| 摘要 |
700,060. Testing materials by ultrasonic vibrations. SPERRY PRODUCTS, Inc. March 5, 1952 [March 30, 1951], No. 5746/52. Drawings to Specification. Class 118 (2). In a system for detecting the presence of defects in a solid object, a beam of substantially continuous ultrasonic waves of fixed frequency is transmitted by an electro-mechanical transducer into the object at an oblique angle to the surface thereof thereby establishing standing waves between the transducer and the defect and the transducer is moved along the surface so that the distance between the transducer and defect varies and the system becomes resonant at successive instants of time, means being provided for indicating the recurrence rate of successive resonances. As described the transducer is coupled to a superregenerative oscillator with a choke coil in the anode circuit and the pulse developed across the choke at each resonance is applied through a low-pass filter to an aural or visual indicator. Specification 628,116 is referred to.
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