Abstract: A method of monitoring combustion properties in an interior of a furnace is described. A beam of light is projected through a pitch optic including a pitch collimating lens residing outside the boiler interior. The pitch collimating lens projects the beam through a penetration into the boiler interior. The beam of light projected by the pitch collimating lens is reflected from at least one in-furnace retro-reflector, and received with a catch optic substantially identical to the pitch optic residing outside the boiler interior. The pitch optic and the catch optic may be embodied in the same pitch/catch optic. The pitch collimating lens may also be steered toward another of the at least one in-furnace retro-reflectors. Combustion properties may be calculated for each retro-reflector based on retro-reflector zones within the furnace.

Abstract: A method of monitoring combustion properties in an interior of a furnace is described. A beam of light is projected through a pitch optic including a pitch collimating lens residing outside the boiler interior. The pitch collimating lens projects the beam through a penetration into the boiler interior. The beam of light projected by the pitch collimating lens is reflected from at least one in-furnace retro-reflector, and received with a catch optic substantially identical to the pitch optic residing outside the boiler interior. The pitch optic and the catch optic may be embodied in the same pitch/catch optic. The pitch collimating lens may also be steered toward another of the at least one in-furnace retro-reflectors. Combustion properties may be calculated for each retro-reflector based on retro-reflector zones within the furnace.

Abstract: A method of monitoring combustion properties in an interior of a boiler of the type having walls comprising a plurality of parallel steam tubes separated by a metal membrane. First and second penetrations are provided in the metal membrane between adjacent tubes on opposite sides of the boiler. A beam of light is projected through a pitch optic comprising a pitch collimating lens and a pitch relay lens, both residing outside the boiler interior. The pitch relay lens projects the beam through a penetration into the boiler interior. The beam of light is received with a catch optic substantially identical to the pitch optic residing outside the boiler interior. The strength of the collimated received beam of light is determined. At least one of the pitch collimating lens and the catch collimating lens may then be aligned to maximize the strength of the collimated received beam.

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.

Abstract: A method of absorption spectroscopy to determine a rapidly variable gas parameter. The method includes transmitting light from a synchronization light source to a synchronization detector. The transmitted light is periodically interrupted by a moving mechanical part between the synchronization light source and synchronization detector. The output from the synchronization detector is used to generate a repeating time signal having variable phase delay. This signal is used to control the timing of laser spectroscopy wavelength scans. Multiple spectroscopic scans may be repeated at multiple selected time signal phase delay and the results averaged for each phase. Apparatus for implementing the above methods are also disclosed.

Abstract: A method for measuring combustion parameters within a combustion zone of a gas turbine engine, the combustion zone being defined between an inner and outer casing. The method includes transmitting a beam from a transmit optic optically coupled to a bore in the outer casing off a portion of the inner casing and receiving a portion of the beam reflected off the inner casing with a receiving optic optically coupled to a bore in the outer casing. An apparatus for practicing the method includes a laser generating a beam and a transmitting/receiving optics pair, the transmitting/receiving optics pair being configured for operative association with a port in an outer casing of a gas turbine engine, whereby the transmitting/receiving optics are in optical communication by reflecting the beam off a portion of an inner casing.

Abstract: A method of absorption spectroscopy including obtaining absorption data at multiple wavelengths along more than one line-of-sight path through a quantity of gas of interest. The method further includes identifying more than one temperature and gas species concentration bin along the multiple line-of-sight paths and creating a map of temperature and gas species concentration. The map thus created will have at least two-dimensional information derived from select temperature and gas species concentration bins identified along more than one line-of-sight path. Apparatus for implementing the above method is also disclosed.

Abstract: A method of calibrating an absorption spectroscopy measurement wherein the calibration method includes projecting laser light through a sample of a first quantity of a gas of interest and a second irrelevant quantity of a spectroscopically identical or similar gas (10). The first and second spectroscopic absorptions of the laser light are measured over specific first and second absorption lines. A functional relationship is determined between the first and second measured spectroscopic absorptions and two unknown variables. The function relationships may then be simultaneously solved to determine one or both unknown variables and thereby obtain a measurement relating to the first quantity of the gas of interest, calibrated for the second irrelevant quantity of gas.

Abstract: An optical mode noise averaging device including a multimode optical fiber and means for averaging a modal noise induced signal level variation of light propagating within the multimode optical fiber. The device may average modal noise induced signal level variations by cyclically varying an index of refraction of the multimode optical fiber over a select period of time, scrambling a light distribution within the multimode optical fiber, or both. The index of refraction of the multimode optical fiber may be cyclically varied by cyclically varying the temperature of the multimode optical fiber. Alternatively, the index for refraction may be varied or the light distribution within the multimode optical fiber may be scrambled by cyclically manipulating the multimode optical fiber.

Abstract: A method of sensing a process utilizing a sensing apparatus consisting of more than one diode laser having select lasing frequencies, a multiplexer optically coupled to the outputs of the diode lasers with the multiplexer being further optically coupled to a pitch side optical fiber. Multiplexed laser light is transmitted through the pitch side optical fiber to a pitch optic operatively associated with a process chamber which may be a combustion chamber or the boiler of a coal or gas fired power plant. The pitch optic is oriented to project multiplexed laser output through the process chamber. Also operatively oriented with the process chamber is a catch optic in optical communication with the pitch optic to receive the multiplexed laser output projected through the process chamber. The catch optic is optically coupled to an optical fiber which transmits the multiplexed laser output to a demultiplexer.

Abstract: A diode laser spectroscopy gas sensing apparatus having a diode laser with a select lasing frequency, a pitch optic coupled to the diode laser with the pitch optic being operatively associated with a process chamber and oriented to project laser light along a projection beam through the process chamber. This embodiment additionally includes a catch optic in optical communication with the pitch optic to receive the laser light projected through the process chamber and an optical fiber optically coupled to the catch optic. In addition, the catch optic is operatively associated with a catch side alignment mechanism which provides for the alignment of the catch optic with respect to the projection beam to increase a quantity of laser light received by the catch optic from the pitch optic and coupled to the optical fiber and a detector sensitive to the select lasing frequency optically coupled to the optical fiber.

Abstract: A method for measuring combustion parameters within a combustion zone of a gas turbine engine, the combustion zone being defined between an inner and outer casing. The method comprises transmitting a beam from a transmit optic optically coupled to a bore in the outer casing off a portion of the inner casing and receiving a portion of the beam reflected off the inner casing with a receiving optic optically coupled to a bore in the outer casing. An apparatus for practicing the method comprises a laser generating a beam and a transmitting/receiving optics pair, the transmitting/receiving optics pair being configured for operative association with a port in an outer casing of a gas turbine engine, whereby the transmitting/receiving optics are in optical communication by reflecting the beam off a portion of an inner casing.

Abstract: A pitch side optical system for use in diode laser spectroscopy consisting of more than one diode laser having select lasing frequencies with each diode laser being coupled to an end of a distinct input optical fiber. The pitch side optical system further consists of a multiplexer optically coupled to the other end of less than all of the input optical fibers with the multiplexer outputting multiplexed laser light to a pitch side optical fiber. The pitch side optical system further consists of a coupler optically coupled to the far end of the pitch side optical fiber and the far end of an unmultiplexed input optical fiber with the coupler combining the multiplexed laser light and the unmultiplexed laser light and outputting the combined light to a transmission optical fiber. Typically, the coupler is located near the combustion process. The pitch side optical system further consists of a pitch optic coupled to the transmission optical fiber.

Abstract: A sensing apparatus consisting of more than one diode laser having select lasing frequencies, a multiplexer optically coupled to the outputs of the diode lasers with the multiplexer being further optically coupled to a pitch side optical fiber. Multiplexed laser light is transmitted through the pitch side optical fiber to a pitch optic operatively associated with a process chamber which may be a combustion chamber or the boiler of a coal or gas fired power plant. The pitch optic is oriented to project multiplexed laser output through the process chamber. Also operatively oriented with the process chamber is a catch optic in optical communication with the pitch optic to receive the multiplexed laser output projected through the process chamber. The catch optic is optically coupled to an optical fiber which transmits the multiplexed laser output to a demultiplexer.

Abstract: A (de)multiplexer for use in optical communications systems for multiplexing and demultiplexing an optical signal consisting of optical channel(s) of different wavelength(s) includes a multiplex optical waveguide propagating a plurality of optical channels and a plurality of single channel optical waveguides, each propagating a single channel. Each of the waveguides has a receiving/transmitting end. A diffraction grating is optically coupled between the multiplex optical waveguide and the single channel optical waveguides for diffracting an optical signal between the receiving/transmitting end of the multiplex optical waveguide and the receiving/transmitting end of the single channel optical waveguide.

Abstract: An apparatus for use in optical communication systems to multiplex/demultiplex an optical signal consisting of an optical channel(s) of distinct wavelength(s) having a select channel spacing within a select wavelength range. The apparatus includes a plurality of optical waveguides aligned generally along the same optical axis with each having a propagating end. At least two of the optical waveguides each propagate a distinct multiplexed optical signal comprising a plurality of channels, with the multiplexed optical waveguides being arranged in a multiplexed linear array. The others of the optical waveguides are single channel waveguides arranged in a two dimensional array with linear rows perpendicular to the multiplex linear array and with each linear row corresponding to a multiplex optical waveguide.

Abstract: An apparatus for multiplexing or demultiplexing optical signals in an optical communication system includes a plurality of optical waveguides aligned generally along the same optical axis each having a propagating end. A reflective grating is optically coupled to the plurality of optical waveguides along the optical axis and has a surface receiving an optical signal emitted from at least one of the optical waveguides. The surface diffracts the optical signals into at least one other of the optical waveguides. A collimating/focusing optic having a select focal length is optically coupled between the plurality of optical waveguides and the reflective grating along the optical axis. The collimating/focusing optic is positioned relative to the propagating ends of the plurality of optical waveguides and the reflective echelle grating to propagate a telecentric optical beam(s) into the at least one other of the optical waveguides.

Abstract: A fiber pigtail template assembly includes first and second silicon wafers each having a planar surface with a plurality of corresponding grooves therein extending from a leading edge toward a trailing edge. The plurality of corresponding grooves, with the planar surfaces in abutment and the corresponding grooves aligned define a plurality of fiber channels. The first and second silicon wafers further cooperatively define a receptacle between the fiber channels and the trailing edges of the first and second silicon wafers with the planar surfaces of the silicon wafers in abutment with the grooves aligned. A minor diameter leading portion of an optical fiber is received in each fiber channel and the receptacle is sized to receive major diameter trailing portions of each fiber without causing a bending radius of the fiber sufficient to materially degrade wavelength propagation.

Abstract: A bulk optic (de)multiplexer for fiber optic communications systems includes a diffraction grating having a diffraction surface, a waveguide array including a plurality of waveguides having an input/output end for emitting and receiving optical signals, and a focusing optic in optical communication between the diffraction grating and the waveguide array along an optical axis. The focusing optic focuses beams from the diffraction surface of the grating for optical coupling with the input/output ends of the waveguides. The (de)multiplexer further includes a frame. A fixed mount is provided between the focusing optic and the frame. A first adjustable mount is provided between the waveguide array and the frame and a second adjustable mount is provided between the diffraction grating and the frame. Preferably, the optical axis corresponds to a Z axis of orthogonal X, Y, Z axes and the waveguides of the waveguide array are aligned with the input/output ends along an input/output axis.

Abstract: An apparatus for use in optical communication systems to multiplex/demultiplex an optical signal consisting of an optical channel(s) of distinct wavelength(s) having a select channel spacing within a select wavelength range. The apparatus includes a plurality of optical waveguides aligned generally along the same optical axis with each having a propagating end. At least two of the optical waveguides each propagate a distinct multiplexed optical signal comprising a plurality of channels, with the multiplexed optical waveguides being arranged in a multiplexed linear array. The others of the optical waveguides are single channel waveguides arranged in a two dimensional array with linear rows perpendicular to the multiplex linear array and with each linear row corresponding to a multiplex optical waveguide.