【摘要】 推导了调制的平顶光束激励下基于Fresnel衍射积分的表面热透镜理论,通过数值模拟,比较了平顶光束和高斯光束激励下样品内部温度场、表面形变场和探测光衍射信号的径向分布,分析了影响表面热透镜信号的实验参数.结果表明,在最佳探测位置,平顶光束激励下的表面热透镜系统比相同情况下高斯光束激励下的灵敏度高,最高时约2倍,更有利于薄膜吸收测量.更多还原

【Abstract】 The theoretical model based on the Fresnel diffraction integral is developed to describe the surface thermal lens (STL) signal excited by a cw modulated top-hat beam. The three-dimensional profile of temperature rise,the radial profile of the surface displacement and the diffraction signal of the probe beam obtained with both top-hat and Gaussian beam excitations are compared by numerical calculation. The dependence of the surface thermal lens amplitude on the experimental parameters are discussed. Numerical results show that the top-hat beam STL instrument is more sensitive than the Gaussian beam STL instrument,with a maximum sensitivity enhancement factor of approximately 2.更多还原