title: Time-lapse interferometry and contouring using television systems.
abstract: A novel approach to time-lapse interferometry and contouring is introduced that uses television rather than photographic techniques. A first interferogram is stored on a video storage device such as a magnetic disk. After a change in the stress of the object, a second interferogram is electronically compared to the stored pattern to form a signal representative of the fringe pattern caused by the deformation. This signal may be directly displayed on a cathode-ray tube or employed by some automatic inspection device.
authors.forename: A
authors.initials: A
authors.lastname: Macovski
authors.forename: S D
authors.initials: SD
authors.lastname: Ramsey
authors.forename: L F
authors.initials: LF
authors.lastname: Schaefer