METHOD AND APPARATUS FOR MEASURING A THREE-DIMENSIONAL CURVED SURFACE SHAPE

A method and apparatus adapted to measure a three-dimensional curved surface shape quantitatively with high speed. A pattern of interference fringes on a surface of an object to be measured is picked up so that while moving a reference plane (or the object to be measured) in the direction of an optical axis, the resulting video signal is processed to form a composite image in which a value of each of picture elements is represented by a position of the reference plane (or a position of the object to be measured) at an instant that one of positions on the object surface corresponding to that picture element in the image attains a maximum brightness. Then, a three-dimensional curved surface shape of the object to be measured is measured on the basis of the composite image.