Laser dimension comparator

Claim 1

A distance measuring apparatus for providing an output correlatable to a distance dimension of a workpiece, said apparatus comprising: a. a coherent light source means for directing coherent light onto said workpiece for illuminating said workpiece in a manner to induce backscattered, reflected light therefrom having an area of relatively large intensity gradient; b. light directing means for directing said backscattered light from the workpiece, said directed backscattered light including at least a pair of relatively large intensity gradients which are spaced a distance proportional to the distance to be measured; c. photo responsive detector means positioned to receive said directed backscattered light, for detecting said intensity gradients by providing an instantaneous output proportional to the intensity of the light instantaneously being detected thereby; d. scanning means for presenting said backscattered light to said detector means for detection in a timed scanning sequence; e. signal processing means connected to receive the output of said detector means and being responsive to the time period between the scanned detection of said intensity gradients for converting the output from the detector means to a signal which is correlatable to said distance dimension; f. said light source means providing a single light beam incident upon said workpiece to provide a spot of increased light intensity; g. said light directing means including a pair of spaced mirror means for reflecting a pair of spaced images of said spot to said detector means; h. said detector means and said scanning means comprising an image tube including lenses and scanning means associated therewith; i. said light directing means comprising an optical lens system for imaging said backscattered light in a selected position; j. said detector means comprising an image detecting camera tube having a screen positioned at said selected position; k. said scanning means comprising means for scanning said screen to detect said backscattered light image in a timed sequence; l. pulse shaping means connected to receive the output of said image detecting tube for providing an output pulse having a time width directly proportional to the spacing between said images; m. a scaling oscillator means for generating oscillator pulses at a selected pulse rate; n. a scaling gate means connected to receive the pulses from said pulse shaping means and said scaling oscillator means, said scaling gate means being controlled by said pulses from the pulse shaping means for gating said oscillator pulses to the scaling gate output; o. counting means connected to the scaling gate for counting the scaling gate output pulses in a selected time interval; p. an output storage means for storing a count accumulated in said counting means; q. logic sync means for providing a time-sequence of instruction pulses at its output in response to an input clock pulse, said instruction pulses including a latch pulSe, a clear pulse and a load pulse, said latch pulse being directed to said output storage means for instructing it to transfer and hold the count in said counting means; r. an up-down counter means instructable for algebraically adding each pulse to an accumulated algebraic sum of the number of pulses in an interval of time, said up-down counter means connected to receive the gated scaling oscillator pulses and to receive said clear and load instruction pulses from said logic sync means; s. counter direction control and gating means for controlling the counting direction of the up-down counter, said control and gating means having inputs connected to said up-down counter to count up in response to a selected pulse from said logic sync circuit and in response to the occurrence of a zero state in said up-down counter, and to count down in response to a second selected pulse from said logic sync circuit; t. an operating point storage means for storing the count in said output storage means in response to actuation of a zero set switch having an output connected to said up-down counter means for transferring said operating point storage to said updown counter means in response to the occurrence of said load pulse at said up-down counter; u. a zero set sync switch means connected to interrupt the application of said load pulse from said logic sync means to said up-down counter means and to said counter control and gating means in response to actuation of said zero set switch; and v. a sign storage means connected to said counter control and gating means for going to a negative sign condition in response to a count down instruction and to a positive sign condition in response to a count up instruction.