| 摘要 |
<p>11 ROUGHNESS DETECTOR To detect roughness on a travelling surface of a web such as paper a beam of polarized light is directed at an angle onto the web and focused by a focal lens to illuminate a spot on the surface and a specularly reflected component of the light is collected through a second lens focused on the spot. A detector is aligned to receive a portion of the specularly reflected collimated light from the spot passing through a selecting aperture and generates a signal depending on the intensity of the specular light passing through the aperture and received by the detector thereby to provide an indication of the roughness (or smoothness) of the surface.</p> |
