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一般共焦法布里-佩罗(Fabry-Perot,FP)干涉仪只能检测声场的法向位移分量,而声场的切向位移分量含有法向位移分量所不能表达的材料特性。本文在检测声场法向位移分量共焦FP干涉仪的基础上,自行研制了一新颖的双通道共焦F-P干涉仪,它同时检测来自试样表面+θ和-θ角上的散射光,通过对两路输出信号作简单的信号处理,可以得到试样表面的位移点。用该F-P干涉仪测量了脉冲激光在Ti膜上激发的Lamb波的法向和切向位移,结果与理论预计一致。
The general confocal Fabry-Perot (FP) interferometer can only detect the normal displacement component of the sound field, while the tangential displacement component of the sound field contains material properties that the normal displacement component can not express. Based on the detection of the normal displacement component confocal FP interferometer in the sound field, this paper developed a novel two-channel confocal FP interferometer which simultaneously detects the scattered light at + θ and -θ angles from the sample surface, On the two output signals for simple signal processing, you can get the sample surface displacement point. The F-P interferometer was used to measure the normal and tangential displacements of the Lamb wave excited by the pulsed laser on the Ti film. The results are consistent with the theoretical prediction.