Phase analysis method of interferometric pattern generated for optical axis direction using three laser beam interferometry

In this paper, the authors propose a phase analysis method of an interferometric pattern generated for the optical axis direction using three-beam interferometry. Authors perform shape measurement using the proposed method. In three-beam interferometry, the fringe pattern along the optical axis direction appears by superimposing each two-beam interference fringe. Therefore, the power distribution of the fringe pattern appears along the optical axis direction. This method enables us to directly obtain shape and displacement using the interferometric pattern. Our method intended for wide application with 3D shape measurements and out-of-plane displacement measurements for the inspection and maintenance of large constructions. As the first step of developing a device for 3D shape and displacement measurement, in this paper, simulation and an experiment were used to confirm that interferometric pattern for optical axis directional appeared. Further, slope of object was measured from the phase shift of optical axis directional pattern. © 2019 Japan Society for Precision Engineering. All rights reserved.