Abstract: A system for the rapid and accurate measurement of the diameter of cylindrical objects and the like, such as nuclear reactor fuel pellets. The system essentially operates on the principle that when an infrared emitter and receiver are aligned in diametrically opposed relationship such that the beam from the emitter impinges on the receiver, the output of the receiver is proportional to the amount of energy received by it. Measurement of cylindrical objects such as pellets is accomplished by passing the object to be measured between the emitter and the receiver. The beam initially is arranged so that as the object passes between the two elements, it partially blocks the beam. Those objects having different diameters or a single object of varying diameter will block more or less of the beam, thereby producing a proportional change in the receiver output which can be correlated in terms of the diameter of the object. Suitable provision is made to compensate for temperature variations in the emitter and receiver.

Abstract: An ultrasonic apparatus and technique for rapidly and accurately measuring the inside and outside diameters and wall thickness of a tubular material. The tubes are passed between a pair of diametrically opposed ultrasonic transducers for obtaining the necessary data. A third transducer is employed to obtain a reference signal, which is used to automatically compensate for any temperature variations in the ultrasound couplant medium.