Evaluation of rigid rotations in flexural loading tests by holographic interferometry

The authors develop a simple method based on holographic interferometry for determiningthe Poisson's ratio and the Young's modulus for a specimen subjected to four-point flexura( testing that evaluates and eliminates the effectsoftheunwantedrigid-bodyrotations. Intheexperi- mental setup, they use an additional mirror to record the un- derside and the front surface of the specimen simultaneously. The theoretical analysis shows that it is possible to correlate the holographicfringe pattern of the undersideand front sur- faceofthesample, Eachrotationanglecanbeevaluatedby countingthefringeordersbetweentwo pointschosenonthe two fringe patterns.