共查询到20条相似文献,搜索用时 140 毫秒
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根据表面波声光效应的原理,实验上建立了固体表面微振动的激光衍射测量系统.当激光斜入射到微振动引起的液体表面波上,观察到了清晰、反衬度非常高的衍射图样.利用MATLAB软件对拍摄的衍射图样进行扫描,得到了衍射光斑的光强分布图,并根据衍射图样宽度与表面波振幅的解析关系式,求出了液体表面波的振幅,其大小在微米量级.改变样品池中液体的深度,测得不同深度下液体表面波的振幅,给出了表面波振幅与液体深度之间的解析关系,并发现了液体对微振动的放大效应.利用液体对微振动的放大效应,求出了固体表面微振动的振幅,实现了固体表面微振动的探测. 相似文献
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根据表面波声光效应的原理,实验上建立了固体表面微振动的激光衍射测量系统.当激光斜入射到微振动引起的液体表面波上,观察到了清晰、反衬度非常高的衍射图样.利用MATLAB软件对拍摄的衍射图样进行扫描,得到了衍射光斑的光强分布图,并根据衍射图样宽度与表面波振幅的解析关系式,求出了液体表面波的振幅,其大小在微米量级.改变样品池中液体的深度,测得不同深度下液体表面波的振幅,给出了表面波振幅与液体深度之间的解析关系,并发现了液体对微振动的放大效应.利用液体对微振动的放大效应,求出了固体表面微振动的振幅,实现了固体表面微振动的探测. 相似文献
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《光子学报》2015,(3)
针对基于时间平均数字全息法的微振动原位检测,提出了一种有效提高振动条纹模式对比度的方法,进而可准确获得待测面振幅分布.首先针对实际振动过程中物体存在纵向微位移而引起的相位误差进行校正;然后去除记录过程中物光场散斑引起的相位噪音,有效提高了被第一类零阶贝塞尔函数调制的条纹对比度;最后利用第一类零阶贝塞尔函数的变化规律和条纹级数,定量估计全场的振幅分布.搭建了以声波作为激励源的时间平均全息测振实验系统,采用频率分别为0、1 100、2 000和9 000 Hz的正弦声波激励簧片进行实验验证.结果表明,以振动频率2 000Hz为例,本方法能够有效提高振动调制条纹质量,并计算得到三级零点处的振幅值分别为109.4nm、244.2nm、356.4nm,与理论值相比较,误差分别为6.31%、3.34%和3.78%,在允许范围之内,证明了该方法的有效性. 相似文献
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基于数字全息理论的方法,构建了一套微振动实时测量的实验系统。通过运用基于全息干涉图像的振动快速解算算法,直接从记录的全息图中提取振动信息,实现对振动物体振幅值进行实时测量。该系统的接收光为散射光,使得测量角度不受被测物体结构的影响。通过测量由标准正弦波驱动的被测物微振动情况,对该实验系统进行了实验验证,实验结果表明,该系统能够实时测量微振动的振幅值(算法处理时间约为0.11 ms),在550~2700 Hz频段内被测物的振幅较为稳定,系统稳定性误差为1.66%,真实地反映了其振动情况。 相似文献
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激光外差干涉测量技术是微振动探测的重要手段,随着微纳应用的拓展,人们对精密测量系统的相位检测灵敏度提出了更高的要求.传统提高测量灵敏度的方法有优化外差干涉系统方案、改进相位重建算法和降低关键器件噪声等.本文提出了一种多光束混合干涉的相位增强方法,经过理论推导和实验验证得到如下近似条件:校正光与信号光的初相位相差πrad情况下,两光束的功率越接近,系统对目标的弱振动振幅响应越大.实验设计的两光束功率相差1%时,观察到了最大146倍的增强效果,该方法在微振动物体高灵敏度测量上具有较大的应用价值,在现有器件指标和相位解调算法不变的基础上可大幅提高外差干涉测量系统的探测能力. 相似文献
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微振动的测量在科学技术和工业应用中都有着重要的意义.比如在材料性质的研究中,在高速转动系统的测量和研究中,以及在实现重力波接收的努力中,微振动的测量都是很重要的一个方面。 激光和无线电技术的结合,实现了光频范围的外差测量,利用它的灵敏度高的特点,我们做了一个测量压电陶瓷微振动的实验. 一、实验原理 图1为一个迈克尔逊干涉仪,反射镜M1、M2的坐标已分别标出,在忽略相位常数的情况下(这对原理的叙述无影响),到达接收器D的两路光可分别表示为:若反射镜M1为被测目标,它在作频率为Ω、振幅为η的微振动,即 y一岁。 O81n(0【干9)则… 相似文献
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A method for accurately measuring a sectional profile of a cylinder is proposed in which a sinusoidally vibrating sinusoidal grating is used to generate a sinusoidally vibrating sinusoidal intensity distribution. A light coming from the top point of the cylinder surface is extracted with an optical system to make an image of this point. A sectional profile of the cylinder is measured by detecting a phase of a time-varying signal contained in the image intensity at a position where the amplitude of the signal is maximum. Detection of the amplitude and the phase is carried out easily and exactly. 相似文献
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表面等离子体波检测的新技术研究 总被引:8,自引:2,他引:6
报道表面等离子体波的一种新的检测技术,可以同时获得表面等离子体波激发过程中反射光的相位和光强变化。理论计算表明,表面等离子体激发过程中,P偏振反射波相位的变化可达300°。在此基础上建立了光学外差测量装置,可同时获得相位和强度变化的信息,实验数据和理论计算吻合非常好。此方法比仅能给出强度变化的角度扫描衰减全反射(ATR)方法,提供了更多的信息,而且相位检测比强度检测灵敏度高,为表面光学性质的研究、LB膜特征研究以及表面等离子体波传感器的研究提供了更有力的工具。 相似文献
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S. L. Vinogradov T. R. Vinogradova V. E. Shubin D. A. Shushakov K. Yu. Sitarskii 《Bulletin of the Lebedev Physics Institute》2011,38(5):147-154
One of the most important problems of detecting weak light pulses is the determination of the accurate signal transit time.
In this case, photodetectors capable of detecting single photons are characterized by two main parameters: the photon detection
efficiency and transit time spread. A unified technique for measuring these parameters is proposed. The technique is based
on the probabilistic distribution of transit times, which allows separation of characteristics of single-photon processes
as multiphoton light pulses are fed and under conditions of high dark noises, which seems important, in particular, when operating
with solid-state photomultipliers. 相似文献
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A new method for detecting wavefront aberrations using a Fabry-Perot cavity is described. A Fabry-Perot cavity transmits the cavity eigenmode which satisfies a resonance condition, while the other modes are reflected from the cavity. Utilizing this mode discrimination property, we can extract aberration components from incident aberrated light as reflected light from the cavity. Under the condition of a weak aberration, the amplitude profile of the reflected light can be approximated to the wavefront aberration. We can therefore determine the wavefront aberrations in a visualized form with the technique. We present the detection scheme and the first experimental verification of the technique. The detected aberration using this technique was in good agreement with the result on the basis of a conventional wavefront sensor. 相似文献
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A new mathematical model of cross-polarized heterodyning is proposed for measuring glass panels. An optical system is presented for obtaining relative thickness variation and difference distribution of refractive indices simultaneously, and the dual-balanced coherent demodulation technique is used. The experiment results show that the transmittance of light beam can be less than 0.5% when the vibration amplitude of the glass panels is equal to 5 mm. It takes about 200 s to scan the whole glass sample with size of 1430 × 1360 mm2. The resolution of the thickness variation is 0.3 μm, and the lateral sampling resolution is 1 mm. 相似文献
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In this paper we propose a simple divided spectrum balanced detection (DSBD) for spectral amplitude coding (SAC) optical code division multiple access (OCDMA) systems. SAC OCDMA systems are limited by phase induced intensity noise (PIIN), which is a signal dependent source of noise. Our proposed technique reduces the PIIN by dividing the spectrum of the signal into two or more, and detecting each spectrum by a different photodiode. The DSBD scheme reduces the detected optical power at photodetection, thus resulting in a higher mitigation of the PIIN. Theoretical results show that DSBD demonstrate noticeable improvement over traditional balanced detection technique, for example an up to 33% increase in the number of active users can be achieved, and at least 1 × 10−3 b/s Hz increase in the spectral efficiency is obtained. However, the SDBD is more complex and append more constrains on system components. 相似文献