Liu Yang, Seresini Tommaso, Liu Jun-Yan, Liu Liwang, Wang Fei, Wang Yang, Glorieux Christ
Laboratory for Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Leuven, B-3001, Belgium.
State Key Laboratory of Robotics and System, Harbin Institute of Technology, Harbin, 150001, China.
Photoacoustics. 2021 Aug 31;24:100299. doi: 10.1016/j.pacs.2021.100299. eCollection 2021 Dec.
Light absorption induced thermoelastic and photoacoustic excitation, combined with laser Doppler vibrometry, was utilized to analyze the dynamic mechanical behavior of a microcantilever. The measured frequency response, modal shapes, and acoustic coupling effects were interpreted in the framework of a simple Bernouilli-Euler model and quantitative 3D finite element method (FEM) analysis. Three opto-mechanical generation mechanisms, each initiated by modulated optical absorption and heating, were identified both by an analytical and finite element model. In decreasing order of importance, optically induced cantilever bending is found to be caused by: (i) differences in photoacoustically induced pressure oscillations in the air adjacent to the illuminated and dark side of the cantilever, resulting from heat transfer from the illuminated cantilever to the nearby air, acting as a volume velocity piston, and (ii) thermoelastic stresses accompanying temperature and thermal expansion gradients in the cantilever, (iii) photoacoustically induced pressure oscillations in the air adjacent to the illuminated cantilever holder and frame.
光吸收引起的热弹性和光声激发，结合激光多普勒振动测量法，被用于分析微悬臂梁的动态力学行为。在简单的伯努利 - 欧拉模型和定量三维有限元方法（FEM）分析的框架内，对测量得到的频率响应、模态形状和声耦合效应进行了解释。通过解析模型和有限元模型，确定了三种光 - 机械产生机制，每种机制均由调制光吸收和加热引发。按重要性递减顺序，发现光致悬臂梁弯曲是由以下原因引起的：（i）悬臂梁受光面和暗面附近空气中光声诱导压力振荡的差异，这是由于热量从受光悬臂梁传递到附近空气中，空气作为体积速度活塞起作用；（ii）悬臂梁中伴随温度和热膨胀梯度的热弹性应力；（iii）受光悬臂梁支架和框架附近空气中光声诱导的压力振荡。
