Girardeau Vadim, Jacquin Olivier, Hugon Olivier, Lacot Eric
Appl Opt. 2018 Sep 10;57(26):7634-7643. doi: 10.1364/AO.57.007634.
This paper examines the detection of ultrasound vibrations with nanometric amplitude by using a laser optical feedback imaging (LOFI) setup. By means of numerical simulations, we show typical examples of ultrasound vibrations having different temporal shapes (harmonic and transient), extracted from the laser output power modulation induced by the frequency-shifted optical feedback. Considering the laser quantum noise dynamic and the detection noise separately, we show that the simulated vibration noise is in good agreement with the theoretical prediction. Also, we demonstrate that ultra-high frequencies (in the gigahertz range) can be detected by using a usual LOFI setup with a low-power laser (few mW) and a conventional detection with a usual white noise level. Then we show how the noise of a short transient vibration can be reduced by the reconstruction of its wide vibration spectrum by concatenation. Finally, the experimental detection of transient-harmonics ultrasound vibrations propagating in water and detected at the air/water interface is presented.
本文研究了利用激光光学反馈成像（LOFI）装置检测纳米级振幅的超声振动。通过数值模拟，我们展示了从频移光学反馈引起的激光输出功率调制中提取的具有不同时间形状（谐波和瞬态）的超声振动的典型示例。分别考虑激光量子噪声动态和检测噪声，我们表明模拟的振动噪声与理论预测吻合良好。此外，我们证明了使用低功率激光器（几毫瓦）的常规LOFI装置和具有常规白噪声水平的常规检测方法可以检测到超高频（吉赫兹范围）。然后我们展示了如何通过级联重建其宽振动谱来降低短瞬态振动的噪声。最后，展示了在水中传播并在空气/水界面检测到的瞬态谐波超声振动的实验检测结果。
