Patent ID: 6594015
Filing Date: 2003-07-15
Classification: G01B

Abstract:
A method for calibrating equipment for determining the surface uniformity of film or sheet material, said equipment comprising a measuring position in which the material is arranged to pass over a rotating measuring shaft, a light source arranged to illuminate the horizon formed by the outer surface of the material exactly where it is in contact with the periphery of the measuring shaft, and a light detector for detecting light transmitted from the light source and emitting corresponding electric signals to subsequent signal-processing apparatus in order to determine the dimensions, number and locations of the irregularities from the shadows produced by the surface irregularities, characterized in that at least one calibration shaft is produced having a diameter corresponding to the diameter of the measuring shaft and the thickness of the material being calibrated, after which a number of elevations are produced on the peripheral surface of the shaft and the actual dimensions of the elevations determined, and in that the calibration shaft is thereafter rotated in said equipment with the calibration shaft in said measuring position and the dimensions of the elevations are determined from transmitted light detected by the light detector, and comparing dimensions thus determined with the actual dimensions of the elevations in order to calibrate the equipment.