Gradient analysis of sound pressure field by opt-acousticwave-frontal detection

Opt-acoustical measurement is a potential candidate of non-invasive measurement over the acoustic wave field. In this paper, a novel method for grading vector measurement of the sound pressure field which is based on the Fraunhofer diffraction is proposed. The proposed method has an ability to capture the projection of the gradient vector of acoustic wave field through the eccentricity of the zeroth-order Fraunhofer diffraction. In this study, the theoretical analysis of the process of the above projection is discussed and their physical meanings are investigated through numerical experiments and acousto-optical experiments.