Evaluation of low light absorption material by photoacoustic microscope

Abstract

New methods of evaluating low light absorption materials by a photoacoustic (PA) microscope with a low laser power were proposed. For an optically transparent material, laser light was absorbed by an opaque substrate under a transparent material, and a heat source was generated. The thermal wave was reverse-propagated in a transparent material. For an optically reflectivity material, surface plasmon was used. From experimental results of a thin film of silver, the new method was about 20 times more effective than conventional methods for observing PA signals.