| 摘要 |
PURPOSE:To improve the defect detection performance by measuring the distances between probes and an object to be inspected to find the eccentricity quantity, and finding a detection sensitivity correcting value from the relation between the eccentricity quantity and defect detection sensitivity to correct the detection sensitivity. CONSTITUTION:Signals are led out of respective probes 2-1 to 2-4 in parallel, a distance measuring circuit 4 measures the distances l1 to l4 between the probes and the object to be inspected from the rising position of the surface echo of the object 1 to be inspected, and an eccentricity quantity arithmetic circuit 5 finds the eccentricity quantity. Then a sensitivity correction quantity arithmetic circuit 6 finds the sensitivity correcting value corresponding to the eccentricity from data on the relation between the eccentricity quantity and sensitivity and outputs it to an automatic gain control(AGC) circuit 7, which corrects the probes by necessary quantities by each probe 2-1 to 2-4. Therefore, the sensitivity of the probes can be corrected corresponding to relative position shifts between the object 1 to be inspected and probes 2-1 to 2-4, so the flaw detection sensitivity is increased and the defect detection performance can be improved. |
