Optoplan as

United States of America as Represented by the Secretary of the Air Force

Audun Hordvik

Jon Thomas Kringlebotn

Morten Eriksrud

Methods for coating an optical fiber with optical fiber Bragg grating (FBG) with a hermetic coating, particularly a coating of carbon, are employed to avoid ingress of gases, vapors or fluids in the ambient environment. This ingress can be from water or hydrogen, which can diffuse in the fiber glass and cause deviation/drift in the measured Bragg measurements. Bragg gratings that maintain the grating strength at temperatures in excess of 1000&#xb0; C. are used and can be formed by heating the fiber above 1000&#xb0; C. in a chamber with a reactive gas that produces deposition of carbon.

Method for preparing an optical fibre, optical fibre and use of such

Signal cable for transmission of optical signals, especially in oil and gas wells, includes at least one elongated optical fiber, and an elongated, generally tubular container within which the optical fiber is disposed, the container having an inner wall and an outer wall, a space being defined between the optical fiber and the inner wall. At least one of the inner wall and the outer wall has a thin continuous surface coating of gold or a gold alloy.

Gold coated signal cable

A photoacoustic method of simultaneously determining optical bulk and surface absorption coefficients in solids in which a transducer is attached to the solid for measuring the amplitude of the acoustic wave generated by a beam of incident radiation as a function of distance of the transducer to the incident beam at a wavelength where bulk and surface losses, respectively, are heavily dominant. The transducer is chosen so as to give different functional dependencies for the bulk and surface absorption curves, respectively. The solid sample is also calibrated at wavelengths where bulk and surface absorption, respectively, are known. The output versus position or distance is measured at the wavelength of interest, and values of surface and bulk absorption coefficients are fitted to the respective pure curves so that they will add up to the experimentally generated composite curve. After the bulk and surface absorption curves have been determined for the wavelength of interest, the values of bulk and surface absorption coefficients can be determined by using the calibration constants found earlier.

Growing community of inventors

Trondheim, Norway

Audun Hordvik