Progressive addition lenses power map measurement using Ronchi test techniques

Progressive ophthalmic lenses involve high resolution technological manufacturing processes, due to the particular non-symmetrical, aspherical form of their convex surface. However, the testing of the surfaces is not usually performed using whole-field methods because of the high dynamic range and resolution required for the slope changes in the convex surface. Applying some simple enhancements, a robust Ronchi test technique can be used to obtain accurate power distribution maps of commercial progressive lenses. In this technique, a CCD detector is used as a high resolution slope map, which combined with multiple acquisition techniques, allow for high resolution measurements of both lateral displacement (10-4 m) and slope measurements (10-5 rad) with the required dynamic range in slope measurements for progressive power lenses. The power maps of different types of progressive lenses are presented, showing the differences between lens design and manufacturing. The ability of the enhanced Ronchi test technique to quantitatively map power variations with important slope changes is demonstrated.