Abstract: A method of monitoring a rotor blade 14 is provided. The method includes disposing a probe 22 including an optical sensor 25 within a mounting hole in a turbine casing 36 of a turbine engine. A laser beam is them emitted by a light source 54 radially inward from the probe position onto a rotor blade tip 100 of the rotor blade 14. The rotor blade 14 is positioned such that it periodically passes the laser beam. The rotor blade tip 100 includes a predetermined pattern 120. The reflected light images from the rotor blade tip 100 are received by the optical sensor 25. From the reflected light images, a blade profile is constructed. Based on this constructed blade profile from the reflected light images off the predetermined pattern 120, a position of the rotor blade 14 is determined. A system of monitoring a rotor blade 14 is also provided.

Abstract: A fiber optic sensing apparatus is presented. An optical fiber sensor is enclosed within a housing. A sleeve is interposed between the housing and the optical fiber sensor such that the sleeve encloses the optical fiber sensor and is coaxial with the housing, the sleeve extending continuously along the entire length of the optical fiber sensor effective to constrain movement of the optical fiber sensor between the housing and the sleeve. A method to construct a flexible fiber cable having strain relief for the optical sensor as well as a method to accurately sense temperature conditions in a gas turbine are also provided.

Abstract: A microphone array for detecting acoustic emissions generated by equipment. The array includes at least one grid having a plurality of sensors each including a compact arrangement of optical fiber having first and second optical fiber ends wherein the first optical fiber end of a first sensor is terminated. The array also includes an optoelectronic device coupled to a second optical fiber end of a second sensor, wherein the optoelectronic device generates laser light that is transmitted through the plurality of sensors in the grid and is reflected back to the optoelectronic device to enable detection of acoustic emissions.

Abstract: A microphone array for detecting acoustic emissions generated by equipment. The array includes at least one grid having a plurality of sensors each including a compact arrangement of optical fiber having first and second optical fiber ends wherein the first optical fiber end of a first sensor is terminated. The array also includes an optoelectronic device coupled to a second optical fiber end of a second sensor, wherein the optoelectronic device generates laser light that is transmitted through the plurality of sensors in the grid and is reflected back to the optoelectronic device to enable detection of acoustic emissions.

Abstract: A distributed sensing system for detecting a flashback condition in a combustor for a gas turbine engine The distributed sensing system includes one or more strategically positioned fiber optic cables provided upstream of the combustion area in the combustor. The distributed sensing system employs Rayleigh backscattering and swept-wavelength interferometry to measure temperature and reliably identify the location of the flashback condition The fiber optic cable is specially fabricated to have a high temperature resistance suitable for those temperatures existing during flashback conditions. The fiber optic cable can be wrapped on an inside of a combustion basket or on an outside of the combustion basket, and in a serpentine manner or otherwise.

Abstract: Apparatus and method for thermally mapping a component in a high temperature environment. An optical probe (10) has a field of view (14) arranged to encompass a surface of a component (15) to be mapped. The probe (10) captures infrared (IR) emissions in the near or mid IR band. An optical fiber (16) has a field of view to encompass a spot location (18) on the surface of the component within the field of view (14) of the probe (12). The fiber (16) captures emissions in the long IR band. The emissions in the long IR band are indicative of an emittance value at the spot location. This information may be used to calibrate a radiance map of the component generated from the emissions in the near or mid IR band and thus map the absolute temperature of the component regardless of whether the component includes a TBC.

Abstract: Operational gas turbine engine housing or casing dynamic strain, temporary or permanent displacement and/or temperature is measured by a distributed fiber optic sensing system (DFOSS) utilizing optical frequency domain reflectometry (OFDR) that is coupled to the turbine engine housing. The DFOSS/OFDR system measures localized variances in strain along the length of an optical fiber (OF), which are correlated with turbine engine housing displacement. Temperature influence on the measured localized strain variances is accounted for by obtaining temperature information from an another measurement system or by taking the same type OFDR measurements on unrestrained optical fiber (OF) and deriving compensated strain measurements that are not temperature influenced. The derived strain measurements along the DFOSS are correlated with housing displacement. Other embodiments include separate displacement measuring modules, each including DFOSS optical fibers, coupled along the engine housing.

Abstract: Operational gas turbine engine housing or casing dynamic strain, temporary or permanent displacement and/or temperature is measured by a distributed fiber optic sensing system (DFOSS) utilizing optical frequency domain reflectometry (OFDR) that is coupled to the turbine engine housing. The DFOSS/OFDR system measures localized variances in strain along the length of an optical fiber (OF), which are correlated with turbine engine housing displacement. Temperature influence on the measured localized strain variances is accounted for by obtaining temperature information from an another measurement system or by taking the same type OFDR measurements on unrestrained optical fiber (OF) and deriving compensated strain measurements that are not temperature influenced. The derived strain measurements along the DFOSS are correlated with housing displacement. Other embodiments include separate displacement measuring modules, each including DFOSS optical fibers, coupled along the engine housing.

Abstract: Apparatus and method for thermally mapping a component in a high temperature environment. An optical probe (10) has a field of view (14) arranged to encompass a surface of a component (15) to be mapped. The probe (10) captures infrared (IR) emissions in the near or mid IR band. An optical fiber (16) has a field of view to encompass a spot location (18) on the surface of the component within the field of view (14) of the probe (12). The fiber (16) captures emissions in the long IR band. The emissions in the long IR band are indicative of an emittance value at the spot location. This information may be used to calibrate a radiance map of the component generated from the emissions in the near or mid IR band and thus map the absolute temperature of the component regardless of whether the component includes a TBC.

Abstract: A distributed sensing system for detecting a flashback condition in a combustor for a gas turbine engine The distributed sensing system includes one or more strategically positioned fiber optic cables provided upstream of the combustion area in the combustor. The distributed sensing system employs Rayleigh backscattering and swept-wavelength interferometry to measure temperature and reliably identify the location of the flashback condition The fiber optic cable is specially fabricated to have a high temperature resistance suitable for those temperatures existing during flashback conditions. The fiber optic cable can be wrapped on an inside of a combustion basket or on an outside of the combustion basket, and in a serpentine manner or otherwise.

Abstract: A short laser cavity (up to 30 cm in length) comprising a free-space tunable MEMS Fabry-Perot filter, a collimating lens and a section of erbium-doped phosphate gain fiber (2-25 cm) is formed between a pair of broadband reflectors. The cavity is optically pumped to excite the erbium ions and provide gain, which establishes an initial longitudinal mode structure that spans the C-band with a mode spacing of at least 0.3 GHz and a roundtrip unsaturated gain of at least 8 dB over the tuning range. A controller tunes the MEMS filter, which has a filter function whose spectral width is at most ten and preferably less than four times the longitudinal mode spacing, to align its transmission maxima to one of a plurality of discrete output wavelengths that span the C-band. A thermal control element adjusts the longitudinal mode structure to align a single mode with the transmission maxima of the filter.

Abstract: A compact low-cost continuous single-mode fiber laser delivers output powers in excess of 50 mW over the C-band (1530 nm-1565 nm). The phosphate glass fiber supports the high doping concentrations of erbium and ytterbium (Er:Yb) without self-pulsation that are required to provide sufficient gain per centimeter needed to achieve high power in the ultra short cavity lengths necessary to support single-mode lasers. The use of fiber drawing technology provides a lower cost solution than either combined solution doping/MCVD fiber fabrication or waveguide fabrication. The ability to multi-mode clad pump the fiber further reduces cost, which is critical to the successful deployment of fiber lasers in the burgeoning metro markets.

Abstract: A short laser cavity (up to 30 cm in length) comprising a free-space tunable MEMS Fabry-Perot filter, a collimating lens and a section of erbium-doped phosphate gain fiber (2-25 cm) is formed between a pair of broadband reflectors. The cavity is optically pumped to excite the erbium ions and provide gain, which establishes an initial longitudinal mode structure that spans the C-band with a mode spacing of at least 0.3 GHz and a roundtrip unsaturated gain of at least 8 dB over the tuning range. A controller tunes the MEMS filter, which has a filter function whose spectral width is at most ten and preferably less than four times the longitudinal mode spacing, to align its transmission maxima to one of a plurality of discrete output wavelengths that span the C-band. A thermal control element adjusts the longitudinal mode structure to align a single mode with the transmission maxima of the filter.

Abstract: A long-long coupled-cavity glass laser includes a pair of active waveguide cavities that are coherently coupled using a passive waveguide cavity. The active and passive waveguide cavities are of sufficient length so that multiple supermodes and multiple peaks in the coupling coefficient are created over the width of the gain spectra. The supermodes are gain flattened so that the one supermode that coincides with a peak in the coupling coefficient will oscillate. Tunability is achieved by changing the optical path length of either the passive or active waveguide cavities to match a different supermode to a different coupling coefficient peak.

Abstract: A compact low-cost continuous single-mode fiber laser delivers output powers in excess of 50 mW over the C-band (1530 nm-1565 nm). The phosphate glass fiber supports the high doping concentrations of erbium and ytterbium (Er:Yb) without self-pulsation that are required to provide sufficient gain per centimeter needed to achieve high power in the ultra short cavity lengths necessary to support single-mode lasers. The use of fiber drawing technology provides a lower cost solution than either combined solution doping/MCVD fiber fabrication or waveguide fabrication. The ability to multi-mode clad pump the fiber further reduces cost, which is critical to the successful deployment of fiber lasers in the burgeoning metro markets.

Abstract: A long-long coupled-cavity glass laser includes a pair of active waveguide cavities that are coherently coupled using a passive waveguide cavity. The active and passive waveguide cavities are of sufficient length so that multiple supermodes and multiple peaks in the coupling coefficient are created over the width of the gain spectra. The supermodes are gain flattened so that the one supermode that coincides with a peak in the coupling coefficient will oscillate. Tunability is achieved by changing the optical path length of either the passive or active waveguide cavities to match a different supermode to a different coupling coefficient peak.