A system and method for providing a radiation source. In one arrangement, the radiation source includes an optical fiber that is hollow, and has an axial direction, a gas that fills the hollow of the optical fiber, and a plurality of temperature setting devices disposed at respective positions along the axial direction of the optical fiber, wherein the temperature setting devices are configured to control the temperature of the gas to locally control the density of the gas.

According to examples, an optical fiber-based sensing membrane may include at least one optical fiber, and a substrate. The at least one optical fiber may be integrated in the substrate. The optical fiber-based sensing membrane may include, based on a specified geometric pattern of the at least one optical fiber, an optical fiber-based sensing membrane layout. The substrate may include a thickness and a material property that are specified to ascertain, via the at least one optical fiber and based on the optical fiber-based sensing membrane layout, a thermal and/or a mechanical property associated with a device, or a radiation level associated with a device environment.

An apparatus has a cassette configured to hold optical fiber comprising one or more optical sensors. The cassette has a spool configured to one or more of extract and retract the optical fiber from the cassette. A pre-strain mechanism is configured to apply a predetermined pre-strain to the one or more optical sensors. An optical fiber installation tool is configured to mount the optical fiber comprising the one or more pre-strained optical sensors to a surface.

There is described a method for interrogating optical fiber comprising fiber Bragg gratings (“FBGs”), using an optical fiber interrogator. The method comprises (a) generating an initial light pulse from phase coherent light emitted from a light source, wherein the initial light pulse is generated by modulating the intensity of the light; (b) splitting the initial light pulse into a pair of light pulses; (c) causing one of the light pulses to be delayed relative to the other of the light pulses; (d) transmitting the light pulses along the optical fiber; (e) receiving reflections of the light pulses off the FBGs; and (f) determining whether an optical path length between the FBGs has changed from an interference pattern resulting from the reflections of the light pulses.

There is described a method for interrogating optical fiber comprising fiber Bragg gratings (“FBGs”), using an optical fiber interrogator. The method comprises (a) generating an initial light pulse from phase coherent light emitted from a light source, wherein the initial light pulse is generated by modulating the intensity of the light; (b) splitting the initial light pulse into a pair of light pulses; (c) causing one of the light pulses to be delayed relative to the other of the light pulses; (d) transmitting the light pulses along the optical fiber; (e) receiving reflections of the light pulses off the FBGs; and (f) determining whether an optical path length between the FBGs has changed from an interference pattern resulting from the reflections of the light pulses.

An assembly having a bearing with an axis of rotation, and a fibre-based sensor for sensing strain or temperature of the bearing is disclosed. The sensor extends in a direction parallel to the axis of rotation. An aircraft system is disclosed including a wheel supported on an axle by a first bearing and a second bearing. The system further includes a first fibre optic sensor for sensing a strain or temperature of the first bearing, a second fibre optic sensor for sensing a strain or temperature of the second bearing, and an interrogator to analyse optical signals from the sensors to determine differences in the strains or temperatures of the first bearing and the second bearing.

An assembly having a bearing with an axis of rotation, and a fibre-based sensor for sensing strain or temperature of the bearing is disclosed. The sensor extends in a direction parallel to the axis of rotation. An aircraft system is disclosed including a wheel supported on an axle by a first bearing and a second bearing. The system further includes a first fibre optic sensor for sensing a strain or temperature of the first bearing, a second fibre optic sensor for sensing a strain or temperature of the second bearing, and an interrogator to analyse optical signals from the sensors to determine differences in the strains or temperatures of the first bearing and the second bearing.

The invention relates to a method for in-life testing of the formation of the solid electrolyte interface layer of a battery cell, comprising the following steps: sensing the temperature within the battery cell, recording a first set of temperature (T) and/or pressure data related to the temperature variation (ΔT) and/or pressure variation within the battery cell over a first charge of the battery cell, and determining a positive or negative datum relating to the formation of solid electrolyte interface layer of the battery cell according to said first set of temperature and/or pressure data

The invention relates to a method for in-life testing of the formation of the solid electrolyte interface layer of a battery cell, comprising the following steps: sensing the temperature within the battery cell, recording a first set of temperature (T) and/or pressure data related to the temperature variation (ΔT) and/or pressure variation within the battery cell over a first charge of the battery cell, and determining a positive or negative datum relating to the formation of solid electrolyte interface layer of the battery cell according to said first set of temperature and/or pressure data

An assembly is provided for an aircraft. This aircraft assembly includes a fuselage and a second system. The fuselage includes a wall and a hatch configured to close an opening in the wall. The sensor system includes an optical fiber, a transmitter and a receiver. The optical fiber is arranged at an interface between the hatch and the wall. The transmitter is configured to transmit first electromagnetic radiation into the optical fiber. The receiver is configured to detect second electromagnetic radiation received from the optical fiber to provide receiver data. The sensor system is configured to detect fluid leakage across the interface between the hatch and the wall based on the receiver data.