Abstract
The grid illuminating moire method is known as a simple means of measuring the surface contour of an object. But when this method is evaluated from the standpoint of practical use, some problems remain to be solved. That is, the concave and convex regions of an object with a complicated shape cannot be discriminated from the fringe pattern formed, and when the experiment is carried out under the condition that the surface to be measured is out of contact with the grid plane, the fringe index cannot be determined. In this paper, it is shown that these problems can be solved easily by using the fringe patterns formed before and after the object to be measured is shifted in the direction normal to the gird plane.
