DE102006022023A1 - Transmitter for optical signals between relatively rotary units includes two collimators for coupling optical fibres, with second collimator rotatable about axis - Google Patents

Abstract

Both collimators (21,22) are fitted with coupled optical fibers (2), second collimator (22) is rotatable about axis (24) with respect to first collimator (21) in light path between both collimators is located derotary optical element (23).At least one collimator includes support plate and lens for coupling of optical fibres to support plate. Lens may be formed of plate surface to couple optical fibre to polate surface. Independent claims are included for collimator and its manufacture.

Description

technical area

The The invention relates to a device for transmitting optical signals between mutually rotatable units (rotary joint). It should transmit multiple optical signals in multiple channels simultaneously become.

For transmission optical signals between mutually rotatable units different transmission systems known.

In the US 5,568,578 discloses a multi-channel optical rotary transformer with a Dove prism. For coupling or decoupling of the light from glass fibers, an arrangement with several GRIN lenses is provided. Here, the individual GRIN lenses are received in holes in a carrier plate. The ends of the glass fibers are held in ferrules and are glued via these ferrules with the GRIN lenses. For exact adjustment, the individual ferrules can be moved together with the fiber ends held therein above the surface of the ground GRIN lenses.

A Improvement of this embodiment is disclosed in WO 01/98801 A2. Thus, a micro-optical system is specified therein, which optical and having mechanical cal components as a one-piece component. By this configuration can be a much higher one Achieve packing density of the individual glass fibers. In addition, the deleted complex Adjustment of the individual glass fibers or ferrules in relation on the lenses, since the geometry of the holder already by the predetermined monolithic manufacturing process of the micro-optical system is. Such micro-optical systems are in particular for multimode fibers very expensive in the production, since the lenses required here relatively large and with the well-known micro-optics manufacturing technologies are difficult to produce. Furthermore, the micro-optical systems for high Channel numbers due to their size only with disproportionately high Costs can be produced because the costs increase disproportionately to the area.

Presentation of the invention

Of the Invention is based on the object, a rotary transformer for multi-channel transmission optical signals in such a way that different channel numbers, especially for Singlemode optical fibers can be produced at low cost.

Inventive solutions of this Task are in the independent claims specified. Further developments of the invention are the subject of the dependent claims.

The inventive device has at least two collimators, which about an axis against each other are rotatably arranged. Between at least one first collimator and at least one opposite this rotatably arranged second collimator is an optical Path to transfer of light. There is at least one in this optical path derotierendes element, which for an image of the light emitted by a first collimator on a second collimator as well as in the opposite direction, independently by the rotational movement between the two collimators ensures. Such a derotating element may, for example, be a Dove prism be. The term collimator stands for a beam-guiding one in the broadest sense or beam-forming element. The task of such Collimators is the implementation of the in an optical fiber, for example, a single-mode fiber or a multi-mode fiber out Light in a beam path, which through the rotary transformer and in particular be guided by the derotating element can. This corresponds to a beam path in the free space or in an optical medium, such as glass or oil. As well can by a collimator also a conversion in the opposite direction, i.e. from the beam path in the rotary transformer in an optical waveguide. Of course they are within a collimator also implementations in both directions conceivable.

One Collimator according to the invention now has at least one support plate of an optical material to which at least one, preferably but several lenses are attached. Possible fastening methods are gluing, laser welding and fusion splicing.

By the attachment, or gluing the lenses are these in exactly defined Fixed positions. The adjustment can for example by a positioning or by mechanical means.

The inventive design, it is now possible to integrate a plurality of lenses for multimode optical fibers with little effort in a single unit. Thus, in the ideal case, an optical rotary transformer has only a single first collimator and a single second collimator, each collimator having a carrier plate with glued-on lenses. Because the lenses in the production can be fixed with precisely defined, minimal tolerances on the support plate, in the final assembly only an adjustment of the support plate together with the lenses as a unit is necessary. Likewise or alternatively, the individual optical waveguides, preferably in ferrules, be adjusted adjusted to the support plate. This eliminates the adjustment of a plurality of individual lenses or optical fibers in the final assembly. The arrangement on a support plate results in a highly robust and space-saving embodiment.

There with the previously known methods for producing micro-optical Components or systems only optical components smaller Dimensions, as for example for singlemode optical fibers are suitable to produce, the invention provides an economical Alternative to making collimators with larger lenses, which also for Multimode optical fiber suitable are.

By the areal Sticking on lenses whose bottom is planar, they can attached to a carrier plate (wafer) with very low tolerance and exactly to the surface be aligned. Furthermore you can any different fiber types are combined.

alternative or additionally can also lenses without a planar surface, for example, spherical Lentils in V-grooves, pyramidal Wells or other microstructures are used. These Structures can preferably filled with glue or other plastic material.

Furthermore, at least one optical waveguide 2 fixed to the surface of the carrier plate. The fixation can, for example, by splicing, gluing, or by means of a ferrule 8th respectively. Optionally, two carrier plates may be connected flat to each other, wherein one of the carrier plates for receiving the optical waveguide and the other carrier plate for receiving the lenses is used. Preferably, however, only one carrier plate is present, wherein the optical waveguides are fixed on one side and the lenses are mounted on the opposite side.

The Lenses themselves consist of an optical transparent to the light to be transmitted Material, such as glass, plastic, germanium, silicon, preferably but of the same material as the carrier plate.

In a further advantageous embodiment of the invention at least one carrier plate Glass or PMMA (polymethyl methacrylate).

A Another advantageous embodiment of the invention has a carrier plate on, which is designed as a plane-parallel plate. Instead of a plane-parallel Plate can also be a plate with two at an angle to each other extending boundary surfaces be used. This allows the Reflections are reduced at decoupling point.

The Thickness of a plane-parallel plate is advantageously such dimensioned that the ends of the attached optical fibers (Fibers) lie at a defined distance from the lenses.

A Further advantageous embodiment of the invention provides that at least one, but preferably several lenses for automatic assembly, preferably by an SMD placement machine, but also through a handling system for Micro-optics are configured. For this purpose, the lenses have a shape on which of a placement head can be taken up well. Furthermore, it is advantageous if the lenses for this in a standardized magazine, or even in assembly harnesses, as used for receiving electronic components, are made up. Furthermore, through an adhesive dispenser at the placement machine the glue to the desired Position on the glass plate on or through a static dispenser be applied to the lens. The positioning accuracy of available today placement machines is on an order of magnitude of 30 μm and is therefore sufficient for fitting lenses for customization of multimode fibers with diameters of 50 μm / 125 μm or 62.5 μm / 125 μm.

alternative can the lenses also applied by a mold for positioning the lenses become. The adhesive-coated lenses can then, for example, with Help the mold to be pressed onto the glass plate. Alternatively, these can also positioned loosely on the glass plate by the mold become. In that case, would then by the surface tension a parallel alignment to the glass plate surface done.

In a further embodiment of the invention, at least one MLA is attached to the surface of the carrier plate. The attachment can be done here, for example, by gluing. The term MLA is understood to mean so-called microlens arrays (micro lens array). These preferably have a multiplicity of microlenses in a monolithic unit. They correspond to the micro-optical components or systems defined in WO 01/98801 A2. By this embodiment of the invention it is now possible to combine on a support plate both micro-optical components for coupling to singlemode optical fibers and optical components (Lin sen) for coupling of multimode optical fibers. As a result, it is now possible with little effort to make rotary transformer for several types of optical fibers.

A Another embodiment of the invention provides that in a fixed given grid alternately lenses and micro-optical components on the carrier plate are arranged. Such a grid can, for example in hexagonal Arrangement, chosen so be that an optimal space utilization takes place.

A Further invention according to the preamble of claim 1 sees For example, at least one collimator has an MLA in which individual ones Microlenses for Singlemode fibers are provided. Furthermore, between these single microlenses empty spaces for holding larger lenses, for example Multimode fibers provided.

A Further advantageous embodiment of the invention provides that in at least one MLA structures for positioning respectively Attachment of lenses are introduced. These structures are with the same manufacturing principle, preferably monolithic, such the microlenses made. The structures can, for example, surveys or depressions. Through the structures, the distances the individual lenses in different axes given or be set. Thus, for example, one of the focal length the respective lenses dependent distance longitudinal be adjusted between lens and fiber.

A Another advantageous embodiment of the invention provides that several light-conducting fibers taken in a common bracket are. Through this common version they can then also together be polished so that a uniform, flat surface is created. This can now on a glass plate, for example by gluing be attached. You can do this the entire area or even only certain areas can be coated with adhesive. By Structures on the surface the glass plate can be specifically controlled a bleeding of the adhesive become. Here you can in particular the areas around fibers, through which high optical Transfer services be left out from the adhesive. This can be, for example, too thereby achieve that the fibers of high power in the middle of a bundle are arranged of a plurality of fibers, and the adhesive only at the edge, in the area of the outer fibers is applied. This embodiment can be used with any of the inventions listed here combine.

In a further advantageous embodiment of the invention are the Lenses optional, as spherical Lentils, as aspherical Lenses or as GRIN lenses executed. A GRIN lens may be as well as a spherical or an aspherical lens on a carrier plate or an MLA. To achieve a higher strength, rod-shaped lenses, especially GRIN lenses be provided with a ferrule.

A Another embodiment of the invention provides that in a collimator fixed at least two MLA at a predetermined distance from each other are. In this case, the intermediate space preferably with a medium filled be. Advantageous is a medium with a smaller refractive index than the Refractive index of the MLAs, for example air or even a medium with a higher refractive index like oil.

A Further embodiment of the invention provides that the rotary transformer in the area between the first collimator and the second collimator with a liquid Medium, such as oil is filled. This makes it possible in particular to realize pressure-resistant rotary joints, for example for deep-sea applications.

Furthermore, the invention relates to a mounting method in which initially lenses 4 on a carrier plate 5 or an MLA 3 be applied. In a further step, photoconductive fibers with the carrier plate 5 or the MLA 3 in such a way that the beam shape and / or squint angle of the light emerging from the collimator are within a predetermined tolerance range. These two steps are also interchangeable in their order. In a further step, a final assembly takes place for assembling the entire device with the derotierenden element. Here, only a simple assembly step for adjusting the two collimators to each other is necessary.

A further method according to the invention for producing a collimator ( 21 . 22 ) for an optical rotary transformer comprises the steps - providing a carrier plate ( 1 ) and - loading of lenses ( 4 ) by means of an SMD placement machine.

description the drawings

The Invention will be described below without limiting the general inventive concept of exemplary embodiments described by way of example with reference to the drawings.

1 shows in general form schematically an arrangement according to the invention.

2 shows an exemplary embodiment of a collimator in plan view.

In 3 an arrangement of Figure two is shown in side view.

In 4 an arrangement according to the invention is shown with an MLA.

In 5 another embodiment is shown with a MLA with raised structures, wherein on the raised structures small lenses 4a are provided.

In 6 For example, an embodiment is shown with a MLA with raised structures, with large lenses on the raised structures 4b are attached.

In 7 an embodiment is shown in which the fibers 2 from a holder 5 being held.

In 8th a device with GRIN lenses is shown.

In 9 Another device is shown with GRIN lenses.

10 shows an arrangement of a MLA with GRIN lenses.

11 shows a device according to the invention with an MLA 3 on which a holder 9 is arranged for rod-shaped lenses.

In 12 a device according to the invention with two interconnected MLA is shown.

13 shows an embodiment with two interconnected MLA, wherein the cavity between the MLA is filled with a medium having a refractive index less than the refractive index of an MLA.

14 shows an embodiment with two interconnected MLA, wherein the cavity between the MLA is filled with a medium having a refractive index greater than the refractive index of an MLA.

15 shows an embodiment with two interconnected MLAs, wherein both MLAs have different refractive indices.

16 shows an embodiment with an MLA, are placed on the lenses.

17 shows another embodiment with an MLA, are placed on the lenses.

1 shows in schematic form an inventive arrangement in section. The optical rotary transformer according to the invention comprises a first collimator 21 for coupling optical waveguides 2 , as well as a second collimator 22 for coupling further optical fibers 2 , The second collimator 22 is opposite the first collimator 21 around the axis of rotation 24 rotatably mounted. To compensate for the rotational movement is located in the beam path between a first collimator 21 and a second collimator 22 a derotating element 23 , This derotating element is shown here by way of example as a dove prism.

2 shows an exemplary embodiment of a collimator in plan view. Here are on a support plate 1 in a given grid alternately large lenses 4b as well as small lenses 4a arranged. The large lenses could be used, for example, to transmit the signals from multimode fibers, while the small lenses are designed to transmit the signals from single-mode fibers.

In 3 an arrangement of Figure two is shown in side view. Here are the lenses of different sizes 4a and 4b clearly visible. The supply or removal of optical signals takes place by light-conducting fibers (optical waveguides), in which case different fibers, for example single-mode fibers 2a in conjunction with small lenses and multimode fibers 2 B shown in conjunction with large lenses.

In 4 an arrangement according to the invention is shown with an MLA. The MLA 3 (Microlens array) has on its surface an integrated structure of the small lenses 4a For example, for singlemode fibers. Between the small lenses are big lenses 4b , For example, attached to multi-mode fibers, preferably glued.

In 5 another embodiment is shown with a MLA with raised structures, wherein on the raised structures small lenses 4a are provided. Due to the height of the structure, the distance of the lens, for example to the fiber can be defined. Thus, an adjustment of the distance in dependence on the focal length of the lens is possible. The little lenses 4a are preferably integrated with the MLA.

In 6 For example, an embodiment is shown with a MLA with raised structures, with large lenses on the raised structures 4b are attached. These lenses are preferably glued here. Again, the structure height of the Distance between lens and fiber can be defined.

In 7 an embodiment is shown in which the fibers 2 from a holder 5 being held. The holder 5 is fixed to the carrier plate 1 connected. To get a run of the glue with which the fibers 2 with the carrier plate 1 are glued to prevent are stop devices 6 intended for the adhesive. If the use of glue is dispensed with in principle, even higher optical powers can be transmitted. The use of adhesive is becoming increasingly unproblematic when the beam is further widened, so for example in the vicinity of the lenses.

In 8th a device with GRIN lenses is shown. The GRIN lenses 7 are here preferably in a ferrule 8th taken to increase the mechanical stability. On one side of the GRIN lenses are the fibers 2 attached. The other side of the lenses is on the carrier plate 1 attached.

In 9 Another device is shown with GRIN lenses. Here, the GRIN lenses are arranged on the other side of the carrier plate.

10 shows an arrangement of a MLA with GRIN lenses. To adjust the distance of the fiber ends to the lenses holes can be provided in the MLA, so that the GRIN lenses can be recessed in this introduced. By this measure, the mechanical stability can be further increased.

11 shows a device according to the invention with an MLA 3 on which a holder 9 is arranged for rod-shaped lenses. In this illustration, the holder 9 drawn drawn. In the grooves of the holder, for example, a rod-shaped lens 7 how a GRIN lens was taken. To allow a free passage of light from the small lenses 4 to allow the holder has gaps 10 on.

In 12 a device according to the invention with two interconnected MLA is shown. A first MLA 3a has small lenses 4a on. The above arranged MLA 3b contains large lenses 4b , Furthermore, in this MLA blind holes 13 provided in an area above the lenses of the lower MLA. Alternatively or additionally, through holes 14 be provided over the lenses of the lower MLA.

13 shows an embodiment with two interconnected MLA, wherein the cavity between the MLA is filled with a medium having a refractive index less than the refractive index of an MLA. Again, the little lenses 4a , For example, for coupling singlemode fibers 2a in the lower MLA 3a educated. The above arranged MLA 3b has larger lenses 4b on. The order of the lenses along the beam can also be reversed, ie first multi-mode and then single-mode. The reason for this is the higher numerical aperture of the fibers and thus the beam expansion with increasing distance. At the same time, the focal lengths of the lenses are preferably selected to be larger for multi-mode.

Of the Cavity between the two MLA is filled with a medium whose Refractive index is less than the refractive index of one, or both MLA's. Such a medium is for example air or another gas.

14 shows an embodiment with two interconnected MLA, wherein the cavity between the MLA is filled with a medium having a refractive index greater than the refractive index of an MLA. Again, the little lenses 4a , For example, for coupling singlemode fibers 2a in the lower MLA 3a educated. The above arranged MLA 3b has larger lenses 4b on. The cavity between the two MLAs is filled with a medium whose refractive index is greater than the refractive index of one, or both MLA. Such a medium is for example oil or another liquid.

15 shows an embodiment with two interconnected MLAs, wherein both MLAs have different refractive indices. The first MLA 3a preferably has a larger refractive index than the second MLA 3b on. The lenses shown by way of example 4a . 4b are formed from both MLAs. You are here from the first MLA 3a out and stand out in the second MLA 3b into it. Equally feasible is an embodiment in which the lenses are designed in the opposite direction, wherein the first MLA has a smaller refractive index than the second MLA.

16 shows an embodiment with an MLA 3 , on the lenses 4a . 4b are set up. The MLA has corresponding lenticular protrusions that fit into the attached lenses 4a . 4b protrude. The positioning of the lenses takes place on the protrusions of the MLA. Here, the position of the lenses is determined exclusively by the MLA, which allows minimal manufacturing tolerances light. Thus, it is particularly advantageous to produce optical systems for singlemode fibers.

17 shows another embodiment with an MLA, are placed on the lenses. Here the arrangement is opposite to that from 16 , Advantageously, the refractive index of the MLA 3 smaller than the refractive index of the lenses 4a . 4b , The imaging systems listed in this document with MLA can also be used in a variety of optical applications outside of rotary encoders, such as plugs.

18 shows a further embodiment with ferrules ( 8a . 8b ) for receiving the optical waveguides ( 2a . 2 B ). Such ferrules for receiving the optical waveguides can be combined with all other of the embodiments shown here.

1

support plate

2

optical fiber (Glass or plastic fiber)

3

MLA

4

lens

5

holder

6

stopping device for glue

7

Rod-shaped lens

8th

ferrule

9

holder for rod-shaped lens

10

gap

13

Blind hole

14

Through Hole

15

medium small refractive index

16

medium greater refractive index

17

lens

21

first collimator

22

second collimator

23

de-rotating optical element

24

axis of rotation

Claims (15)

Optical rotary transformer comprising at least one first collimator ( 21 ) for coupling a plurality of first optical waveguides ( 2 ) and a second collimator ( 22 ) for coupling a plurality of second optical waveguides ( 2 ), which faces the first collimator ( 21 ) about a rotation axis ( 24 ) is rotatably mounted, and at least one derotierenden optical element ( 23 ) which lies in the light path between at least one first collimator ( 21 ) and at least one second collimator ( 22 ), characterized in that at least one collimator ( 21 . 22 ) a carrier plate ( 1 ) of an optical medium, and at least one lens ( 4 ) for the coupling of optical waveguides on a carrier plate ( 1 ) and / or from the surface of the carrier plate ( 1 ) is formed, and at least one optical waveguide ( 2 ) is fixed to the surface of the carrier plate. Apparatus according to claim 1, characterized in that at least one support plate ( 1 ) consists of glass or PMMA. Device according to one of the preceding claims, characterized characterized in that at least one support plate as a plane-parallel Plate executed is. Device according to one of the preceding claims, characterized in that the thickness of a plane-parallel support plate ( 1 ) is advantageously dimensioned such that the ends of the attached optical fibers ( 2 ) at a defined distance to the lenses ( 4 ) lie. Device according to one of the preceding claims, characterized in that at least a part of the lenses ( 4 ) is configured for automatic placement, preferably with an SMD placement machine. Device according to one of the preceding claims, characterized in that at least one MLA ( 3 ), which combines in a monolithic structure a plurality of jet-guiding or jet-forming or also mechanical elements, on at least one carrier plate ( 1 ) is attached. Apparatus according to claim 5, characterized in that in a fixed predetermined grid alternately lenses ( 4 ) and / or MLA ( 3 ) on the carrier plate ( 1 ) are mounted. Device according to the preamble of claim 1, characterized in that at least one collimator ( 21 . 22 ) an MLA ( 3 ), in which empty spaces are provided between individual microlenses for singlemode optical waveguides for receiving larger lenses for multimode optical waveguides. Device according to one of the preceding claims, characterized in that in at least one MLA ( 3 ) Structures for positioning or attachment of lenses ( 4 ) are introduced. Device according to one of the preceding claims, characterized in that a plurality of optical waveguides ( 2 ) are mounted in a common holder and are polished together to form a uniform, flat surface, so that it can be fastened to a glass plate. Device according to one of the preceding claims, characterized in that at least one lens ( 4 ) optionally, as a spherical lens, as an aspherical lens or as GRIN lenses is executed. Device according to one of the preceding claims, characterized in that at least two MLAs ( 3 ) are fixed at a predetermined distance from each other. Device according to one of the preceding Claims, characterized in that the area of the rotary transformer between the first collimator ( 21 ) and second collimator ( 22 ) has a filling with a liquid medium, preferably oil. Collimator for optical rotary joints comprising a support plate ( 1 ) of an optical medium and at least one lens ( 4 ) for coupling optical waveguides which are mounted on a carrier plate ( 1 ) is attached and / or integrated in the carrier plate. Method for producing a collimator ( 21 . 22 ) for an optical rotary transformer comprising the steps - providing a carrier plate ( 1 ) - loading of lenses ( 4 ) by means of an SMD placement machine.