Noncontact thickness measurement of metal foil by means of differential white light interferometry

Abstract

A new differential white light interference technique for the thickness measurement of metal foil is presented. In this work, the differential white light system consists of two Michelson Interferometers (MI) in tandem, of which reflective surfaces measured are corresponding surfaces of metal foil. Therefore, the measured result only relates to the thickness but not to the position of metal foil. The method is non-contact, non-destructive, has advantage of high accuracy, fast detection and compact structure. Theoretical analysis and preliminary experimental results have shown that the technique can measure the thickness of foil in the range of 1 μm to 80 μm with satisfactory accuracy and repeatability.