In photothermal science, the form of the profile of the illuminating laser beam is crucial, defining the usefulness as well as the accuracy of a given methodology. In this paper, the thermal photoinduced effects on a low absorption sample by illuminating it with a ring-shaped laser beam are theoretically investigated. The main advantage of the ring-shaped laser beam is that it produces a temperature profile with a flat-topped form at a steady-state. The heat diffusion and thermoelastic equations are analytically solved providing the temperature distribution, surface displacement, stresses, and optical path for a sample with a thick-disk geometry. It is shown that, when the internal radius of the laser beam is zero, the results for the ring-shaped laser are reduced to the top-hat laser beam case. Additionally, the finite element method is applied to determine the temperature, displacement, stresses, and optical path profiles based on the same set of equations. The comparison between numerical and analytical solutions was performed as a form of validation, which showed a good agreement between both types of results. Our analytical results can be useful in the study of materials using photothermal techniques, as well as in the design of optical components and the configuration of experimental systems.

中文翻译：

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由环形激光束激发的厚盘几何材料的热弹性响应

在光热科学中，照明激光束的轮廓形式至关重要，它定义了给定方法的实用性和准确性。在本文中，从理论上研究了通过用环形激光束照射低吸收样品对低吸收样品的热光致效应。环形激光束的主要优点是它在稳态下产生平顶形式的温度分布。热扩散和热弹性方程经过解析求解，为厚盘几何形状的样品提供温度分布、表面位移、应力和光路。结果表明，当激光束的内半径为零时，环形激光器的结果被简化为顶帽激光束的情况。此外，有限元方法用于根据相同的方程组确定温度、位移、应力和光路分布。数值解与解析解之间的比较是作为一种验证形式进行的，这表明两种类型的结果之间具有良好的一致性。我们的分析结果可用于使用光热技术研究材料，以及光学元件的设计和实验系统的配置。