科研之友
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摘要
Usually, ultrasonic detection is obtained by conventional contact techniques. In some critical cases such as working at hard environmental conditions (hot oven or nuclear field) or sensitive surfaces, then non-contact optical techniques should be used. However, for all optical techniques, low sensitive ultrasonic detection still a common problem. This paper presents a self building homodyne laser interferometer system which is modified by polarization state to improve the detection performance and to increase the sensitivity limit. The introduced interferometer system has been used to detect ultrasonic signal generated in coated quartz sample around its 10 MHz resonance frequency. He-Ne laser source has been used at 633 nm wavelength with low optical power of 1 mu W. The generated ultrasonic signal has been observed by two different photodetectors to investigate the better performance one. Band pass electrical filter with certain specifications has been used to obtain suitable signal to noise ratio as demonstrated through this work.
- 出版日期2014-3
