Abstract: The invention relates to optical devices for measuring pressure or force, comprising an clectromagnetic radiation source, and a pressure membrane or a spiral spring which has a surface that at least partially reflects the electromagnetic rays of the electromagnetic radiation source. The inventive devices are especially characterized in that they allow, inter alia, measurement of even the slightest pressure changes of fluids and other flowable materials in the stationary and/or flowing state or even the slightest mechanical deformations on spiral springs. In order to do this, the rays of an electromagnetic radiation source are incident on the at least partially reflective surface of the pressure membrane or spiral spring. At least one section of a stationarily located body or of a stationarily located body having a reflective layer is disposed in the path of the reflected rays, upstream of a photodetector for said rays, and projects into said rays.

Abstract: A system for monitoring deformations of a tire fitted on a rim associated with a vehicle includes a reflecting element positioned on an inner surface of the tire and a moving station located in a predetermined position on the rim. The reflecting element reflects an optical beam and includes a region having at least one area of high light reflection and at least one area of low light reflection. The moving station sends the optical beam toward the inner surface, receives one or more reflections of the optical beam from the inner surface or the reflecting element, and emits a signal proportional to the deformations of the tire in a longitudinal direction, in a transverse direction, and in a vertical direction.

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.

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: The invention relates to a DFB fiber laser sensor (1). A measurement quantity makes it possible to induce a linear birefringence between mode pairs of the laser-amplifying fiber (2) and to measure an associated beat frequency (&Dgr;&ngr;1, &Dgr;&ngr;2, &Dgr;&ngr;3). According to the invention, the laser-amplifying fiber (2) has a nonrotationally symmetrical structure, so that it is possible to detect isotropic pressures p, acoustic waves or chemical substances that can be added radially to the laser-amplifying fiber (2). In a second aspect of the invention, an emission wavelength range and parameters (a, b, &Dgr;N) of the laser-amplifying fiber (2) and also a grating period L of the fiber Bragg grating resonator (3) are coordinated with one another such that at least two different spatial modes (LP01, LP11even, LP11odd, LP21even) are propagatable and it is possible to measure beat frequencies (&Dgr;&ngr;1, &Dgr;&ngr;2, &Dgr;&ngr;3) between oscillatory longitudinal laser modes assigned to them.

Abstract: A pressure sensor is mounted integrally in a hydraulic valve body. The sensor has a base which extends into a bore formed in the valve body. The valve body bore is in communication with a pressurized hydraulic fluid. A first circumferential groove formed in the sensor base carries an O-ring which forms a seal between the sensor and the wall of the valve body bore. A second circumferential groove formed in the sensor base carries a spring ring which extends into a corresponding groove formed in the wall of the valve body groove. The spring ring cooperates with the sensor base and valve body bore grooves to retain the sensor in the valve body bore.

Abstract: A monitoring system with a power supply built therein, which is capable of setting installation expenses at low cost and obtaining a stable result of monitoring for a predetermined period. The monitoring system comprises a sensor unit having sensors and a power supply incorporated therein, and a portable data logger having a communication module and a power supply built therein. Physical quantities such as vibrations, temperatures, and pressure, of an object to be monitored are detected by the sensors, followed by transmission to the portable data logger, whereby the state of operation of the object is displayed.

Abstract: For measurement of a liquid level, an optical fiber connected at its one end portion to force receiving means movably arranged in liquid to receive force from the liquid is dipped in the liquid together with the force receiving means, and a change in the force acting on said force receiving means when the liquid level changes is detected as a change in strain in the optical fiber by means of an optical fiber strain gauge connected to the other end of the optical fiber, thus measuring a water level of the liquid.

Abstract: A fluid diffusion resistant tube-encased fiber grating pressure sensor includes an optical fiber 10 having a Bragg grating 12 impressed therein which is encased within a sensing element, such as a glass capillary shell 20. A fluid blocking coating 30 is disposed on the outside surface of the capillary shell to prevent the diffusion of fluids, such as water molecules from diffusing into the shell. The fluid diffusion resistant fiber optic sensor reduces errors caused by the diffusion of water into the shell when the sensor is exposed to harsh conditions.

Abstract: A fiber Bragg grating based sensor is disclosed. The sensor comprises an optical waveguide having a core and a cladding. The core comprises a pressure sensor such as a fiber Bragg grating. In one embodiment, a support is affixed around the cladding which has two first portions each having a first diameter. The pressure sensor is located at a second portion of the support positioned between the two first portions which has a second smaller diameter, thus giving the sensor a “dog bone” shape. In another embodiment, the dog bone shape is imparted by positioning the pressure sensor at a portion of a waveguide having a reduced cladding diameter.

Abstract: An apparatus for measuring pressure in a medium includes a laser for emitting linearly polarized light; a polarizing beam splitter that reflects the linearly polarized light from the laser; a first lens that receives and focuses the linearly polarized light from the polarizing beam splitter; an optical fiber having first and second ends, the first end for receiving the linearly polarized light from the first lens, the second end comprising a tip disposed in the medium, the tip receiving reflected light from the medium, the reflected light being transmitted back through the optical fiber and the first lens to the polarizing beam splitter; the polarizing beam splitter transmitting the reflected light that has polarization orthogonal to the linearly polarized light emitted by the laser but not transmitting the reflected light that has polarization substantially parallel to the linearly polarized light emitted by the laser; a second lens for receiving the reflected light that has polarization orthogonal to the li

Abstract: A planar pressure transducer is disclosed which is useful for interposing between living tissue and a medical device that applies pressure to the tissue in order to estimate the pressure applied to a selected area of the tissue. The planar pressure transducer comprises a pair of opposed plates between which the proximal ends of optical fibers and a deformable polymer structure are disposed. When the plates are subjected to a pressure acting normally to the plane of the plates an optical signal is obtained via the distal ends of the fibers and related to the pressure acting on the plates.

Abstract: A fluid diffusion resistant tube-encased fiber grating pressure sensor includes an optical fiber 10 having a Bragg grating 12 impressed therein which is encased within a sensing element, such as a glass capillary shell 20. A fluid blocking coating 30 is disposed on the outside surface of the capillary shell to prevent the diffusion of fluids, such as water molecules from diffusing into the shell. The fluid diffusion resistant fiber optic sensor reduces errors caused by the diffusion of water into the shell when the sensor is exposed to harsh conditions.

Abstract: A pressure gauge device for a toy water gun having a pressure chamber, includes a housing, a light source mounted to the housing, a coloured transparency mounted movably to the housing, a pneumatic actuator communicating with the chamber and moving the transparency, and a display receiving light from the light source that has passed through the transparency.

Abstract: A pressure sensor configured to sense an applied pressure, comprising a diaphragm support structure, a diaphragm coupled to the diaphragm support structure and configured to deflect in response to applied pressure, a moveable member coupled to the diaphragm and configured to move in response to deflection of the diaphragm, and an optical interference element coupled to the moveable member and configured to interfere with incident light, wherein the interference is a function of position of the moveable member.

Abstract: The fiber optic pressure sensing system includes a sensor housing formed using MEMS processing. The sensor housing has ribs and grooves in both horizontal and vertical directions relative to the surface to allow the membrane to flex in a consistent manner. The flexing of the membrane allows the pedestal to be repeatedly positioned in response to pressure acting on the extension of the sensor head and membrane.

Abstract: An Improved Bellow-Type Pressure Sensing Apparatus is disclosed. Also disclosed is, an apparatus that provides increased pressure sensitivity without added cost and complexity in the electronic detector circuitry. The apparatus further is less sensitive to gravity, vibrations or other external influences. It is a still further object that the apparatus be available with curved bellow head, formed with either concave or convex reflective surfaces.

Abstract: A sensor for detecting localized pressure bearing on the sensor, comprises a volume of compressible, light translucent material having light-scattering centers evenly dispersed throughout the material. A light emitter communicates with the material to form a virtual optical cavity within the material; the intensity of scattered light is detected by a detector. A second detector is positioned at some distance removed from the first detector, outside the virtual optical cavity. Pressure bearing on the material increases the intensity of scattered light within the optical cavity. The decreased intensity is measured by the second detector. A signal processor receives signals from the first and second detectors, and resolves these signals into information indicative of pressure bearing on the sensor.

Abstract: A method for measuring a pressure between a pair of pressing surfaces in point or linear contact with each other by utilizing a pressure measuring film which causes a pressurized portion thereof to develop a color in proportion with the pressure applied. An elastic sheet is disposed between the pressing surface having the point/linear contact portion and the pressure measuring film so as to decrease the pressure transmitted and applied to the pressure measuring film. The pressure distribution obtained from the colored image formed on the pressure measuring film is used to determine the actual maximum pressure applied between the pressing surfaces. It is possible to measure the large pressure which falls in or exceeds the measurable pressure range of the pressure measuring film.

Abstract: An optical pressure monitoring system includes a tube from an infusion set and an optical signal sensor disposed to detect changes in the diameter of the tube and thereby determine pressure changes within the tube. By selecting the position of the tube relative to the optical signal emitter and optical signal receiver, the optical signal sensor can both detect pressure changes and provide an integrity check for both the functioning of the optical signal sensor and the placement of the tube. By modifying the tube to exaggerate changes in tube diameter responsive to pressure changes, the sensitivity of the optical signal sensor can be increased.

Abstract: Several associated techniques and fiber optic constructions are disclosed to protect a diaphragm type fiber optic cylinder pressure sensor from the effects of maximum under hood temperatures and to minimize errors associated with rapidly changing under hood and engine temperatures. The techniques include electronic compensation in response to temperature change, fuel system cooling of the optoelectronic interface, construction of the interface and construction of the sensor tip.

Abstract: A pressure gauge includes a Bourdon tube coupled to a pinion of a spindle with a link and a sector gear, and to rotate the spindle in correspondence with a pressure in the Bourdon tube. The rotational movement of the spindle or the deformation of the Bourdon tube may be converted into a digital output and shown in a displayer. A disc is secured to the spindle and has a number of openings formed in the peripheral portion. A photo detecting device may be used for detecting a light emitted through the openings of the disc and for detecting the rotational movement of the disc.

Abstract: An optical pressure monitoring system includes a tube from an infusion set and an optical signal sensor disposed to detect changes in the diameter of the tube and thereby determine pressure changes within the tube. By selecting the position of the tube relative to the optical signal emitter and optical signal receiver, the optical signal sensor can both detect pressure changes and provide an integrity check for both the functioning of the optical signal sensor and the placement of the tube. By modifying the tube to exaggerate changes in tube diameter responsive to pressure changes, the sensitivity of the optical signal sensor can be increased.

Abstract: An apparatus for non-intrusively sensing fluid flow within a pipe is provided. The apparatus includes an array of sensors that include a plurality of optical fiber coils. The array of sensors senses the fluid flow inside the pipe. At least one optical reflective device is disposed between adjacent optical fiber coils. An isolation pad is disposed between each optical reflective device and the pipe.

Abstract: A fiber grating pressure sensor 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.

Abstract: A fused tension-based fiber grating pressure sensor includes an optical fiber having a Bragg grating impressed therein. The fiber is fused to tubes on opposite sides of the grating and an outer tube is fused to the tubes to form a chamber. The tubes and fiber may be made of glass. Light is incident on the grating and light is reflected from the grating at a reflection wavelength &lgr;1. The grating is initially placed in tension as the pressure P increases, the tension on the grating reduced and the reflection wavelength shifts accordingly. A temperature grating may be used to measure temperature and allow for a temperature-corrected pressure measurement.

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.

Abstract: A fiber Bragg grating reference module provides a precise temperature reference for a temperature probe, including a thermistor, located in close proximity thereto, and includes an optical fiber having a fiber Bragg grating therein, a glass element and a reference housing. The fiber Bragg grating has two ends and with a coefficient of thermal expansion. The glass element anchors the two ends of the fiber Bragg grating, and has a substantially similar coefficient of thermal expansion as the coefficient of thermal expansion of the fiber Bragg grating to ensure that the glass element does not substantially induce strain on the fiber Bragg grating as the ambient temperature changes. The reference housing has a cavity and also has a means for receiving and affixing one end of the fiber Bragg grating and for suspending the fiber Bragg grating in the cavity leaving the other end of the fiber Bragg grating free to move as the ambient temperature changes without inducing strain in the fiber Bragg grating.

Abstract: Non-intrusive pressure sensors 14-18 for measuring unsteady pressures within a pipe 12 include an optical fiber 10 wrapped in coils 20-24 around the circumference of the pipe 12. The length or change in length of the coils 20-24 is indicative of the unsteady pressure in the pipe. Bragg gratings 310-324 impressed in the fiber 10 may be used having reflection wavelengths &lgr; that relate to the unsteady pressure in the pipe. One or more of sensors 14-18 may be axially distributed along the fiber 10 using wavelength division multiplexing and/or time division multiplexing.

Abstract: A pressure sensor assembly for determining the pressure of a fluid in a harsh environment includes a pressure sensor suspended within a fluid filled housing. The assembly includes a pressure transmitting device which transmits the pressure of the fluid to sensor and maintains the fluid within the housing in a void free condition. The pressure sensor assembly maintains the sensor in a near zero base strain condition and further protects the sensor from shock and vibration. The pressure sensor assembly further includes bumpers that limit the movement of the sensor within the housing.

Abstract: A fiber grating pressure sensor 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.

Abstract: An improved optical pressure sensor determines the pressure of the fluid to be monitored by the deflection of a diaphragm in the pressure chamber of the sensor which has an inlet from the measured vessel. The deflection of the diaphragm is determined by monitoring the interference of diode light reflected from the diaphragm and a silicon grating structure superimposed over the diaphragm, at critical positions. Intensity detectors are placed at critical positions such as the specific orders of the diffraction grating to measure the interference intensity of the reflected light. The interferometric accuracy with which the pressure measurement is made with the present invention far exceeds that obtained with optical pressure sensors described in the prior art.

Abstract: An optical fiber pressure sensor having a base layer 20 with an optical fiber hole, a fiber stop layer 28 and, optionally, an etch stop layer 24. The fiber stop layer optionally has a fiber stop hole 33 that is smaller than the optical fiber 22. A diaphragm cap layer 32 is bonded to the fiber stop layer 28. The diaphragm cap layer 32 has a diaphragm 34 spaced apart from the optical fiber. The optical fiber and diaphragm form an Etalon that changes cavity length with applied pressure. Optionally, the device is made almost entirely of silicon, and so has reduced mechanical stress problems caused by thermal expansion mismatches. This allows the present sensor to be used in high temperature environments such as internal combustion engines.

Abstract: A differential pressure detecting system having a compliant first chamber, which is contained within a second environment, in combination with a sensor system for monitoring change in volume/shape of the compliant first chamber. In use the internal volume of the compliant first chamber is caused to access a first environment, so that pressure differences between the first and second environments can be detected via monitoring of change in volume/shape of the compliant first chamber. The compliant first chamber expands when the pressure therein is greater than that in the second environment, but does not expand, or decreases if already expanded, when the pressure in the second environment is equal to or greater than that inside the compliant first chamber. The detector system can be of any functional type that does not significantly affect the compliant first chamber volume/shape by its interrogation thereof in developing a signal.

Abstract: A device (100) for measurement of pressure in fluids is disclosed that includes a cylindrical housing (101) having a pressure port (103), an inner cavity (102) and an opening (102b). A closed pipe (131) is situated in the cavity (102) and closes the opening (102b) in the housing (101) and establishes a cavity (134) between the pipe (131) and the inner wall of the housing (101). A connection element (133) is situated in the pipe (131), so that one end of the element (133) is connected to the free end of the pipe (131) for transfer of axial length change of the pipe (131), whereas the connected element (133) is arranged for establishing a cavity (132) between the connection element (133) and the pipe (131). An optical fiber (171) is laid in a slot (171) in the external surface of the housing (101), and includes a Bragg grating (150) fixed between the housing (101) and the connection organ (133) by fastening points (151, 152).

Abstract: A method and apparatus for precise measurement of pressure dependence of head fly height using transitional thermal signals is disclosed. A slider is positioned relative to a rotating a disk having at least one laser bump. Calibration data is gathered by decreasing the pressure and measuring the fly height until a contact positive TA signal is detected. A non-contact negative TA signal is then normalized using the gathered calibration data. The TA signal amplitude may then be used to ascertain the fly height and pressure for a head.

Abstract: A quartz sensing system includes a quartz sensor, an electromechanical converter, an optical source, an optical fiber and a signal processor. The quartz sensor responds to a pressure, and further responds to an electrical power signal, for providing a quartz sensor electrical signal containing information about the pressure. The electromechanical converter responds to the quartz sensor signal, for providing an electromechanical converter force containing information about the sensed voltage or current signal. The optical source for provides an optical source signal. The optical fiber responds to the electromechanical converter force, for changing an optical parameter or characteristic of the optical source signal depending on the change in length of the optical fiber and providing an electromechanical converter optical signal containing information about the electromechanical converter force.

Abstract: A sensor for detecting localized pressure bearing on the sensor, comprises a volume of compressible, light translucent material having light-scattering centers evenly dispersed throughout the material. A light emitter communicates with the material to form a virtual optical cavity within the material; the intensity of scattered light is detected by a detector. A second detector is positioned at some remove from the first detector, outside the virtual optical cavity. Pressure bearing on the material increases the intensity of scattered light within the optical cavity. The decreased intensity is measured by the second detector. A signal processor receives signals from the first and second detectors, and resolves these signals into information indicative of pressure bearing on the sensor.

Abstract: An optical pressure sensor assembly integrated with a spark plug (16) and spark plug boot (12). The pressure sensor comprises an optical fiber (34) with a pressure diaphragm (36) at the tip to sense pressure and pressure changes within the combustion chamber (32) of a spark ignition engine. A channel (30) is provided in the spark plug to hold the sensor. The diaphragm (36) of the sensor is located closer to the spark electrode than to the electric conductor which is encased by the boot (12). The optical fiber (34) is contained within a shaft that is routed through the boot (12) and into the channel (30). The optical fiber (34) is operatively and electrically connected to the vehicle's engine controller. The opto-electric connection to the vehicle's engine controller is made adjacent a coil (72) in the boot (12) or removed from the coil (72). The fiber (34) is surrounded by a nonmetallic shaft (22) outside the engine. Inside the spark plug (16), the shaft is metallic.

Abstract: A pressure measuring device which utilizes an array of optical, non-acoustic pressure sensors with a laser light source which generates a pulsed light signal into a light transmitting cable, wherein the pulsed light signal propagates along the light transmitting cable through the array of optical pressure sensors. A plurality of optical couplers are attached to the light transmitting cable at multiple locations spaced apart from one another in order to branch off at least a portion of the pulsed light each location. Each of the plurality of optical couplers includes a respective optical pressure sensor and a pressure insensitive reflector, wherein the branched off portion of the pulsed light signal is transmitted into to both the optical pressure sensor and the reflector. Each optical pressure sensor reflects a pressure indicating signal back into the optical coupler, while the pressure insensitive reflector reflects a reference signal back into the optical coupler.

Abstract: The present noninvasive load and pressure sensing system makes use of a transparent pressure vessel that is filled with a compressible fluid, whose refractive index changes as a function of the pressure applied to the compressible fluid to redirect the path of a light beam that is transmitted through the transparent pressure vessel. An incident beam of coherent monochromatic light is applied to a transparent segment of a wall of the transparent pressure vessel, where this incident light beam is refracted by the compressible fluid contained in the transparent pressure vessel. The refracted light beam traverses the transparent pressure vessel and exits the transparent pressure vessel at a point along the opposite wall of the transparent pressure vessel as determined by the refractive index of the compressible fluid, which is determined by the pressure of the compressible fluid.

Abstract: A pressure sensor capable of measuring pressure in a harsh environment includes at least one intrinsic fiber optic sensor element formed within a core of an optical fiber. A length of the optical fiber containing the sensor element is attached to a pressure sensitive structure. A dimension of the pressure sensitive structure changes in response to changes in the pressure of a pressure field of the environment. The sensor element is responsive to all input signal and to a strain caused by changes in the dimension of the pressure sensitive structure for providing a pressure signal indicative of the pressure. A temperature compensation sensor is also formed in the fiber near the location of the pressure sensor. The temperature sensor is isolated from strain associated with the pressure for providing temperature compensation of the pressure sensor.

Abstract: A sensor for detecting environmental media and pressure comprises two types of optical fibers. An intrinsic fiber containing a portion of the fiber with the jacket removed is sensitive to its surroundings as some light traveling through the fiber will escape. The change in light intensity is received by a light detector, and this information is interpreted to correspond to a certain media, a change in media, or a phase change in media. An extrinsic fiber with a membrane and mirror located at one end is placed vertically in the media. Pressure from the media changes the position of the membrane and the mirror, resulting in a change in the intensity of the light reflected back through the fiber to the light detector. The pressure can then be used to determine the volume of the media in the container. Pressure determination can be continuous. In addition, both types of sensors can be networked, allowing information from one sensor to influence the gathering of information from the other.

Abstract: A fiber optic pressure catheter includes a light source, an optical fiber coupled to receive light from the light source and a sensor head that is optically coupled to the optical fiber. The sensor head has a housing defining a chamber coupled to an end of the optical fiber opposite the light source. The housing has an opening which is enclosed by a membrane. The membrane is responsive to pressure differentials between the chamber and outside the sensor head. A resilient ribbon is coupled within the chamber and has a first end fixedly coupled to a support. The ribbon has a second end that is movable in front of the optical fiber. The ribbon is mounted so that the middle portion of the ribbon touches the membrane and is biased by the membrane in response to various pressure differentials. Thus, various amounts of light are reflected back into the optical fiber based on the amount of pressure at the membrane.

Abstract: An improved fluid pressure sensor/sensor array is shown to provide high resolution, sensitivity which can be easily controlled based on anticipated or detected pressure range, and reliable pressure measurements with easy installation and low fabrication cost. A fluid pressure sensor is provided having a substantially incompressible mounting structure with a cavity formed therein. An elastic membrane is attached to said mounting structure and across said cavity, separating the cavity from the fluid to be measured. At least one non-contact transducer is attached to the mounting structure in the cavity to detect deflection at a selected plurality of regions on the membrane. The sensitivity and pressure range of the sensor can be chosen by preselecting the elasticity of the membrane, stretching the membrane across the cavity under a preselected tension, maintaining a predetermined reference pressure in the cavity, and/or actively controlling the membrane tension.

Abstract: In a tactile opto-electronic pressure sensor having a body with a rigid matrix including axially extending bores in which hollow cylinders of an elastic material are firmly disposed such that the front ends of the hollow cylinder project from one side of the matrix while the opposite ends of the hollow cylinders are flush with the other side of the matrix, a light emitting electro-luminescent foil is disposed on the front faces of the hollow cylinders such that light emitted therefrom shines through the hollow cylinders and is recorded by an evaluation device arranged at the other side of said matrix, the hollow cylinders being axially compressible such that their openings become smaller with increasing forces acting thereon, the light intensity received by the evaluation units depending on the forces applied to the hollow cylinders.

Abstract: An incident ray is emitted into a vacuum probe manufactured by a transparent material inside a cavity and is totally reflected according to the invention. Based on Fresnel's equation, when an angle of incidence is fixed, the phase difference between a s-polarized light and p-polarized light is a function of two refractive indexes on the both sides of an interface. Therefore, when the refractive index of gas inside the cavity varies with pressure therein, the phase difference between the s-polarized light and p-polarized light can be measured by a total-internal-reflection heterodyne interfermetry. Next, the refractive index of the vacuum cavity can be estimated based on the variation of the phase difference. Then, the pressure inside the cavity is obtained from the measured refractive index of the vacuum cavity cooperating a known pressure contrast list, so that vacuum degree inside the cavity is known.

Abstract: A Bourdon tube pressure gauge is mounted for sensing the pressure of a system. The Bourdon tube is connected to at least one optical strain sensor mounted to be strained by movement of the Bourdon tube such that when the Bourdon tube is exposed to the pressure of the system, movement of the tube in response to system pressure causes a strain in the optical sensor. The optical sensor is responsive to the strain and to an input optical signal for providing a strain optical signal which is directly proportional to the pressure. A reference or temperature compensation optical sensor is isolated from the strain associated with the pressure of the system and is responsive to temperature of the system for causing a temperature-induced strain. The reference optical sensor is responsive to the temperature induced strain and the input optical signal for providing a temperature optical signal which is directly proportional to the temperature of the system.

Abstract: The present invention provides a new synchronized optical method for measuring surface pressure on rotating objects such as propellers or other rotating objects. The technique is based on the phenomenon of oxygen quenching of luminescence coatings and synchronized optical imaging. A surface coating, referred to as a pressure sensitive paint (PSP), is formed by mixing photo-luminescence molecules in an oxygen permeable polymer. The luminescence excited by an appropriate light source decreases as the oxygen concentration rises due to quenching. As a result, the luminescence intensity of light emitted from the coating varies as a function of the partial pressure of oxygen. A digital camera measures the luminescence intensity distribution over the object and the pressure distribution can be computed.

Abstract: A pressure measuring instrument that utilizes the change of the refractive index of a gas as a function of pressure and the coherent nature of a laser light to determine the barometric pressure within an environment. As the gas pressure in a closed environment varies, the index of refraction of the gas changes. The amount of change is a function of the gas pressure. By illuminating the gas with a laser light source, causing the wavelength of the light to change, pressure can be quantified by measuring the shift in fringes (alternating light and dark bands produced when coherent light is mixed) in an interferometer.