Patent ID: 6696685
Filing Date: 2004-02-24
Classification: G01N

Abstract:
A device for detecting properties of a moving web of paper, comprising:a housing having a front plate facing the web of paper; an infrared lighting device operable to illuminate the web of paper with infrared light and a detector device for detecting light reflected or transmitted by the web of paper, the infrared lighting device comprising a rod-shaped infrared emitter having a longitudinal axis oriented parallel to the paper web, the infrared emitter being accommodated within the housing; and an exit window arranged in the front plate of the housing such that light emitted by the infrared emitter passes through the window and is incident on the paper web, the exit window comprising a circular cylindrical rod lens whose length substantially equals that of the infrared emitter and which is replaceably inserted in an aperture formed in the front plate such that circular cylindrical rod lenses of different diameters can be inserted, the cylindrical rod lens being received in the aperture in a tight-fitting manner so that the housing is sealed from debris.