This invention describes the structure and function of an integrated multi-sensing systems in stacked configuration. Integrated systems described herein may be configured to form a microphone, pressure sensor, gas sensor or accelerometer. The method uses Fabry-Perot Interferometer in conjunction with light source and a photodetector integrated in stacked configuration. It also describes a configurable method for tuning the integrated system to specific resonance frequency using electrostatic actuators.

A multi-mode sensor includes an inductive sensor module configured to measure a first physical quantity based on magnetic induction. The inductive sensor module includes a coil wound around a coil axis. A non-inductive sensor module is provided to measure a second physical quantity using a non-inductive sensing mode. A portion of the non-inductive sensor module is radially inward of a portion of the coil relative to the coil axis.

A transformer system includes a transformer and a transformer tank. The transformer tank houses the transformer in a bath of a dielectric fluid. The transformer system also includes a controller, and a fiber optic pressure sensor communicatively coupled to the controller. The fiber optic sensor is disposed in the dielectric fluid and operative to provide an output that varies with the pressure of the dielectric fluid. The controller is operative to determine the pressure of the dielectric fluid based on the output of the fiber optic pressure sensor.

An optical system having an optical sensor with an ultra-short FP cavity, and a low-resolution optical interrogation system coupled to the optical sensor and operational to send light signals and receive light signals to and from the optical sensor is disclosed. The optical system may operate in a wavelength range including the visible and near-infrared range. Optical assemblies and methods of interrogating optical sensors are provided, as are numerous other aspects.

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.

There is described an optical pressure sensor comprising a sensor housing and an optical pressure cell mounted within the sensor housing and dividing the sensor housing into a first fluid space and a second fluid space. The optical pressure cell comprises a front side exposed to a pressure in the first fluid space and a back side exposed to a pressure in the second fluid space. The optical pressure sensor further comprises a fluid communication arrangement allowing pressure equalization between the pressure in the first fluid space on the front side and the pressure in the second fluid space on the back side of the optical pressure cell.

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 fuel sensing system utilizes a fiber optic sensor comprising a membrane made of a direct band gap semiconductor material (such as gallium arsenide) that forms an optical cavity with an optical fiber inside a hermetically sealed sensor package located at the bottom of a fuel tank. The optical fiber inside the fuel tank is not exposed to the fuel. The optical cavity formed by the bottom surface of the membrane and the surface of the distal end of the internal optical fiber is capable of behaving as a Fabry-Prot interferometer. Multiple light sources operating at different wavelengths and multiple spectrometers can be coupled to the confronting surface of the membrane via the optical fiber inside the fuel tank, a hermetically sealed fiber optic connector that passes through the wall of the fuel tank, and a fiber optic coupler located outside the fuel tank.

The present invention relates to an optical gas detector for detecting a gas absorbing light at a known wavelength, wherein the gas detector comprises two essentially identical, parallel membranes defining a volume between them containing the gas to be investigated, and a modulated first light source emitting light at said known wavelength into said volume at a chosen frequency, the detector is adapted to detect relative movements between said membranes and said movements having a frequency corresponding to the rate or a multiple of the rate of said pulsed light source, and wherein the said volume has at least one opening allowing the gas to unrestricted flow or diffuse into said volume.

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.