Scanning moiré method and automatic measurement of 3-D shapes

A new type of moiré and its application to topography are discussed. moiré fringes are generated by observing a grating projected on an object under test with a scanning imaging device. The general equations of the projection-type moiré topography are given. By controlling the phase, the pitch, or the direction of the virtual grating corresponding to the scanning lines of the imaging device, the automatic sign determination of the contour lines is accomplished. By the use of a high precision flying spot scanner with CRT(DD-tube) and a minicomputer system, an experimental measurement system is developed. Very significant is the fact that a contour line system and a sectional shape of the object are automatically reconstructed and displayed on a color TV monitor.