Investigation of three interferometric techniques for detection of surface flaws in elastomers

Non-destructive testing of rubber by optical means presents a challenge because rubber has different mechanical properties from conventional solids when subjected to stress. The size of flaws introduced in rubber during the manufacturing process is an important characteristic as they increase the stress in the specimen when it is in use. The use of electronic speckle pattern interferometry, electronic speckle pattern shearing interferometry and white light interferometry for non-destructive material characterization of rubber is presented. It is shown that electronic speckle pattern shearing interferometry can be of some use for visualisation of flaws on the rubber surface under thermal stress. White light interferometry gives a complete profiling of the elastomer surface and it is only one of the three interferometric techniques for measuring flaws on the rubber surface.