Radiant energy inspection system for rotating objects

Claim 1

Apparatus for determining the geometric qualities of a rotating object by monitoring the radial displacements of first and second diametrically opposite surface locations comprising: an object rotating at a given angular frequency, means for rotating said object, source means for producing first and second parallel and substantially collimated beams of radiant energy having respective reference boundaries which are fixed in space, said source means including pulsed excitation means such that the beams are intermittent in character at a high repetition rate, means for directing the beams tangentially along the respective surface locations such that each beam is partially intercepted by the object to a degree related to the radial position of the surface location intercepting the beam relative to the reference boundary of the beam, first and second detector means for receiving the unintercepted portion of the first and second beams, respectively, and for producing first and second signals relating substantially proportionally to the distances between the surface locations intercepting the beams and the reference boundaries, and output means including circuit means for smoothing the intermittent pulses received for the beams and being connected to the detector means for comparing the relative values of the first and second signals.