Ultrasonic flaw detectors such as this were developed to detect flaws in samples of metal or other materials. They are particularly useful in the aerospace industry to spot evidence of fatigue in components. In this technique sound waves are transmitted into the component from a vibrating crystal presed against the outer surface. These sound waves are then received and displayed on an oscilloscope. Discontinuities and variations in structure can be determined from the oscilloscope's trace and may be evaluated quantitatively. Made by Kelvin and Hughes Scientific Instrument Company.
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