Abstract: The optical pressure-sensing system essentially comprises a light source, a resonant cavity and a detector, where the light source is used for generating a light with a predetermined wavelength, the resonant cavity includes a stationary wall with a stationary plane and a movable wall with a movable plane, and the detector is used for detecting a resonated light generated in the resonant cavity by resonating the light between the stationary plane and the movable plane. According to the present invention, a first light is generated and resonated in a resonant cavity to amplify the interaction between the first light and gas molecules in the resonated cavity. The interaction is measured, and the pressure in the resonant cavity is calculated based on the interaction. The interaction between the light and gas molecules in the resonant cavity may change the polarization angle or the phase of the light.

Abstract: A pressure-sensitive sensor which is a load detecting device of the present invention is structured to include: an optical fiber of a predetermined length; a light-emitting element, disposed at a longitudinal direction one end side of the optical fiber, for emitting light and making the light incident from one end of the optical fiber; a light-receiving element, disposed at a longitudinal direction other end side of the optical fiber, for receiving light which has passed through the optical fiber and outputting a signal corresponding to an amount of received light; and a power source wire for light-emission and a ground wire for light-emission which are wound around an outer periphery of the optical fiber, and are formed in spiral forms along the outer periphery, and are connected to the light-emitting element.

Abstract: Disclosed herein is an optical sensor design and method for continually interrogating that sensor to produce an accurate representation of a dynamic event (such as a change in strain, pressure or temperature) being monitored by the sensor. The sensor design preferably constitutes continuous wave optical source/detection equipment coupled in series to a first fiber Bragg grating (FBG), a long period grating (LPG), and a second FBG formed in an optical waveguide. The LPG broadly attenuates light in the vicinity of the Bragg reflection wavelength &lgr;2B of the second FBG, and this attenuation profile shifts in wavelength in accordance with the dynamic event being monitored. Perturbation of the attenuation profile thus attenuates the intensity of the light reflected from the second FBG, i.e., I(&lgr;B2), because such reflected light must pass (twice) through the LPG. Accordingly, continually monitoring I(&lgr;B2) as a function of time allows the dynamic event to be recreated and processed accordingly.

Abstract: A compact force measurement system having high sensitivity and a wide dynamic range. A polymer transducer is capable of measuring static, dynamic and transient force changes in tension and compression using changes in optical properties at the molecular level of a pre-stressed polymer or birefringent crystalline material under a loaded condition. A force sensing linkage acts as a load sensor which measures both compression or tension type forces. The transducer is capable of directional force, pressure, and acceleration measurements and is extremely accurate for measuring small-force levels. Since the force transducer of the present invention is based upon optical techniques it is relatively immune to electronic noise and allows measurement of rapidly changing loads. The invention can be miniaturized to accommodate a wide variety of measurements requiring miniature force and/or pressure measurement devices.

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: The object of the invention is a measuring device for measuring small forces and displacements having in a body (1) of the device a detector means comprising a light source (4) and a position-sensitive detector (5), and a sensing means comprising a spring means (2) to be loaded by a force to be measured and a shading means (3) mounted to this spring means (2), which shading means moves under the influence of the force loading the spring means (2) in a light source (4) of the detector means, the beam being directed towards an active surface of the detector (5). It is characterizing for the invention that the detector means and the sensing means are arranged to a common clamp (8) arranged to the body (1) of the device.

Abstract: In a preferred embodiment, the invention provides a fiber optic pressure sensor apparatus which includes a light source, a reflective sensor diaphragm movable in accordance with pressure in a medium and an optical fiber coupled to the light source for delivering a first wavefront of light to the reflective sensor diaphragm. The optical fiber has an endface which is separated from the reflective sensor diaphragm by a gap, the endface receiving a second wavefront of light reflected from the reflective sensor diaphragm. The first and second wavefronts constructively and destructively interfere to create a modulated optical signal. A spectrometer is coupled to the optical fiber for converting the optical signal into a series of digital values, and means for analyzing the digital values is provided for obtaining a measurement of the pressure in the medium. An optical coupler is preferably provided for coupling the light source, the optical fiber, and the spectrometer.

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 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 ink management system for an offset printing press includes a cartridge of offset printing press ink, wherein the cartridge has an exit opening in one end through which ink is dispensed and an open end opposite said exit opening. A movable member is disposed within said ink cartridge for dispensing ink from said ink cartridge. Movement of the movable member dispenses ink into an ink fountain through the exit opening. The displacement of the movable member is determined in order to track an amount of ink dispensed during, for example, a printing run.

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: 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: The object of the invention is a device for measuring the surface pressure of a film formed at the interface of a liquid and gaseous phase, the device comprising a detector means and a sensor means. The detector means comprises a light source and a position-sensitive detector, the active surface of which is situated in the light beam of the light source, and the sensor means comprises a sensor which can be brought into contact with the film to be measured, and a shading means which, in correspondence with the force applied to the sensor by the film, moves in the light beam between the active surface of the detector and the light source.