Acoustic surface wave detection of radiative absorption

Abstract

A new technique is presented to study surface absorptive properties by utilizing the interaction of an acoustic surface wave with a radiatively heated surface region. Phase changes are induced in a surface wave on Y‐cut quartz by the absorption of 10.6‐μ laser radiation. Quantitative measurements of the process agree with a theory describing the interaction in which there are no free parameters. The sensitivity and response time of this detection process are indicated by phase change signals occurring in a ∼10‐μ absorbing film which correspond to a radiative heating of ∼13 μJ and have a rise time of ∼125 nsec.