An example method injects a source light into a sensor cavity body, configured with an optical path including first and second reflecting surfaces, and structured to change the optical path distance between the first and second surface in response to subject condition. Sensor reflection optical signals are received from the senor cavity body, with first reflection signals from the first reflecting surface and se second reflection signals from the second reflecting surface and routed to an interferometer with a first optical path to a first reflector and a second optical path to a second reflector. Interferometer reflector signals, including reflections of the sensor reflection signals from the first reflector and the second reflector are received and phase shift coupled into separate channel signals, including first channel signals, second channel signals, and third channel signals, mutually spaced with respect to phase. A computerized dynamic obtains dynamic measurement of the subject condition, through detecting changes in the optical path distance based on the first, second, and third channel signals.

A method and apparatus for measuring a pressure. A pressure gauge includes a first plate having a resonant frequency related to a pressure at the pressure gauge. The first plate is thermally-excited at a selected frequency, and a sensor measures a first power level of a first light having a first wavelength reflected from the first plate and a second power level of a second light having a second wavelength reflected from the first plate. A processor determines a thermal drift in the resonant frequency of the first plate due to the thermal excitation of the first plate from the first power level and the second power level, corrects a pressure measurement determined from the resonant frequency of the first plate for the thermal drift of the resonant frequency, and operates a device based on the pressure measurement.

A sensor apparatus and system for measuring pressure, temperature or both with a single interrogator includes a sensor having a cavity, a diaphragm and an optical element or base for conducting energy to and from the cavity and diaphragm. The two surfaces of the diaphragm and a surface of optical element and either surface of the diaphragm are partially reflecting surfaces and respectively define two optical path distances (OPDs) that produce preferential reflections and interference patterns at different optical frequencies or wavelengths that are respectively affected by pressure or temperature. Arranging the OPDs such that the fundamental frequency and harmonics of preferential reflections one OPD do not coincide with the fundamental frequency or harmonics of another OPD provides for both temperature and pressure measurement with a single interrogator and without complex spectral analysis.

An example system includes a fuel tank, fittings mounted through a wall of the fuel tank, and optical sensors positioned within the fittings. A respective optical sensor includes a first pressure sensing end inserted through a fitting and internally into the fuel tank and a second end extending externally from the fuel tank. The system also includes an optical fiber bundle mounted external to the fuel tank, and having an optical fiber connected to each of the plurality of optical sensors for guiding light to each of the plurality of optical sensors.

Methods, apparatus, and systems are provided for sensing pressure. One example apparatus includes a housing having a first port, a chamber disposed in the housing and having a second port, wherein the second port is coupled to the first port such that a volume inside the chamber is in fluid communication with an environment external to the housing, and a pressure sensor assembly at least partially disposed in the chamber and configured to sense a pressure of a fluid in the chamber. The chamber may be mechanically coupled to the housing via a portion of an exterior surface of the chamber such that a pressure response of the pressure sensor assembly is independent of extraneous loading on the housing.

An optoelectronic system for measuring physical parameters comprising: two narrow band light sources with different peak frequencies coupled together into a combined light using a coupler. The combined light is split into a first Fabry-P?rot interferometer arranged to be exposed to both temperature and physical parameter of interest and a second Fabry-P?rot interferometer arranged to be exposed only to temperature. The system further comprises first and second optical detectors arranged to receive light reflected from the cavities of the first and second Fabry-P?rot interferometers respectively through an optical path comprising a combination of lenses and/or mirrors and a Fizeau interferometer. A processor is arranged to analyze the data received by the first optical detector and second optical detector and calculate a value for temperature and the physical parameter of interest.

A miniature diaphragm-based fiber-optic tip FP pressure sensor, and fabrication method and application thereof. A miniature diaphragm-based fiber-optic tip FP pressure sensor includes an optical fiber, a hollow-core optical fiber, and a pressure sensing diaphragm, wherein the optical fiber and the hollow-core optical fiber have the same diameter, the two are spliced by arc welding; and the pressure sensing diaphragm is bonded to the endface of the hollow-core optical fiber by hydroxide catalysis bonding. The FP pressure sensor can not only realize the all-silica structure of a sensor, but also make the joint of each component free of organic polymer, and has extremely high long-term stability and thermal stability. Meanwhile, by a fabrication method of the miniature diaphragm-based fiber-optic tip FP pressure sensor, the application range and service life of the sensor are increased, and fabrication costs are reduced.

A sensor is provided for measuring a flow of a fluid in a physiological environment, such as within a vessel of a human or animal subject. The sensor comprises an interrogation light guide extending from a proximal end to a distal end of the sensor. The interrogation light guide is configured to transmit interrogation light to, and receive reflected interrogation light from, the distal end of the sensor. The sensor further comprises an excitation light guide configured to transmit excitation light to the distal end of the sensor. The excitation light is provided for heating the fluid (directly or indirectly). The sensor further comprises a sensing element located at the distal end of the sensor. The sensing element comprises at least two etalons for reflecting interrogation light back along the interrogation light guide towards the proximal end of the sensor. Each etalon has a respective optical path length and further has at least one reflective surface external to the interrogation light guide. The sensing element is configured to be in thermal contact with the fluid such that the optical path length of at least one etalon is dependent on a temperature of the fluid. The reflected interrogation light forms an interferogram which is dependent on the optical path lengths of the respective etalons.

A sensor network having a series arrangement of fiber-coupled, reflective sensors is disclosed. In operation, a first light signal having multiple wavelength bands is launched in an upstream direction on a fiber bus. Each sensor includes a wavelength filter and an FP sensor that is sensitive to a parameter. Each wavelength filter (1) selectively passes a different one of the wavelength bands to its FP sensor and (2) reflects the remaining wavelength bands back into the fiber bus to continue upstream. The FP sensor imprints a signal based on the parameter onto its received light and reflects it as a second light signal. The collimator, wavelength filter, and FP sensor of each sensor are arranged such that each second light signal is returned to the fiber bus, which conveys them in a downstream direction to a processor that measures them and estimates the parameter at each sensor.

An optical pressure sensor and a manufacturing method of an optical pressure sensor. The optical pressure sensor includes first and second members, and an optical transmission medium. The first member has a lateral wall portion extending from a first plate-shaped portion of the first member, and joined to a second plate-shaped portion of the second member. An airtight space is defined by the plate-shaped portions and the lateral wall portion. The optical transmission medium is attached to one of the plate-shaped portions on a side opposite to the airtight space side. A first reflective film is formed on the first plate-shaped portion facing the airtight space. The second plate-shaped portion on the first member side includes a first region facing the airtight space, and a second region facing the distal end surface of the lateral wall portion. A second reflective film is formed on the entire first region.