摘要 |
A method and apparatus for monitoring the surface of an elongated, normally-smooth object, such as coated cable, for certain flaws. The object is longitudinally movable along a path. Radiation, such as white light, is directed at the object such that it is incident therewith throughout a narrow zone extending substantially entirely around the object's perimeter. The angle of incidence of the light with the object is such that a normally smooth surface specularly reflects light at a relatively large angle, whereas particular flaws, such as pips and the like, scatter the light in a particular direction longitudinally of the object and at a relatively smaller or limited angle thereto. A slotted mirror is disposed concentrically about the object's path and reflects the scattered light to imaging and detecting devices, such as a charge injection device. Analytical electronics connected to the detector analyze its electrical signal to indicate the presence of a flaw. The electronics may include a counter for size-quantifying the image on the detector, as a condition to indicating the existence of a flaw.
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