EP2914991A1

EP2914991A1 - Optical rotary transmitter

Info

Publication number: EP2914991A1
Application number: EP13789742.7A
Authority: EP
Inventors: Hans Poisel; Olaf Ziemann; Alexander Bachmann; Martin Bloos; Roman Kruglov
Original assignee: Georg Simon Ohm Hochschule fuer Angewandte Wissenschaften Fachhochschule Nurnberg
Current assignee: Georg Simon Ohm Hochschule fuer Angewandte Wissenschaften Fachhochschule Nurnberg
Priority date: 2012-10-31
Filing date: 2013-10-31
Publication date: 2015-09-09
Also published as: CN104969105A; DE102012021453B4; DE102012021453A1; US9678280B2; WO2014068059A1; JP2016502681A; US20150316726A1

Abstract

The invention relates to an optical rotary transmitter for transmitting optical signals, comprising a first light coupler (1) that has one or a plurality of first light guides (11) the end faces of which are designed to transmit optical signals and are arranged on a first ring about a central rotational axis Z, a second light coupler (3) that has one or a plurality of second light guides (31) the end faces of which are designed to transmit optical signals and are arranged on a second ring about the central rotational axis Z, a fibre mirror (5) comprising a plurality of third light guides that are arranged between said two light couplers (1, 3) and are designed to compensate for the effect, on the transmission of the optical signals, of the two light couplers (1, 3) rotating relative to one another, the end faces of the third light guides being designed to transmit optical signals and arranged on a third and fourth ring about the central rotational axis Z. Light inlet/outlet surfaces that are formed by the third and fourth rings are substantially gap-free such that the optical signals can be continuously transmitted without interruption.

Description

Optical rotary transformer

The invention relates to an optical rotary transformer and an associated method for transmitting optical signals.

Such a rotary transformer is known, for example, from WO 2011/137983 and may be a constituent of e.g. one

Rotary coupling or other device with

rotatable, spaced apart parts, be. It allows unidirectional or bidirectional

Transmission of optical signals between the relatively rotatable parts regardless of their rotational position and angular velocity. The wavelength range can range from long-wave IR radiation to short-wave UV radiation. In this sense, the following are the terms

To understand "optical" and "light".

From US-A-4 943 137 a rotary transformer is known, by means of which light from an optical transmitter, the one of the two relatively rotatable parts

is assigned, is passed via optical fibers and collimators on a optical coupling assembly and from this on to an optical receiver, which is associated with the other rotatable part. The coupling assembly is used to derotation of the light and rotates at half the angular velocity of the two relatively rotatable parts. This coupling assembly is shown in Figure 3 to illustrate the

shown in principle construction, without being further described in detail here. Reference should be made to the disclosure of said publication.

With this rotary transformer, it is possible to transmit several channels in parallel, since each light guide of the one

rotatable part is fixedly assigned to a light guide of the other rotatable part. Theoretically, as many channels can be transmitted as light readers are used. However, because of crosstalk into adjacent channels, the number of channels actually available is usually about half of the fiber.

This document also shows the use of collimators for coupling the light in the end faces of the

Light guide. The collimators are arranged along the circumference of the fiber mirror with an intermediate spacing. A problem with this configuration is that upon rotation of the device, a variation of the amplitude of the transmitted optical signal occurs, between a maximum when a light guide of the rotatable part hits a light guide in the fiber mirror and which is minimal when the light guide of the rotatable part lies exactly between two light guides of the fiber mirror. In many

Transfer tasks is such a variation of

Signal strength unacceptable.

Furthermore, it is known from DE 019529527 C1, by thermally induced swelling of the fiber of a Lichtleitrs, whose end portions to give a nearly rectangular or square cross-section.

All these known rotary transformer have the problem that a continuous signal transmission with good

Quality and high transmission rate can not be done with a large free space inside.

The invention is based on the object, a

Rotary transmission to provide the at

comparatively simple construction ensures a reliable and continuous transmission of a plurality of optical signals simultaneously in physically separate channels between the relatively rotatable parts.

This object is achieved by a rotary transformer according to claim 1. The dependent claims relate to further advantageous embodiments of the invention.

The rotary transformer can operate unidirectionally or bidirectionally. In the following, therefore, the terms "send" and "receive ¹¹ are interchangeable.

As a result of its simple and largely symmetrical structure of the rotary transformer is inexpensive to produce and

ensures at the same time independent of the angular velocity of the relatively rotatable parts, high signal transmission security. The light guides are preferably made of optical waveguides in the form of fiber optic fibers, which are expediently combined at their input or Auskoppelende to form a bundle. At the input or Auskoppelende can be coupled directly or via a concentrator one of the usual optical semiconductor transmitter or receiver.

Alternatively, but more elaborately, each fiber optic fiber can end at a transmitting or receiving element associated with it. In this case, all transmission elements must be controlled in parallel and the reception signals of the reception elements must be brought together. The higher light transmit power improves the signal-to-noise ratio of the signals on the receive side.

The invention is described below with reference to the drawing

explained in the schematically simplified

Embodiments of the essential parts of

Drehübertragers are shown. It shows:

1 shows an optical rotary transformer according to the invention with fiber mirror,

2 shows an embodiment of a collimator,

Fig. 3 is a detail view of a known fiber mirror of the prior art to illustrate the basic structure of a Faserspiegeis; and Fig. 4 shows a preferred arrangement of the end faces of

Optical fiber of a fiber mirror according to the invention.

Figure 1 shows the essential parts of the rotary transformer. It comprises a first light coupler 1 and a second one

Light coupler 3. The two light couplers 1, 3 are arranged opposite each other. The first light coupler 1 is associated with a first, not shown part of the rotary transformer, the second light coupler 3 a second part of this rotary transformer, which is rotatable relative to the first part about a common axis of rotation Z.

The first light coupler 1 comprises a plurality of first

Light guide 11, the end faces 13 configured for transmitting optical signals and arranged on a first ring about the rotation axis Z. Likewise, the second light coupler 3 comprises a plurality of second light guides 31, the end faces of which are designed to transmit optical signals and are arranged on a second ring about the rotation axis Z.

The first light coupler 1 comprises a first collimator group 7. Analogously, the second light coupler 3 comprises a second collimator group 7

Collimator group 9. The first collimator group 7 preferably comprises uniformly on the circumference of a circle

distributed collimator arrangements. The second collimator group 9 comprises collimator arrangements arranged in an analogous manner. The

Kollimatoranordnungen send or receive light in

Substantially parallel to the common axis of rotation Z. The radiation direction is indicated in Fig. 1 only by way of example by the single arrows, in which case the

Light coupler 1 of the transmission light coupler and the light coupler 3 of the receiving light coupler is. Of course, this relationship is reciprocal.

Between the two light couplers 1, 3, a fiber mirror 5 is arranged. The fiber mirror 5 is designed to rotate in a known manner at half the rotational speed with the one rotating light coupler 1, 3 with. The fiber mirror 5 has a plurality of third optical fibers, which are arranged between the two light couplers 1, 3 and

are configured to compensate for the influence of a relative rotation between the two light couplers 1, 3 on the transmission of the optical signals, wherein the end faces 53, 55 of the third optical fiber designed to transmit optical signals and on a third and fourth ring about the axis of rotation Z. are arranged. such

Fiber mirrors are known and exemplarily described in US 4,943,137. The light guides and their course in the interior of the fiber mirror is not shown in Fig. 1. However, the principle is shown in Figure 3 based on the known Faserspiegeis.

The first ring is opposite the third ring, and the second ring is opposite the fourth ring.

The fiber mirror 5 comprises a third collimator group 72 and a fourth collimator group 92. The third and fourth collimator groups 72, 92 comprise uniform and

distributed contiguously on the circumference of a circle Kollimatoranordnungen so that these light entrance / light exit surfaces of the fiber mirror on the third and fourth ring form, which are substantially continuous, so that a continuous transmission of the optical signals without interruption is made possible.

The collimator assemblies also transmit and receive light substantially parallel to the common axis of rotation.

The light guides in the light couplers 1, 3 and in the

Fiber mirrors 5 are preferably fiber optic fibers.

The fiber optic fibers in the light couplers 1, 3 are combined into a bundle, which is then continued to a suitable transmitter or receiver.

The collimator groups 7, 72 and 9, 92 are designed such that they are coupled via the respective fiber optic fiber

Transform light signal into a parallel beam or couple the received parallel beam in the connected fiber optic fiber.

The circular or annular shape of the Kollimatorgruppn 7, 9, 72, 92 leaves an inner diameter of the light coupler 1, 3 and the fiber mirror 5 free, so that e.g. via bores other parts, not shown, of the rotary transformer, e.g. a

Drive shaft passed or not shown

Rotary bearings can be arranged.

FIG. 2 illustrates, by way of example only, the structure of a collimator arrangement of each of the collimator groups 7, 9, 72, 92, showing a centrically connected fiber optic fiber. The collimator arrangement comprises a lens 15, over the imaging surface of which a parallel beam of rays enters. The lens 15 is followed by a conical body 17 for guiding the light towards a surface followed by optical concentrators 19 which adjust the diameter and aperture of the light beam to the coupling diameter and aperture of the respective fiber optic fiber. The fiber optic fiber is connected via a non-illustrated and known per se connection device in the form of a connection and coupling point with the collimator preferably directly, that is without air gap, connected. The collimator assemblies of the light couplers 1, 3 may be spaced apart on the first and second rings. Their number is determined by the number of people to be transferred

parallel signal channels. At least one collimator assembly and one optical fiber are to be provided in each light coupler per channel. Advantageously, a channel simultaneously via a plurality of optical fibers and Kollimatoranordnungen the

Light coupler 1, 3 transmitted to increase the reliability of the transmission.

Thus, it is preferred that the light guides 51 of the

Fiber mirror 5 relative to the optical fibers 11, 31 of the

Light coupler 1, 3 are arranged on the respective light entry / light exit surfaces so that whenever at least one optical fiber of a light coupler 1, 3 is aligned with a light guide 51 of the fiber mirror 5 for transmitting an optical signal exactly, at least one other optical fiber of a light coupler. 1 , 3 is aligned with another light guide 51 of the fiber mirror 5 offset by a portion of the diameter of the end face of a light guide.

For example, the light guides of the light couplers can be arranged so that, if one a certain channel

is aligned exactly with a light guide of the fiber mirror, another one of the same channel transmitting light guide of the same light coupler is between two light guides of the fiber mirror, so be

Signal is distributed to two optical fibers of the fiber mirror. In this way, the variations in the transmission of the channel are reduced. A part of the signal is always swallowed by the lateral surfaces of the receiving optical fibers.

In a transmission of the same channel on three light guides of a light coupler, the arrangement should be such that when one of the light guides of the light coupler is aligned with its counterpart of the fiber mirror, another by a

Drittle the diameter of the end face of a light guide staggered, while the third light guide is offset by 2/3. The number of optical fibers and the Kollimatoranordnungen each Lichtkopplers here is an integer multiple of the number of channels. Experiments have shown that 150 independent channels can easily be transmitted.

The Kollimatoranordnungen on the side of the fiber mirror are formed adjacent to each other, so that a in

Essentially gap-free light entrance / light exit surface is formed both on the third ring and on the fourth ring. Since the diameters of the collimator arrangements are a multiple of the diameter of the end faces of the

Make out light guides is the number of needed ones

Kollimatoranordnungen much smaller than, if attempted, the gap-free light entrance / light exit surface of the fiber mirror only with a circular cross-section

To form light guides.

Taking as an example a free inner diameter of 1 m, so can when using 1 mm light guides on the fiber mirror and optics with a diameter of 15 mm, the number of

Fiber optics in the fiber mirror are reduced to 1/15, compared to the case without Kollimatorgruppen, i. about 200 optical fibers in the fiber mirror are sufficient, instead of the 3000 in the prior art.

Nevertheless, one or two collimator arrangements of the fiber mirror will always face a collimator arrangement of the light coupler, so that almost the entire closes

Obertragende light is forwarded.

The structure of the fiber mirror is considerably simplified.

Because of each fiber optic collimator almost

axis-parallel rays emerge, the axial distance is not critical for the losses in the transition into the optical fiber Kollimatorgruppe the fiber mirror. The same applies to the transition from the fiber mirror to the

Output side light couplers of a further advantageous embodiment of the invention, a plurality of coaxial arrangements of this type are mounted with increasing diameter in order to increase the number of channels to be transmitted.

In principle, the fiber mirror can be made from any number of light guides. It turns out, however it is expedient to design the fiber mirror such that the number of fibers is divisible by at least 2, better by 4 integer.

In order to keep the number of fibers in acceptable dimensions for large free inner diameters, in the first embodiment described here both the light couplers 2, 3 and the fiber mirror 5 are of collimator type

each equipped with a plurality of

Kollimatoranordnungen 7, 71, 9, 91 are constructed, as described above.

Conveniently, each collimator assembly becomes one

Have cross-sectional area, which allows no gaps on the ring of the endstitches of the associated light guide. For this purpose, the Kollimatoranordnungen can also be square or so trapezoidal.

For better use of the fiber mirror with

On the receiving side, when transmitted, collimated signals can be used with a lens having an area equal to that of two lenses of the fiber mirror and also having a focal length adapted to this new diameter.

In an alternative embodiment, in addition to or instead of the collimator groups of the fiber mirror, the end faces provided there may be deformed the optical fibers, for example from approximately to approximately square, for example by

thermally induced swelling of the fiber. Also in this way it is possible to optimize the used area for the coupling.

As an alternative to deformation, it is possible to anyone

Optical fiber through a bundle of individual fibers with

small diameter, and then these individual fibers on the end face of the light guide of a

to form a circular arrangement into a square or rectangular arrangement.

In a further preferred embodiment, with or without collimator groups on the fiber mirror, two layers of optical waveguides which are circular in cross section may be gap-shaped

be arranged only half the diameter of the have feeding optical fiber. Thus, the surface coverage with the incoming and outgoing optical fibers can be almost uniform, resulting in smaller attenuation differences. This is shown by way of example in FIG. 4.

To further improve the transmission, it is possible to transmit the same signal to two or more channels of the fiber mirror, the positions of the transmitters should be offset by a part of a distance of two channels of Faserspiegeis.

Although the invention has been described in terms of preferred embodiments, those skilled in the art will recognize that it can make numerous other modifications and variations. So it is not mandatory that the two light couplers have the same diameter. A difference in diameter can be compensated by the fiber mirror. It is also possible in principle to align the two light couplers in the same direction, for example, to receive a light filter in the interior of the other light guide. In this case, the fiber optic fibers should be routed so that the light enters and exits the Sete.

When the faces of the deformed light guide as

can be described rectangular or square, so this is not to be understood in the strict geometric sense. This refers to any deformation of the end faces, which makes it possible to construct a substantially gapless surface from the end faces of a plurality of optical fibers.

Claims

claims

1. Optical rotary transformer for transmitting optical signals with

a first light coupler (1), the one or a

A plurality of first optical fibers (11) whose end faces are configured to transmit optical signals and are mounted on a first ring about a central axis of rotation (Z)

are arranged;

a second light coupler (3) having one or a plurality of second optical fibers (31) whose

Front surfaces for transmitting optical signals

configured and on a second ring around the central

Rotation axis (Z) are arranged;

a fiber mirror (5) having a plurality of thirds

Light guides, which are arranged between the two light couplers (1, 3) and designed to compensate for the influence of a relative rotation between the two light couplers (1, 3) on the transmission of the optical signals, wherein the end faces of the third optical fibers for transmitting optical Signals are arranged and arranged on a third and fourth ring about the central axis of rotation (Z);

characterized in that

formed by the third and fourth ring light entry / light exit surfaces are substantially seamless, so that a continuous transmission of the optical signals without interruption is made possible.

2. Optical rotary transformer according to claim 1, characterized

marked that

the first and the second light coupler (1, 3) comprise a number of collimator arrangements arranged in such a way that that their focus falls on the face of a light guide; and

Light entrance / light exit surfaces of the third and fourth ring of the fiber mirror are formed by a plurality of further Kollimatoranordnungen, wherein at the focal point of each Kollimatoranorndnung the Faserspiegeis is the end face of a light guide of the fiber mirror.

3. Optical rotary transformer according to claim 1, characterized

marked that

the end portions of the third optical fibers (51)

are designed so that their faces in the

form substantial gapless areas on the third and fourth ring.

4. Optical rotary transformer according to claim 3, characterized

marked that

the end portions of the third optical fibers are formed from a bundle of thin individual fibers.

5. Optical rotary transformer according to claim 3, characterized

marked that

the end portions of the third optical fibers are formed of thermally deformed fibers of approximately rectangular cross-section.

6. Optical rotary transformer according to claim 3, characterized

marked that

the end portions of the third optical fibers in two rows offset in space fill the surfaces of the third and fourth rings, wherein the cross section of the third optical fibers is half the cross section of the first and / or second

Light guide is.

7. Optical rotary transformer according to one of claims 1 to 6, characterized in that the number of optical fibers of the fiber mirror is integer by two, preferably divisible by four.

8. Optical rotary transformer according to claim 7, characterized

marked that

the light guides (51) of the fiber mirror (5) relative to the light guides (11, 31) of the light couplers (1, 3) on the respective light entrance / exit surfaces so

are arranged so that whenever at least one optical fiber of a light coupler (1, 3) with an optical fiber (51) of the fiber mirror (5) for the transmission of an optical signal is exactly aligned, at least one other optical fiber of a light coupler (1, 3) with a another optical fiber (51) of the fiber skein (5) to a part of the diameter of the

End face of a light guide is offset aligned.