GB2247089A - Optical fibre rotating joint with coupling lenses - Google Patents
Optical fibre rotating joint with coupling lenses Download PDFInfo
- Publication number
- GB2247089A GB2247089A GB9018070A GB9018070A GB2247089A GB 2247089 A GB2247089 A GB 2247089A GB 9018070 A GB9018070 A GB 9018070A GB 9018070 A GB9018070 A GB 9018070A GB 2247089 A GB2247089 A GB 2247089A
- Authority
- GB
- United Kingdom
- Prior art keywords
- optical
- rotating joint
- optical fibre
- lenses
- fibre rotating
- 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
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
-
- 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
- G02B6/32—Optical coupling means having lens focusing means positioned between opposed fibre 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
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Optical Couplings Of Light Guides (AREA)
- Mechanical Coupling Of Light Guides (AREA)
Abstract
An optical fibre rotating joint comprises a first F1 and second part S2, rotatable with respect to each other, about a common axis. A free space path is provided between the two parts. Each part has several coupling lenses 10, 11 positioned to form a circle and each lens may be connected to an optical coupler 4, 8 by a respective pigtail optical fibre 9, 12, the optical coupler may be connected to a wavelength division multiplexer which is connected to an optical transmitter and an optical receiver. Therefore a transmission path exists between each part via the optical rotating joint. Each transmit lens 10 is suitably shaped or is provided with an anamorphic prism pair to generate an elliptical beam 13 which overlaps adjacent beams thereby forming an annular beam when an optical signal is transmitted from one part to the other part. The lenses 11 in the receiving part are arranged to intercept the annular beam and couple the optical signal in to their respective optical fibres 12. <IMAGE>
Description
AN OPTICAL FIBRE ROTATING JOINT
The present invention relates to an optical fibre rotating joint. The invention finds utility in any application where first and second parts of a body are rotatable with respect to each other, and where there is a requirement to pass information between equipment located in the first and second parts.
The present invention may also be used in a fibre distributed data interface (FDDI) local area network (LAN) application or may be used to send other digital and/or analog (RF, IF or base band) signals between the two parts. Optical fibre rotating joints are available where the transmission path is either along the axis of rotation of the first and second parts or concentric to this axis of rotation. The first type of joints are known as 'on axis' optical fibre rotating joints. Such joints are limited to the amount of information that can be transmitted through and therefore a requirement of the present invention is to provide an 'off axis' optical fibre rotating joint in which very much more information can be transmitted between the two parts.
An object of the present invention is to provide an optical fibre rotating joint, of the 'off axis' type, wherein the amount of information that can be passed between the various parts of the joint is very much increased with respect to the known on axis type of joint. In addition, due to mechanical constraints the on axis transmission path may not be available, and hence an off-axis rotating joint is required.
To minimise the free space coupling lenses between the first and second parts of the optical rotating joint, the transmit fibre to free space coupling lenses are optimised to provide a divergent elliptical beam. The receive free space to fibre coupling lenses are optimised to couple the maximum free space signal into the attached optical fibre.
By using such techniques the optical rotating joint provides a low loss path between the first and second parts and a higher low return path between the second and first parts.
According to the present invention there is provided an optical fibre rotating joint comprising a first part and a second part rotatable with respect to each other about an axis substantially common to both parts, and having a free space path there between, each part having a plurality of coupling lenses arranged to form a circle, connecting the respective fibre to free space, the lens of the first part being arranged substantially opposite to the lenses of the second part, and each transmitting lens is arranged to generate an elliptical beam which overlaps adjacent beams to form an annular beam when an optical signal is transmitted from the lenses, and the receiving lenses in the opposite part are arranged to intercept the annular beam and couple the optical signal into their respective optical fibres.
According to an aspect of the present invention the optical fibres in the first part are connected to a l:N optical coupler.
According to a further aspect of the present invention the optical fibres in the second part are connected to an N:l optical coupler.
According to a further aspect of the present invention each part is provided with a plurality of coupling lenses positioned on respective concentric circles thereby generating a plurality of concentric annular beams.
For low loss duplex operation two concentric off-axis optical rotating joints are used to carry the two directions of signal prepagation.
The present invention offers the following advantages:
(i) The use of a continuous annular beam enables the transmission of real time analog and/or digital signals where time delays are to be minimised. In addition, this technique reduces the signal amplitude variation with rotation.
(ii) The use of a multiway optical splitter to form the annular beam simplifies the free space optical design and size of the optical beam forming components. The use of a multiway optical combiner to perform the coherent combining of the various free space beams provides a compact, low loss beam combining technique.
(iii) The use of a number of free space beams in the optical rotating joint enables its reliability to be enhanced.
A number of the coupler fibre pigtails or coupling lenses can be damaged but the optical rotating joint will still function, but at a reduced signal level. This characteristic also allows for a coupling lens cleaning system to be implemented without interrupting the operation of the optical link.
An embodiment of the present invention will now be described with reference to the accompanying drawings wherein:
Figure 1 shows a schematic diagram of an optical fibre rotating joint in accordance with the present invention, and,
Figure 2 shows a typical layout of the optical fibre rotating joint.
Referring to Figure 1, a first part Fl and second part S2 is shown which are rotatable with respect to each other.
The general arrangement of a dual channel used in the optical rotating joint is shown in Figure 1. This shows an optical transmitter 1 (optical wavelength X1), a two channel wavelength division multiplexer (WDM) 2, an optical transmitter 3 (wavelength X2) and a multiway (l:N) optical coupler 4 mounted in the first part Fl. In the second part S2 is mounted an optical receiver 5 (optical wavelength > 2), a two channel wavelength division multiplexer WDM, 6, an optical receiver 7 (wavelength Xi) and a multiway (N:l) optical coupler 8. A four channel wavelength division multiplexer and additional optical transmitters and receivers can be used to implement a four channel optical rotating joint.
An electrical signal applied to input 1 is converted in the optical transmitter 1 to produce a suitably modulated optical signal at wavelength X1. The modulated optical signal is directed by the wavelength division multiplexer, 2 to the multiway (l:N) optical coupler 4. The optical signal is split
N ways by the coupler 4.
The circular free space output beams obtained from the fibre pigtails 9 are modified to provide an elliptical beam shape by the use of suitably selected fibre to free space coupling lenses 10. The fibre pigtails 9 and coupling lenses 10 are positioned to form a circle around the periphery of an opening either side of the part Fl and part S2 interface. The free space path between the coupling lenses 10 mounted in the first part Fl and the coupling lenses 11 mounted in the second part S2 is approximately 5 cm.
After transmission across the free space path the optical signals are coupled via the coupling lenses 11 into the fibre pigtails 12 of the N:l optical coupler 8 mounted in the part S2. After coherent combining of the N optical signals the single output of the optical coupler 8 is directed by the wavelength division multiplexer 6, to the optical receiver 7 where signal 1 is converted back to an electrical signal.
The transmission of signal 2 from the part Fl to the part S2 is similar to that described for signal 1, however, an optical wavelength > 2 is used instead of 1 and output receiver 5 converts signal 2 back to an electrical signal.
The wavelength division multiplexer provides isolation between the two optical signals and allows the dual channel link to operate over a single rotating joint.
A four channel duplex link can be implemented by using two concentric off-axis optical rotating joints as described above.
The optical rotating joint can be extended to four channels by using a four channel wavelength division multiplexer operating at optical wavelengths 1' ,\2' 2 > 3 and 44. Additional optical transmitters and receivers are also required in both the parts Fl and S2.
A single off-axis duplex link can be implemented but at the expense of a higher insertion loss and a more complex, wavelength sensitive, fibre for free space and free space to fibre dual coupling lens design.
The diagram shown in Figure 2 gives the mechanical arrangement and beam characteristics for the free space section of the optical rotating joint. An output from an optical transmitter mounted in the part Fl is split into N free space optical beams by the l:N way optical coupler 4.
The fibre to free space coupling lenses 10 convert the circular output beam obtained from the optical fibre 9 to an elliptical beam 13. The N elliptical beams are arranged to overlap each other and form an annulus with a diameter compatible to the opening.
After transmission across the free space optical path the optical signals are intercepted in the part S2 by the free space to fibre coupling lenses 1, which are optimised to couple the received optical signal into the optical lenses 12.
The coupling lenses 10 and optical fibres 9 are mounted in close proximity to those mounted in the part S2 and on the same axis of rotation. The intercepted optical signals are coherently combined in the N:l optical coupler 8 and then send via a single optical fibre to the optical receiver.
The coupler splitting/combining ratio (l:N/N:l) is determined by the circumference of the optical rotating joint, free space path length and coupling lens characteristics.
For an optical rotating joint diameter of 1 m, free space path length of 5 cm and a coupling lens free space beamwidth of 200 by 1200 requires an optical coupler spitting ratio (N) of 32.
To achieve low loss coherent optical combining of the
N optical signals the fibre pigtail lengths used with the l:N and N:l couplers should be cut to similar lengths and the variation in free space optical path length should be minimised.
The allowable loss budget of an FDDI node to node link is determined by the transmitter optical output power (-12 dBm) and the optical receiver sensitivity (-33 dBm for a BER of l0-). This gives a maximum loss budget of 21 dB.
The link loss for the optical rotating joint is dependent on the loss of the two wavelength division multiplexers (1 dB per WDM), optical splitter and combiner excess loss (3 dB per 32 way coupler), optical fibre connection losses (2 dB) and the free space coupling loss (7 dB for a unidirectional link). This connection losses (2 dB) and the free space coupling loss gives an (7 dB for a insertion loss of 17 dB and a link margin of 4dB.
To provide a larger link margin a laser diode optical source could be used in place of the light emitting diode assumed in the above calculation. A laser diode suitable for use at FDDI data rates would provide an average optical output power in excess of 0 dBm. Hence by using a laser diode source the allowable loss budget would be increased by 12 dB to 33 dB.
Higher receiver sensitivity could be achieved by the use of an avalanche photodiode (APD) detector in place of the
PIN photodiode used in a standard FDDI node optical receiver.
An APD detector would provide between 5 and 10 dB improvement in receiver sensitivity.
Hence by optimising the optical source or photodetector characteristics, the link margin can be significantly improved over that which can be achieved by using standard FDDI node components.
For operation with an FDDI LAN for optical rotating joint would use four concentric off-axis channels to interconnect a dual attachment station in the rotating part of the body.
Although the FDDI PmD-l (physical medium devices) standard specifies the use of 50/125 or 62.5/125 pm diameter multimode optical fibre and an optical wavelength of 1300 nm, the optical rotating joint can be configured to operate with a range of multimode (50/125 to 200/280Jum and single mode (8/125 pm) optical fibres and at either 350, 1300 or 1550 nm wavelengths.
Wavelength division multiplexed systems can be continuations of wavelengths in the 850/1300 or 1300/1550 JIm fibre transmission windows.
The number of channels that can be handled by the optical rotating joint can be increased by using a larger number of optical wavelengths. This is limited by the type of wavelength division multiplexer and optical source used. For a system using laser optical sources and direct optical detection a total of ten channels is feasible.
It will readily be understood by those skilled in the art that alternative arrangements for implementing the invention may be envisaged which fall within the spirit and scope of the present invention. For example the elliptical beam may be generated by suitably shaped lenses or may be generated by an anamorphic prism pair. Furthermore, to increase the amount of data that can be transmitted across the free space path, a number of concentric mounted lenses and fibre pigtails may be employed in both the first part F1 and second part S2 which would be connected to a number of respective optical coupler of suitable size to handle the extra pigtails.
It will also be appreciated that there are various ways of implementing the duplex link. A dual lens close spaced arrangement, optimised for the transmit and receive paths, mounted in both parts F1 and S2 may be used. This would require an additional 1:2 way coupler or a two-channel wave division multiplexer to combine/split the transmit/ receive signals. Alternatively, two optical couplers may be used in the first and second parts F1 and S2. The separation of the 850 and 1300 nm wavelength signals would be performed by the use of a band pass optical filter at the output of each transmitter and at the input to each receiver.
Claims (15)
1. An optical fibre rotating joint comprising a first part and a second part rotatable with respect to each other about an axis substantially common to both parts, and having a free space path there between, each part having a plurality of coupling lenses arranged to form a circle, connecting a respective fibre to free space, the lenses of the first part being arranged substantially opposite the lenses of the second part, and each transmitting lens is arranged to generate an elliptical beam which overlaps adjacent beams to form an annular beam when an optical signal is transmitted from the lenses, and the receiving lenses in the opposite part are arranged to intercept the annular beam and couple the optical signal into their respective optical fibres.
2. An optical fibre rotating joint as claimed in claim 1, wherein the optical fibres in the first part are connected to a l:N optical coupler.
3. An optical fibre rotating joint as claimed in claim 2, wherein the optical coupler is connected to a wavelength division multiplexer providing at least dual channel operation.
4. An optical fibre rotating joint as claimed in claim 1, wherein the optical fibres in the second part are connected to an N:l optical fibre.
5. An optical fibre rotating joint as claimed in claim 4, wherein the optical coupler is connected to a wavelength division multiplexer providing at least dual channel operation.
6. An optical fibre rotating joint as claimed in claims 3, wherein the wavelength division multiplexer is connected to optical transmitters receiver.
7. An optical fibre rotating joint as claimed in claim 5, wherein the wavelength division multiplexer is connected to optical receivers.
8. An optical fibre rotating joint as claimed in claim 1, wherein the free space between the first and second part is substantially 5 cm for a circle diameter of 1 metre upon the circumference of which the optical coupling lenses are positioned.
9. An optical fibre rotating joint as claimed in claim 8, wherein each transmit coupling lens produces a beam width of 200 by 1200.
10. An optical fibre rotating joint as claimed in claims 2 and 4, wherein the optical coupler has a splitting ratio of N = 32.
11. An optical fibre rotating joint as claimed in claim 8, wherein each transmit and receive lenses are suitably shaped to provide the required beam width and efficient free space for fibre coupling.
12. An optical fibre rotating joint as claimed in claim 8, wherein each transmit lens is provided with an anamorphic prism pair to provide the required beam width.
13. An optical fibre rotating joint as claimed in any preceding claim, wherein a plurality of concentric lenses are provided in the first and second parts generating a plurality of concentric annular beams thereby increasing the number of channel which can be transmitted across the optical fibre rotating joint.
14. An optical fibre rotating joint substantially as hereinbefore described.
15. An optical fibre rotating joint substantially as hereinbefore described with reference Figures 1 and 2 of the accompanied drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9018070A GB2247089B (en) | 1990-08-17 | 1990-08-17 | An optical fibre rotating joint |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9018070A GB2247089B (en) | 1990-08-17 | 1990-08-17 | An optical fibre rotating joint |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9018070D0 GB9018070D0 (en) | 1990-10-03 |
| GB2247089A true GB2247089A (en) | 1992-02-19 |
| GB2247089B GB2247089B (en) | 1993-11-03 |
Family
ID=10680810
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9018070A Expired - Fee Related GB2247089B (en) | 1990-08-17 | 1990-08-17 | An optical fibre rotating joint |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2247089B (en) |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2716318A1 (en) * | 1994-02-17 | 1995-08-18 | Giat Ind Sa | Electrical signal transmission between relatively rotating parts e.g. for armoured vehicle with turret |
| EP2015118A3 (en) * | 2007-06-21 | 2009-01-21 | Schleifring und Apparatebau GmbH | Optical Rotary Joint |
| WO2011137983A1 (en) | 2010-05-04 | 2011-11-10 | Georg-Simon-Ohm Hochschule für angewandte Wissenschaften Fachhochschule Nürnberg | Optical rotary transmitter |
| CN102576131A (en) * | 2009-08-31 | 2012-07-11 | 旭化成电子材料株式会社 | Optical rotary joint |
| CN103149642A (en) * | 2013-03-22 | 2013-06-12 | 上海理工大学 | Off-axis optical fiber rotary connector |
| DE102012021453A1 (en) * | 2012-10-31 | 2014-04-30 | Georg-Simon-Ohm Hochschule für angewandte Wissenschaften Fachhochschule Nürnberg | Optical rotary transformer |
| WO2015071197A1 (en) * | 2013-11-13 | 2015-05-21 | Leoni Kabel Holding Gmbh | Optical slip ring arrangement |
| JP5841665B2 (en) * | 2012-08-24 | 2016-01-13 | 中部日本マルコ株式会社 | Non-contact connector |
| RU2619796C1 (en) * | 2016-05-25 | 2017-05-18 | АКЦИОНЕРНОЕ ОБЩЕСТВО "Научно-исследовательский институт оптико-электронного приборостроения" (АО "НИИ ОЭП") | Device for information transmission |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4109997A (en) * | 1976-03-04 | 1978-08-29 | The United States Of America As Represented By The Secretary Of The Navy | Optical sliprings |
-
1990
- 1990-08-17 GB GB9018070A patent/GB2247089B/en not_active Expired - Fee Related
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4109997A (en) * | 1976-03-04 | 1978-08-29 | The United States Of America As Represented By The Secretary Of The Navy | Optical sliprings |
Cited By (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2716318A1 (en) * | 1994-02-17 | 1995-08-18 | Giat Ind Sa | Electrical signal transmission between relatively rotating parts e.g. for armoured vehicle with turret |
| EP2015118A3 (en) * | 2007-06-21 | 2009-01-21 | Schleifring und Apparatebau GmbH | Optical Rotary Joint |
| CN102576131B (en) * | 2009-08-31 | 2015-09-02 | 旭化成电子材料株式会社 | Optical rotary joint |
| US8983246B2 (en) | 2009-08-31 | 2015-03-17 | Asahi Kasei E-Materials Corporation | Rotary optical link joint |
| CN102576131A (en) * | 2009-08-31 | 2012-07-11 | 旭化成电子材料株式会社 | Optical rotary joint |
| WO2011137983A1 (en) | 2010-05-04 | 2011-11-10 | Georg-Simon-Ohm Hochschule für angewandte Wissenschaften Fachhochschule Nürnberg | Optical rotary transmitter |
| DE102010036174A1 (en) * | 2010-05-04 | 2011-11-10 | Georg-Simon-Ohm Hochschule für angewandte Wissenschaften Fachhochschule Nürnberg | Optical rotary transformer |
| US9291777B2 (en) | 2010-05-04 | 2016-03-22 | Technische Hochschule Georg Simon Ohm | Optical rotary transmitter |
| JP5841665B2 (en) * | 2012-08-24 | 2016-01-13 | 中部日本マルコ株式会社 | Non-contact connector |
| DE102012021453A1 (en) * | 2012-10-31 | 2014-04-30 | Georg-Simon-Ohm Hochschule für angewandte Wissenschaften Fachhochschule Nürnberg | Optical rotary transformer |
| WO2014068059A1 (en) * | 2012-10-31 | 2014-05-08 | Georg-Simon-Ohm Hochschule für angewandte Wissenschaften Fachhochschule Nürnberg | Optical rotary transmitter |
| DE102012021453B4 (en) * | 2012-10-31 | 2015-05-28 | Georg-Simon-Ohm Hochschule für angewandte Wissenschaften Fachhochschule Nürnberg | Optical rotary transformer |
| US9678280B2 (en) | 2012-10-31 | 2017-06-13 | Venturetec Mechatronics Gmbh | Optical rotary transmitter |
| CN103149642B (en) * | 2013-03-22 | 2014-10-15 | 上海理工大学 | Off-axis optical fiber rotary connector |
| CN103149642A (en) * | 2013-03-22 | 2013-06-12 | 上海理工大学 | Off-axis optical fiber rotary connector |
| WO2015071197A1 (en) * | 2013-11-13 | 2015-05-21 | Leoni Kabel Holding Gmbh | Optical slip ring arrangement |
| US9684132B2 (en) | 2013-11-13 | 2017-06-20 | Leoni Kabel Holding Gmbh | Optical slip ring arrangement |
| RU2619796C1 (en) * | 2016-05-25 | 2017-05-18 | АКЦИОНЕРНОЕ ОБЩЕСТВО "Научно-исследовательский институт оптико-электронного приборостроения" (АО "НИИ ОЭП") | Device for information transmission |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2247089B (en) | 1993-11-03 |
| GB9018070D0 (en) | 1990-10-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19950817 |