Vibration analysis of single curved shells by the time average reflection grating principle

If a line grating is observed via the reflective surface of a periodically vibrating object during one or more periods of its motion, an interference effect comes into existence. The interference fringes represent the slope contours of the object relative to the extreme deformation state. This principle was developed for vibration analysis of plates. It is also applicable for slope measurement of vibrating shells. The slope values again can be deduced from the arising interference effect. This interpretation is described.