AbstractHolographic interferometry was investigated as a method for nondestructive testing of flat sheets of glass‐fiber reinforced plastics. Initially, the deformation behavior of faultless sheets was examined by means of holographic interferometry. The interferograms which resulted from various loading conditions (i.e., tensile load, bending) were compared to results obtained mathematically. The interferograms of faultless sheets were then compared to those of defective laminates. By suitable loading of the smaples a range of laminate faults could be readily and qualitatively detected. The influence of these faults on the tensile strength was examined. Not only the mechanical loading of the laminates, but also an acoustic stimulation of the sheets proved suitable for interferometric detection of laminate fault