J041033 近接場光を利用した超音波の発生に関する検討([J041-03]超音波計測・解析法の新展開(3))

抄録

New approach of generating acoustic waves utilizing near-field optics is presented. The evanescent wave is a non-propagating electromagnetic wave that exhibits exponential decay with distance from the surface at which the total internal reflection of light is formed. Because an evanescent wave can illuminate objects smaller than the wavelength of light, such as biological single molecules, much attention has been given to evanescent wave techniques. In this research, the evanescent wave during total internal reflection at prism surface is utilized for generating acoustic wave in aluminum and the feasibility for ultrasonic measurements is examined. It has been demonstrated that the amplitude of the acoustic waves by means of evanescent waves are about 1/15 as large as the one generated by the conventional pulsed laser. This reveals the possibility of using a laser ultrasonic technique with near-field optics for measuring objects smaller than the wavelength of light which is almost the same as the diffraction limitation of light.