Optical comparators, also referred to as profile projectors and contour projectors, were first introduced in the 1940s and they are still widely used today in a broad range of industries to verify that manufactured parts are within tolerance. These versatile instruments are easy to use and the fact that they are very robust makes them well suited for use on the shop floor as well as in the metrology and quality control labs. They are well suited to complex geometries (i.e., shapes not easily described by simple elements like lines and circles) and, up until now, they have been the easiest way to quickly compare a part to its drawing to allow the operator to make an overall pass/fail determination.

 …