A COMPACT DUAL-PURPOSE CAMERA FOR SHEAROGRAPHY AND ELECTRONIC SPECKLE-PATTERN INTERFEROMETRY

A dual-purpose camera for both shearography and electronic speckle-pat tern interferometry (ESPI) based on the concept of additive-subtractiv e phase-modulated speckle interferometry has been designed and tested. The compact camera can be operated either in ESPI mode or in shearogr aphy mode by simply adjusting a moving mirror in the camera head. This camera has been designed as an optical part of an automatic inspectio n system for disbond detection in aircraft structures. The primary adv antage is the possibility of obtaining information both about an objec t's displacement and about its gradient using a single low-cost device suitable for field applications.