A Fabry-Prot sensor assembly includes an optical element defining a Fabry-Prot optical cavity therein. A sensor ferrule is affixed to the optical element. The sensor ferrule is configured to physically connect to an optical fiber, optically aligning and spacing the optical fiber with the optical cavity. The sensor ferrule defines a bore for receiving the optical fiber. The bore extends along a longitudinal axis that extends to the optical element. The optical cavity is a second optical member defined between a first optical member and a third optical member spaced apart from the first optical member along the longitudinal axis. The first optical member includes a curved lens surface facing away from the optical cavity and into the bore, configured to collimate light passing through the first optical member.

A fiber-optic apparatus has a multi-mirror optical sensor having an optical source side and an air source side opposite the light source side. The multi-mirror optical sensor has a single-mode optical fiber connected to an optical source and a photodetector on the optical source side and connected to a hollow tube forming a first Fabry-Perot Interferometer on the air source side. The core of the single-mode optical fiber and the air cavity of the first Fabry-Perot Interferometer form a first mirror for reflecting optical light from the optical source. The air source side of the hollow tube is connected to a side-hole optical fiber forming a second Fabry-Perot Interferometer, the side-hole optical fiber has at least two hollow cavity holes symmetrically positioned around the core of the side-hole optical fiber and running longitudinally the length of the side-hole optical fiber. The air cavity of the first Fabry-Perot Interferometer to the optical fiber core of the side-hole optical fiber forms a second mirror for reflecting optical light from the optical source. The at least two hollow cavity holes of the side-hole optical fiber provide an air flow channel to the air cavity of the hollow tube from the air source side of the multi-mirror optical sensor. The end of the optical fiber core of the side-hole optical fiber at the air source side forms a third mirror for reflecting optical light from the optical source.

Apparatus and associated methods relate to measuring pressure of an external environment using a graded index (GRIN) lens and first and second Fabry-Perot interferometers, each axially aligned with one another. The GRIN lens collimates a beam diverging from a face of an optical fiber so as to direct the collimated beam to the first and second Fabry-Perot interferometers. The first Fabry-Perot interferometer is pressure isolated from the external environment but not temperature isolated. Therefore, the resonant frequency of the first Fabry-Perot interferometer is indicative of temperature. The second Fabry-Perot interferometer has a cavity that changes dimension in response to changes in pressure and temperature of the external atmosphere. The second Fabry-Perot interferometers has a second resonant frequency that is not integer multiple of the first resonant frequency. Pressure is determined based on the first and second resonant frequencies.

A method for integrating a sensor into a metal part including creating, by additive printing, of a first portion of the part, including a volume for housing a sensor. The volume has a width greater than that of the sensor. The method also includes depositing the sensor in said housing volume and creating, by additive printing, a second portion of the part covering the sensor and forming a molten puddle in the housing volume, on either side of the sensor.

There is disclosed an optical sensor for detecting one or more measurands such as temperature or pressure, comprising a probe light source arranged to generate probe light, and a sensor head arranged to receive the probe light from the probe light source and impose on the probe light an interference signal responsive to the one or more measurands. The sensor then also comprises an interrogator arranged to receive the probe light from the sensor head, measure the imposed interference signal, and determine the one or more measurands from the measured interference signal, and an optical fibre arranged to carry the received probe light at least some of the way from the sensor head to the interrogator, wherein the optical fibre is disposed within a protective conduit. A granular material may then be packed within the conduit so as to restrict or prevent lateral movement of the optical fibre within the conduit. The optical fibre may also or instead be disposed within one or more flexible sleeves within the conduit.

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.

An optical sensing device includes a support with an aperture. The optical sensing device can removably hold a sample against the support around the aperture. Accordingly, a portion of the sample is free to deform through the aperture in response to a change in an environmental condition. An optical waveguide is fixedly arranged with respect to the support whereby an end of the optical waveguide faces the aperture. The end of the optical waveguide forms an optical interferometric cavity with a refractive index discontinuity at a surface of the portion of the sample that is free to deform through the aperture.

A temperature-tolerant, shock and vibration resistant absolute pressure sensor may be constructed by joining a ruggedized lens assembly and optical fiber assembly to create a stable beam of collimated light. The lens may be captured by brazing or welding to high-strength spherical metal components. The light delivery assembly may be comprised of a metal jacketed optical fiber, ceramic ferrule, and metal alignment sleeves that are mechanically and/or chemically joined to one another using high temperature sealing glass preforms or brazing materials. The optical fiber assembly may be joined to the lens assembly securing the end face of the optical fiber in the operative focal position relative to the lens. The joined assembly results in a structure where no parts are subject to movement even at extreme temperatures or when subjected to severe shock and vibration. All the air-to-glass interfaces may have anti-reflection coatings to reduce optical losses, back reflection, and false signals. This rugged collimated beam assembly may be joined to a sensor assembly comprised of a diaphragm and window which comprise a Fabry-Perot interferometer. The external wetted surfaces of the diaphragm may be coated to reflect the radiant energy or with passive conductive and convective arrangements to keep the sensor cool and to minimize the long-term change in sensitivity of the diaphragm due to oxidation. The resulting sensors can be further enhanced by attaching the sensor to an absolute, hermetically sealed connector comprised of a lens assembly which is aligned and welded to the sensor transducer body. The resulting sensors can be further enhanced with windows for collecting UV energy and may use wide spectral band optical fibers to multiplex UV, visible, and IR energy from the sensing environment. These enhancements can be used to detect the presence of a flame and to make temperature measurements resulting in safety-certified optical sensors for use in many harsh industrial applications.