A fire or overheat detection device includes a diaphragm adjacent to a chamber with a gas inside the chamber, wherein the diaphragm contacts the gas. The fire or overheat detection system also includes a Fabry-Perot interferometer. At least a portion of the Fabry-Perot interferometer is coupled to the diaphragm via a linkage. A light source is configured to direct an input light into the Fabry-Perot interferometer.

A system for measuring pressure, temperature or both includes a diaphragm that responds to a change in temperature or pressure, and a base connected to the diaphragm that has a sapphire element. Between the diaphragm and the base is a cavity. An optical fiber that conducts light reflected off of a surface of the diaphragm is adjacent the cavity. An interrogator is used for detecting a deflection of the diaphragm based on at least two reflected light signals having similar wavelengths and coherence lengths. A quadrature phase detection unit demodulates signals received by the interrogator.

A method for making a housing that defines a cavity for a pressure sensor, the method comprising: providing a bulk of material that will form the housing; focusing a radiation beam on internal portions of the bulk of material so as to modify the internal portions, thereby defining the housing's shape, wherein upstream of the focus of the radiation beam other portions of the bulk material remain unmodified; and discarding either the modified portions or the unmodified portions of the bulk material so as to form the cavity.

An intravascular rotary blood pump possesses a catheter (10), a pumping device (50) disposed distally of the catheter and having at its distal end a flexible flow cannula (53) through which blood is either sucked or discharged by the pumping device (50) during operation of the blood pump, and at least one pressure sensor (27, 28A, 30) having at least one optical fiber (28A) which is laid along the flow cannula (53). The optical fiber (28A) and, where applicable, a sliding tube (27) in which the optical fiber (28A) is laid extend along a neutral fiber of the flow cannula (53).

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-Pérot interferometer arranged to be exposed to both temperature and physical parameter of interest and a second Fabry-Pérot 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-Pérot 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 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 pressure sensor includes a movable electrode formed in a movable region of a diaphragm, and a fixed electrode formed opposite to the movable electrode. A pressure receiving surface of the diaphragm is held in an inactive state. The inactive pressure receiving surface of the diaphragm is in a state in which molecules of gas to be measured are hard to absorb onto the pressure receiving surface. The pressure receiving surface of the diaphragm can be made inactive by predetermined surface treatment. A layer for making the pressure receiving surface of the diaphragm inactive is formed by the surface treatment, and the pressure receiving surface of the diaphragm is held inactive with the presence of the layer.

Disclosed are a Fabry-Perot sensor and a method for manufacturing the same. A Fabry-Perot sensor including: a base part; a cavity formed between the base part and a pressure-sensitive film, and enclosed by the base part and the pressure-sensitive film; the pressure-sensitive film, fixed to the base part, wherein the pressure-sensitive film has one or more localised areas, each localised area has a doping substance doped into a base material of the pressure-sensitive film to produce stress, no localised area penetrates the entire thickness of the pressure-sensitive film, and under the effect of stress, the pressure-sensitive film has a corrugated structure; an optic fibre used for conducting a light signal, one end part of the optic fibre being fixed to an optic fibre mounting part of the base part, and the optic fibre mounting part being located at an end part of the base part opposite the cavity.

There is provided a fiber-optic pressure sensor (110), which includes a waveguide (112) having an end, an optical deflection unit (301) connected to the end of the waveguide (112), and a sensor body (300) at which an optical resonator (302) is formed by way of a diaphragm (303). The waveguide (112) and/or the deflection unit (301) is/are attached to the sensor body (300) by way of a curable adhesive or a solder connection.

A system and method for monitoring Fabry-Perot cavity (FPC) displacement implementing a predictor-corrector scheme. The system includes an optical interrogator apparatus and a data processing apparatus. The optical interrogator apparatus interrogates the FPC, obtains a spectral interference pattern and outputs a corresponding signal including data associated with a plurality of peaks. The data processing apparatus processes the output signal to produce a prediction for a peak location based on the data associated with the plurality of peaks, and then uses the prediction to identify as correct one of the plurality of peaks. The data processing apparatus then determines and outputs a plurality of FPC length variations. In one embodiment, the data processing system implements a period tracking algorithm to produce the prediction based on the data associated with the plurality of peaks, and uses a phase tracking algorithm to determine an FPC length variation using the identified peak.