Laser diagnostics of acoustic emission in solids

The acoustic emission of the ensemble of the growing germs of the new phase in solid, the scattering of hypersonic wave by an indicated ensemble and the transition processes initiated by an hypersonic pulse were investigated. Two characteristic stages of germ formation-initial and late (stage of coalescention) were considered. The analysis of acoustic emission showed, that the ensemble of growing germs generates acoustic waves which frequencies ω_Å are simply connected with the size R of heterogeneities (germs), and the intensity of each spectral component is determined by their concentration n(R). If we direct a laser beam on the sample, the radiation will be dispersed on the hypersonic waves, and the scattering angle will be simply connected in the frequency of an acoustic wave and therefore with the sizes of a germ R.