Identification and location of fiber optic cables
AssigneeRadio Detection Limited
InventorsStuart John Russell, Andrew Biggerstaff Lewis, John Philip Dakin
Life of this patent
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Abstract
In order to identify a fiber optic cable (10) a beam (14) of polarized light is caused to pass down the cable to a first site (A) at which an electromagnetic field (24) is applied to the cable (10). The electromagnetic field (24) traverses the cable (10) in an essentially transverse direction and has a time-varying component orientated along the length of the cable (10) at the first site (A), with the component varying so that the line integral thereof along the cable (10) is non-zero. This results in a variation in the polarization of the light, which can then be detected by a polarization discriminator (20) at a second site (B), thereby to identify the cable (10).
Claims8
A method of identifying a fiber optic cable (10), comprising:
- causing a beam (14) of light to pass down the cable (10);
- applying an electromagnetic field (24) to the cable at a first site A, thereby to vary the polarisation of the light;
- and
- detecting (26) the variation in the polarisation at a second site (B), thereby to identify the fiber optic cable;
- characterised in that:
- the electromagnetic field is applied by causing said electromagnetic field (24) to traverse the fiber optic with (10) in an essentially transverse direction, the electromagnetic field (24) having a time-varying component orientated along the length of the fiber optic cable (1) at the first site (A), said component varying such that the line integral thereof along the cable (10) is non-zero.
A method according to any one of the preceding claims, wherein the state of polarisation of the beam of light (14) is modulated prior to the application of said electromagnetic field to the cable.
An apparatus for identifying a fiber optic cable (10) comprising:
- a light generator (22) for causing a beam (14) of light to pass down the cable (10);
- an antenna (16) for applying an electromagnetic field (24) to the cable (10) at a first site (A), thereby to vary the polarisation of the light;
- and
- a detector (26) for detecting the variation in polarisation at a second site (B), thereby to identify the fiber optic cable (10);
- characterised in that:
- the antenna is arranged to cause said electromagnetic field (24) to traverse the fiber optic with (10) in an essentially transverse direction, the electromagnetic field (24) having a time-varying component orientated along the length of the fiber optic cable (1) at the first site (A), said component varying such that the line integral thereof along the cable (10) is non-zero.
Dependencies are inferred from the claim text.