Abstract: An overheat detection system for an aircraft, the system comprising a first bleed monitoring computer, BMC1, configured to identify leakages in a pneumatic system, the BMC1 including a first optical controller, a second bleed monitoring computer, BMC2, the BMC2 including a second optical controller, an optical fiber link connecting the first optical controller of the BMC1 and the second optical controller of the BMC2 for communication between the BMC1 and the BCM2 and between the first optical controller and the second optical controller, wherein the first and the second optical controllers are configured to detect overheat of the optical fiber link based on a wavelength shift of a modulated optical signal transmitted through the optical fiber link, and transmit signals to the first BMC1 and the second BMC2 based at least on the detected overheat.

Abstract: A temperature monitoring apparatus configured to monitor a temperature of a portion of a vehicle's electrical energy distribution network is disclosed. The apparatus includes a first optical fibre including one or more temperature sensing sections, each temperature sensing section being for thermal contact with a portion of a vehicle's electrical energy distribution network. Each temperature sensing section is arranged to produce, in response to an optical input signal, an optical output signal indicative of the temperature of the temperature sensing section. The apparatus is arranged to determine a temperature of the portion of the vehicle's electrical energy distribution network based on one or more of the output optical signals in use.

Abstract: An optical sensor system with two or more optical sensors; two or more receivers; and an optical de-multiplexing system. Each optical sensor includes a fibre grating with a different wavelength characteristic. Each receiver includes a slope filter and a light detector and is associated with a respective one of the optical sensors. The optical de-multiplexing system is arranged to route light from each of the optical sensors to its associated receiver based on a wavelength of the light.

Abstract: An optical network including an input to receive from an optical network light comprising plural wavelength components. An optical wavelength selective filter, optically connected to the input, extracts a first wavelength component of the plural wavelength components from the light, thereby providing a first optical signal including the first wavelength component and a second optical signal including a remainder of the plural wavelength components a light emitter to provide a modulated broadband optical signal. A first output, optically connected to the optical wavelength selective filter, receives a first portion of the second optical signal for transmission to a light detector and a second output, optically connected to optical wavelength selective filter, receives a second portion of the second optical signal for transmission to the optical network.

Abstract: An optical network including an input to receive from an optical network light comprising plural wavelength components. An optical wavelength selective filter, optically connected to the input, extracts a first wavelength component of the plural wavelength components from the light, thereby providing a first optical signal including the first wavelength component and a second optical signal including a remainder of the plural wavelength components a light emitter to provide a modulated broadband optical signal. A first output, optically connected to the optical wavelength selective filter, receives a first portion of the second optical signal for transmission to a light detector and a second output, optically connected to optical wavelength selective filter, receives a second portion of the second optical signal for transmission to the optical network.

Abstract: An overheat detection system for an aircraft, the system comprising a first bleed monitoring computer, BMC1, configured to identify leakages in a pneumatic system, the BMC1 including a first optical controller, a second bleed monitoring computer, BMC2, the BMC2 including a second optical controller, an optical fiber link connecting the first optical controller of the BMC1 and the second optical controller of the BMC2 for communication between the BMC1 and the BCM2 and between the first optical controller and the second optical controller, wherein the first and the second optical controllers are configured to detect overheat of the optical fiber link based on a wavelength shift of a modulated optical signal transmitted through the optical fiber link, and transmit signals to the first BMC1 and the second BMC2 based at least on the detected overheat.

Abstract: A system installed on an aircraft. The system includes a memory storing static information in one or more optical fibre gratings; and an interrogator. The interrogator includes a light source configured to transmit interrogation light to the memory, a receiver configured to receive return light from the memory, and an analyser configured to analyse the return light to obtain the static information.

Abstract: An optical network including an input to receive from an optical network light comprising plural wavelength components. An optical wavelength selective filter, optically connected to the input, extracts a first wavelength component of the plural wavelength components from the light, thereby providing a first optical signal including the first wavelength component and a second optical signal including a remainder of the plural wavelength components a light emitter to provide a modulated broadband optical signal. A first output, optically connected to the optical wavelength selective filter, receives a first portion of the second optical signal for transmission to a light detector and a second output, optically connected to optical wavelength selective filter, receives a second portion of the second optical signal for transmission to the optical network.

Abstract: A method of measuring a height of a fuel in an aircraft fuel tank (21)b including illuminating the fuel in the aircraft fuel tank and detecting reflected light from the fuel. Optical coherence tomography is used to determine the height of a surface of fuel in the fuel tank. An apparatus (30) is used to measure a height of a surface of fuel in an aircraft fuel tank, and an aircraft fuel tank system with a fuel tank and an apparatus for measuring a height of a surface of fuel in the aircraft fuel tank.

Abstract: A system installed on an aircraft. The system includes a memory storing static information in one or more optical fibre gratings; and an interrogator. The interrogator includes a light source configured to transmit interrogation light to the memory, a receiver configured to receive return light from the memory, and an analyser configured to analyse the return light to obtain the static information.

Abstract: A method of measuring a surface of a liquid, the surface of the liquid having an edge which contacts a solid structure and an interior area which does not contact the solid structure. The surface of the liquid and the solid structure are illuminated with a pattern so that an upper part of the pattern is projected onto the solid structure to form an upper projected pattern and a lower part of the pattern is projected onto the interior area of the surface of the liquid to form a lower projected pattern. An image of the upper projected pattern is acquired and analysed to determine a height of the edge of the surface of the liquid. An image of the lower projected pattern is acquired and analysed to determine a characteristic of the interior area of the surface of the liquid.

Abstract: A method of estimating a quantity of a liquid fuel in a fuel tank of an aircraft is disclosed. A surface of the fuel is illuminated with light so that the light is reflected or scattered by the surface of the fuel onto an array of sensors. The light travels to and from the surface of the fuel via a measurement path containing a transmission medium. A measured time of flight is made at each sensor for the light which travels via the measurement path to that sensor. At least one of the sensors is illuminated with light via a reference path containing a transmission medium with substantially the same refractive index as the transmission medium in the measurement path, the reference path having a known reference distance which does not vary in accordance with the quantity of the fuel.

Abstract: An optical sensor system with two or more optical sensors; two or more receivers; and an optical de-multiplexing system. Each optical sensor includes a fibre grating with a different wavelength characteristic. Each receiver includes a slope filter and a light detector and is associated with a respective one of the optical sensors. The optical de-multiplexing system is arranged to route light from each of the optical sensors to its associated receiver based on a wavelength of the light.

Abstract: A fiber-optic communication system for an aircraft including: a light source operable to generate light; a transceiver in optical communication with the light source, the transceiver including a control input and a reflector; an optical fiber in optical communication with the transceiver; and a light detector in optical communication with the optical fiber. The transceiver is operable to generate an amplitude modulated light signal by selectively reflecting the light received from the light source into the optical fiber using the reflector according to information received at the control input. The light detector is operable to receive the amplitude modulated light signal from the optical fiber and to detect an amplitude of the amplitude modulated light signal to extract the information.

Abstract: A temperature monitoring apparatus configured to monitor a temperature of a portion of a vehicle's electrical energy distribution network is disclosed. The apparatus includes a first optical fibre including one or more temperature sensing sections, each temperature sensing section being for thermal contact with a portion of a vehicle's electrical energy distribution network. Each temperature sensing section is arranged to produce, in response to an optical input signal, an optical output signal indicative of the temperature of the temperature sensing section. The apparatus is arranged to determine a temperature of the portion of the vehicle's electrical energy distribution network based on one or more of the output optical signals in use.

Abstract: A communication apparatus for a fiber-optic communication system for an aircraft that includes: an optical coupler; an input port optically coupled to the optical coupler via a first waveguide, the input port arranged to receive light; a modulator optically coupled to the optical coupler via a second waveguide, the modulator having a logic input and a fiber having a fiber Bragg grating (FBG) receiving light from the input port via the optical coupler, the modulator operable to vary a strain force applied to the fiber according to a logic signal received at the logic input to modulate a wavelength of a modulated light signal reflected by the FBG back to the optical coupler; and an output port optically coupled to the optical coupler via a third waveguide to receive the modulated light signal therefrom, the output port being operable to output the modulated light signal.

Abstract: A communication apparatus for a fibre-optic communication system for an aircraft that includes: an optical coupler; an input port optically coupled to the optical coupler via a first waveguide, the input port arranged to receive light; a modulator optically coupled to the optical coupler via a second waveguide, the modulator having a logic input and a fibre having a fibre Bragg grating (FBG) receiving light from the input port via the optical coupler, the modulator operable to vary a strain force applied to the fibre according to a logic signal received at the logic input to modulate a wavelength of a modulated light signal reflected by the FBG back to the optical coupler; and an output port optically coupled to the optical coupler via a third waveguide to receive the modulated light signal therefrom, the output port being operable to output the modulated light signal.

Abstract: A fibre-optic communication system for an aircraft including: a light source operable to generate light; a transceiver in optical communication with the light source, the transceiver including a control input and a reflector; an optical fibre in optical communication with the transceiver; and a light detector in optical communication with the optical fibre. The transceiver is operable to generate an amplitude modulated light signal by selectively reflecting the light received from the light source into the optical fibre using the reflector according to information received at the control input. The light detector is operable to receive the amplitude modulated light signal from the optical fibre and to detect an amplitude of the amplitude modulated light signal to extract the information.

Abstract: A tank assembly with a tank for storing liquid hydrocarbon, the tank having a floor for supporting a weight of the liquid hydrocarbon. A filter is fitted to the floor of the tank. The filter is arranged to allow liquid water in the tank to drain out of the tank through the filter but substantially prevent the liquid hydrocarbon in the tank from doing so. The filter has a permeation member, such as a membrane, which is formed from a material such as graphene oxide which allows liquid water in the tank to drain out of the tank by permeating through the permeation member but substantially prevent the liquid hydrocarbon in the tank from doing so.

Abstract: A method of measuring a height of a fuel in an aircraft fuel tank (21) b including illuminating the fuel in the aircraft fuel tank and detecting reflected light from the fuel. Optical coherence tomography is used to determine the height of a surface of fuel in the fuel tank. An apparatus (30) is used to measure a height of a surface of fuel in an aircraft fuel tank, and an aircraft fuel tank system with a fuel tank and an apparatus for measuring a height of a surface of fuel in the aircraft fuel tank.