Abstract: The present invention provides a sensor system for measuring a parameter (e.g. volume, temperature or pressure) of a target, the system comprising a diaphragm, a sensor for measuring the axial spacing between the sensor and the diaphragm, and an axially adjustable mount. The mount has a first axial end for mounting the diaphragm which is axially movable relative to the sensor and an opposing, second axial end which is axially fixed relative to the sensor. The diaphragm and mount define a chamber for receiving the target or for being received within the target. In use, the axial spacing between the first axial end and the second axial end of the mount and thus the axial spacing between the diaphragm and sensor varies as a result of a change in the parameter differential across the diaphragm.

Abstract: The purpose of the present invention is to provide a bonded structure, a method for manufacturing the same, and a bonding state detection method which are capable of determining whether or not members are bonded together appropriately. A bonded structure 10 includes a laminated sheet 12A, a laminated sheet 12B, an adhesive 14 that bonds the laminated sheet 12A and the laminated sheet 12B together, and a distributed optical fiber 16 sandwiched between the laminated sheet 12A and the laminated sheet 12B. The cross-sectional shape of the distributed optical fiber 16 is deformed in accordance with the bonding state.

Abstract: An optical pressure sensor is disclosed having a pressure sensing optical cavity. A temperature sensing optical cavity at the sensing head is used by an interrogator to correct a pressure signal for effects of temperature. The optical cavities may be, for example, Fabry Perot cavities in the sensor head.

Abstract: The application describes methods and apparatus for seismic monitoring using fiber optic distributed acoustic sensing (DAS). The method involves interrogating a first optical fiber (102) deployed in an area of interest to provide a distributed acoustic sensor comprising a plurality of longitudinal sensing portions of fiber and also monitoring at least one geophone (107) deployed in the area of interest. The signal from the at least one geophone is analyzed to detect an event of interest (105). If an event of interest is detected the data from the distributed acoustic sensor acquired during said event of interest is recorded. The geophone may be co-located with part of the sensing fiber and in some embodiments may be integrated (307) with the sensing fiber.

Abstract: An electronic device includes an input surface area for receiving a force applied by a user and one or more optical waveguides that include Bragg gratings. The optical waveguide or waveguides is operatively affixed to the input surface area. At least one light source is optically coupled to the optical waveguide or waveguides. At least one wavelength interrogator is coupled to the optical waveguide or waveguides.

Abstract: A pressure detecting apparatus made by 3D printing technologies being able to be used in dangerous areas is provided. It mainly comprises a light source, a processor, a coupler, and at least one pressure transducer. The pressure transducer comprises a main body and a fiber grating. The fiber grating comprises a fiber Bragg grating sensor, and the fiber grating is fixed on the main body and covers the fiber Bragg grating sensor. When the main body is placed in a fluid area, the fluid would flow through the opening to deform the strain layer and generate a strain variation on the fiber Bragg grating sensor to cause a signal variation in the reflection frequency spectrum. The coupler is configured to couple to the light source and the pressure transducer to decode the signal variation into pressure parameters.

Abstract: A removable material is deposited or otherwise applied to a flat substrate surface in a pattern corresponding to desired corrugations in a membrane, e.g., a deflection diaphragm. The applied material serves as a scaffold for a polymeric material, which is applied thereover, and following cure or hardening, the polymeric material is removed to form a finished corrugated membrane.

Abstract: Some embodiments of an infusion pump system may include an occlusion sensor that can be used to detect when an occlusion exists in the fluid path between the medicine reservoir and the infusion site on the user's skin. Such an occlusion may occur, for example, when the fluid flow line (e.g., a cannula, infusion set tubing, or the like) is kinked. If the medicine dispensation path to the user is occluded, the user may receive no dosage or a lower dosage of the medicine. As such, the occlusion sensor can be used to indicate when the fluid is flowing or not flowing, thereby permitting the infusion pump system to communicate an alarm to the user if an occlusion exists.

Abstract: An optical sensor is disclosed for measuring pressure and/or temperature. The optical sensor is adapted for use in high temperature environments, such as gas turbines and other engines. The optical sensor comprises an optical assembly having a sensor element, a spacer and a lens arranged along the optical axis. The sensor element is spaced from the lens by the spacer. An optical fiber is coupled to the optical assembly for illuminating the sensor element. The optical assembly is resiliently mounted in a housing such that the optical assembly is insulated from shock to the housing. There is also disclosed a method of assembling the optical sensor.

Abstract: The present invention relates to a high stable fiber fabry-perot pressure sensor with glue-free packing and its fabrication method. The sensor includes a sensor head, a sensor body with a through-hole in the axial direction and a optical fiber. The sensor head is a 4-layer structure, which includes the first silicon wafer, the first Pyrex glass wafer, the second silicon wafer and the second Pyrex glass wafer. The rear surface of the first silicon wafer forms the first reflecting surface of the fabry-perot (F-P) cavity, and the second silicon wafer provides the second reflecting surface for the F-P cavity. The second Pyrex glass wafer is welded together with the sensor body. The optical fiber is fixed in the sensor body by a CO2 laser welding to achieve the glue-free packing. When the external pressure is applied to deform the first layer silicon wafer, the F-P cavity length will change.

Abstract: An apparatus and method for finding part position relations of parts of mechanical and opto-mechanical machining and quality control systems, and for recognizing these parts, is disclosed. The present invention relies on optical contactless sensing technology, with recording of optical fiducial patterns and therefrom determining positions close to the work positions without physical contact. Part positions of machines are determined by associating or mechanically integrating fiducial patterns (1) with key parts, and optically detecting the images of these patterns. Part positions and displacements according to given part position finder (6) strategies are found, by associating fiducial pattern images (14) and machine position data (17) to parts that are members of a part geometry relation (15), and under part displacement constraints (16), finding given part positions or displacements (18).

Abstract: A holographic pressure sensing apparatus includes a first optical fiber with a diffractive element at its end face, and a light-coupling component for receiving from the first optical fiber end face first and second images respectively formed by interaction with the diffractive element of a first light of a first wavelength and a second light of a second wavelength. Displacement of the light-coupling component, toward or away from the first optical fiber end face, will adjust an overlap of the first and second images, such that a change in a measurement of said overlap will indicate a change of the pressure in the fluid surrounding the casing.

Abstract: Ultra-miniature surface-mountable optical pressure sensor is constructed on an optical fiber. The sensor design utilizes an angled fiber tip which steers the optical axis of the optic fiber by 90°. The optical cavity is formed on the sidewall of the optic fiber. The optical cavity may be covered with a polymer-metal composite diaphragm to operate as a pressure transducer, Alternatively, a polymer-filled cavity may be constructed which does not need a reflective diaphragm. The sensor exhibits a sufficient linearity over the broad pressure range with a high sensitivity. The sensitivity of the sensor may he tuned by controlling the thickness of the diaphragm. Methods of batch production of uniform device-to-device optical pressure sensors of co-axial and cross-axial configurations are presented.

Abstract: Various embodiments include apparatus and methods to measure pressure using an optical fiber. The optical fiber can be structured with fiber Bragg gratings arranged along the optical fiber. Optical signals can be transmitted through the optical fiber, where the optical signals have a wavelength of a slow-light peak of a respective one of the fiber Bragg gratings. Signals resulting from the optical signals transmitted through the optical fiber can be detected and a value of pressure from the detected signals can be determined.

Abstract: An optical pressure sensor is disclosed having a pressure sensing optical cavity. A temperature sensing optical cavity at the sensor head is used by an interrogator to correct a pressure signal for effects of temperature. The optical cavities may be, for example, Fabry Perot cavities in the sensor head.

Abstract: A pressure sensing system includes a pressure sensor, an optical fiber in operable communication with the pressure sensor, and a body having a diaphragm integrally formed therein and separated a distance from the optical fiber.

Abstract: A valve apparatus includes substantially co-aligned first and second valve seats and substantially co-aligned first and second valve members. The first valve member is moveable relative to the first valve seat between at least an open position in which the first valve member is spaced from the first valve seat and a closed position in which the first valve member is seated against the first valve seat. The second valve member is moveable relative to the second valve seat between at least an open position in which the second valve member is spaced from the second valve seat and a closed position in which the second valve member is seated against the second valve seat. An armature is operable for moving the first and second valve members, in response to a magnetic field generated by a coil.

Abstract: The disclosed invention describes an unpowered apparatus which can wirelessly sense pressure based on microfluidics for point-of-care glaucoma diagnosis. Moreover, the disclosed invention teaches methods to construct the invention using microfabrication processing. Finally, a detailed and illustrative schematic of the wireless readout system is disclosed.

Abstract: A combination of sensors are strategically placed along a pipeline to measure critical properties such as temperature and pressure of the flow product. The sensors are a combination of fiber optic sensing devices that are specifically designed to measure a range of properties within particular bandwidth, with a method to reduce light attenuation over the long pipeline distances. The pipeline is typically subsea and can range widely in diameter. In many cases the pipeline has a coating that acts as a barrier to the corrosive sea water and additional thermal barriers.

Abstract: The present invention relates to a high stable fiber fabry-perot pressure sensor with glue-free packing and its fabrication method. The sensor includes a sensor head, a sensor body with a through-hole in the axial direction and a optical fiber. The sensor head is a 4-layer structure, which includes the first silicon wafer, the first Pyrex glass wafer, the second silicon wafer and the second Pyrex glass wafer. The rear surface of the first silicon wafer forms the first reflecting surface of the fabry-perot (F-P) cavity, and the second silicon wafer provides the second reflecting surface for the F-P cavity. The second Pyrex glass wafer is welded together with the sensor body. The optical fiber is fixed in the sensor body by a CO2 laser welding to achieve the glue-free packing When the external pressure is applied to deform the first layer silicon wafer, the F-P cavity length will change.

Abstract: An optical sensor is disclosed for measuring pressure and/or temperature. The optical sensor is adapted for use in high temperature environments, such as gas turbines and other engines. The optical sensor comprises an optical assembly having a sensor element, a spacer and a lens arranged along the optical axis. The sensor element is spaced from the lens by the spacer. An optical fibre is coupled to the optical assembly for illuminating the sensor element. The optical assembly is resiliently mounted in a housing such that the optical assembly is insulated from shock to the housing. There is also disclosed a method of assembling the optical sensor.

Abstract: There is described a miniature fiber optic pressure sensor design where sensitivity around specific biased pressure is optimized. In an embodiment, the pressure sensor is a Fabry-Perot (FP) sensor which comprises a substrate; and a diaphragm mounted on the substrate. The diaphragm has a center and comprises: a first layer comprising a first material; and a second layer comprising a second material. The second layer forms a dot or a ring. The dot or ring is mounted on the first layer and is centered about the center of the diaphragm. The second material comprises internal pre-stresses to cause the center of the diaphragm (in the case of a dot) or the peripheral area about the center of the diaphragm (in the case of a ring) to camber away from the substrate upon relaxing the internal pre-stresses.

Abstract: A fiber optical system for pressure measurement has a pressure sensor element (4) with at least two parallel partially reflecting surfaces (5, 7), one of which is arranged on a diaphragm (6) movable with respect to another fixed said surface as a consequence of pressure differences across said diaphragm. Said surfaces are arranged so as to cause interference phenomena of light inciding substantially perpendicularly onto and reflected by the two surfaces depending upon the actual 10 distance between these surfaces. The pressure sensor element is made of material being stable at a continuous temperature up to at least 800° C. At least said diaphragm (6) of the sensor element is made of Si C, and at least a part (23) of the optical fiber (3) connecting to said sensor element is made of a material able to withstand a continuous temperature of at least 800° C.

Abstract: A new type of optical pressure sensor with adjustable sensitivity is proposed based on the fiber Bragg grating (FBG). In this technique, the pressure changes the length of a metal bellows which is placed behind a spring. The fiber grating is fixed over the bellows between a fixed position and the connection point of bellows and spring. The wavelength change of FBG is caused by the change in the bellows length; however, the spring controls the total length expansion of the bellows. It will bring two benefits: first it is easy to change the pressure sensing range by changing the spring rate; and secondly the spring improves the linearity of the wavelength sift due to the pressure. The FBG is installed outside of the bellows and is not in contact with the material in which the pressure should be measured (gas or liquid) in contrast with other pressure sensors where the FBG is inside the bellows.

Abstract: A fiber Bragg grating (FBG) based sensor is used as a strain sensing element to determine frame foot loading of a generator. Three FBGs may be used in tandem to form a basic Frame Foot Loading Module (FFL Module). Two modules are fixed on each vertical support gusset at the corner of the generator frame, with one module on the front of the gusset and a second module on the back of the gusset. Thus, each gusset may be instrumented with six FBG strain gauges or sensors. The gussets are chosen on each of the four corners of the generator. For two-pole generators the first three gussets at each corner may be used and, for four-pole generators the first four gussets may be used.

Abstract: Method for optical pressure measurement of a gas in a closed container by directing a radiation of a radiator through the container and measuring the transmitted radiation by a detector, wherein the radiation of the radiator covers at least one first wavelength range in which there is an absorption of the radiation by the gas, the intensity of the transmitted radiation is detected in a second wavelength range by the detector, wherein the second wavelength range overlaps at least partially with the first wavelength range, and an accumulated intensity of the detected radiation in the second wavelength range is assigned to a pressure of the gas.

Abstract: Systems and methods that are capable of measuring pressure or temperature based on luminescence are discussed herein. These systems and methods are based on spin-allowed broadband luminescence of sensors with orthorhombic perovskite structures of rare earth aluminates doped with chromium or similar transition metals, such as chromium-doped gadolinium aluminate. Luminescence from these sensors can be measured to determine at least one of temperature or pressure, based on either the intense luminescence of these sensors, even at high temperatures, or low temperature techniques discussed herein.

Abstract: A method of obtaining submicron resolution IR absorption data from a sample surface. A probe microscope probe interacts with the sample surface while a tunable source of IR radiation illuminates the sample-tip interaction region. The source is modulated at a frequency substantially overlapping the resonant frequency of the probe and may be modulated at the contact resonance frequency of the probe when the probe is in contact with the sample surface. The modulation frequency is continually adjusted to account for shifts in the probe resonant frequency due to sample or other variations. A variety of techniques are used to observe such shifts and accomplish the adjustments in a rapid manner.

Abstract: A holographic pressure sensing apparatus includes a first optical fiber with a diffractive element at its end face, and a light-coupling component for receiving from the first optical fiber end face first and second images respectively formed by interaction with the diffractive element of a first light of a first wavelength and a second light of a second wavelength. Displacement of the light-coupling component, toward or away from the first optical fiber end face, will adjust an overlap of the first and second images, such that a change in a measurement of said overlap will indicate a change of the pressure in the fluid surrounding the casing.

Abstract: A sensor device for use in a medical fluid delivery system, or an infusion pump device, comprises a fluidic chamber with a deformable cover closing at least an area of the chamber and an optical detection system comprising at least one light emitter for emitting one or more incident light beams and a sensor unit for monitoring one or more reflected light beams is presented. In a pressurized state of the fluidic chamber, the deformable cover is deformed such that it forms an inflexion point area within the deformed cover. The one or more incident light beams emitted by the light emitter are directed on the cover such that the one or more incident light beams are reflected essentially in the inflexion point area.

Abstract: The present application provides a fiber optic sensor system. The fiber optic sensor system may include a small diameter bellows, a large diameter bellows, and a fiber optic pressure sensor attached to the small diameter bellows. Contraction of the large diameter bellows under an applied pressure may cause the small diameter bellows to expand such that the fiber optic pressure sensor may measure the applied pressure.

Abstract: A pressure sensor for use with a fluid delivery system having good sensitivity at low pressure, but also configured to remain in operating condition after being exposed to high pressures is disclosed herein. In one variation, the pressure sensor includes a fluid path set, a deformable element associated with the fluid path set and configured to deform in response to an external pressure, and a pressure transducer for monitoring deformation of the deformable element. In certain embodiments, the pressure sensor is configured to measure fluid pressure within the range of between about 0 mm Hg to about 300 mm Hg. However, the sensor pressure is also be configured to remain functional after being exposed to pressure in excess of about 60,000 mm Hg.

Abstract: Provided is a modified fluorescent protein which enables the detection of a power applied to a liquid where the fluorescent protein exists. A modified fluorescent protein, wherein a peptide linker is inserted into a position homologous to the position between the 144th and 145th amino acids in the amino acid sequence of a wild type fluorescent protein from jellyfish or a fluorescent protein derived from said wild type fluorescent protein, characterized in that the fluorescence properties of said modified fluorescent protein change depending on a change in a pressure that is applied to a liquid where said modified fluorescent protein exists.

Abstract: The present application provides a fiber optic sensor system. The fiber optic sensor system may include a small diameter bellows, a large diameter bellows, and a fiber optic pressure sensor attached to the small diameter bellows. Contraction of the large diameter bellows under an applied pressure may cause the small diameter bellows to expand such that the fiber optic pressure sensor may measure the applied pressure.

Abstract: One embodiment relates to a pressure sensor apparatus, including a housing with a flexible member and an aperture configured to receive a fluid. The pressure sensor apparatus further includes a first member disposed on the flexible member, a second member removeably coupled to the first member configured to move in response to a pressure of the fluid and a sensor configured to detect the movement of the second member.

Abstract: Disclosed herein is a carrier for an optical fiber having a plurality of optical sensors located thereon. The carrier has a test section comprising a cavity and at least one geometric discontinuity, wherein in response to a pressure applied to the test section, a stress concentration is formed proximate to the geometric discontinuity, and wherein the optical sensor is adhered to at least a part of the geometric discontinuity. The cavity may be filled with a liquid or a gel. A temperature optical sensor may also be provided adjacent to the pressure optical sensor.

Abstract: A temperature correcting pressure gauge which has a substrate having at least one surface coupled to a source of pressure to be measured, the substrate first surface having a first fiber Bragg grating from a first optical fiber attached in an appropriately sensitive region of the substrate, a fiber Bragg grating from a second optical fiber attached to the opposite surface from the first fiber Bragg grating, the first and second fiber Bragg gratings reflecting or transmitting optical energy of decreasing or increasing wavelength, respectively, in response to an applied pressure. The first and second fiber Bragg gratings have nominal operating wavelength ranges that are adjacent to each other but are exclusive ranges and the fiber Bragg gratings also have closely matched pressure coefficients and temperature coefficients.

Abstract: A container of an electrochemical double-layer capacitor for holding electrodes and electrolyte includes a housing having a cavity and a cap portion coupled to the housing forming a fluid-tight reservoir with the cavity. The container also includes a plurality of terminals incorporated into one or more of the housing or the cap portion, where the plurality of terminals adapted to be electrically coupled to the electrodes, and a pressure-compliant membrane incorporated into one of the housing or the cap portion. A pressure monitoring system that monitors the pressure inside the container includes a displacement measuring device adapted to measure a deflection of the pressure-compliant membrane.

Abstract: The disclosed invention describes an unpowered apparatus which can wirelessly sense pressure based on microfluidics for point-of-care glaucoma diagnosis. Moreover, the disclosed invention teaches methods to construct the invention using microfabrication processing. Finally, a detailed and illustrative schematic of the wireless readout system is disclosed.

Abstract: Processes of identifying small pressure irregularities in a system used for continuous plasma deposition are provided. Sensitive light scattering is used to detect the presence of nucleated particles in a detection area that is outside the plasma region of high electric field whereby the presence of the particles indicates a pressure abnormality in the plasma deposition chamber. The pressure of the plasma deposition chamber is then adjusted to reduce or eliminate the presence of particles within the detection area and to optimize deposition of material on a substrate.

Abstract: A statistical methodology is disclosed to provide time-to-event estimates for oilfield equipment. A method according to the present invention extracts unbiased information from equipment performance data and considers parameters interactions without recourse to data thinning. The analysis explicitly accounts for items of equipment that are still operational at the time of analysis. A method according to the present invention may also be utilized to apply survival analysis to any oilfield equipment components where time-to-event information has been recorded. The method of the present invention allows comparative reckoning between different components present in the system comprising several or many individual components and allows analysis of these components either individually or simultaneously, i.e., in the presence of other components.

Abstract: A pressure sensor is disclosed with at least one pressure sensing element, the pressure induced changes in the optical properties of which are evaluated by illumination with at least one light source. The pressure sensor can include at least two semiconductor-based pressure sensing elements located in individual pressure chambers, which sensing elements are located essentially adjacent to each other. The sensing elements can be irradiated with the same light source, wherein the light transmitted through the sensing elements is detected using at least two corresponding detectors, and wherein the differential pressure in the two pressure chambers is evaluated based on the output of these detectors.

Abstract: A fluid pressure monitoring apparatus for use in high temperature, harsh environment applications, is described. The apparatus comprises an elongated member, having a free end and a fixed end, and a blind bore extending through the elongated member the bore having an opening through which fluid is provided to the bore when in use. The bore is offset from a central axis of the elongated member such that the elongated member deflects in response to the pressure of the fluid when provided to the bore. The apparatus further comprises a sensing device adapted to sense the change in distance between a first position, and a second position, in response to the deflection of the elongated member.

Abstract: Method for optical pressure measurement of a gas in a closed container by directing a radiation of a radiator through the container and measuring the transmitted radiation by a detector, wherein the radiation of the radiator covers at least one first wavelength range in which there is an absorption of the radiation by the gas, the intensity of the transmitted radiation is detected in a second wavelength range by the detector, wherein the second wavelength range overlaps at least partially with the first wavelength range, and an accumulated intensity of the detected radiation in the second wavelength range is assigned to a pressure of the gas.

Abstract: The sensor includes a deformable diaphragm responsive to applied pressure and a rigid beam mounted to move as the diaphragm deforms. The rigid beam includes a mirrored surface for receiving light from and reflecting light into an optical fiber thereby forming a Fabry-Perot cavity to detect changes in the position of the rigid beam. The rigid beam further includes inter-digital fingers extending from the mirrored surface and moving with the rigid beam with respect to fixed inter-digital fingers to create a change in electrical charges in the fingers to detect changes in the position of the rigid beam thereby providing two measures of rigid beam displacement which are measures of pressure. In a preferred embodiment, the optical fiber is a single mode optical fiber.

Abstract: There is described a miniature fiber optic pressure sensor design where sensitivity around specific biased pressure is optimized. In an embodiment, the pressure sensor is a Fabry-Perot (FP) sensor which comprises a substrate; and a diaphragm mounted on the substrate. The diaphragm has a center and comprises: a first layer comprising a first material; and a second layer comprising a second material. The second layer forms a dot or a ring. The dot or ring is mounted on the first layer and is centered about the center of the diaphragm. The second material comprises internal pre-stresses to cause the center of the diaphragm (in the case of a dot) or the peripheral area about the center of the diaphragm (in the case of a ring) to camber away from the substrate upon relaxing the internal pre-stresses.

Abstract: Ultra-miniature surface-mountable optical pressure sensor is constructed on an optical fiber. The sensor design utilizes an angled fiber tip which steers the optical axis of the optic fiber by 90°. The optical cavity is formed on the sidewall of the optic fiber. The optical cavity may be covered with a polymer-metal composite diaphragm to operate as a pressure transducer. Alternatively, a polymer-filled cavity may be constructed which does not need a reflective diaphragm. The sensor exhibits a sufficient linearity over the broad pressure range with a high sensitivity. The sensitivity of the sensor may be tuned by controlling the thickness of the diaphragm. Methods of batch production of uniform device-to-device optical pressure sensors of co-axial and cross-axial configurations are presented.

Abstract: A technique for measuring pressure of a material directs one or more laser beams at the material (e.g., a pressurized fluid) to create a distribution of electromagnetic field intensity which varies over an intensity range and induces dielectric breakdown in the material. An emission pattern of broadband light from the dielectric breakdown is detected, and a value of a characteristic of the emission pattern (e.g., location of a threshold intensity or of a peak intensity) is processed (e.g., by a computer or similar electronic processor) to generate a pressure measurement signal representing a pressure of the material. Processing typically employs a pre-established calibration function which associates a set of stored values of the characteristic with corresponding known pressures of the material, obtained for example by preceding similar measurements of the same material under conditions of known pressures.

Abstract: An optical fiber sensing device for detecting physical parameters such as pressures, strains and temperatures comprises a probe housing therein an optical fiber. The distal end of the probe houses a distal portion of the optical fiber having a section provided with a fiber Bragg grating. The proximal end of the probe is mounted into a holder. The optical fiber is sealably mounted into the probe housing with a first seal overlaid the proximal portion of the optical fiber The seal may extend to about the proximal end of the optical fiber section with the Bragg grating. A second seal is overlaid the distal portion of the optical fiber and extends from the distal end of the probe to about the distal end of the optical fiber section with the Bragg grating. The proximal end of the probe is communicable with a fiber Bragg grating interrogation system.

Abstract: A pressure sensor assembly comprises a sensor housing having a flexible wall that is configured to deform in response to a pressure difference between the interior and exterior of the sensor housing; -a first fiber optical cable section that is bonded to the flexible wall of the sensor housing such that the length of the first fiber optical cable section changes in response to deformation of the wall in response to the said pressure difference; a second fiber optical cable section which is bonded to a thermal reference body, which body is connected to the sensor housing by a strain decoupled connection mechanism, such as a tack weld or flexible glue, and is configured to deform substantially solely in response to thermal deformation, such that the length of the second fiber optical cable section solely changes in response to thermal deformation of the thermal reference body.