Holographic display of defects - in materials scattering ultrasonic rays, esp. cast iron or austenite, using phase controlled transducer array

摘要

A phase-controlled transducer (6) produces a narrow, focussed beam of sound waves fed at successive angles into the workpiece (7) by an array of emitter-receivers in the transducer (6), which is kept stationary on piece (7). The signals obtd. for each angle are stored and added. After completion of the electronic swivelling of the signals over the total zone being inspected, the transducer (6) is moved to a new zone and the process is repeated. The stored values of the reflected signals received are numerically converted by an electronic circuit contg. a computer to a two-dimensional display on a TV screen. An improved signal/noise ratio is obtd. esp. when examining clad materials used in the pressure vessels of nuclear reactors.