Patent ID: 7880902

Claim:
Optical probe including opto-electrical means that assumes a predetermined electrical state when situating said probe ( 3 ) at a preset target distance from a surface ( 2 A, 2 B) that is at least partially reflective and assumes an electrical state other than said predetermined electrical state when situating said probe ( 3 ) at a distance other than the preset target distance from the surface ( 2 A, 2 B), said probe including: a light source ( 20 ); shaping means ( 24 , 25 , 21 ) for shaping a beam emitted by said light source into an incident beam ( 5 ) converging toward a focus (F 1 ) situated at said target distance and for shaping the beam coming from said surface by virtue of reflection of said incident beam ( 5 ) when said surface is in the vicinity of said target distance into a beam ( 5 ′) to be detected converging toward a focus (F 2 ), separate from said light source, occupying a predetermined location when said surface is at said target distance; and an optical detection system ( 22 ) including a diaphragm ( 26 ) including a pinhole, disposed at said predetermined location, and a photoelectric sensor ( 28 ) producing a voltage peak ( 31 ) when said surface is at said target distance; wherein: said shaping means ( 24 , 25 , 21 ) also shape said beam coming from said surface into a discrimination beam ( 5 ″) converging toward a focus separate from said light source and from said focus of the beam to be detected, occupying another predetermined location when said surface is at said target distance; and said probe further includes an optical discrimination system ( 23 ) including a diaphragm ( 27 ) including a hole larger than said pinhole, disposed at least in the vicinity of said other predetermined location, and a photoelectric sensor ( 29 ) producing a voltage higher than said voltage produced by said detection sensor ( 28 ) except when said surface ( 2 A, 2 B) is at the target distance, whereby said predetermined electrical state is that in which the voltage produced by the detection sensor ( 28 ) is greater than the voltage produced by the discrimination sensor ( 29 ).