US Patent 7286246 Method and apparatus for non-contact three-dimensional surface measurement

A non-contact three-dimensional surface measurement method is provided in which a grating pattern projected onto an object being measured, while the phase of the pattern is being shifted, is observed in a different direction from a projection direction to analyze the contrast of a grating image deformed in accordance with the shape of the object and thereby obtain the shape thereof. The method enables measurement of a three-dimensional shape over a large measurement range in a short time in a non-contact manner by successively shifting the focus on the projection and the imaging sides to enlarge the measurement range in the direction of depth.