Non-stereoscopic method for deflectometric measurement of reflecting surfaces

General deflectometric methods are subject to an ambiguity regarding the determination of the surface normals. A typical way to resolve this is to use two cameras (Stereo Deflectometry). Here we present a deflectometric method, which uses only one camera image. The ambiguity is resolved by a priori information about one point of the surface and by an iteration loop. At each iteration, a virtual surface, constructed in the previous step, is used to determine the normals. The new height distribution is then created with shifted base functions (SBF). After this, the virtual surface is shifted vertically, so that the known point agrees. The iteration starts with a plane surface. The algorithm converges after a few iterations and the height distribution of the measured surface is obtained with high accuracy. One application of this method is the elimination of the time consuming focus search in systems biology, where a lot of individual experiments on one thin and therefore deformed glass substrate are observed by microscopy.