Moiré topography by slit beam scanning.

A new method of moiré topography is suggested in which a slit beam is used in a scanning mode to generate moiré fringes. One remarkable feature of this method is that, as opposed to existing shadow and projection types, height differences between two consecutive fringes become constant so that absolute fringe orders need not be identified. This advantage makes it possible to measure three-dimensional surface profiles in an automatic manner simply by using a computer-aided image-processing technique. In addition this method can be easily implemented in a conventional coordinate measuring machine with a minimum addition of optical hardware.