Measurement of cylindrical objects by laser telemetry in an ambulatory context

The generalization of a new method for robust noncontact diameter determination of cylindrical objects is studied. The principle lays on laser telemetry under structured lighting, where laser planes create lines on the object under test which are observed by a CCD camera. The calculation is performed thanks to what we call the "three-tangents method" which was proved as the most reliable one taking into account the curve's particular characteristics. So far the object was supposed standing perpendicular to the plane of the camera; we extend the method to the diameter measurement of cylinders randomly tilted in regard to the camera's optical axis. Experimental results obtained on a preprototype caliper are given. A general accuracy of 1% for 10 to 30 cm diameter cylindrical objects is claimed for distances up to 2 m.