Patent ID: 7925134

Claim:
A measurement system comprising: two optical fibers, each optical fiber from said two optical fibers being coated with a substantially hydrophobic and substantially non-outgassing substance; one optical fiber from said two optical fibers having a length different from another optical fiber from said two optical fibers; a first fiber optic coupler for receiving electromagnetic (EM) radiation; and splitting the EM radiation into a measurement path and a reference path; said reference path including a second fiber optic coupler for receiving said EM radiation from the reference path; and splitting said EM radiation into each of said two optical fibers; a third fiber optic coupler for receiving EM radiation from said two optical fibers; and providing said received EM radiation to a single fiber; and a detector for calibrating, from said single fiber, a difference in length between said two optical fibers; and calculating a distance along said measurement path as a function of said difference in length, wherein said reference path is in a Mach-Zehnder configuration, and said substantially hydrophobic and substantially con-outgassing substance is selected from polyimide, ultraviolet cured acrylate, teflon, tefzel, hytrel, or nylon.