Application of SLM generated patterns for laser-ultrasound

Abstract

We use a spatial light modulator to shape the excitation laser spot of a laser-ultrasound system. With periodic excitation patterns we are able to excite ultrasound waves of a particular, single wavelength. In combination with temporal intensity modulation of the excitation laser, only waves of specific wavelength and frequency are generated. We experimentally validated this principle and applied the method to scan the two-dimensional dispersion relation of surface acoustic waves on coated samples. Results obtained with different periodic patterns were compared. We also used the setup to produce laser spots of different size to study the excitability of Lamb modes.