High-accuracy measurement for small scale specular objects based on PMD with illuminated film

In this paper we describe an approach to measure small glossy objects by illuminated film based on Phase Measuring Deflectometry (PMD) system. In this setup, the standard sinusoidal fringe patterns are produced by the photographic film frame (135-film), which is illuminated from behind using LED and diffuser, instead of the well-known LCD monitor plane or digital projector. This setup can avoid the influence of electronic noise and screen refreshing, and fulfill the test of small objects in low cost. Moreover the system is easily calibrated with its vertical setup. With the experiments of measuring a plastic contactless smartcard and a metal plate, it is proven that the setup can reach sub-micrometer accuracy with respect to the data of the Wyko white light interferometer. This setup will be promising in the small scale measurement field.

► This method is to measure small glossy objects.
► The photographic film frame is used to produce the sinusoidal fringe patterns.
► The setup is low cost and easy to be calibrated.
► This setup can avoid the influence of electronic noise and screen refreshing.
► This setup can reach sub-micrometer accuracy.