| 摘要 |
PURPOSE:To measure the top end position of the crack of a fatigue test piece by microscopes with high accuracy without contact by detecting the reference position and the top end position of the crack from the luminance level and binary coded signal of an image signal which picks up the image of the fatigue test piece and calculating the distance between both positions. CONSTITUTION:The microscopies 20, 21 are disposed to face the surfaces on both sides of the fatigue test piece 10 on which a reference line for measuring the position of the crack are drawn. The image signal of the test piece magnified through the microscopes 20, 21 is fed to a means 32 for detecting the reference line and a means 33 for detecting the position of the top end of the crack. The means 32 integrates the luminance level of the image signal in the same direction as the direction of the reference line and detects the reference line position from the max. luminance level position. The means 33 codes the image signal to a binary value and detects the top end position of the crack from the discrimination on the continuity of a high level value. The distance between the reference line and the top end position of the crack is detected from the detected values of the means 32, 33 in a distance detecting part 40.
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