Interferometric thickness profiles with maintenance of a flatness of the moving material

摘要

A method for determining a thickness of a moving material having at least two optical interfaces. A length of material is transported along a transport path (12) through a measurement region (102), and is maintained at a substantially constant velocity and a predetermined flatness of at least one degree for precise interferometric measurement. A channel with a recessed track is used and rollers (74,76) are driven slightly different, static buildup is eliminated (64). The interferometer apparatus generates an interference signal representative of the collected light and analyzes a plurality of the interference signals to determine a thickness profile of the material in the first direction. Dual interferometer with fiber head used in an autocorrelation mode. <IMAGE>