White light is launched into one end of the optical fiber.
This fringe pattern, which resembles a series of sine curves, travels down the fiber to a spectroscopic detector. The detector is connected to a computer that reads the interference fringes. Because fringe spacing varies with temperature changes, the computer can convert the detector data into temperatures by determining the distances between the fringes. An engineering prototype of this sensor is currently being tested on the NASA Lewis OV-10D airplane to measure the exhaust gas temperature. Benefits - The sensor can cover the entire temperature range required for propulsion system control.