Laser Shadow & Eddy-Current Scanner

SHADYSCAN a non-contact profile thickness measuring system that combines the signal of a through-beam sensor with the signal of an inductive eddy current sensor. SHADYSCAN has many applications. In particular it is suitable to measure the thickness of expanded sheets that cannot be measured with absorption systems such as X-rays and Beta rays.

The light beam is aimed tangentially to the surface of the film and redirected over the measurement roller. The through-beam is collected by a CCD camera which monitors the increase and decrease of the shadow generated by the film. This measurement depends on the relative movement between the roller and the sensing beam, as well as the variation of the film thickness. In order for the variation of the shadow to be proportional only to the variation of the film thickness, it is necessary to compensate for any mechanical displacement between the parts. This is achieved by means of an inductive eddy current sensor that constantly detects the distance between the camera and the roller along the thickness axis.