Mitigation of optical signal noise using a multimode transmit fiber

摘要

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.

主权项

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.