 毫秒
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搭建了光纤光栅检测超声应力波系统,并阐述其工作原理,以动态应变与光纤光栅中心波长漂移量间关系为基础,推导得出输出电压与板中应变成线性关系.采用超声信号发生器发射28kHz的脉冲信号激励超声振子,通过有机玻璃楔形块将激励传递至5052铝合金薄板产生超声应力波,并利用光纤光栅应变传感器对其进行探测.在板上开一98mm长裂缝,测得超声应力波中出现新的波包,通过计算损伤前后新增波包到来的时间差确定裂缝位置,所测结果与实际位置偏差为2.7mm.该实验表明光纤光栅可代替超声探头来实现对低频超声波的探测. 相似文献
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复杂流场的超声-激光测量原理研究 总被引:1,自引:1,他引:0
本文从复杂流场—旋涡场参量的超声—激光测试方法的需要出发,论述了超声波产生的声相位光栅对激光产生的偏转效应.并研制了适用于产生空气超声相位光栅的大功率高频超声换能器、位移灵敏接收器、数字相位差测定仪等设备,采用了超声发射的匹配技术等,从而获得了明显的空气超声-激光偏转效应,并且测定了两光束的偏转时间差.本文的结果为利用超声-激光的空气声光偏转效应测量空气旋涡流场参量提供了实验依据. 相似文献
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理论上分析了超声光栅衍射和液体表面波光栅衍射,得到了表面波光栅衍射图样与表面波参数的解析关系.实验上得到清晰的衍射图样,利用表面波光栅衍射法测量了液体表面波波速,实验结果与理论值误差不超过1%. 相似文献
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声光Naman-Nath衍射特性的研究 总被引:3,自引:1,他引:2
讨论了液体介质中的超声相位光栅的形成,根据声光相互作用类型的区分标准,在液体介质的超声光栅实验中声光相互作用一般为Naman-Nath衍射;相位光栅可以由声行波和声驻波形成,且形成的各级衍射条纹极大均由相同的光栅方程决定,各级衍射条纹的强度由相应阶次的J2m函数值决定;在此基础上给出了衍射条纹和衍射光强的分布特点. 相似文献
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We present a technique for liquid leak detection in which ultrasonic and optical waves are introduced into a fiber simultaneously. The system is based on an ultrasonic technique using an ultrasonic actuator and a fiber Bragg grating receiver. A fiber-guided ultrasonic wave is utilized to stress the fiber Bragg grating, which is remote from the ultrasonic transmitter. When the traveling ultrasonic wave encounters a liquid, part of the wave will leak out from the fiber, which results in an ultrasonic strain decrease in the fiber Bragg grating. The ultrasonic wave and its attenuation are detected by the light variation of a narrowband laser source reflected and transmitted from the fiber Bragg grating, and the amplitude variation of the ultrasound can eventually be correlated with the fiber area coupled with the liquid. 相似文献
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π相移光纤光栅用于水中超声传感时,超声波沿光纤轴向入射和垂直光纤入射时的传感波形及幅度显著不同。针对这一现象,本文建立了基于光学传递矩阵的光纤光栅声传感理论模型,计算了超声波分别沿轴向和沿垂直方向入射时π相移光纤光栅中的非均匀应变场分布,进而分析了光谱偏移,揭示了两种入射角度下π相移光纤光栅的传感特性与声传播导致的应变场分布相关,并通过实验进行了验证。结果表明,两种入射角度产生的不同的非均匀应变场分布对π相移光纤光栅的传感特性影响明显。超声波垂直入射时的传感波形和幅度均优于轴向入射,且π相移处对传感有显著作用。当入射位置远离π相移处时,垂直入射的响应也明显降低。本研究可为π相移光纤光栅超声传感的机理分析提供参考。 相似文献
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The diffraction of ultrasonic radiation on an amplitude diffraction grating in the near-field area (Fresnel diffraction) has been studied. The effect of self-imaging of the grating (Talbot effect) has been detected for ultrasonic radiation at distances from the grating in the range from z = 0 to z = 2L T, where L T is the Talbot length. The fractional Talbot effect, i.e., the ultrasonic image of the grating with the period d/2, has been observed. 相似文献
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为了研究声光效应中声致折射率变化情况,以超声光栅实验为基础,用CCD结合光强分析软件,分析了衍射光的强度分布;通过数值计算衍射光相对强度,比较得到了在超声场频率为10.27 MHz时,介质中的声光相位延迟Δ=1.2855 rad,声致折射率变化量Δn=3.014×10-6;进而讨论了电声换能器的机电耦合效率与超声频率的关系,给出当超声频率为10.33 MHz时,耦合效率最高,介质中折射率变化量最大;结果表明,在超声光栅实验中,引入这些测量内容,不仅能丰富实验内容,更能加深学生理解声光效应,扩展学生的知识面. 相似文献
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K. Patorski 《Ultrasonics》1981,19(4):169-172
A simple optical method is proposed for studying the Raman-Nath parameter of plane, sinusoidal, ultrasonic beams. The Fresnel diffraction field of a continuous ultrasonic grating illuminated by a collimated laser beam is measured by a photodetector placed mid-way between the self-image planes of the grating. Measurement of the amplitude of the fundamental of the output signal enables the absolute determination of the depth of phase modulation. A comparison of the proposed method with the techniques discussed in the literature is presented. 相似文献
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K Patorski 《Ultrasonics》1981,19(3):120-124
An optical far-field method is described for studying ultrasonically-produced phase gratings with very small phase variations. An ultrasonic grating is illuminated by two plane waves mutually inclined at an angle properly matched to the diffraction angle of the inspected grating. The expressions for the time-dependent irradiance in the far-field diffraction orders are derived. They enable the extraction of the Raman-Nath parameter of a progressive ultrasonic beam. The application of the technique to pulsed ultrasound beams is proposed. 相似文献