| 摘要 |
PURPOSE: To always detect the defect in a test specimen with the same accuracy by altering the gains before and after the surface echo from the test specimen is detected. CONSTITUTION: An ultrasonic inspection apparatus can be DAC controlled, radiates an ultrasonic signal to a test specimen with a pulse trigger point as a starting point, and retrieves the point where the echo reception signal from the test specimen exceeds a predetermined threshold value. The retrieval is continued while a gate generator 8 outputs a gate signal. If the echo reception signal from the specimen test exceeds the predetermined threshold value, i.e., the surface echo is detected, a DAC trigger signal is supplied to a DAC curve generator 9, which outputs a DAC control signal, and supplies it to a preamplifier 3. Thus, the output level of a video amplifier 7 becomes substantially constant without depending upon the measuring time, i.e., the depth of the test specimen. |
