激光双光栅法研究音叉的振动——一种新的高精度测量小振幅的方法

我们最近利用了与光栅移动速度成正比的移动光栅的多普勒效应;并且采取双光栅的办法,把移频和非移频二束光直接平行叠加获得光“拍”;再通过光电的平方律检波器检测,取出差频讯号的简易办法,可以取得振动的振幅与速度的物理量。方法简易、精度高,是一种新的办法。     

VISUALIZATION OF UHF ACOUSTIC TRAVELING WAVEFRONT BY CW LASER:THEORY AND EXPERIMENT OF SPATIAL AND TEMPORAL CORRELATION

Using spatial and temporal information correlation theory which is different from the idea oftraditional stroboscope geometrie imaging formation,we've described how to obtain the opticalphase figure of UHF acoustic traveling wavefront in space by CW laser beam and convert it into anamplitude figure.We've also described that there is temporal frequency spectrum in spatialfrequency spectrum,and summarized the methods to get a 2-D high contrast optical figure ofacoustic traveling wavefront by correct spatial filtering concepts so as to clarify some confusions inusual acoustic imagng formation explanation. The experiment and some interesting results have been obtained.As an example,we've obtainedsuccessful results for 37.5 MHz ultrasonic traveling wave from not only bulk wave but also SAWdevice.The method is in real time and simple.We may expect that it becomes a method thatpromises well in researches on ultrasonic waves.     

超声驻波波面的激光相关成像

本文利用傅氏光学概念分析激光通过声驻波后的远场光场,不但被分解成空间频谱,而且在空间频谱中又有时间频谱。以此为依据,分析了超声驻波成稳定像的原理和过程:通过时间互相关过程,得出不同空间频谱中同时间频率光的非零相关值;再由不同时间频率的非相干光进行强度线性叠加,最后形成超声驻波波面的稳定像。从而澄清了声驻波成像中的一些理论上的混淆,找到了成像的新途径,实验上也得到了证实。     

连续激光显示超高频声行波波前图象——空时信息相关理论和实验

本文和传统的频闪几何光学成像观点不同,根据空间与时间信息相关理论用连续激光在空间获得超高频声行波波前的光学位相图像,再转换为光学振幅图像的办法,分析了空间频谱中具有不同的时间频谱。并以相同的时间频率相关概念,得到了强度线性叠加成稳定像的结果。又以明确的滤波概念得到高对比度二维图像的途径。实现超高频声行波波前的光学图像的实验是以37.5MHz声光行波器件为例,效果满意,办法实时、简易。可望有相当的应用前景。