Accession Number : ADD018123

Title :   In-Line Fiber Etalon Strain Sensor.

Descriptive Note : Patent, Filed 9 Sep 94, patented 18 Jun 96.

Corporate Author : DEPARTMENT OF THE NAVY WASHINGTON DC

Personal Author(s) : Putnam, Marty ; Sirkis, Jim ; Berkoff, Timothy A ; Kersey, Alan D ; Friebele, Edward J

Report Date : 18 Jun 1996

Pagination or Media Count : 9

Abstract : An in-line fiber etalon strain sensor, and method for making the sensor, is disclosed. The in-line fiber etalon strain sensor uses a short segment of silica hollow-core fiber spliced between two cleaved sections of single-mode fiber to form a mechanically robust in-line cavity. In making the sensor, a portion of a protective coating is removed from one end of each of the two cleaved sections of the single-mode fiber to form a bare portion adjacent to a partially reflective end face on each fiber section. The silica hollow core fiber is fabricated to have the same outside diameter as each of the bare portions of the fiber sections. One end of the silica hollow core fiber is then fusion spliced in-line with the partially reflective end face of one of the fiber sections, before the other end of the silica core fiber is fusion spliced in line with the partially reflective end face of the other fiber section to form a cavity within the silica hollow core fiber that is bounded by the two partially reflective end faces. Operation of the in-line fiber etalon is based on interference between the Fresnel reflections from the two glass/air interfaces formed by the cleaved surfaces of the single mode fibers at each end of the hollow core fiber. Strain induced changes result in a concomitant change between the two optical paths. The phase changes can then be demodulated and related to the input strain stimuli.

Descriptors :   *FIBER OPTICS, *DETECTORS, *STRAIN(MECHANICS), CORES, AIR, INTERFACES, SILICON DIOXIDE, PATHS, CAVITIES, GLASS, FABRY PEROT INTERFEROMETERS, INTERFERENCE, PROTECTIVE COATINGS, FRESNEL LENSES, PATENTS

Subject Categories : Optics
      Inorganic Chemistry
      Physical Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE