Abrading – Abrading process – Glass or stone abrading
Reexamination Certificate
2000-02-09
2001-02-13
Banks, Derris H. (Department: 3723)
Abrading
Abrading process
Glass or stone abrading
C451S278000, C451S359000
Reexamination Certificate
active
06186871
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an apparatus for performing a polishing operation on a fiber of a fiber optic cable in a cable termination.
DESCRIPTION OF THE PRIOR ART
Fiber optic cables transmit data as pulses of light along a fiber comprising a core contained in a cladding having a different refractive index. Typically the fiber may have a diameter of only 50-300 microns. To allow the light pulses to pass from the core of the fiber at a termination of the cable into another core where two cables are joined, or to data handling apparatus where the cable terminates, the fibre must be accurately aligned and optically prepared.
To achieve this, the fibre optic cable is terminated in a termination which holds the cable and provides for connection to another termination or other connector. The fibre of the cable is set relative to the termination with an adhesive, and an end of the fibre which projects from a surface of the termination is polished to an optical flat.
The polishing process is critical to achieving a required quality of transmission of the light pulses, as pool polishing can introduce cracks and deep scratches into the fibre which cannot be removed. Such cracks and deep scratches can seriously affect the quality of the light transmission, resulting in loss of bandwidth or even corrupted data.
Whereas the fibre could be polished manually, various apparatus are known for more automated polishing. In each case a polishing surface or film is used, and relative movement is performed between the polishing surfacing and the fibre optic core.
Polishing apparatus for use in a laboratory environment are known which comprise a glass plate on which polishing film is mounted, and a fixture to hold the termination with the fibre projecting from a surface thereof. However known such apparatus require a high degree of skill to achieve satisfactory results consistently. Furthermore such apparatus are not portable.
It is desirable to be able to perform a polishing operation on a fibre of a fibre optic cable in a cable termination in situ, for example on board an aircraft where fibre optic cables are used for data transmission. In such environments there may be no readily available power supply for operating a polishing apparatus, and polishing may need to be carried out in very confined spaces, where no work surface is available. Also the persons expected to carry out such polishing may not be skilled in that task. Because in situ there may be little spare length of fibre optic cable, re-working of cable terminations may not be possible. The problems of in situ fibre optic repair and the like are aggravated because of the variety of different termination types in use, some having spring loaded parts which means that the terminations require particular handling.
Hand held fibre optic polishing apparatus have been proposed, but by the nature of their construction, they have not performed adequately and have been unable to handle a variety of termination types.
SUMMARY OF THE INVENTION
According to a first aspect of the invention we provide an apparatus for performing a polishing operation on a fibre of a fibre optic cable in a cable termination, the apparatus including means to receive the termination with the fibre extending therefrom towards a polishing surface, an operating means to bring the extending fibre and the polishing surface together, means to move the polishing surface relative to the termination and the fibre with the fibre and polishing surface in contact, to perform polishing of the fibre, characterised in that the operating means includes a manually operable member which is pivotal about a pivot axis, and means to bring the extending fibre and polishing surface together in response to pivoting movement of the manually operable member in a direction transverse to the pivot axis.
Thus by virtue of the simple construction of the apparatus, a simply operated and versatile apparatus may be provided, particularly suited for hand held use in situ by unskilled persons.
The apparatus may comprise a body and the manually operable member may be mounted on the body, whilst the means to receive the termination may be provided by a support assembly which is moveable relative to the body in response to pivoting movement of the manually operable member. To facilitate its use in confined conditions by unskilled persons, the apparatus may have guide means to guide the movement of the support assembly relative to the body in a direction normal to the pivot axis of the manually operable member, so that the projecting fibre and polishing surface are reliably brought together in a desired relative orientation in response to a simple manual movement of the manually operable member.
In one construction the manually operable member may be pivoted at one end to the body and may act to move the support assembly through a lever which is also pivotally mounted on the body and preferably also to the support assembly.
To prevent too much pressure being applied between the polishing surface and the projecting fibre by operation of the manually operable member, preferably the support assembly comprises a first part on which the manually operable member acts, and a second part which provides the means to receive the termination, the first part being moveable relative to the second part when the support assembly has been moved relative to the body so as to bring the termination and projecting fibre optic core into contact with the polishing surface at a predetermined pressure.
Desirably guide means are provided between the first and second parts of the support assembly to allow relative movement therebetween, and resilient means act between the first and second parts of the support assembly to resist relative movement therebetween until the predetermined pressure is applied by the manually operable member. Thus the first and second parts will move in concert in response to movement of the manually operable member to bring the polishing surface and projecting fibre together, but in the event that excess pressure is applied, the resilient means will permit of continued movement of the first part, movement of the second part is relieved.
The means which receive the termination may comprises an opening in the support assembly, preferably in the second part of the assembly, the opening being adapted so that the fibre extends from the termination in a direction substantially normal to the direction of movement of the support assembly relative to the body. To enable the apparatus to be used with a variety of termination types the opening may be provided in a removable insert which is adapted to receive a termination of a particular configuration and thus which may readily be exchanged for a removable insert which is adapted to receive a termination of another particular configuration.
In addition to any resilient means which act between the first and second parts of the support assembly, resilient means may act between the body and the support assembly to resist movement of the termination and projecting fibre towards the polishing surface in response to operation of the manually operable member, thus to improve control of the polishing process and to move the support assembly away from the polishing surface when the manually operable member is released.
An apparatus according to the invention may include a motor to move the polishing surface relative to the termination, and a housing for a power supply for the motor so that no external drive means or power supply is required.
For most efficient use of the polishing surface the polishing surface may be moved relative to the termination by a transmission which provides for relatively eccentric motion of the polishing surface relative to the termination.
According to a second aspect of the invention we provide a method of performing a polishing operation on a fibre of a fibre optic cable in a termination of the cable utilising a portable hand held apparatus including means to receive the termination with the fibre extending therefrom towa
Crocker Jason Paul
Saunders Nigel
Banks Derris H.
GKn Westland Helicopters Limited
Larson & Taylor PLC
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