| 摘要 |
PURPOSE:To accurately measure the shape and contour of a through hole bored in a work by adding a lens which is shallow in depth of field and has its focus on the surface of the body to be measured to a light receiving part, and reducing the quantity of light received from the background. CONSTITUTION:Light from a light source 18 for measurement is projected on the through hole 13 of the body 11 to be measured and its periphery, and direct light which is incident on the background 17 is cut off by a light shielding plate 16. Further, the light receiving part 19 has a telephoto lens 19 which has shallow depth of field and decreases in the quantity of light extremely where an image is out of focus and the focus of the lens 19a is set on the surface of the through hole 13. Consequently, the lightness difference between the periphery of the through hole 13 and background 17 is emphasized and detected and the contour of an image of the through hole 13 is clear; and light information from the CCD camera of the light receiving part 19 is sent to a display part 21 through an image processing part 20 and displayed as the through hole image A. Then a judgement part 22 receives the through hole information and compares it with the shape, etc., of a reference through hole information signal to judge whether or not the information is within a permissible range, thereby displaying the judgement result on the display part.
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