光彈可視化下橫波遇到橫孔的傳播

說的英語聽不懂，哪位高手可翻一下？
還有那個波形轉(zhuǎn)換得到的“head wave”不明白。

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前面一段講的什么 ？大家看看給講講？

{:soso_e181:}

視頻第一部分原理內(nèi)容（紅色為不確定部分）：
Initial studies in the photo elastic techniques seem to have been in 1937 with Highdman and hush. But photo elastic visualization of ultrasound was first practically developed by Doctors Hence and White in UK around 1968. In the 1970’s it was popularized by Dr King hall at British area.
The image shown is provided by Dr hence shows a multiple exposure of 4 MHz pulse refracted at 45 degrees. The principle is relatively simple, pulse light is passing through the light source at a fix  repetition frequency on the order of 100 Hz. Unpolarised light from the spark gap passes through a polarizing filter. This changes the light that pass through the polarizer to linear polarized light.
This is followed by a quarter wave plate that changes the linear polarized light to circular polarized light, a second quarter wave plate and a analyzer are inserted into the light path, and the orientation can figured to none of the light passing through the analyzer.
A clear transparent solid such as glass is inserted in the light path, between the quarter wave plates. When stress in the glass are set up by mechanical disturbing such as ultrasonic pulse. It causes a change the rotation of polarized light, change the stress along the light path change the conditions that none of the light passing through the analyzer.
So a small amount of light can then pass through the observer on the other side of the analyzer. by adding a delay circuit, we can adjust the position along the sound path that is illuminated by the pulse, and the camera allows the observer to record the image.  

希望能幫上忙，另外，關(guān)于光彈部分內(nèi)容可以給您介紹清華的一位老師，他對這研究頗深。

楊彬  2013 12 31   
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yangbinjsk123 發(fā)表于 2013-12-31 23:24
視頻第一部分原理內(nèi)容（紅色為不確定部分）：
Initial studies in the photo elastic techniques seem to h ...

謝謝，辛苦了！
順便說下，你不就是楊彬嗎？看你昵稱

糟老頭子 發(fā)表于 2014-1-2 09:39
謝謝，辛苦了！
順便說下，你不就是楊彬嗎？看你昵稱

不客氣

是的，這是我的聯(lián)系方式，清華的老師姓陳。