Optical caliper and edge detector-follower for automatic gaging

Claim 2

An automatic optical gage for making linear measurements of objects comprising an optical system including a laser light source for deriving and projecting narrow continuous gaging and reference light beams and for focusing said gaging light beam to a small diameter spot, a pivoted beam deflector for producing linear displacement of the focused gaging light beam relative to the edge of the object, gage and reference electro-optical photodetectors for respectively sensing said gaging and reference light beams and generating electrical output signals indicative of the intensity thereof, servo feedback control means including a difference circuit for deriving a linear servo error voltage dependent on the relative magnitudes of the two photodetector output signals, and a servomechanism for adjusting said pivoted beam deflector to a position in which said focused gaging light beam is partially interrupted by the edge of the object, and readout means for obtaining a measurement dependent on the distance between the adjusted position of said gaging light beam and a reference position.

Claim 3

An automatic optical caliper for gaging workpieces comprising the combination of a laser light source for deriving a narrow source light beam, a pair of aligned, independently operating optical gage units for automatically seeking respective opposite edges of the workpiece, each optical gage unit including a gage carriage guided for linear movement on which is mounted an optical system that receives said source light beam and projects continuous parallel gaging and reference light beams, gage and reference electro-optical photodetectors supported for movement with said gage carriage for respectively sensing the light transmitted by said gaging and reference beams past the edge of the workpiece and for generating electrical output signals indicative of the intensity thEreof, servo feedback control means controlled by said photodetector output signals and including a digitally operated servomechanism for actuating said gage carriage and positioning each gaging light beam to be partially interrupted by one edge of the workpiece, and digital electronic readout means for measuring the distance between the two gaging light beams when so positioned and for indicating a measurement dependent on this measured distance.

Claim 4

An automatic optical caliper for gaging workpieces comprising the combination of a laser light source for deriving a narrow source light beam, a pair of aligned, independently operating optical gage units for automatically seeking respective opposite edges of the workpiece, each optical gage unit including a gage carriage guided for linear movement on which is mounted an optical system that receives said source light beam and projects continuous parallel gaging and reference light beams, gage and reference electro-optical photodetectors supported for movement with said gage carriage for respectively sensing the light transmitted by said gaging and reference beams past the edge of the workpiece and for generating electrical output signals indicative of the intensity thEreof, servo feedback control means controlled by said photodetector output signals and including a digitally operated servomechanism for actuating said gage carriage and positioning each gaging light beam to be partially interrupted by one edge of the workpiece, and digital electronic readout means for measuring the distance between the two gaging light beams when so positioned and for indicating a measurement dependent on this measured distance.

Claim 5

A construction according to claim 2 in which said servo feedback control means, in each optical gage unit, comprises a differential amplifier for generating a servo error voltage based on the relative magnitudes of said photodetector output signals, and a pulse generator actuated by said error voltage, and in which said digitally operated servomechanism is a stepping motor energized by the pulses produced by said pulse generator for adjusting said gage carriage, said digital electronic readout means including a circuit for making a relative count of the pulses supplied respectively to the two stepping motors in the two optical gage units.

Claim 6

A construction according to claim 2 equipped for profile gaging by further including means for simultaneously moving the two gage carriages and components mounted thereon along the axis of the workpiece so that the two gaging light beams automatically seek and follow the opposing edges of the workpiece for profile gaging.

Claim 7

An automatic optical caliper for gaging workpieces comprising a laser light source for deriving a single narrow source light beam, a pair of aligned, independently operating optical gage units for automatically seeking opposite edges of the workpiece, each optical gage unit including an optical system for receiving said source light beam and deriving therefrom and projecting a continuous gaging light beam and a continuous reference light beam, adjusting means for moving at least said gaging light beam relative to one end of the workpiece, gage and reference photodetectors for respectively sensing said gaging and reference light beams and generating output signals indicative of the intensities thereof, servo feedback control means responsive to said photodetector output signals for actuating said adjusting means and positioning said gaging light beam to be interrupted by the one edge of the workpiece, and optical interferometer readout means for obtaining a measurement based on the distance between the two gaging light beams when positioned to be interrupted by the opposite edges of the workpiece, said readout means including means for deriving from said gaging light beams and subsequently combining a pair of interferometer beams whose only path length difference is the actual distance between the two gaging light beams.

Claim 8

An automatic optical caliper for gaging workpieces comprising a laser light source for deriving a single narrow source light beam, a pair of aligned, independently operating optical gage units for automatically seeking opposite edges of the workpiece, each optical gage unit including an optical system for receiving said source light beam and deriving therefrom and projecting a continuous gaging light beam and a continuous reference light beam, adjusting means for moving at least said gaging light beam relative to one end of the workpiece, gage and reference photodetectors for respectively sensing said gaging and reference light beams and generating output signals indicative of the intensities thereof, servo feedback control means responsive to said photodetector output signals for actuating said adjusting means and positioning said gaging light beam to be interrupted by the one edge of the workpiece, and optical interferometer readout means for obtaining a measurement based on the distance between the two gaging light beams when positioned to be interrupted by the opposite edges of the workpiece, said readout means including means for deriving from said gaging light beams and subsequently combining a pair of interferometer beams whose only path length difference is the actual distance between the two gaging light beams.

Claim 9

A construction according to claim 5 wherein said optical interferometer readout means further includes means for detecting and counting the cyclical interferences between said pair of interferometer beams.

Claim 10

An automatic optical caliper for gaging workpieces comprising a laser light source for deriving a single narrow source light beam, a pair of aligned, independently operating optical gage units for automatically seeking opposite edges of the workpiece, each optical gage unit including an optical system including a first mirror element for deriving from said source light beam and projecting a gaging light beam, adjusting means for moving said gaging light beam relative to one edge of the workpiece, a gage photodetector for sensing said gaging light beam and generating an output signal indicative of the intensity thereof, servo feedback control means responsive to said photodetector output signal for actuating said adjusting means and positioning said gaging light beam to be interrupted by the one edge of the workpiece, and optical interferometer readout means for obtaining a measurement dependent on the actual distance between the two gaging light beaMs when positioned to be interrupted by the opposite edges of the workpiece, said optical interferometer readout means including a beam splitter and a second mirror associated with each optical gage unit for deriving from each gaging light beam an interferometer beam which is reflected back to the associated first mirror element, one of said interferometer beams further being reflected from one of said first mirror elements to the other and combined with the other interferometer beam, and means for detecting and counting the cyclical interferences of the combined interferometer beams.

Claim 11

An automatic optical caliper for gaging workpieces comprising a laser light source for deriving a single narrow source light beam, a pair of aligned, independently operating optical gage units for automatically seeking opposite edges of the workpiece, each optical gage unit including an optical system including a first mirror element for deriving from said source light beam and projecting a gaging light beam, adjusting means for moving said gaging light beam relative to one edge of the workpiece, a gage photodetector for sensing said gaging light beam and generating an output signal indicative of the intensity thereof, servo feedback control means responsive to said photodetector output signal for actuating said adjusting means and positioning said gaging light beam to be interrupted by the one edge of the workpiece, and optical interferometer readout means for obtaining a measurement dependent on the actual distance between the two gaging light beaMs when positioned to be interrupted by the opposite edges of the workpiece, said optical interferometer readout means including a beam splitter and a second mirror associated with each optical gage unit for deriving from each gaging light beam an interferometer beam which is reflected back to the associated first mirror element, one of said interferometer beams further being reflected from one of said first mirror elements to the other and combined with the other interferometer beam, and means for detecting and counting the cyclical interferences of the combined interferometer beams.