Precise interferometric system for fast contactless measurements of lens thickness

In the process of the lens production it is extremely important that a total time of measuring the lens thickness, taking into account also the time needed to insert the lens into a system, should be short enough to test the substantial part of the series of products. Currently used methods of measuring lens thickness apply various solutions [1, 2], but none of them offers a fast and cost effective system which is capable to perform contactless measurement combined with high accuracy. For optical reflection measurements (e.g. employing the Michelson interferometer), which are the most common, the lens alignment must be very precise, so it takes a lot of time (even a few minutes, which depends on the lens parameters, such as radius of curvature) to perform measurement of a single lens.