Optical system for determining the variation of curvature of an object on a zone of small dimensions

An optical system for determining the curvature or the variation of curvature of an object (9) in a zone of small diameter, comprising:

• (a) a light source (1);
• (b) first optical means (3) for forming a first parallel light beam (2b) from the beam emitted by said source;
• (c) a semi-reflecting element (4) disposed on the path of said first parallel light beam and transmitting a second parallel light beam (2c);
• (d) second optical means (7) for focusing said second parallel light beam (2c), said second optical means (7) being movable parallel to the direction of propagation of said second light beam and having an image focus (8) which may be brought to merge at least substantially with the center of curvature (C) or the surface (S) of said object (9), said object (9) reflecting the light beam focused by said second optical means, in the direction of said second optical means (7) which forms a third light beam (2d) addressed to said semi-reflecting element (4);
• (e) third optical means (10) receiving said third light beam (2d) coming from said semi-reflecting element (4) and focussing said third light beam (2d) for forming an image (12) of said object (9);
• means for detecting (11) said image and
• (f) means (15) for displaying said image (12), said second optical means (7) being moved in order that said image (12) on said displaying means be clear.