WO1998005945A1

WO1998005945A1 - Inspection apparatus

Info

Publication number: WO1998005945A1
Application number: PCT/GB1997/002089
Authority: WO
Inventors: Michael John Phillips
Original assignee: Michael John Phillips
Priority date: 1996-08-01
Filing date: 1997-08-01
Publication date: 1998-02-12
Also published as: GB9616191D0

Abstract

Apparatus for inspection of optical fibre connection devices comprises a body member including a lens system for focusing on the ferrule surface of an in situ connector and generating an image thereof, means for illumination of said ferrule surface, means for electronically recording said image, and means for transmitting said image to a remote image viewer, in which the body member is elongate and is dimensionally adapted to be manipulated in use to be positioned within and at the rear of the chassis of optical fibre distribution equipment.

Description

INSPECTION APPARATUS

This invention relates to apparatus for inspection of optical fibre connection devices, especially but not exclusively when in use in a manifold or distribution apparatus for optical fibre transmission equipment.

Optical fibres are being increasingly used as replacements for electrical transmission lines in a variety of applications but, if they are to have low attenuation or transmission loss, the mechanical condition not only of the fibres themselves but also of their connectors is of the utmost importance. The two main types of fibre connections are fibre splices, where the joints are permanent or semipermanent, and demountable connectors, where removable joints are required which allow fast manual coupling and uncoupling of fibres. Especially in the latter case and in order to minimise optical loss at the joint interface, it is important that the fibre axes are in alignment, that the fibre ends are smooth and perpendicular to the fibre axes, and that the connector itself is clean and not scratched or otherwise damaged.

Various types of connection device are known but the most commonly used is the ferrule or concentric sleeve connector, in which the fibres to be connected are bonded with epoxy resin in metal plugs known as ferrules which have an axial hole in which the fibre, with its buffer coating removed, is located. The two ferrules are placed within the connector in an alignment sleeve which allows the fibre ends to be held in a butt jointed relationship. The ferrules are held in place within the connector shell by for example a spring. To minimize attenuation losses, the exposed end face of the fibre is commonly polished after insertion and bonding so that it is flush with the end face of the ferrule and can thus form a butt joint with the face of the other fibre, the quality of which keeps transmission losses to a minimum.

Both during the production process of connectors and during use thereof, it is necessary from time to time to inspect them for dirt or damage. However, recent developments in distribution equipment have resulted in cables being plugged into the connectors at the back of the equipment chassis rather than at the face-plate and the connectors are therefore more difficult to inspect by traditional techniques involving a conventional hand-held microscope with the addition of an extension tube to provide the required focal length enhancement, simply because it is necessary to have access to the connectors at the rear of the chassis in a restricted space. This has hitherto required some disassembly of the backplane or front-panel connectors so that the in si tu connector and adaptor guide can be separately inspected. This is a time-consuming procedure which carries the inherent risk of causing damage to the connectors or cabling where perhaps none existed prior to disassembly.

It is an object of the invention to provide apparatus which permits the user to carry out an inspection of connection devices even in restricted or remote locations in for example distribution equipment without having to disassemble the backplane or front-panel connector of the equipment .

According to an aspect of the present invention, apparatus for inspection of optical fibre connection devices comprises a body member including a lens system for focussing on the ferrule surface of an in si tu connector and generating an image thereof, means for illumination of said ferrule surface, means for electronically recording said image, and means for transmitting said image to a remote image viewer, in which the body member is elongate and is dimensionally adapted to be manipulated in use to be positioned within and at the rear of the chassis of optical fibre distribution equipment.

Preferably, the body member is cylindrical or tubular, whereby the light follows a linear pathway, and is electrically insulated so that it can be inserted with safety in the gap left when a plug-in card is removed from the chassis of the distribution equipment. The dimensions of the body member are preferably less than 50 cm in length and 30 mm in diameter, for example 35 cm in length and 20 mm in diameter. The focal length of the lens system may be adjustable to allow accurate focussing on the ferrule surface; preferably, adjustment is effected from the user end of the body member to permit focussing in si tu .

The body member may additionally include an adaptor for demountable attachment to the sleeve or shell of the connector, for viewing the face of one of the ferrules therein, preferably without physical contact therewith, when the other ferrule has been temporarily removed from the connector. The adaptor itself may be demountable, whereby interchangeable adaptors may be provided for different connectors such as SC, ST or FC style front panel connectors or AMP SC backplane connectors, the adaptor preferably including connector locator means on the tip thereof. The body member may also include a secondary external light source to illuminate the localized surroundings of the connectors in the equipment, to assist in accurate manoeuvring and positioning thereof, although in a preferred arrangement an external light source is provided towards the remote end of the body member which illuminates the localized surroundings and also directs light through a window in the body member wall to provide axial subject illumination via suitable reflector means .

The means for electronically recording the image may comprise a miniature closed-circuit detector camera contained within the body member. Power for the camera and image transmission means may comprise rechargeable batteries which may conveniently be located in a pistol- grip type handle for the body member or may be provided from a remote source via a flexible electrical cable.

The remote image viewer may comprise any compatible personal computer or other display which, conveniently, may include a large display screen for simultaneous viewing by several people .

It has been found in a specific embodiment that, without the need for fine adjustment, a clear monochrome image of the ferrule surface, at an approximate magnification of x200, can be obtained. The image may be displayed via a video lead and a PC card video frame store or image grabber on a suitable Notebook or Laptop computer or other display. Ensuring that the connectors are clean and damage-free can be accomplished quickly, conveniently and with precision. The use of the inventive apparatus with the elongate body member containing the integral lens system allows more convenient and accurate focussing on the ferrule end surface with the required magnification and with a greater depth of field than is the case with conventional apparatus using extension tubes .

Although the invention has been particularly described with reference to its use for inspection of connectors when located in distribution equipment, it additionally has utility as a quality control tool for use during the manufacturing process of connectors.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawing, which shows a side elevation of apparatus for inspection of optical fibre connectors.

The apparatus illustrated includes a rigid tubular probe 11, typically 350mm in length and 16mm in diameter, preferably formed from a suitable metallic material and carrying an electrically-insulating, anti-static sleeving. The front or remote end of the probe carries a demountable adaptor 12 for locating on a particular type of front panel or backplane connector and interchangeable with other adaptors. In the particular embodiment shown, a central locator 13 is provided and has an axial hole for light transmission purposes. An objective lens is housed in the end portion 14 of the probe. The probe 11 carries a suitable lens train to enable the miniature CCD camera, located in the enlarged upper end 15 of the apparatus, to 'focus on the ferrule surface of an in si tu connector to provide a clear image of the ferrule surface at the required magnification and which can be viewed on a compact monitor (not shown) or displayed via a suitable video image grabber on a large external monitor for simultaneous viewing by several people. Rechargeable batteries are housed in the pistol grip handle 16 of the apparatus, although mains power may optionally be used via an external power adaptor and battery recharger .

At the front or remote end of the probe is carried an external light bulb 17 which provided general external illumination to assist in location by the user. The probe wall is formed with a window 18 adjacent the bulb; a part-silvered mirror is mounted within the portion 14 of the probe, to the rear of the objective lens, adjacent the window at an angle of 45° to receive a portion of light emitted by the bulb and to reflect it axially onto the subject, the image light being transmitted through the mirror to the camera. The light may be focussed by the objective lens to provide a greater illumination intensity on the subject. An on/off switch 19 is provided in the end of the handle.

In use, the probe is inserted in the gap remaining when a plug-in cord is removed from an equipment chassis, the dimensions of the probe ensuring that it is insertable through a narrow gap and can reach to the rear of the chassis. The length of the probe also enhances the depth of filed of the apparatus. The external light source, providing ambient illumination within the confines of the chassis, enables the probe tip to be easily located on the connector receptacle while the axial light provides subject illumination once the probe has been thus located.

Claims

CLAIMS :

1. Apparatus for inspection of optical ibre connection devices, the apparatus comprising a body member including a lens system for focussing on the ferrule surface of an in si tu connector and generating an image thereof, means for illumination of said ferrule surface, means for electronically recording said image, and means for transmitting said image to a remote image viewer, in which the body member is elongate and is dimensionally adapted to be manipulated in use to be positioned within and at the rear of the chassis of optical fibre distribution equipment.

2. Apparatus according to claim 1, in which the body member is cylindrical or tubular, and is electrically insulated.

3. Apparatus according to claim 1 or claim 2 , in which the focal length of the lens system is adjustable.

4. Apparatus according to any preceding claim, in which the body member includes an adaptor for demountable attachment to the sleeve or shell of the connector.

5. Apparatus according to any preceding claim, in which the body member includes a secondary external light source to illuminate the localized surroundings of the connectors in the equipment.

6. Apparatus according to claim 5, in which the external light source is provided towards the remote end of the body member and also directs light through a window in the body member wall to provide axial subject illumination via suitable reflector means.

7 . Apparatus according to any preceding claim, in which the means for electronically recording the image comprises a miniature closed-circuit detector camera contained within the body membe .