Mitigation of optical signal noise using a multimode transmit fiber
First Claim
1. An apparatus for measuring a combustion parameter in a zone, the apparatus comprising:
- a laser generating a transmit beam of light of a select wavelength;
a multimode transmitting optical fiber optically coupled to the laser;
a transmitting optic optically coupled to the multimode transmitting optical fiber for transmitting the transmit beam into the zone;
a reflecting surface in the zone;
a receiving optic positioned to receive a reflection of the transmit beam from the reflecting surface;
wherein the transmitting optic and the receiving optic are the same optic; and
means operatively associated with the multimode transmitting optical fiber for averaging modal noise induced signal level variation of light propagating within the multimode transmitting optical fiber.
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Accused Products
Abstract
An apparatus and methods for measuring combustion parameters in the measurement zone of a gas turbine engine. The measurement zone is defined as being between an outer casing and an engine component having a reflecting surface inside the outer casing. The apparatus comprises a laser generating a transmitting beam of light of a select wavelength and a multimode transmitting fiber optically coupled to the laser. A transmitting optic is optically coupled to the multimode optical fiber for transmitting the beam into the measurement zone. The reflecting surface is configured to provide a Lambertian reflection. A receiving optic is positioned to receive the Lambertian reflection. Means are provided in operative association with the multimode transmitting fiber for averaging modal noise induced signal level variation of light propagating within the multimode transmitting fiber.
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Citations
20 Claims
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1. An apparatus for measuring a combustion parameter in a zone, the apparatus comprising:
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a laser generating a transmit beam of light of a select wavelength; a multimode transmitting optical fiber optically coupled to the laser; a transmitting optic optically coupled to the multimode transmitting optical fiber for transmitting the transmit beam into the zone; a reflecting surface in the zone; a receiving optic positioned to receive a reflection of the transmit beam from the reflecting surface; wherein the transmitting optic and the receiving optic are the same optic; and means operatively associated with the multimode transmitting optical fiber for averaging modal noise induced signal level variation of light propagating within the multimode transmitting optical fiber. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An apparatus for measuring a combustion parameter in a zone, the apparatus comprising:
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a laser generating a transmit beam of light of a select wavelength; a multimode optical fiber optically coupled to the laser; a transmitting/receiving optic optically coupled to multimode optical fiber; and a reflecting surface in the zone, the reflecting surface being constructed and arranged to reflect at least a portion of the transmit beam transmitted from the transmitting/receiving optic back to the transmitting/receiving optic; wherein the multimode optical fiber carries both the transmit beam and the at least a portion of the transmitted beam reflected back to the transmitting/receiving optic; and wherein the transmitting/receiving optic is configured to transmit the transmit beam into the zone, and receive the at least a portion of the transmitted beam reflected from the reflecting surface. - View Dependent Claims (10, 11, 12, 13)
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14. A method of measuring a property within a zone, the method comprising:
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transmitting a beam of light of a select wavelength through a multimode optical fiber and a transmit optic optically coupled to the zone; reflecting at a reflecting surface at least a portion of the transmitted beam to a receiving optic; receiving from the reflecting surface a reflection of the at least a portion of the transmitted beam with the receiving optic optically coupled to the transmit optic; the transmitting optic and the receiving optic being the same optic; and averaging modal noise induced signal level variations of the beam of light propagating within the multimode optical fiber. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification