Optoacoustic and Photothermal Imaging and Microscopy

Abstract

Modulated radiation shining on an absorbing sample causes a temperature modulation which can be detected in different ways. The classical method is based on the gas pressure modulation when the sample is kept in a gas-filled cell One One can also detect the modulated thermal expansion of the solid sample itself by using piezoceramic material or even a strain gauge attached to it ^2–4. While these are optoacoustic (also called photo-acoustic) methods^5,6 in photothermal detection the temperature is monitored via the modulation of infrared thermal emission correlated with it ⁷, as is described by P.E. Nordal and S.O. Kanstad in this book. It is true remote sensing like the “mirage effect” where the change of sample temperature causes deflection of a monitoring beam of light ⁸ (see article by D. Fournier and A.C. Boccara in this book).