Patent ID: 7054013

Claim:
A process for measuring distances by optical means, on a specular or quasi-specular metal strip or surface in continuous motion in an installation, said process comprising the following steps: a light beam, referred to as incident beam, is emitted by a source incorporated into a measurement head, said source projecting a pattern in the form of a line, arranged along an axis that is essentially perpendicular to the motion direction of the metal surface, in a incidence direction upon a fixed part of said installation; firstly, said beam is partially reflected by said fixed part, essentially along the same path as that of the incident beam and in the opposite direction towards a detector belonging to said measurement head and located in the immediate vicinity of said source; secondly, said beam is partially reflected by fixed part towards said metal strip, from where it is further reflected in the direction of said detector, so that each point of the image coming from the metal strip appears to correspond to a virtual point, which is essentially the point that is symmetrical with the corresponding point of the incident beam upon said fixed part with respect to a central plane passing through said strip.