Abstract: The improved method and means for detecting the edges of a sample part operates on the Gaussian distribution of light intensity across a laser beam and uses analog signal and simple logical circuits to produce highly accurate, highly repeatable and rapid edge position indications. A multi-segment detector is configured with reference to the dimensions of the laser beam to provide independent outputs representative of relative position of the reflected or transmitted portion of the laser beam upon the detector as the edge of the sample part moves across the beam. An improved detector for operation with a beam having non-uniform intensity distribution thereacross includes a central segment and four perimeter segments oriented about othogonal axes that are substantially aligned with the axes of movement of the sample part across the beam.

Abstract: An improved method and apparatus for detecting the edges of a sample part operates on the Gaussian distribution of light intensity across a laser beam and uses analog signal and simple logical circuits to produce highly accurate, highly repeatable and rapid edge position indications. A multi-segment detector is configured with reference to the dimensions of the laser beam to provide independent outputs representative of relative position of the reflected or transmitted portion of the laser beam upon the detector as the edge of the sample part moves across the beam.