FIBER OPTIC SENSOR USABLE OVER WIDE RANGE OF GAGE LENGTHS

摘要

A fiber optic sensor includes two reflective elements in series. The first reflective element is formed as a partially mirrored surface on the end of a single-mode optical fiber lead which is bonded into a ferrule. A sleeve is used to join the ferrule to a second ferrule which is turn is bonded to a length of single-mode optical fiber. The second reflective element is a partially mirrored surface on the cleaved end of the second fiber. The second fiber may be affixed to or embedded in a structure to be monitored and changes its optical path length in response to a condition of the structure. The ease of fabrication and functionality of the sensor is significantly improved by the use of reflective elements within the ferrule which have a prescribed angle of incidence relative to the light path within the optical fiber.