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 the 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 m µ to 80 m µ with satisfactory accuracy and repeatability.

Nanometrology based on white-light spectral interferometry in thickness measurement

“…In continuous spectrum interference system, the light of all wavelengths would intervene respectively. Supposing that λ 1 and λ 2 are wavelengths of two adjacent maximum intensity [2] :…”