SURFACE CONTACT ELEMENT FOR OPTICAL SENSOR

摘要

A sensing element having a face adapted to contact the surface of a travelling web or sheet of paper, said face formed into a convex surface that substantially is in the form of a single base segment of a sphere having a radius between 35 and 10 mm. The surface of the web is pressed against the face so that the area of contact between the surface and the face has a minimum dimension of 2 mm. In the preferred application of the present invention the element is as a optical window in an optical sensing device wherein light is passed through the window in a direction and is reflected to sensors positioned on the same side of the window as the light source.