Detection of in‐plane and out‐of‐plane ultrasonic displacements by a two‐channel confocal Fabry–Perot interferometer

Simultaneous detection of in‐plane and out‐of‐plane ultrasonic displacements by a two‐channel confocal Fabry–Perot optical receiver is described. Accuracy is tested by measuring the in‐plane and out‐of‐plane displacements produced by Rayleigh surface waves generated by a piezoelectric transducer and a laser.