The Texas A&M University System

American Gas Association

Matthew O Spears

Henry F Taylor

William N Gibler

Robert A Atkins

Victor P Swenson

James J McCoy, Jr

CHung-Eun Lee

Mark D Oakland

Chung E Lee

Robert X Perez

Ta-Wei Kao

Gregory M Beshouri

James H Gardner

James Gardner

A fiber optic fiber Fabry-Perot interferometer diaphragm sensor and method of measurement is provided. A fiber Fabry-Perot interferometer diaphragm sensor (,) includes a base (,) and a diaphragm (,) with an optic fiber (,) coupled under tension between the base (,) and the diaphragm (,). A fiber Fabry-Perot interferometer element (,) is contained within the optic fiber (,) and operates to sense movement of the diaphragm (,). In a particular embodiment, the diaphragm (,) moves in response to a pressure (P) applied to the diaphragm (,). In another embodiment, a proof mass (,) is coupled to the diaphragm (,) such that the diaphragm (,) moves in response to an acceleration (A). In yet another embodiment, a magnetic body (,) is coupled to the diaphragm (,) such that the diaphragm (,) moves in response to a magnetic field (M).

Fiber optic fiber Fabry-Perot interferometer diaphragm sensor and method of measurement

A method and apparatus are provided for measuring pressure in a combustion chamber of an internal combustion engine is provided with a non-intrusive, metal-embedded fiber optic pressure sensor. A Fabry-Perot Interferometer is arranged in a terminated, single mode fiber to function as a pressure gauge. The fiber Fabry-Perot Interferometer (FFPI) is embedded in a metal part which is disposed in the cylinder head of the engine. The metal part and FFPI experience a longitudinal compression in response to the pressure in the chamber. In another aspect of the invention, a non-intrusive fiber containing the FFPI is embedded in a hole drilled or otherwise provided in the metal housing of a spark plug. The spark plug is threaded into the cylinder head of an internal combustion engine and is directly exposed to the combustion chamber pressure. Consequently, the spark plug housing and FFPI experience a longitudinal strain in response to the pressure in the chamber.

Method and apparatus for measuring pressure with fiber optics

A method and apparatus is provided for measuring pressure in a pressure containing vessel with a non-intrusive, metal-embedded fiber optic pressure sensor. The pressure containing vessel may, for example, be the combustion chamber of an internal combustion engine. A Fabry-Perot Interferometer is arranged in a terminated, single mode fiber to function as a strain gauge. The fiber Fabry-Perot Interferometer (FFPI) is embedded in a metal part which may be disposed in a wall of the pressure containing vessel. The metal part and FFPI experience a longitudinal strain in response to the pressure in the vessel. In another aspect of the invention, a non-intrusive fiber containing the FFPI may be embedded along the axis of a metal bolt. The bolt may be used to attach a part or structure, which is directly exposed to the pressure, to the wall of the vessel. Consequently, the bolt and FFPI experience a longitudinal strain in response to the pressure on the part or structure. In this aspect, the part or structure exposed to the pressure may be, for example, a fuel injection valve that is attached by the bolt to a cylinder head of an internal combustion engine.

Method and apparatus for measuring pressure with embedded non-intrusive

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Bryan, TX, United States of America

Matthew O Spears