GB2282503A - Rotatable joint for communication line - Google Patents
Rotatable joint for communication line Download PDFInfo
- Publication number
- GB2282503A GB2282503A GB9320048A GB9320048A GB2282503A GB 2282503 A GB2282503 A GB 2282503A GB 9320048 A GB9320048 A GB 9320048A GB 9320048 A GB9320048 A GB 9320048A GB 2282503 A GB2282503 A GB 2282503A
- Authority
- GB
- United Kingdom
- Prior art keywords
- signals
- pair
- wavelength division
- fed
- beam splitter
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000003287 optical effect Effects 0.000 claims description 2
- 238000001228 spectrum Methods 0.000 claims description 2
- 230000010287 polarization Effects 0.000 abstract 1
- 238000000034 method Methods 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005670 electromagnetic radiation Effects 0.000 description 1
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
- G02B6/26—Optical coupling means
- G02B6/27—Optical coupling means with polarisation selective and adjusting means
- G02B6/2706—Optical coupling means with polarisation selective and adjusting means as bulk elements, i.e. free space arrangements external to a light guide, e.g. polarising beam splitters
- G02B6/2713—Optical coupling means with polarisation selective and adjusting means as bulk elements, i.e. free space arrangements external to a light guide, e.g. polarising beam splitters cascade of polarisation selective or adjusting operations
- G02B6/272—Optical coupling means with polarisation selective and adjusting means as bulk elements, i.e. free space arrangements external to a light guide, e.g. polarising beam splitters cascade of polarisation selective or adjusting operations comprising polarisation means for beam splitting and combining
-
- 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
- G02B6/26—Optical coupling means
- G02B6/27—Optical coupling means with polarisation selective and adjusting means
- G02B6/2753—Optical coupling means with polarisation selective and adjusting means characterised by their function or use, i.e. of the complete device
- G02B6/2773—Polarisation splitting or combining
-
- 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
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/80—Optical aspects relating to the use of optical transmission for specific applications, not provided for in groups H04B10/03 - H04B10/70, e.g. optical power feeding or optical transmission through water
- H04B10/801—Optical aspects relating to the use of optical transmission for specific applications, not provided for in groups H04B10/03 - H04B10/70, e.g. optical power feeding or optical transmission through water using optical interconnects, e.g. light coupled isolators, circuit board interconnections
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/02—Wavelength-division multiplex systems
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/06—Polarisation multiplex systems
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Electromagnetism (AREA)
- Optical Communication System (AREA)
Abstract
First 2, 3 and second 5, 6 pairs of signals 7 the signals of each pair being at a different frequency, are input to first and second wavelength division multiplexers 4, 7 to provide corresponding multiplexed signals 8, 10 of orthogonal polarizations. Polarising beam splitter 9 receives both multiplexed signals and passes them 11 to quarter waveplate 12. The resultant circularly polarized signal passes via the rotatable joint 1 to a second quarter waveplate 13 and thence 14 to a second polarising beam splitter 15, and then 16, 18 to third and fourth wavelength division multiplexers 17, 19. This enables the four input signals to be output 20, 21, 22, 23. <IMAGE>
Description
IMPROVEMENTS IN OR RELATING TO ROTATABLE
JOINTS FOR COMMUNICATION LINES
This invention relates to rotatable joints for communication lines.
Such joints are the subject of our co-pending GB patent application numbers 9219351.5 and 9026669.3 (2250652A) by
Messrs P M Wilton and G M S Joynes respectively, to which attention is hereby directed. The specifications which accompany our co-pending patent applications as referred to above, disclose methods and apparatus for transmitting a number of channels of electromagnetic radiation (such as light or microwave) across a rotating boundary along the axis of rotation using a combination of polarisation multiplexing and wavelength division multiplexing (WDM) techniques. To eliminate the effect of rotation, B/4 waveplates are used to convert two originally linear orthogonal polarisations into opposite circular polarisations for transmission across the rotating boundary and to convert back into two linear orthogonal polarisations.In this way communication is facilitated in a plurality of channels across a rotating joint which may form a part of a radar scanner for example.
The apparatus described in the specifications accompanying our co-pending patent applications although eminently suitable for many applications allow little flexibility in the choice of wavelength division multiplexer (WDM), and this may sometimes be a problem.
It is an object of the present invention to provide apparatus wherein this problem is largely obviated.
According to the present invention, apparatus for communication across a rotatable joint comprises first and second wavelength division multiplexers to which first and second pairs of channel signals respectively are fed thereby to provide in respect of each pair corresponding wavelength division multiplexed signals which define respective channels of each pair, a first polarising beam splitter having one input terminal to which wavelength division multiplexed signals defining the channels of the first pair are fed and another input terminal to which wavelength division multiplexed signals defining the channels of the second pair are fed, a first quarter waveplate means fed from the first polarising beam splitter with signals in which respective pairs of channel signals are mutually orthogonally polarised, a second quarter waveplate means fed via the rotatable joint with signals from the first quarter waveplate means and arranged to feed a second polarising beam splitter, third and fourth wavelength division multiplexers fed from the said second polarising beam splitter with orthogonally polarised signals corresponding to the respective pairs, which wavelength division multiplexers provide output signals corresponding to the channel signals of each pair, one pair being provided by the said third wavelength division multiplexer and the other pair being provided by the said fourth wavelength division multiplexer.
Since in apparatus according to the present invention wavelength division multiplexing is done before polarisation beam splitting, a wavelength division multiplexer (WDM) can be used which is required to work at one polarisation only and this therefore allows greater flexibility in the choice of WDM.
The said respective channels of each pair may be defined by frequencies of A1 and h2.
The channel signals of each pair may be light signals.
The light signals may be produced by LED's or lasers driven by corresponding electrical channel signals.
The output signals from the third and fourth wavelength division multiplexers may be converted to corresponding electrical signals by means of photo-electric detectors.
One embodiment of the invention will now be described by way of example only with reference to the accompanying drawing which is a somewhat schematic block diagram of a multi channel communications system for operation across a rotating boundary.
Referring now to Figure 1, a rotating boundary is shown by means of a broken line 1. Light signals which define a first pair of channel signals are fed to input lines 2 and 3 of a first WDM 4 which convert them to light signals at frequencies B1 and B2 respectively. Similarly a second pair of channel signals are fed to input lines 5 and 6 of a second WDM 7 for conversion to B1 and X2 respectively. The first WDM 4 is arranged to feed one input terminal 8 of a first polarising beam splitter 9 with signals of the first pair of channel signals at frequencies of B1 and B2 respectively.Similarly the second WDM 7 is arranged to feed the other input terminal 10 of the first polarising beam splitter 9 with light signals comprising the second pair of channel signals at the frequencies of X1 and X2 respectively. The first polarising beam splitter 9 serves to polarise the signals fed thereto on the input terminals 8 and 10 whereby they are constrained to be orthogonally related on an output line 11 which feeds an achromatic quarter waveplate 12. The achromatic quarter waveplate 12 produces corresponding circularly polarised signals which are transmitted across the rotating boundary 1 to be received by a second achromatic quarter waveplate 13 which serves to reconvert the signals to orthogonally related signals which are then applied via a line 14 to a second polarising beam splitter 15.The polarising beam splitter 15 serves to separate the orthogonally related pairs of channel signals so that the signals related to one pair are transmitted on a line 16 to a third WDM 17 and the signals on a line 18 are transmitted to a fourth WDM 19.
The WDM 17 provides output signals on lines 20 and 21 corresponding to channels of the said one pair and the WDM 19 provides output signals on lines 22 and 23 corresponding to channel signals of the other pair.
The light signals (which may be white light) which define the channel signals of each pair, may be produced by converting corresponding electrical signals with LED's for example and reconversion may be effected with photo-sensitive detectors.
Any suitable wavelength division multiplexing apparatus may be used to convert white light signals to corresponding light signals at different frequencies such as red and green for example, or to produce corresponding light signals at different light frequencies directly and any suitable polarising beam splitter and quarter waveplate may be used as will be well known to those skilled in the art. It will also be understood that WDM's may comprise selective frequency beam splitter means in an alternative embodiment of the invention.
It will also be apparent that although the present example is concerned more especially with a system using light signals, which may be in the optical frequency range for example, the principle of the invention is just as applicable to microwaves and/or light signals in other frequency spectra such as U.V. or I.R.
Claims (9)
1. Apparatus for communication across a rotatable joint comprising first and second wavelength division multiplexers to which first and second pairs of channel signals respectively are fed thereby to provide in respect of each pair corresponding wavelength division multiplexed signals which define respective channels of each pair, a first polarising beam splitter having one input terminal to which wavelength division multiplexed signals defining the channels of the first pair are fed and another input terminal to which wavelength division multiplexed signals defining the channels of the second pair are fed, a first quarter waveplate means fed from the first polarising beam splitter with signals in which respective pairs of channel signals are mutually orthogonally polarised, a second quarter waveplate means fed via the rotatable joint with signals from the first quarter waveplate means and arranged to feed a second polarising beam splitter, third and fourth wavelength division multiplexers fed from the said second polarising beam splitter with orthogonally polarised signals corresponding to the respective pairs, which wavelength division multiplexers provide output signals corresponding to the channel signals of each pair, one pair being provided by the said third wavelength division multiplexer and the other pair being provided by the said fourth wavelength division multiplexer.
2. Apparatus as claimed in Claim 1, wherein the said respective channels of each pair are defined by frequencies of X1 and h2.
3. Apparatus as claimed in Claim 1 or Claim 2, wherein the channel signals of each pair are light signals.
4. Apparatus as claimed in Claim 3, wherein the light signals are produced by LED's driven by corresponding electrical channel signals.
5. Apparatus as claimed in Claim 3 or Claim 4, wherein the light signals are in the optical frequency spectrum.
6. Apparatus as claimed in any preceding claim, wherein the output signals from the third and fourth wavelength division multiplexers are converted to corresponding electrical signals by means of photo-electric detectors.
7. Apparatus as claimed in any preceding claim and substantially as hereinbefore described with reference to the accompanying drawing.
8. A rotary line communication joint comprising apparatus as claimed in any preceding claim.
9. A rotary antenna including a rotary line communication joint as claimed in Claim 8.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9320048A GB2282503B (en) | 1993-09-29 | 1993-09-29 | Improvements in or relating to rotatable joints for communication lines |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9320048A GB2282503B (en) | 1993-09-29 | 1993-09-29 | Improvements in or relating to rotatable joints for communication lines |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9320048D0 GB9320048D0 (en) | 1993-12-08 |
| GB2282503A true GB2282503A (en) | 1995-04-05 |
| GB2282503B GB2282503B (en) | 1998-03-18 |
Family
ID=10742685
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9320048A Expired - Fee Related GB2282503B (en) | 1993-09-29 | 1993-09-29 | Improvements in or relating to rotatable joints for communication lines |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2282503B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2385403A3 (en) * | 2010-04-28 | 2015-09-16 | Schleifring und Apparatebau GmbH | Polarization maintaining optical rotary joint |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2250652A (en) * | 1990-12-07 | 1992-06-10 | Roke Manor Research | Rotatable communication joints |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2598574B1 (en) * | 1986-05-06 | 1992-02-28 | Matra | OPTICAL FREQUENCY MULTIPLEXED DATA TRANSMISSION METHOD AND DEVICE |
-
1993
- 1993-09-29 GB GB9320048A patent/GB2282503B/en not_active Expired - Fee Related
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2250652A (en) * | 1990-12-07 | 1992-06-10 | Roke Manor Research | Rotatable communication joints |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2385403A3 (en) * | 2010-04-28 | 2015-09-16 | Schleifring und Apparatebau GmbH | Polarization maintaining optical rotary joint |
| US9507093B2 (en) | 2010-04-28 | 2016-11-29 | Schleifring Und Apparatebau Gmbh | Polarization maintaining optical rotary joint |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9320048D0 (en) | 1993-12-08 |
| GB2282503B (en) | 1998-03-18 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 732E | Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977) | ||
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20030929 |