Abstract: An optical fiber feedthrough assembly includes a glass plug disposed in a recess of a feedthrough housing. The glass plug may define a large-diameter, cane-based, waveguide sealed within the recess in the housing and providing optical communication through the housing. Sealing occurs with respect to the housing at or around the glass plug of an optical waveguide element passing through the housing by braze sealing to the glass plug and/or embedding the glass plug in a polymer bonded with the plug to form a molded body that is sealed in the housing by, for example, compression mounting of the molded body or providing a sealing element around the molded body.

Abstract: Optical sensors used in harsh environments require a sealed pressure tight passage of an optical waveguide into an interior of the sensor. In one embodiment, a pressure sensor assembly for determining the pressure of a fluid in a harsh environment includes a sensing element suspended within a fluid filled housing. An optical waveguide that provides communication with the sensing element couples to a feedthrough assembly, which includes a cane-based optical waveguide forming a glass plug sealingly disposed in the housing. The glass plug provides optical communication between the optical waveguide and the sensing element. A pressure transmitting device can transmit the pressure of the fluid to the fluid within the housing. The assembly can maintain the sensing element in a near zero base strain condition and can protect the sensing element from shock/vibration.

Abstract: An optical waveguide feedthrough assembly passes at least one optical waveguide through a bulk head, a sensor wall, or other feedthrough member. The optical waveguide feedthrough assembly comprises a cane-based optical waveguide that forms a glass plug sealingly disposed in a feedthrough housing. A seal fills an annular space between the glass plug and the housing. The seal may be energized by a fluid pressure in the housing to establish sealing engagement. Further, the seal may provide bidirectional sealing. The feedthrough assembly is operable in high temperature and high pressure environments.

Abstract: An optical fiber feedthrough assembly includes a glass plug disposed in a recess of a feedthrough housing. The glass plug may define a large-diameter, cane-based, waveguide sealed within the recess in the housing and providing optical communication through the housing. Sealing occurs with respect to the housing at or around the glass plug of an optical waveguide element passing through the housing by braze sealing to the glass plug and/or embedding the glass plug in a polymer bonded with the plug to form a molded body that is sealed in the housing by, for example, compression mounting of the molded body or providing a sealing element around the molded body.

Abstract: Methods and apparatus enable monitoring conditions in a well-bore using multiple cane-based sensors. The apparatus includes an array of cane-based Bragg grating sensors located in a single conduit for use in the well-bore. For some embodiments, each sensor is located at a different linear location along the conduit allowing for increased monitoring locations along the conduit.

Abstract: A method, apparatus and system are provided to measure the process flow of a fluid or medium traveling in a pipe. The system and apparatus feature a standoff and piezoelectric-based sensor arrangement having a plurality of standoffs arranged on a pipe and a plurality of sensor bands, each arranged on a respective plurality of standoffs, each having at least one sensor made of piezoelectric material arranged thereon to detect unsteady pressure disturbances in the process flow in the pipe which in turn can be converted to the velocity of and/or speed of sound propagating within the pipe, and a cooling tube arranged in relation to the plurality of standoffs for actively cooling the sensor band; and further comprise a processing module for converting one or more sensor signals into a measurement containing information about the flow of the fluid or medium traveling in the pipe, as well as a pump and heat exchanger for processing the cooling fluid flowing through the cooling tube.

Abstract: An optical spectrum analyzer (OSA) 10 sequentially or selectively samples (or filters) a spectral band(s) 11 of light from a broadband optical input signal 12 and measures predetermined optical parameters of the optical signal (e.g., spectral profile) of the input light 12. The OSA 10 is a free-space optical device that includes a collimator assembly 15, a diffraction grating 20 and a mirror 22. A launch pigtail emits into free space the input signal through the collimator assembly 15 and onto the diffraction grating 20, which separates or spreads spatially the collimated input light, and reflects the dispersed light onto the mirror 22. A ?/4 plate 26 is disposed between the mirror 22 and the diffraction grating 20. The mirror reflects the separated light back through the ?/4 plate 26 to the diffraction grating 20, which reflects the light back through the collimating lens 18. The lens 18 focuses spectral bands of light (?1–?N) at different focal points in space.

Abstract: A reconfigurable multifunctional optical device has an optical arrangement for receiving an optical signal, each having optical bands or channels, and a spatial light modulator for reflecting the at least one optical signal provided thereon. The optical arrangement features a free optics configuration with a light dispersion element for spreading each optical signal into one or more respective optical bands or channels for performing separate optical functions on each optical signal. The spatial light modulator includes a micro-mirror device with an array of micro-mirrors, and the respective optical bands or channels reflect off respective micro-mirrors. The free optics configuration includes a common set of optical components for performing each separate optical function on each optical signal. The separate optical functions reflect off separate non-overlapping areas on the spatial light modulator. The separate optical functions include optical switching, conditioning or monitoring functions.

Abstract: A pressure transducer that uses a rhomboidal flexure to provide displacement amplification to an optical sensing element is disclosed. The transducer includes an optical sensor disposed between sides of the flexure. The top portion of the flexure connects to a displacement device, such as a bellows. A first pressure port provides a first pressure to the bellows. A second pressure, preferably greater than the first pressure, is ported into a housing containing the flexure, which tends to compress the bellows and pull apart or expand the flexure. Such expansion pinches or compresses the optical sensing element between the sides of the flexure, and in particular stresses an optical sensing element containing a fiber Bragg grating. Assessing the Bragg reflection wavelength of the grating allows the differential pressure to be determined, although the transducer can also be used to sense an absolute pressure.

Abstract: A highly sensitive accelerometer for determining the acceleration of a structure includes a mass within a housing suspended by opposing support members. The support members are alternately wound around a pair of fixed mandrels and the mass in a push pull arrangement. At least a portion of one of the support members comprises a transducer capable measuring the displacement of the mass within the housing. An embodiment of the invention employs optical fiber coils as the support members for use in interferometric sensing processes. Arrays of such interferometer based accelerometers may be multiplexed using known techniques.

Abstract: A reconfigurable optical blocking filter deletes a desired optical channel(s) from an optical WDM input signal, and includes a spatial light modulator having a micro-mirror device with a two-dimensional array of micro-mirrors that tilt between first and second positions in a “digital” fashion in response to a control signal provided by a controller in accordance with a switching algorithm and an input command. A collimators, diffraction grating, and Fourier lens, collectively collimate, separate and focus the optical input channels onto the array of micro-mirrors. The optical channel is focused on the micro-mirrors onto a plurality of micro-mirrors of the micro-mirror device, which effectively pixelates the optical channels. To delete an input channel of the optical input signal, micro-mirrors associated with each desired input channel are tilted to reflect the desired input channel away from the return path.

Abstract: A chromatic dispersion compensation device selectively delays a respective portion of spectral sections of each respective optical channel of an optical WDM input signal to compensate each optical channel for dispersion compensation, and includes a spatial light modulator having a micromirror device with a two-dimensional array of micromirrors. The micromirrors tilt or flip between first and second positions in a “digital” fashion in response to a control signal provided by a controller in accordance with a switching algorithm and an input command. A collimator, diffraction gratings, and Fourier lens collectively collimate, disperse and focus the optical input channels onto the array of micromirrors. Each optical channel is focused onto micromirrors of the micromirror device, which effectively pixelates the optical channels. To compensate an optical channel for chromatic dispersion, a portion of the spectral sections of each channel is delayed a desired time period by tilting an array of mirrors (i.e.

Abstract: A reconfigurable optical interleaver/deinterleaver device combines/separates a pair of optical input signals from and/or to an optical WDM input signal. The interleaver device includes a spatial light modulator having a micro-mirror device with a two-dimensional array of micro-mirrors that flip between first and second positions in a “digital” fashion in response to a control signal provided by a controller in accordance with a switching algorithm and an input command. A pair of collimators, diffraction gratings and Fourier lens collectively collimate, separate and focus the optical input channels and optical add channels onto the array of micro-mirrors. Each optical channel is focused on a plurality of micro-mirrors of the micro-mirror device, which effectively pixelates the optical channels.

Abstract: An optical corrosion sensor employs an optical fiber Bragg grating 20 embedded within an optical fiber 18. The grating 20 has a coating 40 made of a material, such as aluminum, which corrodes or can otherwise be removed. The coating 40 exerts forces 46 radially inward around and along the grating 20 so as to cause the wavelength bandwidth of the grating reflectivity profile to become broader and to be shifted relative to its uncoated condition. Also, the forces on the grating 20 are reduced when the coating corrodes, thereby causing the wavelength bandwidth and shift of the reflectivity profile of the grating to narrow and to return to its uncoated condition.

Abstract: A strain-isolated bragg grating temperature sensor includes an optical sensing element 20,600 which includes an optical fiber 10 having at least one Bragg grating 12 disposed therein which is encased within and fused to at least a portion of a glass capillary tube 20 and/or a large diameter waveguide grating 600 having a core and a wide cladding and having the grating 12 disposed therein, which senses temperature changes but is substantially not sensitive to strains on the element caused by the fiber or other effects. Light 14 is incident on the grating 12 and light 16 is reflected at a reflection wavelength ?1. The shape of the sensing element 20,600 may be other geometries and/or more than one concentric tube may be used or more than one grating or pair of gratings may be used or more than one fiber or optical core may be used.

Abstract: An optical spectrum analyzer (OSA) 10 sequentially or selectively samples (or filters) a spectral band(s) 11 of light from a broadband optical input signal 12 and measures predetermined optical parameters of the optical signal (e.g., spectral profile) of the input light 12. The OSA 10 is a free-space optical device that includes a collimator assembly 15, a diffraction grating 20 and a mirror 22. A launch pigtail emits into free space the input signal through the collimator assembly 15 and onto the diffraction grating 20, which separates or spreads spatially the collimated input light, and reflects the dispersed light onto the mirror 22. A &lgr;/4 plate 26 is disposed between the mirror 22 and the diffraction grating 20. The mirror reflects the separated light back through the &lgr;/4 plate 26 to the diffraction grating 20, which reflects the light back through the collimating lens 18. The lens 18 focuses spectral bands of light (&lgr;1-&lgr;N) at different focal points in space.

Abstract: A fiber grating pressure sensor includes an optical sensing element which includes an optical fiber having a Bragg grating impressed therein which is encased within and fused to at least a portion of a glass capillary tube and/or a large diameter waveguide grating having a core and a wide cladding. Light is incident on the grating and light is reflected from the grating at a reflection wavelength &lgr;1. The sensing element may be used by itself as a sensor or located within a housing. When external pressure P increases, the grating is compressed and the reflection wavelength &lgr;1 changes. The shape of the sensing element may have other geometries, e.g., a “dogbone” shape, so as to enhance the sensitivity of shift in &lgr;1 due to applied external pressure and may be fused to an outer shell.

Abstract: A pressure transducer that uses a rhomboidal flexure to provide displacement amplification to an optical sensing element is disclosed. The transducer includes an optical sensor disposed between sides of the flexure. The top portion of the flexure connects to a displacement device, such as a bellows. A first pressure port provides a first pressure to the bellows. A second pressure, preferably greater than the first pressure, is ported into a housing containing the flexure, which tends to compress the bellows and pull apart or expand the flexure. Such expansion pinches or compresses the optical sensing element between the sides of the flexure, and in particular stresses an optical sensing element containing a fiber Bragg grating. Assessing the Bragg reflection wavelength of the grating allows the differential pressure to be determined, although the transducer can also be used to sense an absolute pressure.

Abstract: A highly sensitive accelerometer for determining the acceleration of a structure includes a mass within a housing suspended by opposing support members. The support members are alternately wound around a pair of fixed mandrels and the mass in a push pull arrangement. At least a portion of one of the support members comprises a transducer capable measuring the displacement of the mass within the housing. An embodiment of the invention employs optical fiber coils as the support members for use in interferometric sensing processes. Arrays of such interferometer based accelerometers may be multiplexed using known techniques.

Abstract: A fiber grating pressure sensor for use in an industrial process includes an optical sensing element 20,600 which includes an optical fiber 10 having a Bragg grating 12 impressed therein which is encased within and fused to at least a portion of a glass capillary tube 20 and/or a large diameter waveguide grating 600 having a core and a wide cladding and which has an outer transverse dimension of at least 0.3 mm. Light 14 is incident on the grating 12 and light 16 is reflected from the grating 12 at a reflection wavelength &lgr;1. The sensing element 20,600 may be used by itself as a sensor or located within a housing 48,60,90,270,300. When external pressure P increases, the grating 12 is compressed and the reflection wavelength &lgr;1 changes. The shape of the sensing element 20,600 may have other geometries, e.g., a “dogbone” shape, so as to enhance the sensitivity of shift in &lgr;1 due to applied external pressure and may be fused to an outer shell 50.