Detection of sub-terahertz photoacoustic effect for non-contact material sensing

• Main Authors: Natsumi Ichikawa, Yasuaki Monnai
• Format: Article
• Language: English
• Published: Elsevier 2021-12-01
• Series: Measurement: Sensors
• Subjects: Photoacoustic effect; Sub-terahertz waves; Sound speed; Non-contact sensing
• Online Access: http://www.sciencedirect.com/science/article/pii/S2665917421002026

We demonstrate the generation of photoacoustic signals in aqueous samples by continuous sub-terahertz irradiation detectable with a standard microphone. We confirm that the frequency response of the photoacoustic signals is dependent on the sound speed in the sample, demonstrating its potential for non-contact inspection. As a proof of concept, we demonstrate that water temperature can readily be discerned with the proposed method. The use of sub-terahertz waves for excitation and acoustic waves for detection allows us to inspect a sample inside a container through its wall in a non-contact manner.