Systems Research Laboratories

Other

Techmet Company

Francis M Taylor

Harry G Petrohilos

J Montgomery Rainey

The point of focus of an image is swept through a measurement zone in the image space of a lens system by sweeping a plurality of convex specular surfaces through the object space of the lens system to vary the object space. The specular surfaces are formed to approximate involute curves and the optical axis of the lens system is centered upon tangents to a generating circle of the involute curves which are approximated by the specular surfaces. The specular surfaces are mounted in a rotating member and sweep the object space by rotation of the rotating member about the center of the involute generating circle. An object of the lens system includes a light emitter and a light detector positioned adjacent to one another. As the measurement zone is swept, a minimum of the output signal from the light detector occurs when the image is momentarily in focus upon the surface of a workpiece within the measurement zone. The dimension of the object space upon focus is determined by monitoring the angular orientation of the specular surfaces and this angular orientation is utilized to determine the distance to the surface of the workpiece.

Method and apparatus for optically measuring the distance to a workpiece

A microprocessor-based ultrasonic inspection system reliably detects fatigue cracks smaller than 0.030 inch under installed fasteners by means of a unique signal-processing method. The signal-processing used in this invention takes advantage of the fact that crack signals 'walk' in time as a transducer moves around a fastener. Bolt size, scan depth, and angle of incidence of an ultrasonic shear wave are used to determine the 'walk rate' of a defect in the inspection zone. With this geometric information, the signal-processing technique will enhance any pulse-echo return 'walking' at the computed walk rate, and thus significantly improve the ratio of crack signal to other signal sources in the material.

Walking-gate ultrasonic flaw detector

An optical micrometer scans an article passing through its zone of measurement to provide a series of pulses representing the dimension of an article. Each new measurement is compared against a previous measurement, or an average of a predetermined number of previous measurements, and the difference is then compared to a previously established deviation limit. If this difference does not exceed the deviation limit, then the new measurement is transferred to the output of the circuit for utilization by the system, but if this difference exceeds the deviation limit, then the previous measurement signal will be transferred to the output. An alarm is provided whenever a predetermined number of new measurement signals outside the deviation limit occur within a certain number of measurement intervals.

Electronic comparator for process control

In an optical dimension gauging instrument, commonly referred to as a laser micrometer, particularly for use in measuring the outside dimension of elongated cylindrical objects, such as coated wires or steel tubes, in hostile optical environments, including a laser for generating a beam of collimated light, means for directing the light through a measurement zone, photodetector means responsive to the light passing through the measurement zone, and a mirror mounted for rotation by a motor to cause the beam to be scanned repeatedly across the measurement zone, a beam expander is employed to enlarge the output of the laser to a diameter substantially greater than the maximum dimension of normally anticipated foreign objects which might intercept the beam outside the measurement zone, an anamorphic lens further expands the beam in one plane to a size greater than the size of normally anticipated foreign objects both within and without the measurement zone, and a lens system causes the beam to be focused in the other plane in the measurement zone while the expanded beam is projected through the measurement zone with the long dimension of the beam parallel to the cylindrical axis of the article whose outer dimension is being measured.

Optical dimension measuring device employing an elongated focused beam

A narrow collimated light beam, such as a laser beam, is directed towards a mirror which is rotated to effect rotary planar scanning or sweeping of a lens constructed to convert the rotary scanning beam into a parallel scanning beam. An article to be measured is positioned in the path of the parallel scanning beam at generally the focal point of the lens, and interruptions of the parallel scanning beam, as produced by the article, are sensed by a photodetector. The photodetector controls transmission of pulses or signals to means for counting pulses produced by a high frequency generator so that the counted pulses correspond to the dimension of the article at the plane of the parallel scanning beam. In this invention a lens is positioned in the path of the light beam and changes a narrow substantially round light beam into an elongate or substantially flat light beam which is scanned across an object for measurement thereof. The greatest dimension of the light beam is substantially normal to the direction of scan movement. Thus, if there should be irregularities or small particles of foreign material upon the surface of the object or adjacent thereto, the entire light beam is not completely interrupted by such particles or by such irregularities. Thus, a light beam is received by the photodetector in accordance with the average dimension or contour of the object at the measured portion thereof. Thus, the dimension of the object is measured without consideration of small irregularities or small or minute particles of foreign material or the like which may be present upon or adjacent the object at the measured portion thereof.

Growing community of inventors

Xenia, OH, United States of America

Francis M Taylor