Patent ID: 8187424
Filing Date: 2012-05-29
Classification: D21F,D21G,G01N

Abstract:
1. An in-situ time domain spectroscopy (TDS)-based method for non-contact characterization of properties of a sheet material produced by a manufacturing system, comprising: providing a time domain spectrometry system and calibration data for said system, said calibration data comprising transmitted power or field through or reflected power or field from said sheet material as a function of a moisture content of said sheet material; directing at least one pulse of THz or near THz radiation having a frequency between 0.05 THz and 50 THz at a sample location on a sheet material sample while being processed by said manufacturing system; synchronously detecting transmitted or reflected radiation comprising at least one transmitted or reflected pulse from said sample location to obtain sample data, and processing said sample data together with said calibration data to determine at least one property of said sheet material sample selected from caliper, basis weight and moisture content; wherein said calibration data comprises a calibration curve, said calibration curve based on a ratio of a transmitted or reflected power or field for a non-interacted reference pulse sample having a path exclusive of said sheet material and a transmitted power or field through or reflected power or field from said sheet material.