Holographic vibration study of a rotating propeller blade

Holographic interferometry has often been used to determine the natural frequencies and the associated mode patterns of vibrating objects with rigidly fixed or stationary boundaries. This paper describes a new pulse-laser holographic technique whereby the vibration-mode patterns of a rotating propeller blade were determined. This technique consists of rotating the holographic plate on the same axis as the rotating object and using spherically symmetric wavefronts for object and reference beams.