Abstract: A method for monitoring an infrastructure of interest, the method comprising: providing a distributed acoustic sensor, an analysis module, and optical fibre cable adjacent to the infrastructure wherein the optical fibre cable is divided into one or more sections, and the distributed acoustic sensor generates DAS sensor data from the one or more sections; providing a processing module comprising one or more processors and a memory, wherein the memory comprises at least two or more processing algorithms, wherein the one or more processors are configured to execute the processing algorithms with the DAS sensor data as input, wherein each processing algorithm is configured to provide an output state for each section of the optical fibre cable adjacent to the infrastructure of interest.

Abstract: A distributed optical detection system comprising: a broadband optical source; and a phase and amplitude receiver for measuring phases and amplitudes of distributed backscattered signals from a sensing medium. Methods of quantitatively sensing optical path length changes along a sensing medium in a distributed manner are also disclosed.

Abstract: A distributed optical detection system comprising: a broadband optical source; and a phase and amplitude receiver for measuring phases and amplitudes of distributed backscattered signals from a sensing medium. Methods of quantitatively sensing optical path length changes along a sensing medium in a distributed manner are also disclosed.

Abstract: A distributed optical detection system comprising: a broadband optical source; and a phase and amplitude receiver for measuring phases and amplitudes of distributed backscattered signals from a sensing medium. Methods of quantitatively sensing optical path length changes along a sensing medium in a distributed manner are also disclosed.

Abstract: A distributed optical detection system comprising: a broadband optical source; and a phase and amplitude receiver for measuring phases and amplitudes of distributed backscattered signals from a sensing medium. Methods of quantitatively sensing optical path length changes along a sensing medium in a distributed manner are also disclosed.

Abstract: This invention relates to a method of preparing a preform for an optical fibre, and more particularly to a method of preparing a preform for a polymer holey optical fibre. The invention provides a method of preparing a preform for manufacture of a polymer holey optical fibre comprising casting a preform body in a mould from a suitable material, said mould including at least one protrusion adapted to form a corresponding hole within the preform, and subsequently separating the preform body and mould. The invention also provides a method of preparing a preform for manufacture of a polymeric holey optical fibre comprising separately casting one or more elements of a preform in respective mould(s) from a suitable material, and separating said elements from said respective mould(s) and combining said elements to construct a preform having a plurality of holes therein, each hole being formed in an element or formed by the combination of two or more elements.

Abstract: This invention relates to a method of producing a preform for an optical fibre. More particularly, the present invention relates to a method of preparing preforms for the production of holey optical fibres. The invention provides a method of producing an optical fibre, said method comprising applying heat to the interior of a preform and subsequently drawing said optical fibre from said preform. The invention also provides a method of producing an optical fibre, said method comprising preparing a preform comprising a body of optically suitable material and removing material at predetermined locations in the body so as to provide a plurality of holes within the body, applying heat to the interior of the preform and subsequently drawing said optical fibre from said preform.