一、原理当固体表面受激光束周期性加热时,它的表面温度发生周期性变化,从而导致表面附近一薄层气体折射率周期性变化。如另外一束探测激光束穿过这层气体时,将产生偏折,这就是蜃景效应。Boccara等人用此效应研究了热吸收谱;P.K.Kuo等人进一步用横向蜃景效应测量了材料的热扩散率。本文采用机械斩波器调制的CO_2激光作为加热光束(或称泵束),使装置小型化。图1 是横向蜃景效应原理图。 First, the principle When the solid surface is periodically heated by the laser beam, its surface temperature changes periodically, resulting in a periodic change in the refractive index of a thin layer of gas near the surface. If the other probe laser beam through this layer of gas, there will be deflection, which is the mirage effect. Boccara et al. Used this effect to study the heat absorption spectra; P.K. Kuo et al. Further measured the thermal diffusivity of the material using a transverse mirage effect. In this paper, the mechanical chopper modulated CO_2 laser as a heating beam (or pump), the device miniaturization. Figure 1 is a schematic diagram of the horizontal mirage effect.