Abstract: A liquid level sensing system, including: an input acoustic waveguide, and an output acoustic waveguide, positioned extending into liquid to be sensed; the input waveguide being arranged to receive acoustic energy; an acoustic sensor attached to the output waveguide for sensing acoustic energy at the output waveguide that has been transferred from the input waveguide to the output waveguide by being acoustically coupled by the liquid; and a processor arranged to process timing characteristics of the sensed acoustic energy to determine a measure of the liquid level.

Abstract: A damage sensor comprises a probe track, a sense track, and a signal generator operable to input a probe signal to the probe track. The probe track and the sense track are electromagnetically coupled by a structure on which they are provided, such that the probe signal induces, in dependence on the degree of electromagnetic coupling between the probe track and the sense track, a sensed signal in the sense track. The magnitude, phase and frequency of the sensed signal can be analysed in order to determine whether and where damage has occurred to the structure.

Abstract: A damage sensing system, and a method of sensing damage using the system, are described. The system comprises: a plurality of tuned circuits arranged in parallel, each tuned circuit having a different resonant frequency; and processing means for discriminating the response of the different tuned circuits according to their respective different resonant frequencies, for example by processing changes in the respective Q-factors of the respective tuned circuits; wherein each of the plurality of tuned circuits comprises a respective damage sensor, each damage sensor comprising at least one direct write resistive element applied to an area of a substrate by a direct write process. Each tuned circuit may comprise a common resistor in series with the respective damage sensor. The plurality of the tuned circuits may be coupled to the processing means by a shared single pair of external connections.

Abstract: A damage sensor, for example a crack gauge, a method of providing the same, and a method of sensing damage using the same, are described. The damage sensor comprises at least one direct write resistive element applied to an area of a substrate by a direct write process. Conductive tracks may be connected along two separated portions of the perimeter of the area of the direct write resistive element. The damage sensor may comprise plural direct write resistive elements, for example rectangular-shaped elements, each extending between and connected to two conducting tracks. In a further damage sensor, plural annular resistive elements are positioned in an annular arrangement with respect to each other. In all the damage sensors, the resistive elements may be applied around a hole in a substrate, or extending over a bonded edge between two substrates.

Abstract: Described herein is an apparatus which is, under a range of atmospheric conditions, capable of maintaining the emission of light at a point remote from a light source. Notably, the apparatus is able to heat and distribute a fluid, and by doing so, prevents condensation and ice from forming which could hamper the emission of light. The apparatus comprises a light source and a light emitter, with a light conduit and a fluid conduit running between. A method for using such apparatus is also described.

Abstract: Described herein is an apparatus which is, under a range of atmospheric conditions, capable of maintaining the emission of light at a point remote from a light source. Notably, the apparatus is able to heat and distribute a fluid, and by doing so, prevents condensation and ice from forming which could hamper the emission of light. The apparatus comprises a light source and a light emitter, with a light conduit and a fluid conduit running between. A method for using such apparatus is also described.

Abstract: A damage sensor comprises a probe track, a sense track, and a signal generator operable to input a probe signal to the probe track. The probe track and the sense track are electromagnetically coupled by a structure on which they are provided, such that the probe signal induces, in dependence on the degree of electromagnetic coupling between the probe track and the sense track, a sensed signal in the sense track. The magnitude, phase and frequency of the sensed signal can be analysed in order to determine whether and where damage has occurred to the structure.

Abstract: A method of and an apparatus for coupling a first optical transmission means (10,42), such as an optical fibre, embedded within an aircraft composite (12,40) to a second optical transmission means (14), such as an optical fibre, external to the composite (12,40) is described. The method comprises locating the position of the first optical means (10,42) embedded within the composite (12,40) using X-ray scanning for example; forming a passageway (20,62) by laser machining or drilling within the composite (12,40) to the first optical transmission means (10,42); and establishing an optical connection between the first and second optical transmission means (10,42,14) at the intersection of the passageway (20,62) and the first optical transmission means (10,42).

Abstract: A composite for use in the aircraft construction industry includes an optical transmission device, such as an optical fiber, embedded within a carrier. The optical transmission device is provided with a high-quality optical interface surface which provides for optical connection to the optical transmission means from outside the carrier. The optical interface surface is provided as part of a micro-optical component which processes the optical signals to improve light extraction from a supply to the optical transmission means. The buried optical transmission device is accessed by a passageway formed in the carrier to the interface surface. If the passageway is formed prior to completion of finishing processes on the composite, a protective plug is provided to close the passageway until the optical connection is required.

Abstract: A surface-mountable interface module is attached to a central surface portion of a composite structure to interface with an optical transmission means embedded in the composite structure. The module has a mating surface for coupling to the composite structure to define an intersection between the module and the central surface portion, and contains interface optics to manipulate light that, in use, passes between the module and the optical transmission means through the intersection. A ‘smart’ variant of the module contains interrogation means for interrogating a sensor system associated with the optical transmission means, and power means for powering components within the module.

Abstract: A method of and an apparatus for coupling a first optical transmission means (10,42), such as an optical fiber, embedded within an aircraft composite (12,40) to a second optical transmission means (14), such as an optical fiber, external to the composite (12,40) is described. The method comprises locating the position of the first optical means (10,42) embedded within the composite (12,40) using X-ray scanning for example; forming a passageway (20,62) by laser machining or drilling within the composite (12,40) to the first optical transmission means (10,42); and establishing an optical connection between the first and second optical transmission means (10,42,14) at the intersection of the passageway (20,62) and the first optical transmission means (10,42).