Abstract: A system that calibrates instruments for measuring the light or air permeability of a material, and includes a calibration target which can be used for calibration of either light-based or air-based instruments. The calibration target simulates the material whose permeability is being measured, and includes a plate having multiple, angled or parallel rows of perforations provided therethrough. The permeability measuring instrument measures the permeability of the calibration target, and compares the measured permeability with a predetermined permeability of the calibration target and calibrates the permeability measuring instrument based upon the comparison.

Abstract: A system for measuring the permeability of a material includes a light source for illuminating the material, and a stray light sensor for detecting stray light traveling through the material from the light source and outputting a stray light signal indicative of the stray light detected. The system further includes a direct light sensor for detecting direct light traveling through holes in the material from the light source and outputting a direct light signal indicative of the direct light detected. Finally, the system includes a digital processing device for receiving the stray light and direct light signals and calculating the permeability of the material.

Abstract: An optical inspection system mounts on a cigarette making machine or like system and detects the presence of bands having irregular widths or spacings. In response to the detection of irregular bands, the optical inspection system instructs the cigarette making machine to reject cigarettes which will be subsequently made from portions of the cigarette paper containing the irregular bands. The optical inspection system includes a sensor which can accommodate different types of cigarette paper and band material having varying reflectance properties. In operation, sensor circuitry detects the range of voltages produced by a sensor detector, and formulates a peak value (or average peak value) for the range of voltages. The circuitry then takes a percentage of this peak value to form a threshold value. This threshold value is compared with the AC signal from the sensor detector. If the AC signal exceeds the threshold, then the circuitry asserts a signal to indicate that a band is present.