Application of the LPD (Laser Photo Deflection) Method to the Vibrational Diagnosis of a Brick Wall

In this paper, we present the results of the optical evaluation of the vibrational behavior of a wall (brick).The procedure used is Laser Photo Deflection (LPD), where a laser beam reflected off the sample is redirected to a deflection detector, which detects the sample's vibrations.Using various excitation alternatives, it is possible to establish definitely the first 10 Eigen vibration modes, from which a simple formation pattern based on 2 digits (n,m) can be clearly recognized, for example mode (1,1) (the fundamental mode) corresponds to 29.4 Hz and mode (2,1) to 37.3 Hz, and so on.