In many optical applications, the quality of the image formed by a lens is of critical importance. A high quality lens begins with a good design which is tolerant to small manufacturing errors. Next, the manufacturing process must be tightly controlled, from the individual lens elements to the final assembly. However, since small errors in manufacturing can result in serious loss of performance, end-of-line testing is then necessary to identify lenses that fail to meet the desired quality requirements. Therefore, there is a need for an objective and automated quality test to perform this task.