Nowadays in mechanical material testing strains are measured only between two distinctive points on the specimen with probes or by optical analysis of two marked positions on the surface of the specimen. Information about eventual inhomogeneous strain distribution between these two points can not be obtained by these methods. A new laseroptic strain sensor overcomes these restrictions by using the principle of laser speckle interferometry for measure-ment. In the one dimensional measuring case the specimen is symetrically illuminated by two bundles of laser light and the image recorded with a high resolution CCD-camera. Computer evaluation of the images shows deformations and strains on the surface of the specimen with high sensitivity. An extended design uses two of these optical set-ups to provide two inplane measuring directions. Special interest was layed onto the optical set-up which guarantees uniform measuring sensitivities in the whole measuring field and as well very limited adjustment requirements. The laseroptic strain sensor requires no marking on the specimen and gives full field measuring information without contact on nearly any surface. In this paper the operation principle of the laseroptic strain sensor is described. Typical application examples in material testing are given.
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