DETERMINATION OF THE OPTICAL-ABSORPTION COEFFICIENT VIA ANALYSIS OF LASER-GENERATED PLATE WAVES

A technique has been demonstrated which measures the optical absorptio n coefficient in weakly to moderately absorbing homogeneous isotropic elastic plates, This technique involves generating plate waves with a pulsed Nd:YAG laser and then detecting the disturbances in the acousti c far field where the majority of the acoustic energy has been coupled into the first symmetric, s(o), and antisymmetric, a(o), plate modes, The optical absorption coefficient is determined by comparing the exp erimental and theoretical expression for the ratio of the integrated p ower spectra of the s(o) and a(o) modes.