A scanning acoustic microscope based on picosecond ultrasonics

• Published in: Ultrasonics Vol. 56; no. C; pp. 153 - 159
• Main Authors: Che, S., Guduru, P.R., Nurmikko, A.V., Maris, H.J.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-02-2015; Elsevier
• Subjects: Acoustic lens; Acoustic microscope; Acoustic microscopes; Femtosecond; Holes; Lenses; Metrology; Scanning; Sound; Thin films; Acoustic lens; Acoustic microscope
• ISSN: 0041-624X; 1874-9968
• DOI: 10.1016/j.ultras.2014.02.010

We report on the development of a new type of scanning acoustic microscope. We use a femtosecond light pulse to generate a short sound pulse, and then focus this sound onto the sample by means of a specially designed and microfabricated acoustic lens of radius a few microns. The sound travels to the sample through a thin layer of water. The sound reflected from the sample is collected by the lens and then passes through a monolithically integrated optical resonant cavity. The induced change in the properties of this cavity are measured using a time-delayed probe light pulse. We describe some of the challenges involved in the construction and operation of this high-precision metrology apparatus and present some preliminary results.