Abstract: A caliper measuring system is provided for determining the thickness of a moving sheet. The system comprises first and second caliper sensing heads having first and second sensing shoes positioned on opposite sides of the moving sheet for engaging the sheet. A gap sensor is associated with the first and second sensing shoes for generating distance signals representative of the distance between the first and second sensing shoes and for determining the thickness of the moving sheet based upon the distance signals. The gap sensor includes a processor which determines the thickness of the moving sheet from the distance signals, generates a count of lumps sensed in the moving web, and generates a baring profile representative of rapid thickness variations along the moving sheet in the direction of movement of the sheet.

Abstract: An apparatus and process for measuring physical parameters of sheet material via infrared absorption phenomena is disclosed. The invention employs an integral filter-detector package comprising at least two optical filter-detector combinations. The package is contained within a conventional sensor housing which traverses back and forth across the sheet material. The package may comprise an additional filter-detector combination that is selected to produce a detector response having a significantly higher signal-to-noise ratio than the response of remaining detectors. The former response is used in combination with synchronous detectors to provide a reference of the general shape and phase of the latter responses in the absence of high noise.