Novel Passive Compensation Technique Applied To A White Light Interferometric System

White light interferometry provides a precise method of determining the path difference in a remote sensing interferometer when it is compared with a locally controlled reference interferometer. Interference fringes will be detected when the path length of each interferometer is greater than the coherence length of the optical source and the relative path difference between them is less than the source's coherence length [1,2]. White light interferometric sensing systems have previously been employed to monitor a variety of external measurands such as; displacement [3], pressure [4], temperature [5] and refractive index [6]. In all these cases the change in the measurand induces a change in the path length of the sensing interferometer. This variation in path length is monitored at the reference interferometer and can be directly related to the measurand change.