System for optically measuring the surface contour of a part using more fringe techniques

摘要

An optical measuring system comprises an illumination arrangement including a light source, grating, and lens, and an image acquisition arrangement, including a lens, grating, and camera. A mechanical translation device moves the grating in a plane parallel to a reference surface to effect a phase shift of a projected image of the grating on the contoured surface to be measured. A second mechanical translation device moves the lens to effect a change in the contour interval. A first phase of the points on the contoured surface is taken, via a four- bucket algorithm, at a first contour interval. A second phase of the points is taken at a second contour interval. A controller, including a computer, determines a coarse measurement using the difference between the first and second phases. The controller further determines a fine measurement using either the first or second phase. The displacement or distance, relative to the reference plane, of each point is determined, via the controller, using the fine and coarse measurements.