DE102006058621A1 - Method for producing a light guide for an optical rotary transformer - Google Patents

Abstract

A method for producing a mirrored trench as a light guide in optical rotary transmitters comprises the steps of forming a trench in a support structure, electroplating a reflective layer by means of a shape anode having a contour corresponding to the contour of the trench, and rolling the surface to reduce the surface roughness ,

Description

Technical area

The The invention relates to a method for producing a light guide for one optical rotary transformer, in the light by means of a mirrored trench in a circular path is distracted.

State of the art

For transmission optical signals between mutually rotatable units, in particular with a free inner diameter, various devices are known. in principle There is the problem herein, a means for transporting light along the scope of the device as well as suitable means for on and Decoupling of light. For use in computer tomographs have to such devices large have free inner diameters of the order of 1 meter. The peripheral speed of rotation can be on an order of magnitude of 20 m / s. At the same time, data rates should exceed 1 gigabit per second (GBaud) possible be.

In the EP 1 476 969 A a device for broadband signal transmission by means of a mirrored trench is disclosed. Here, light is coupled into a mirrored trench as a light guide of a first unit and guided along a circular path. The second unit, which is rotatable relative to the first unit, has a light coupler to extract light from the mirrored trench. Since the light now has to be guided along the circumference over a distance of several meters, the attenuation of the light must also be as low as possible. Such rotary joints have hitherto mostly been built only as prototypes because, inter alia, a circular unit with a mirrored trench, which has an acceptably low damping, was scarcely economical to manufacture.

The DE 199 00 173 C1 discloses a method of electrochemical metalworking using a preformed electrode for material removal.

In the JP 60159194 a device for Tampongalvanik is disclosed. An impregnated with an electrolyte and connected to a power source tampon is passed manually over a surface to be processed. Due to the current flow, a metal layer is deposited on the surface to be processed.

Presentation of the invention

Of the Invention has for its object to provide a method with an optical rotary transformer and in particular a mirrored trench as a light guide with lower damping is economically producible.

A inventive solution this Task is in the independent claims specified. Further developments of the invention are the subject of the dependent claims.

investigations have revealed that a mirrored trench provided with a gold surface a permanently low insertion loss allows. Therefore, according to the invention preferably gold as surface material used, since this hardly corroded even after a long time. An essential Aspect of the invention is to have as uniform a surface as possible to produce low roughness on the trench. Furthermore, gold has with infrared optical signals as the material for the reflection layer due Its excellent reflection properties are well proven. Corresponding can but also for other wavelengths other suitable materials such as silver or copper be used.

• – Herstellen eines Grabens in einer Trägerstruktur,
• – Galvanisches Auftragen einer Reflexionsschicht mittels einer Formanode, welche eine Kontur entsprechend der Kontur des Grabens aufweist;
• – Rollieren der Oberfläche, um die Oberflächenrauhigkeit zu verringern.

A method according to the invention comprises the following steps:

• Producing a trench in a support structure,
• - Galvanisches applying a reflection layer by means of a shape anode, which has a contour corresponding to the contour of the trench;
• - Rolling the surface to reduce the surface roughness.

preferably, consists of the support structure Metal, more preferably brass or aluminum. Likewise the support structure but also metallized or at least coated with a conductive surface Insulator material such as a plastic include. The reflection layer has the function of a mirroring of the surface on which the optical Propagate signal through multiple reflections along the circumference can.

The Formanode is usually operated as an anode and includes a suitable Anode material, preferably a solid material, more preferably a metal, such as stainless steel, which corresponds to the contour of the Grabens is adjusted.

In a further advantageous embodiment of the invention is the Form anode formed as a tampon electrode and comprises a preferably elastic and preferably absorbent material for receiving of electrolyte. Such a form anode may be, for example, a cotton fleece, but preferably comprise a glass fiber fleece.

alternative For example, a tampon electrode may also have a solid support, which in turn a conductive surface having. This can also be a cotton fleece, preferably but include a fiberglass fleece.

The Galvanization power source is between the anode and the support structure connected, wherein typically the anode form the anode and the support structure the cathode is.

The Rolling takes place by means of a rotationally symmetrical tool, which is adapted to the contour of the mirror trench, and along of the trench being unrolled in this. The tool is preferred pressed into the trench by means of a constant contact force. For this the tool is preferably pressed by means of a spring. Especially Cheap is an active spring force control.

Especially Cheap is it, if an additional Step of rolling before applying the reflective layer and advantageously before applying an optional barrier layer he follows. As a result, the contour of the mirror trench is exactly to the Adjusted geometry of the tool and thus minimizes the tolerances. Advantageously, the galvanic coating now takes place with the reflective layer and another step of rolling in the same clamping or on a workpiece carrier, so that the step of rolling after the application of the reflective layer with minimal tolerances with respect to the mirror trench can. Advantageously, for this step of rolling one in its dimensions around the middle one Thickness of the reflection layer reduced rotationally symmetric tool used.

A further advantageous embodiment of the method has an additional Step of coating the surface of the trench with a conductive substrate on, if the support structure no conductive surface having. This process step is after the production of the Trenching and before the galvanic application of the reflective layer executed.

In Another embodiment of the method is even before the application the reflective layer comprises a barrier layer, preferably comprising nickel, applied. The order is also preferably galvanic here. The barrier layer prevents diffusion of the reflection layer in the underground of the support structure and diffusion of the material of the support structure or one thereon located layer in the reflective layer. especially the second type of diffusion would to an impairment the reflection properties of the reflective layer lead. Therefore this must be effectively prevented.

In another embodiment of the method is carried out after the rolling another polishing of the surface of the trench.

In a further advantageous embodiment of the invention is the Form anode designed such that it to edges of the trench contour a greater distance as to the surfaces that of the ditch. at a uniform distance the mold anode would ditch at locations with edges due to the higher current concentration reinforced Order of material done. To compensate for this, the Increased the distance of the anode form at these points.

In a further advantageous embodiment of the form anode has this isolated areas through which no current can flow so that a partial galvanization of the surface of the trench is possible.

A inventive device for the galvanization of trench-shaped surfaces comprises a shape anode, which in the vicinity of edges and / or projections the trench profile a greater distance for digging, as to the surfaces of the trench.

In In a further embodiment of the invention, the shape anode is in taken a bracket, which a uniform distance the form anode to the surface the trench ensured. These Holder can, for example, the tool spindle of a machine tool be. As generic rotary transformer to the leadership the second light coupler a hydrostatic or hydrodynamic Have storage, this can also lead to and / or storage of Formanode can be used. Thus, the form anode preferably also like the second light coupler on such storage. Because the movement speeds during galvanization much lower than the speeds are in operation of the device, the anode can also on the support structure slide. For this purpose, advantageously sliding bearing surfaces provided the form anode.

In Another embodiment of the invention is an automatic one Feed device provided which the mold anode with respect to the trench emotional.

A Another embodiment of the invention provides that the controller the movement of the anode of the mold as a function of at least one the following parameters galvanization progress, current, anode voltage, Distance of the anode shape is controlled by the trench.

In a further embodiment of the inventions The galvanization current is controlled as a function of the speed of movement between the anode and the trench.

A Further embodiment of the invention provides that means for supply or removal of an electrolyte are provided. So is preferably in the direction of movement in front of the anode mold a hose or a pipe to the feeder of electrolyte. Behind the form anode is another hose or another tube for the extraction of electrolyte.

A inventive device to carry out of the method according to the invention at least one cleaning unit, and a receiving device for the Formanode and a drive to the support structure in a continuous To move the rotary motion. Optional is still a storage or suspension the support structure intended. The cleaning unit is arranged such that they in a continuous rotational movement of the support structure in front of the anode of the form passes through or cleans the areas to be electroplated can.

Description of 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 a general form schematically a device according to the invention.

2 schematically shows a device according to the invention in plan view.

3 shows a tampon according to the invention.

4 shows an apparatus for performing a method according to the invention.

5 shows a detail of the device 4 on average.

1 shows in schematic form a device according to the invention in section. Therein are both the transmitting unit 1 as well as the receiving unit 2 as discs with centric bore, which around the axis of rotation 6 are rotatably mounted, shown. The light guide 3 is shown here as on the inside mirrored trench. It extends around the entire circumference of the first unit. Engaged with this trench is a second light coupler 5 , which at the receiving unit 2 is arranged. This light coupler picks up the guided in the light guide light and conducts it with a light-conducting fiber 7 further. For exact alignment of the light guide and the second light coupler in one axis, a hydrostatic or hydrodynamic bearing and an electrodynamic position control are provided. The hydrodynamic bearing is based on a thin film of air, which is due to the movement of the two units against each other between the first bearing surface 21 and the second storage area 20 is trained. An actuator 8th serves for the exact height adjustment of the light coupler. The sensors 9a and 9b serve to determine the height of the light coupler over the light guide.

2 shows in schematic form a device according to the invention in plan view. A transmitting unit 1 serves to receive an annular light guide 3 , This light guide is, for example, a mirrored trench on the inside. A receiving unit 2 turns with respect to the first unit around the axis of rotation 6 , The second unit contains a second light coupler 5 , Light from a transmitter, not shown, is in phase with respect to the modulation signal by means of the two first light coupler 4a . 4b in the light guide 3 fed. The light from the first light coupler 4a runs on the right side of the picture to the absorber 13 , At the same time the light of the first light coupler is running 4b on the left to the absorber 13 , The absorber is arranged symmetrically with respect to the coupling-in point of the first light coupler, so that the light paths 32 are the same length on both sides. The tapping of the light takes place by means of a second light coupler 5 which is about the axis of rotation 6 along the path of the light guide 3 is rotatably mounted and the tapped light by means of the photoconductive fiber 7 to an optical receiver. For simplicity, the optical receiver is also not shown. An evaluation unit 40 for determining and regulating the exact position of the second unit is in the receiving unit 2 integrated. Furthermore, a central control unit 41 intended to control the entire device.

3 shows a tampon according to the invention. In the carrier structure 51 is a ditch 55 , which serves with its mirroring as a light guide. The tampon 52 is adapted in its contour to the contour of the trench. To achieve better power distribution is according to the edge 54 the support structure a recess 53 provided on the tampon. The length of the anode is usually a few centimeters, typically 2 to 4 cm. The shape anode can optionally rest close to the trench, resulting in a flat contact. In this case, through the recess 53 on the edge 54 achieved a lower contact pressure and thus a lower current density.

4 shows an apparatus for performing a method according to the invention. The support structure 51 is powered by a drive in turning direction tung 60 emotional. During the rotation, cleaning is first carried out by means of a cleaning unit 62 which, for example, removes dirt by electrostatic or mechanical means. Likewise, a chemical cleaning is conceivable. This is followed by galvanization using the anode 52 passing through a receiving device 61 is held. For example, a pressure spring ensures even pressure. Through a supply line 64 Electrolyte is supplied. A suction line 63 behind the anode, the electrolyte sucks again. Thus, only a small amount of electrolyte is always used on the support structure. To promote electrolyte, a pump, preferably with an additional filter and a reservoir can be used.

5 shows a detail of the device 4 on average. The support structure 51 is preferably U-shaped. The vertical and horizontal surfaces shown here in the interior of the U-shaped support structure are used in the normal operation of the device as hydrostatic or hydrodynamic bearing surfaces. During the galvanization of the surface of the trench 55 These can continue to guide a recording device 61 serve. This receiving device takes the form anode 52 on. The formanode 52 is shown here in section, but it has an elongated shape with a typical length of a few centimeters. The shape anode can also be reinforced mechanically in areas above the trench, so that it has a greater material thickness and thus also a higher mechanical stability and a better current carrying capacity. Furthermore, the anode is connected via form not shown electrical contact means with a power supply. The receiving device is preferably made of a non-conductive plastic material, so that only the area around the anode of the form in the trench 55 is electroplated while the surface of the support structure remains uncoated. The through a recess in the receiving device 61 formed electrolyte channel 65 serves to guide electrolyte, which, for example, through the supply line 53 supplied on one side of the receiving device and through the suction line 54 is sucked on the other side. Preferably, the flow of the electrolyte in the longitudinal direction is therefore perpendicular to the plane of the drawing 5 , Likewise, however, an electrolyte flow across the recording device and thus parallel to the drawing plane would also be possible. By the U-shaped design of the support structure 51 the electrolyte stays inside this structure. Because the whole arrangement is circular ( 4 ) Electrolyte collects at the lowest point at which preferably the receiving device is arranged with the anode form. Alternatively, the shape anode can be slightly offset so that the suction line 54 can be arranged at the lowest point.

1

transmission unit

2

receiver unit

3

optical fiber

4

light coupler (Transmission unit)

5

light coupler at the second unit

6

axis of rotation the rotation between transmitting unit and receiving unit

7

Photoconductive fiber

8th

actuator

9

sensor

10

control unit

11

reference track

13

absorber

20

second storage area

21

first storage area

32

beam of light

40

evaluation

41

headquarters control unit

50

mirrored dig

51

support structure

52

form anode

53

recess at the form anode

54

edge on the support structure

55

dig

60

direction of rotation

61

recording device

62

cleaning unit

63

feed pipe

64

suction

65

electrolyte channel

Claims (17)

Method for producing a mirrored trench as a light guide in optical rotary joints comprising the following Steps: - Produce a trench in a support structure, - Galvanic Applying a reflection layer by means of a form anode, which has a contour corresponding to the contour of the trench; - Rolling the surface, around the surface roughness to reduce. Method according to claim 1, characterized by additional Step coating the surface the trench with a conductive Support material if the support structure no conductive surface after making the trench and before applying a reflection layer. A method according to claim 1 or 2, characterized through the additional Step rolling the surface the trench to minimize the mechanical tolerances of the trench, before applying the reflective layer. Method according to one of the preceding claims, characterized through the extra step Apply a barrier layer before applying the reflective layer. Method according to one of the preceding claims, characterized through the extra step Polishing the surface the trench after rolling. Method according to one of the preceding claims, characterized characterized in that the shape anode is designed such that they are at a greater distance to edges of the trench contour than to the surfaces of the trench contour Grabens complies. Method according to one of the preceding claims, characterized in that the form anode is accommodated in a holder which is a uniform distance the form anode to the surface the trench ensured. Method according to one of the preceding claims, characterized in that an automatic feed device is provided is opposite to the form anode moved to the ditch. Method according to one of the preceding claims, characterized characterized in that the control of the movement of the anode of form in Dependence on at least one of the following parameters galvanization progress, Amperage, Anode voltage, distance of the anode form is controlled by the trench. Method according to one of the preceding claims, characterized characterized in that the galvanization current in dependence from the speed of movement between the anode and the trench is controlled. Apparatus for galvanizing grave-shaped surfaces, characterized characterized in that a shape anode is provided, which in the environment of edges and / or protrusions the trench profile a greater distance for digging, as to the surfaces of the trench. Device according to claim 11, characterized in that that the form anode is accommodated in a holder which has a even distance the form anode to the surface the trench ensured. Device according to claim 12, characterized in that that the holder of the anode form the same hydrostatic or hydrodynamic Storage used as a second light coupler of the rotary transformer. Device according to one of claims 11 to 13, characterized that an automatic feed device is provided, which the form anode opposite moved to the ditch. Device according to one of claims 11 to 14, characterized that the control of the movement of the form anode depending on of at least one of the following parameters galvanization progress, Amperage, Anode voltage, distance of the anode form is controlled by the trench. Device according to one of claims 11 to 15, characterized that the galvanisation current depends on the speed of the Movement between the anode and the trench is controlled. Device according to one of claims 11 to 16, characterized that a cleaning device is provided.