Abstract: Systems and methods are provided for sensing acoustic signals using a floating base vector sensor. A vector sensor according to an embodiment of the present disclosure can be used to detect and characterize low frequency sound wave(s) in a viscous medium (e.g., air, water, etc.) by detecting a periodic motion of the media particles associated with the sound wave(s). The orientation of the particle velocity deduced from such measurements can provide information regarding the wave vector of the sound wave(s), can define the direction of arrival (DOA) for the acoustic signal, and can assist locating the source of the sound of interest.

Abstract: Systems and methods are provided for sensing acoustic signals using a floating base vector sensor. A vector sensor according to an embodiment of the present disclosure can be used to detect and characterize low frequency sound wave(s) in a viscous medium (e.g., air, water, etc.) by detecting a periodic motion of the media particles associated with the sound wave(s). The orientation of the particle velocity deduced from such measurements can provide information regarding the wave vector of the sound wave(s), can define the direction of arrival (DOA) for the acoustic signal, and can assist locating the source of the sound of interest.

Abstract: Systems and methods are provided for sensing acoustic signals using a floating base vector sensor. A vector sensor according to an embodiment of the present disclosure can be used to detect and characterize low frequency sound wave(s) in a viscous medium (e.g., air, water, etc.) by detecting a periodic motion of the media particles associated with the sound wave(s). The orientation of the particle velocity deduced from such measurements can provide information regarding the wave vector of the sound wave(s), can define the direction of arrival (DOA) for the acoustic signal, and can assist locating the source of the sound of interest.

Abstract: Systems and methods are provided for sensing acoustic signals using a floating base vector sensor. A vector sensor according to an embodiment of the present disclosure can be used to detect and characterize low frequency sound wave(s) in a viscous medium (e.g., air, water, etc.) by detecting a periodic motion of the media particles associated with the sound wave(s). The orientation of the particle velocity deduced from such measurements can provide information regarding the wave vector of the sound wave(s), can define the direction of arrival (DOA) for the acoustic signal, and can assist locating the source of the sound of interest.

Abstract: A fiber optic acoustic sensor and a method of using same. The sensor includes a light emitting diode and a fiber optic probe having a transmitting multimode optical fiber and at least one receiving multimode optical fiber. The transmitting multimode optical fiber and the receiving multimode optical fiber are substantially parallel to a longitudinal axis of the probe. The fiber optic probe communicates with the light emitting diode. The sensor further includes a cantilever, which includes a cantilever rod. The cantilever rod includes a proximal end with an edge reflector located thereon. The edge reflector is spaced apart from the fiber probe and oriented to face said fiber probe. The edge reflector is able to move in a direction substantially perpendicular to the longitudinal axis of the fiber optic probe. The sensor further includes a light intensity detector communicating with the fiber optic probe.

Abstract: A fiber optic acoustic sensor and a method of using same. The sensor includes a light emitting diode and a fiber optic probe having a transmitting multimode optical fiber and at least one receiving multimode optical fiber. The transmitting multimode optical fiber and the receiving multimode optical fiber are substantially parallel to a longitudinal axis of the probe. The fiber optic probe communicates with the light emitting diode. The sensor further includes a cantilever, which includes a cantilever rod. The cantilever rod includes a proximal end with an edge reflector located thereon. The edge reflector is spaced apart from the fiber probe and oriented to face said fiber probe. The edge reflector is able to move in a direction substantially perpendicular to the longitudinal axis of the fiber optic probe. The sensor further includes a light intensity detector communicating with the fiber optic probe.

Abstract: A fiber-optic temperature sensor with a cantilever beam including two different material strips with different thermal expansion coefficients, the cantilever beam having a reflective surface on an end of the cantilever beam, an optical fiber probe including a transmitting multimode optical fiber and at least one receiving multimode optical fiber for receiving reflected light from the reflective surface. Temperature changes at the sensor are indicated by a change in reflected light coupled into the receiving multimode optical fiber due to lateral displacement of the edge of the reflective surface caused by bending of the cantilever beam. Some embodiments have additional reference receiving fibers for compensation for noise, changes in gap length, and other factors.

Abstract: An intensity-based fiber optic temperature sensor having a fiber probe with a multimode transmit/receive fiber, a reflector spaced apart from the end of the fiber, and a housing affixed at its ends to the fiber probe and reflector, the housing having a larger or smaller thermal expansion coefficient than those of the fiber probe and reflector. Temperature changes cause a change in the gap distance between the fiber end and the reflector, changing the amount of reflected light coupled into the optical fiber. Temperature sensors can also have a fiber probe with two or more multimode receiving fibers surrounding a transmitting fiber. Other temperature sensors include a fiber probe with a multimode transmitting fiber, a reference multimode receiving fiber and a sensing multimode receiving fiber for reducing noise effects.

Abstract: A fiber optic hydrophone has a reflective diaphragm having an exposed face and a reflective protected face, at least one transmitting multimode optical fiber having an end spaced apart from the protected face of the diaphragm positioned to emit light toward the diaphragm housing, and a reservoir. A cavity is defined by the diaphragm and the interior surface of the housing. Silicone oil and a compliant elastomeric material with embedded air bubbles are located in the cavity. Ports between the cavity and the reservoir and the reservoir and the exterior of the hydrophone allow static pressure communication between the cavity and the exterior of the hydrophone. The fiber optic probe can have one transmitting multimode optical fiber and six receiving multimode optical fibers, or more or fewer optical fibers. A grating can protect the diaphragm from environmental damage.

Abstract: A fiber optic hydrophone has a reflective diaphragm having an exposed face and a reflective protected face, at least one transmitting multimode optical fiber having an end spaced apart from the protected face of the diaphragm positioned to emit light toward the diaphragm housing, and a reservoir. A cavity is defined by the diaphragm and the interior surface of the housing. Silicone oil and a compliant elastomeric material with embedded air bubbles are located in the cavity. Ports between the cavity and the reservoir and the reservoir and the exterior of the hydrophone allow static pressure communication between the cavity and the exterior of the hydrophone. The fiber optic probe can have one transmitting multimode optical fiber and six receiving multimode optical fibers, or more or fewer optical fibers. A grating can protect the diaphragm from environmental damage.

Abstract: An intensity-based fiber optic temperature sensor having a fiber probe with a multimode transmit/receive fiber, a reflector spaced apart from the end of the fiber, and a housing affixed at its ends to the fiber probe and reflector, the housing having a larger or smaller thermal expansion coefficient than those of the fiber probe and reflector. Temperature changes cause a change in the gap distance between the fiber end and the reflector, changing the amount of reflected light coupled into the optical fiber. Temperature sensors can also have a fiber probe with two or more multimode receiving fibers surrounding a transmitting fiber. Other temperature sensors include a fiber probe with a multimode transmitting fiber, a reference multimode receiving fiber and a sensing multimode receiving fiber for reducing noise effects.

Abstract: A fiber-optic temperature sensor with a cantilever beam including two different material strips with different thermal expansion coefficients, the cantilever beam having a reflective surface on an end of the cantilever beam, an optical fiber probe including a transmitting multimode optical fiber and at least one receiving multimode optical fiber for receiving reflected light from the reflective surface. Temperature changes at the sensor are indicated by a change in reflected light coupled into the receiving multimode optical fiber due to lateral displacement of the edge of the reflective surface caused by bending of the cantilever beam. Some embodiments have additional reference receiving fibers for compensation for noise, changes in gap length, and other factors.

Abstract: A fiber optic sensor for detecting acceleration or displacement includes a fiber optic probe with a multimode transmitting optical fiber, a multimode receiving optical fiber and a edge reflector spaced apart from the fiber probe. The reflector moves in a transverse direction substantially normal to the longitudinal axis of the fiber optic probe, so the amount of light received by the receiving fiber indicates a relative acceleration or a relative displacement of the reflective surface with respect to the fiber probe in the transverse direction of motion of the edge of the reflector. The reflector can be mounted on a cantilever beam. The sensor can have one transmitting fiber, two receiving fiber, and a reflector with two edges, each edge partially covering one of the receiving fibers. A triaxial sensor system has at least two two-fiber sensors.

Abstract: A catheter with many fiber optic pressure sensors. The sensor diaphragm is formed from a wafer with a thin silicon layer and a silicon substrate layer separated by a silicon dioxide layer. A method includes masking and etching channels through the silicon substrate layer in a pattern of concentric circles to form a concentric circular etched channels and cylindrical unetched portions of the silicon substrate layer between the channels, exposing the silicon dioxide in the etched regions, and dissolving the exposed silicon dioxide to expose the crystalline silicon layer in the etched regions. The unetched cylindrical portion of the silicon substrate forms the diaphragm support element and the thin silicon layer forms the diaphragm. After applying a reflective coating to the exposed thin silicon layer, the support element face is adhered to the end face of a tubular housing, and a fiber optic probe is inserted in the tubular housing.

Abstract: A strain sensor includes an optical fiber with at least one optical fiber, a reflector body with a reflective surface, a housing affixed to the optical fiber probe and to the reflector body. The reflective surface is spaced apart at a distance d from the ends of the probe's fibers and receives light from the end of the fiber and to reflect at least a portion of the light into the end of the fiber. The housing is attached to the fiber probe at a first end of the housing and attached to the reflector body at a second end of the housing. The housing is affixed to the material to be measured, and in the material causes a change in gap between the fiber end and the reflective surface, modulating the amount of light received in the receiving fiber, detectable by a photodetector connected to the receiving fiber.

Abstract: A strain sensor includes an optical fiber with at least one optical fiber, a reflector body with a reflective surface, a housing affixed to the optical fiber probe and to the reflector body. The reflective surface is spaced apart at a distance d from the ends of the probe's fibers and receives light from the end of the fiber and to reflect at least a portion of the light into the end of the fiber. The housing is attached to the fiber probe at a first end of the housing and attached to the reflector body at a second end of the housing. The housing is affixed to the material to be measured, and in the material causes a change in gap between the fiber end and the reflective surface, modulating the amount of light received in the receiving fiber, detectable by a photodetector connected to the receiving fiber.

Abstract: A catheter with many fiber optic pressure sensors. The sensor diaphragm is formed from a wafer with a thin silicon layer and a silicon substrate layer separated by a silicon dioxide layer. A method includes masking and etching channels through the silicon substrate layer in a pattern of concentric circles to form a concentric circular etched channels and cylindrical unetched portions of the silicon substrate layer between the channels, exposing the silicon dioxide in the etched regions, and dissolving the exposed silicon dioxide to expose the crystalline silicon layer in the etched regions. The unetched cylindrical portion of the silicon substrate forms the diaphragm support element and the thin silicon layer forms the diaphragm. After applying a reflective coating to the exposed thin silicon layer, the support element face is adhered to the end face of a tubular housing, and a fiber optic probe is inserted in the tubular housing.

Abstract: A fiber optic sensor for detecting acceleration or displacement includes a fiber optic probe with a multimode transmitting optical fiber, a multimode receiving optical fiber and a edge reflector spaced apart from the fiber probe. The reflector moves in a transverse direction substantially normal to the longitudinal axis of the fiber optic probe, so the amount of light received by the receiving fiber indicates a relative acceleration or a relative displacement of the reflective surface with respect to the fiber probe in the transverse direction of motion of the edge of the reflector. The reflector can be mounted on a cantilever beam. The sensor can have one transmitting fiber, two receiving fiber, and a reflector with two edges, each edge partially covering one of the receiving fibers. A triaxial sensor system has at least two two-fiber sensors.

Abstract: A fiber optic sensor for measuring static pressure includes a cartridge housing having an end that is exposed to the atmosphere, a thin flexible membrane covering the exposed end of the cartridge housing such that the flexible membrane has an exposed side and a protected side, and a fiber bundle disposed within the cartridge housing, the fiber bundle comprising at least one fiber having a first polished end for transmitting light toward the membrane and a second end for being coupled to a light source or a receiver, the housing arranged to maintain the membrane at a distance from the first end of the fiber in a direction along a fiber axis, with free space between the first fiber end and the protected side of the flexible membrane.

Abstract: A multiplexed fiber optic sensor system including a first optical fiber having a first end arranged to receive light from a light souce, at least two optical fibers having diameters smaller than the first optical fiber, and at least two fiber optic sensors, each of the at least two smaller diameter optical fibers arranged between the first optical fiber and one of the sensors for transmitting light from the first optical fiber to that sensor. The sensors can be static or dynamic pressure sensors, strain sensors, temperature sensors or other environmental sensors.