Abstract:
An apparatus and method are provided employing a single set of reduced-cost optics for (de)multiplexing optical signals whereby the resultant signals have a flat-top response with increased channel spacing. One aspect of the present invention uses an optical interleaver (310) to separate channels from an input multichannel (multiplexed) optical signal (302) with a select channel spacing into, for example, two input signals consisting of alternating channels at twice the select channel spacing. The separated signals are then directed to a multiple-input, such as dual-input, (parallel)(de)multiplexer device (320) which further spacially separates the channels for coupling with single channel transmission fibers (3221-n, 3241-n). The input fibers to the (de)multiplexer are preferably offset relative to each other to accommodate channel shift resulting from the interleaver.
Abstract:
An embedded flight sensor system having a laser and one or more flight sensors in optical communication with the laser plus a data processing device in optical communication with the flight sensors. The flight sensors may be laser based optical components such as a fiber Bragg grating in combination with an optical detector, a spectroscopy grating and detector or an optical detector associated with catch optics. The parameters sensed by the flight sensors may be used to determine any flight parameter. Representative flight parameters include but are not limited to an airframe or external surface temperature, airstream velocity, combustion zone temperature, engine inlet temperature, a gas concentration or a shock front position.
Abstract:
A sensing apparatus (10) consisting of more than one diode laser (12) having select lasing frequencies, a multiplexer (16) 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 (20) operatively associated with a process chamber (22) which may be a combustion chamber or the boiler of a coal or gas fired power plant. The pitch optic (20) is oriented to project multiplexed laser output through the process chamber. Also operatively oriented with the process chamber is a catch optic (24) in optical communication with the pitch optic to receive the multiplexed laser output projected through the process chamber. The catch optic (24) is optically coupled to an optical fiber which transmits the multiplexed laser output to a demultiplexer (28). The demultiplexer (28) demultiplexes the laser light and optically couples the select lasing frequencies of light to a detector (25) with the detector being sensitive to one of the select lasing frequencies.
Abstract:
A diffraction grating (10') for use in multiplexing and demultiplexing optical signals in optical communication systems having reduced polarization sensitivity has a plurality of reflective step surfaces (16') separated by a plurality of riser surfaces (18') defining grooves of the grating. The step surfaces (16') have a reflective coating (22') and the riser surfaces (18') do not have a conductive coating. A method of making a reflective diffraction grating includes forming a plurality of grooves in a substrate, the grooves having a reflective surface for reflecting an incident beam and non-reflective surface and providing a reflective coating on the reflective surface and not on the non-reflective surface.
Abstract:
A reconfigurable add/drop multiplexer (100, 150) for use in an optical communications network includes an input optical waveguide (118, 162) propagating a multi-channel optical signal and a receiver optical waveguide (120, 170) optically aligned with the input waveguide. A transmission filter (106, 164) is in optical communication between the input optical waveguide and the receiver optical waveguide (120, 170) with the transmission filter being tunable to drop a select channel to the receiver optical waveguide (120, 170) and to reflect the remaining channels of the multi-channel optical signal. A retransmission waveguide (118, 162) is in optical communication with the transmission filter to receive the reflected remaining channels. A second receiver waveguide (130, 174) is in optical communication with the receiver waveguide (120, 170). A selectively reflective apparatus (108, 168) is in optical communication between the receiver optical waveguide and the second receiver optical waveguide for selectively reflecting the dropped channel or transmitting the dropped channel to the second receiver waveguide. A second retransmission waveguide (130, 182) in optical communication with the selectively reflective means receives a reflected optical signal. A method of dropping a select channel of a multi-channel optical signal propagated along a main optical waveguide without loss of data includes directing the multi-channel optical signal from the main optical waveguide to an input waveguide. The receiver waveguide is optically aligned with the input waveguide. A tunable transmission filter is provided in optical communication between the input and receiver waveguides. The transmission filter is tuned to drop a select channel to the receiver optical waveguide and to reflect the remaining channels of the multi-channel optical signal to a retransmission optical waveguide in optical communication with the main optical fiber. All dropped channels are reflected for repropagation along the main optical waveguide while the tunable transmission filter is tuned between first and second select channels. The transmission filter (106, 164) may be a wedged-etalon having a cavity that varies uniformly in width between a widest operative end and a narrowest operative end along a filtering axis in optical communication between the input and receiver waveguides. An actuator (107) moves the wedged-etalon out to select positions between the widest and narrowest operative ends to drop a select channel.
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:
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.