LOW-COHERENCE INTERFEROMETRY, AN ADVANCED TECHNIQUE FOR OPTICAL
METROLOGY IN INDUSTRY
M. L. Dufour, G. Lamouche, V. Detalle, B. Gauthier, and P. Sammut
Industrial Materials Institute, National Research Council Canada, Boucherville, Quebec, Canada
Low-coherence interferometry (LCI) is an optical technique that may be used for industrial surface
metrology with accuracy in the micron range. An instrument made with optical fibers is rugged enough to be
used in industrial environments and the fiber- linked optical probe may be miniaturized for accessing tight
locations. Among industrial applications developed at IMI we will present several cases for which LCI has
been particularly useful such as an elongational rheometer (RME), characterization of wear damages on
coating and Laser-induced Breakdown Spectroscopy (LIBS). The RME is an instrument in which a polymer
sample is stretched in a controlled temperature furnace at up to 350oC. LCI has been used for monitoring the
thickness of the samples. Wear damage is quantified by the volume loss after a wear test. It requires a high
depth resolution (axis perpendicular to the surface) but a relatively coarse transverse resolution. The LIBS is
a technique that has been used for analyzing the chemical composition of materials as a function of depth.
LCI has been integrated to a LIBS instrument for measuring accurately the crater depth between each laser
shot. Other industrial applications will also be presented.