Comparative displacement measurement by digital holographic interferometry

摘要

Digital holography is a powerful tool in NDT. Different measuring methods have been developed to perform more flexible measurements and to alleviate the drawbacks of this technique. The rapid development of spatial light modulators in the past few years opened an exciting new area in coherent optical metrology. Commercially available liquid crystal spatial light modulators (SLM's) are capable to optically reconstruct digital holograms in good quality, so the reconstructed real image of an object can be used as a coherent illuminating mask in optical measurement methods like digital holography. Combination of digital holography and TV holography (ESPI) is also possible. In the present work five methods of digital holography are investigated which are able to implement comparative measurement. Both the experimental arrangements and measuring results are presented.