Abstract: An apparatus and method for quantitatively evaluating the finish of a curved surface of a rolling mill roll or a coil of strip. A light beam is directed by the position of a support housing at a specific incident angle onto the curved surface and a plurality of light detectors are positioned by the support housing above the curved surface for measuring the intensity of reflected light in various directions as defined by the positions of the light detectors. The housing is positioned by stabilizing arms at opposite sides of the housing so that the housing and stabilizing arms form three points of contact with the curved surface. A roller with journals at opposite ends is supported by each stabilizing arm. The longitudinal axes of the rollers are parallel to the longitudinal axis of the roll or coil of strip so that the light beam travels in a plane which is also parallel to longitudinal axis of the roll or coil of strip.