Lukasievicz Gustavo V B, Herculano Leandro S, Sehn Elizandra, Belançon Marcos P, Bialkowski Stephen E, Capeloto Otávio A, Astrath Nelson G C, Malacarne Luis C
Departamento de Física, Universidade Tecnológica Federal do Paraná, Medianeira, Brazil.
Departamento de Física, Universidade Tecnológica Federal do Paraná, Pato Branco, Brazil.
Appl Spectrosc. 2020 Oct;74(10):1274-1279. doi: 10.1177/0003702820937364. Epub 2020 Jul 16.
Laser-induced wavefront distortion is detectable by several techniques based on the photothermal effect. The effect is probed by monitoring the phase shift caused by the bulging of the heated area, the photoelastic effects, and the spatial distribution of the refractive index within the sample and in the fluid surrounding it. A simple analytical solution for the wavefront distortion was only possible for low absorbing materials, with the assumption that the stresses obey either the thin-disk or the long-rod type distributions. Recently, a unified theoretical description for the laser-induced optical path change was proposed to overcome part of this limitation for weakly absorbing materials, regardless of its thickness. In this work, we perform an experimental investigation taking the sample-fluid heat coupling effect into account using the thermal lens technique. The experimental investigation presented here validates the unified model. In addition, we show that the heat-coupling model provides an alternative method to obtain physical properties of non-absorbing fluid by using a reference solid sample.
激光诱导的波前畸变可以通过几种基于光热效应的技术来检测。通过监测由加热区域的凸起、光弹效应以及样品及其周围流体中折射率的空间分布所引起的相移来探究这种效应。对于低吸收材料，只有在假设应力服从薄盘或长杆型分布的情况下，才可能得到波前畸变的简单解析解。最近，针对激光诱导的光程变化提出了一种统一的理论描述，以克服弱吸收材料在这方面的部分局限性，而不考虑其厚度。在这项工作中，我们使用热透镜技术进行了一项考虑样品 - 流体热耦合效应的实验研究。这里给出的实验研究验证了统一模型。此外，我们表明热耦合模型提供了一种通过使用参考固体样品来获取非吸收性流体物理性质的替代方法。
