Holographic Interferometry for Non-destructive Inspection and Testing in Manufacture

Holographic interferometry can be used to obtain a complete picture of the deformation of a complex assembly under test, or a map of its vibration modes and their amplitudes. Recent advances in holographic recording materials and digital phase-shifting techniques developed at the Division of Applied Physics (DAP) to acquire and process holographic data, permit displacement measurements to be made on static and vibrating objects within a few seconds with an accuracy of a few nanometres, at arrays of up to 512 x 512 points. The data obtained are in a form suitable for further computer processing such as Finite Element Analysis to evaluate strain and stress fields. Results of a number of applications relevant to the manufacturing industry are presented. The holographic system developed at the DAP is a powerful tool which can be used for quantitative and qualitative non-destructive inspection and testing in manufacturing process control.