Abstract
The accurate thickness measurement of Ultra-thin rolling metallic foil has an important
role in industrial or some special applications. Unfortunately, commercial thickness meters do not
provide high precision measurements non-destructively. A new spectral-domain interferometric
method for measuring absolute thickness of Ultra-thin metallic foil is proposed here. The thickness
is measured by differential white light spectral interferometer. Two differential Michelson
Interferometers (MI) are used as basic measuring system to obtain the spectral interference fringes
on the spectrometers. The spectral interference between both beams, which shows up a periodic
modulation of the source spectrum with the period dependent on the OPD, serves as an illustration
of a technique for measuring both OPDs and displacements in a range dependent on the source
spectrum width. Therefore, the interference fringes only depend on the OPD due to the thickness of
metallic foil and are unrelated to the position of the foils in the system, which is insensitive to the
vibration. The spectral interference fringes are resolved over a wide spectral range and the absolute
thickness of metallic foil can be calculated by measuring the OPD with a modified extremum
method based on the least root mean square (RMS) deviation. The theoretical analysis and
preliminary experiments indicate that the technique can measure the thickness of foils in the range
of 1μm to 80μm, and it requires less than 50ms within the single measurement. Experimental
results are presented.
Publisher
Trans Tech Publications, Ltd.
Subject
Mechanical Engineering,Mechanics of Materials,General Materials Science