Two transparent optical sensors for the positioning of detectors using a reference laser beam

We have developed two different optical systems in order to position detect ors with respect to a reference laser beam. The first system, a telescope, permits the absolute positioning of an element with respect to a reference laser beam. The resolution is of the order of 10 mum in translation and 50 mu rad in rotation. It is highly transparent (similar to 90%) permitting se veral elements to be aligned. A calibration procedure has also been studied and is currently being tested in order to obtain an absolute alignment inf ormation. The second system is a highly transparent (95%) two-dimensional p osition sensor which allows the accurate positioning (below 20 mum) of seve ral (up to 10) elements to which each sensor is attached, transversally to a laser beam used as a reference straight line. The present useful area of the first sensor is 20 x 20 mm(2) and is 15 x 15 mm(2) for the second. In b oth cases it can be further increased to meet the experiment's requirement. (C) 2001 Elsevier Science B.V. All rights reserved.