Abstract: 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.

Abstract: 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.