A ray tracing approach to inverse pattern profilometry

To achieve object matched inverse patterns for the profilometric measurement of the shape of manufactured surfaces, in general at first the shape of a faultless reference object must be known. For these purposes, a separate profilometric measurement cycle employing the reference object as specimen can be executed, if a reference object of adequate quality is available. Based upon this first measurement, an object matched inverse pattern is calculated, and the shape of an arbitrary specimen can then be compared to the ideal shape of the reference object. This paper proposes an algorithm to find inverse patterns for analytically known reference objects based upon ray tracing techniques without requiring a physically existing reference. It further provides methods for the automated derivation of setup parameters for a general profilometric measurement setup.