A compact dual-purpose camera for shearography and electronic speckle-pattern interferometry

A dual-purpose camera for both shearography and electronic speckle-pattern interferometry (ESPI) based on the concept of additive-subtractive phase-modulated speckle interferometry has been designed and tested. The compact camera can be operated either in ESPI mode or in shearography mode by simply adjusting a moving mirror in the camera head. This camera has been designed as an optical part of an automatic inspection system for disbond detection in aircraft structures. The primary advantage is the possibility of obtaining information both about an object's displacement and about its gradient using a single low-cost device suitable for field applications.