
doi: 10.1117/12.22201
We present a simple optoelectronical fringe projection method for topographic or deformation study of objects. Programmed positioning and repositioning can also be performed. 1. DESCRIPTION An incoherent method for fringe projection operations was recently reported'' using photographic procedures. It is extended now to real time operation using an LCD video projector and a CCD camera. Fringes consisting in Rbnchitype rulings are generated in a personal computer and projected onto an object by using a Kodak LCD colour video projector. Its image is then read by a SVHS-CCD Panasonic camera and electronically memorized. This fringe pattern contains information concerning the position and topography of the object stored as fringe phase modulation. A standard state of the object can be frozen in the screen of a monitor and its evolution deformation or misspositioning followed through the Moire between current and stored fringes. Topography of the object expressed as a mathemati cal functi on h ( x y) and its time evolution can alsO be determined from the memorized data. . Besides a conjugated grid can be generated so that when the latter is projected onto the object the observed fringes are corrected to straight lines resembling the original Ronchi rul ings i. e. distortion produced by object topography is cancelled out. Deformations with respect to this state are straightforwardly interpreted by an observer both in magnitude and sign. The system can be made
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