The study assesses the effectiveness of the application of speckle methods in the testing of natural and artificial composites. Most of attention has been given to the testing of wood. This is due to a particular and constantly growing role of this construction material. Comparative tests were performed by coherent speckle photography methods, by the methods of speckle photography in white light and by ESI methods. Quite unexpectedly, the classical coherent speckle photography in the out-of-plane version has proved to be the most sensitive method in non-destructive tests.
"The out-of-plane method in the testing of composite materials", Proc. SPIE 5229, Laser Technology VII: Applications of Lasers, (6 October 2003); doi: 10.1117/12.520774; https://doi.org/10.1117/12.520774