Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/36—Mechanical coupling means
  • G02B6/3604—Rotary joints allowing relative rotational movement between opposing fibre or fibre bundle ends

Definitions

• This invention relates to a full duplex rotating optical fibre coupling for simultaneous wide-band digital signal transmission-
• An object of the invention is to provide a
• .slip ring which can be used without signal degradation in adverse environmental situations, particularly those subject to electromagnetic interference.
• a further object is to have a signal transmission 0 system in which two members with relative motion therebetween can transmit and receive the signal without the need to use brushes or other mechanical transmission devices or the need to use "active" transducers at the interface between members with relative rotation therebetween, and which can, when required, pass isolated signals in opposite directions between the members .
• a further object is to increase the number of signals which can be passed using only axial fibre optic receiving lines.
• the objects are achieved by using a light signal transmitted across an interface between members which have relative rotational motion about a common axis the one in relation to the other, each member having at least a fibre transmission line along which the light is transmitted from one member to the other member across a gap formed at an interface, and in the case of bilateral transmission of isolated signals in opposite direction, each member having a first on-axis fibre and a second fibre inclined to the axis, the inclined fibre being directed to direct light to the on-axis fibre at the interface to transmit a light signal from the inclined fibre line to the on-axis fibre line.
• the invention comprises a light-operated slip ring in which a signal is transmitted across an interface between a first- member and a second member which have relative rotational motion the one to the other about a common axis, characterised by at least one member carrying at least one inclined off-axis fibre transmission line along which the light is transmitted across a gap formed at the interface between the two members, and the other member carrying an on-axis fibre transmission line, the Inclined fibre transmission line being directed towards the end of the axial fibre transmission line at the interface, with each fibre transmission line terminating at the gap at the interface, whereby the fibre optic transmission lines form at least a continuous optical path between members during relative rotation.
• the light-operated slip ring is characterised by bilateral transmission means in which each member has two fibre transmission lines with each member carrying an inclined fibre transmission line directed to an axial fibre transmission line carried by the other member.
• the light- operated slip ring is characterised in that at least one of the members carries a plurality of inclined fibre transmission lines directed to an axial transmission line on the other member, the inclined transmission lines being each adapted to receive different chromatic light signals, there being dichromatic filter means to separate the signals received and transmitted by the axial fibre transmission line.
• FIG. 1 is a longitudinal section of a device incorporating the invention
• FIG. 2 is a schematic view to demonstrate the principle of a two-way signal system showing how an inclined fibre optic transmission line is directed to an axial fibre optics receiving line in each direction.
• FIG. 3 Is a view similar to FIG. 2 but showing how by using dichromatic means a further signal channel results
• FIG. 4 is a view similar to FIG. 2 but showing how transducers can be positioned remote from the actual slip ring itself to thereby provide a "passive" system which will not receive or emit noise, in the vicinity of the slip ring to remove or reduce noise at the gap which does not reach the gap because of the possibility of placing and possible interference sources remote from the slip ring itself.
• the device consists of two halves 1 and 2 of the coupling, at least one rotating collinearly about the axis of the other.
• Each half has two glass core optical fibres which form fibre optics transmission lines 3 and 4, which may be of 1.0 mm diameter, the first fibre transmission line 3 lies on the axis of rotation and the other fibre transmission line 4 is inclined at, for .Instance, 10° to the axis of rotation.
• the spacing between the pair of fibre transmission lines at each coupling face may be 0.2 mm.
• the two halves of the coupling have an air-gap 5 of say 3 mm between them at the coupling face, and the ends of the fibre transmission lines face each other across this air-gap 5.
• the other ends of the on-axis fibre transmission line 3 and the angled fibre transmission line 4 from each half of the coupling may terminate respectively in a detector 6 and a light emitting diode 7 (LED) respectively, shown more" particularly in the schematic illustration FIG. 4.
• Each light emitting diode 7 operates at 'different optical wavelengths, for instance 665 nm and 910 nm. These are situated sufficiently remote from the coupling interface at the air-gap 5 to avoid electrical interference.
• the input electrical digital signals are fed into a modulator 8 which pulses one of light emitting diodes 7, which is situated at the end of the inclined fibre transmission line 4 remote from the other half 1 of the coupling.
• Light pulses are transmitted along the inclined fibre transmission line 4 across the air-gap 5 to the on-axis fibre transmission line 3 in the rotating half 2 of the coupling. Some of this light travels along the on-axis fibre transmission line 3 to the detector 6 which converts these light pulses back into electrical signals.
• Transmission in the opposite direction, from the rotating half 2 to the fixed half 1 is carried out in the same manner as for the fixed half to the rotating half. This provides for transmission of two separate channels, one in either direction at different times or simultaneous bilateral transmission of two channels.
• Some backscatter may be caused by some of the light pulses from the angled fibre transmission line 4 in one half of the coupling being reflected from the faces of the on-axis fibre transmission line 3 and the inclined fibre transmission line 4 in the other half of the coupling.
• an added fibre signal line 12 is used which is inclined to direct the light issuing from its- end at the interface to the on-axis fibre line 3, and the on-axis fibre line has in it a dichromatic mirror 13 which separates the input from the first signal line which is the inclined fibre line 4 and the input from the second signal line which is the inclined fibre line 12 and outputs a first signal to the first signal detector 14 and a second signal to the second detector 15, blocking filters being again added if neccesary as indicated by 16 and 17.
• the coupling of this invention itself is a passive device which will not itself transmit or receive noise and can be used, as earlier stated herein, without signal degradation in adverse environmental situations particularly those subject to electromagnetic inter ⁇ ference, and is readily adapted to pass isolated signals in opposite direction, and if required in multiple form.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Optical Couplings Of Light Guides (AREA)
• Optical Communication System (AREA)
• Arrangements For Transmission Of Measured Signals (AREA)

Applications Claiming Priority (2)

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ID=3692824

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Family Cites Families (10)

• 1984
  • 1984-11-06 WO PCT/AU1984/000225 patent/WO1985002270A1/en not_active Application Discontinuation
  • 1984-11-06 EP EP19840904066 patent/EP0160685A1/de not_active Withdrawn
  • 1984-11-06 JP JP50426484A patent/JPS61501594A/ja active Pending

Non-Patent Citations (1)

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