Measurement Technique of Liquid Film Thickness Using Stimulated Emission of Radiation

Abstract

A new measurement technique of liquid film thickness, such as oil film thickness, was proposed in this study. In this technique, a fluorescent dye was dissolved in the liquid film and excited by a laser light. With appropriate concentration of fluorescent dye, reflectivity of both boundary surfaces of liquid film and intensity of incident Laser light, a beam of light with wavelengths corresponding to a liquid film thickness was emitted perpendicular to the liquid film by stimulated emission of radiation. To evaluate the possibility of proposed technique, the trial experiments were performed using water as a liquid, Rhodamine B as a fluorescent dye and the 2nd harmonic of Nd : YAG Laser light, 532nm, as incident light source. In this paper, the effects of the intensity of laser light, the concentration of fluorescent dye were examined experimentally.