Abstract: Apparatus, methods, and other embodiments associated with monitoring combustion dynamics in a gas turbine engine environment are described herein. In one embodiment of a system for monitoring combustion dynamics in a gas turbine engine environment, the system includes a transducer and an optical fiber. The transducer is positioned within the gas turbine engine environment, and the transducer includes a diaphragm, a window, and a Fabry-Perot gap. The diaphragm has a reflective surface, and the window has a partially reflective surface. The Fabry-Perot gap is formed between the reflective surface of the diaphragm and the partially reflective surface of the window. The optical fiber is positioned proximate to the window and directs light into the Fabry-Perot gap and receiving light reflected from the Fabry-Perot gap.

Abstract: An apparatus to interrogate one or more fiber optic sensors to make high-resolution measurements at long distances between the sensor and the interrogator apparatus. The apparatus comprises a tunable light source, an optical switch for pulsing the light source, at least one sensor (e.g., a Fabry-Perot sensor) for reflecting the laser light, a fiber optic cable interconnecting the sensor with the light source, a coupler for directing the reflected light from the sensor to a detector in order to generate a digital output, and a control logic for tuning the laser light source based on the digital output from the detector. Use of a fiber Bragg grating temperature sensor is also contemplated.

Abstract: The present invention pertains to differential pressure transducers. In an embodiment of the invention, a differential pressure transducer includes a transducer housing, a diaphragm, a bellows, and a sensing assembly. The transducer housing, diaphragm, and bellows are coupled to form a pressure chamber. The pressure chamber is separated into two portions by the diaphragm, with each portion arranged to be filled with a process fluid. A pressure differential across the diaphragm causes displacement of the diaphragm. Such displacement is measured by the sensing assembly and used to calculate the pressure differential between the two process fluids.

Abstract: A method and apparatus for monitoring one or more environmental parameters using interferometric sensor(s), a cross-correlator, a two-dimensional photosensitive array and optical focusing means are described. The method and apparatus allows for near simultaneous monitoring of the parameter(s) of interest.

Abstract: A method for monitoring changes in a gap which corresponds to changes in a particular environmental parameter using a tunable laser and interferometer at high frequency is disclosed. The laser light provided to the interferometer is swept through a small range of wavelengths. Light modulated by the interferometer is detected and a non-sinusoidal light intensity output curve is created, a reference point on the curve identified and subsequent sweep of the laser performed. The difference in time, wavelength, or frequency at the occurrence of the reference point between the two sweeps allows for measuring the relative changes in the gap and, as a result, the change in the environmental parameter.

Abstract: A method and apparatus for detecting seismic vibrations using a series of MEMS units, with each MEMS unit including an interferometer is described. The interferometers on the MEMS units receive and modulate light from two differing wavelengths by way of a multiplexing scheme involving the use of Bragg gratings and light circulators, and an optoelectronic processor receives and processes the modulated light to discern vibrational movement of the system, which in turn allows for monitoring and calculation of a specified environmental parameter, such as seismic activity, temperature or pressure.

Abstract: A signal conditioner to measure the length of an interferometric gap in a Fabry-Perot sensor (interferometer). The invention includes a light source, a Fabry-Perot interferometer capable of spanning a range of gaps in response to physical changes in the environment, a second interferometer that is placed in series with the Fabry-Perot interferometer which does not filter any particular wavelengths of light but acts as an optical cross-correlator, a detector for converting the correlated light signal into electronic signals, and an electronic processor which controls system elements and generates a signal indicative of the length of the gap spanned by the Fabry-Perot sensor.

Abstract: A differential pressure transducer which incorporates a Fabry-Perot sensor for direct quantitative measurements of the distance displaced by a piston abutting two pressure boundaries is described. The apparatus includes a piston with an annular protrusion which is fitted into a transducer housing having a peripheral groove that serves as a stop to prevent damage to the in overpressure situations. A method of measuring differential pressure using a Fabry-Perot sensor is also contemplated.

Abstract: Pressure transducers are used to measure pressure under high temperature, hostile environments, including in gas turbine combustors and internal combustion engines. The present a pressure transducer comprises a member having a first end and a second end, a diaphragm sealed within the member at the first end, a sensor sealed within the member at the first end and in operable communication with the diaphragm, a first plate having a plurality of apertures, the first plate being attached to the member at the second end, a second plate having a plurality of apertures, the second plate being attached to the tubular member at the second end and being spaced from the first plate, and wherein the apertures of the first plate are not aligned with the apertures of the second plate.

Abstract: Linear variable reflector sensors can be used to measure the displacement of objects. These sensors are useful in that they can be very small, do not conduct electricity, and are resistant to electrical interference from EMI/EMP and lightning strikes. The present linear variable reflector system comprises a light source, a light transmitting member in optical communication with the light source, a sensor in optical communication with the light transmitting member. The sensor comprises a moveable transparent body, a reflective material deposited on the transparent body, and at least one film deposited over said reflective material, wherein said reflective material reflects light. Further, the linear variable reflector system comprises a detector coupled to the sensor to detect displacement of the moveable transparent body.

Abstract: A method and apparatus for quantitatively measuring the distance of an unknown variable gap is disclosed. Light is provided to two Fabry-Perot interferometers arranged in a series, one spanning the unknown gap and the other spanning a controllably variable gap. Means for verifying the positioning of the Fabry-Perot interferometer having the controllably variable gap work in conjunction with a signal processor, a correlation burst signal detector and means for conveying the light to the various system elements to perform a comparison of detector signals from the two interferometers and quantitatively establish the gap distance. The invention may also be varied to function on a time basis, include more than one source of light, possess filter means to distinguish between light sources and/or include one or more reference interferometers.

Abstract: A pressure measurement system and method are described. The system uses a tunable laser and a Fabry-Perot sensor with integrated transducer. A detector senses the light modulated by the Fabry-Perot sensor. A signal conditioner, which can be located up to 15 km away, then uses the detector signal to determine the displacement of the diaphragm, which is indicative of pressure exerted against the diaphragm. Use of a temperature sensor to generate a signal, fed to the signal conditioner, to compensate for temperature is also contemplated.

Abstract: A water level indicating apparatus (10) has an optical system (22) for establishing an optical signal indicative of water level which signal is split by a beam splitter (18) to transmit the majority of the optical signal to a fibre optic cable (16) and to reflect a part of the signal to a proximately located (13) glass diffuser (14). The cable (16) extends to a matte screen (12) at a remote location (11) to thus provide a remote (11) optical signal as well as local (13) optical signal indication of the water level.