WO2010102895A1

WO2010102895A1 - Method for the production of a light source comprising a diode laser and a plurality of optical fibers

Info

Publication number: WO2010102895A1
Application number: PCT/EP2010/052141
Authority: WO
Inventors: Klaus Stoppel; Werner Herden; Hans-Jochen Schwarz; Andreas Letsch
Original assignee: Robert Bosch Gmbh
Priority date: 2009-03-11
Filing date: 2010-02-19
Publication date: 2010-09-16
Also published as: DE102009001479A1

Abstract

Disclosed is a method for producing a light source (10), especially a light source (10) for optically exciting a laser device (11), e.g. a laser device (11) of a laser ignition system in an internal combustion engine (109), comprising a diode laser (13) that includes a plurality of emitters (131), and a light guiding device (12) that includes a plurality of optical fibers (121), each of which has a first end (1211) and a lateral surface (1217). The first ends (1211) are arranged in such a way relative to the emitters (131) that light generated by the emitters (131) is injected into the first ends (1211) of the optical fibers (121). The optical fibers (121) are arranged edge to edge along the lateral surfaces (1217) thereof, at least in the area of the first ends (1211) of the optical fibers. The disclosed method is characterized by the following steps: arranging a plurality of optical fibers (121) forming a fiber section (1218) in a subarea, said fiber section (1218) being located between two opposite pressing surfaces (201, 202); heating the fiber section (1218); deforming the fiber section (1218) by applying a force to the heated fibers (121) using the pressing surfaces (201, 202); determining the width of the gap between the pressing surfaces (201, 202) while said force is applied; and stopping to apply the force when the determined width of the gap between the pressing surfaces (201, 202) reaches or exceeds a given value.

Description

description

title

METHOD FOR PRODUCING A LIGHT SOURCE WITH A DIODE LASER AND A VARIETY OF OPTICAL FIBERS

State of the art

The invention relates to a method for producing a light source according to the preamble of the independent claim.

Such a light source is known from DE 10 2004 006 932 B3 and has a diode laser bar with a plurality of narrow emitters, which are arranged in a row next to each other in the direction of their longitudinal axis. The diode laser bar is associated with a device for beam guidance and beam shaping of the laser beam emerging from it, which contains a plurality of juxtaposed in a row of optical fibers into which the laser beam is coupled.

It is likewise known from DE 10 2004 006 932 B3 to produce such a light source by arranging round optical fibers next to one another and placing them with their end region in a shape in which they are brought into a rectangular cross-section by a hot-pressing process, the expansion of the Fibers remain approximately unchanged in a first direction, while the expansion of the fibers in a second direction is reduced by about 25%.

In the industrial use of such methods, it is of great importance that a conversion of the fibers to the desired extent actually takes place, but on the other hand, an excessive squeezing of the fibers is reliably excluded. The invention is therefore based on the object of specifying a method that ensures a defined deformation of the fibers with high accuracy.

Disclosure of the invention

This object is achieved in the production of a light source, in particular a light source for the optical excitation of a laser device, for example a laser device of a laser ignition system of an internal combustion engine, comprising a diode laser with a plurality of emitters and a light guide, wherein the light guide comprises a plurality of optical fibers and each optical Fiber having a first end and a side surface, wherein the first ends are disposed to the emitters such that light generated by the emitters couples into the first ends of the optical fibers, the optical fibers abutting at least in the region of their first ends along their side surfaces are arranged, achieved in that the manufacturing method comprises the following steps:

Arranging a multiplicity of fibers which, in a partial area, form a fiber section which is arranged between two pressing surfaces (201, 202) lying opposite one another,

Heating the fiber section,

Deforming the fiber portion by exerting a force on the heated fibers through the pressing surfaces, wherein during the application of the force, the height of the gap remaining between the pressing surfaces is determined, and the exertion of the force is terminated when the determined height of the remaining between the pressing surfaces Gap reaches or exceeds a predetermined value.

Here, a first end of an optical fiber is to be understood as meaning an end of an optical fiber in the direction of its longitudinal axis, for example in the case of a cylindrical optical fiber a base surface of the cylinder. A lateral surface of an optical fiber is to be understood as meaning the surface which delimits an optical fiber perpendicular to its longitudinal axis, for example in the case of a cylindrical optical fiber the lateral surface of the cylinder. Optical fibers which are butted along their side surfaces are understood to be the optical fibers, all or nearly all of them all, for example more than 90% of the optical fibers, touch immediately adjacent optical fibers along their side surfaces.

It is provided in particular that the optical fibers are arranged at least in the fiber section along its side surfaces in abutment.

Advantageously, the value of the predetermined height is selected so that at the end of the exercise of the force, the fibers at least largely fill an area between the pressing surfaces.

In particular, it is provided that for the deformation of the optical fibers, the pressing surfaces are moved toward one another along a defined path length.

In this case, provision is made in particular for the method to provide for the deposit or the measurement of the distance between the pressing surfaces when the pressing surfaces are placed on the optical fibers, and also for depositing or measuring the proportion of the free cross-sectional area between the pressing surfaces in the region of the optical fibers when placing the components Pressing surfaces on the optical fibers provides and that the path length is given by the product of the two stored or measured sizes.

In one embodiment, it is provided that the pressing surfaces are moved towards each other via a high-precision drive, in particular via a piezo-based drive.

Advantageously, the determination of the height of the gap remaining between the pressing surfaces comprises a referencing of the measuring device, which takes place either in that the beginning of the deformation of the optical fibers is detected, for example by a suitable sensor system, or by being carried out regularly, for example at the beginning of the layer , the pressing surfaces are so far approached that they touch.

Advantageously, following the detection of the beginning of the deformation of the fibers, the pressing surfaces are moved towards each other by a defined path length, the path length being given by the distance between the pressing surfaces at the beginning of the deformation of the fibers and the proportion of the free cross-sectional area between the pressing surfaces in the region the fibers at the beginning of the deformation of the fibers. It is possible that these two factors at the beginning of the deformation of the fibers by a However, the fibers are arranged in a layer and have a round cross-section with a known diameter. The distance is then given at least approximately by the product of the diameter of the fibers with the factor (l-pi / 4).

One of the two pressing surfaces is advantageous or both pressing surfaces are part of one or two fiber carriers, which enter into a particularly cohesive connection with the optical fibers by the method according to the invention. In these cases, it is advantageous for improving the accuracy of the optical fiber reforming when the optical fibers consist of one or more first glasses and when the fiber carrier or the fiber carriers consist of one or more second glasses and if the softening temperature of the second glass or Softening temperatures of the second glasses have a higher value ha1 / than the softening temperature of the first glass or the softening temperatures of the first glasses. If the glasses are selected accordingly, it is ensured that under the action of the force, a deformation of the fibers, but not the fiber carrier takes place. Preferably, the softening temperatures are more than 20K apart.

drawing

FIG. 1 shows a schematic representation of an internal combustion engine with a laser ignition device.

FIG. 2 schematically shows a laser ignition device in detail.

Figures 3a, 3b, 3c and 3d show schematically an example of a light source.

Figures 4, 4a show schematically the structure and arrangement of optical fibers.

FIG. 4b schematically shows an example of the arrangement of light-conducting device and diode laser.

Figures 5a, 5b and 5c show schematically another example of a light source. FIGS. 6, 7a, 7b, 7c, 7e, 7f, 7g, 7h and 7i show by way of example and schematically the production of a light source.

Figures 8a, 8b, 8c, 8d and 8e and Figures 9a and 9b show schematically another example of the production of a light source.

Figures 10 and 11 show further examples of the production of a light source.

Description of the embodiment

An internal combustion engine carries in Figure 1 in total the reference numeral 109. It serves to drive a motor vehicle, not shown, or a generator, also not shown. The engine 109 includes a plurality of cylinders 129, one of which is shown in FIG. A combustion chamber 14 of the cylinder 129 is bounded by a piston 16. Fuel 229 enters the combustion chamber 14 directly through an injector 18, which is connected to a fuel pressure accumulator 209.

Fuel 229 injected into the combustion chamber 14 is ignited by means of a laser pulse 24 which is emitted by an ignition device 27 comprising a laser device 11 into the combustion chamber 14 and focused by means of focusing optics 261. The laser device 11 is fed by a light source 10 via a light guide 12 with a pumping light. The light source 10 is controlled by a control and regulating device 32, which also controls the injector 18.

In addition to the light-conducting device 12, the light source 10 also includes a diode laser 13, which outputs a corresponding pumping light via the light-guiding device 12 to the laser device 11 as a function of a control current.

FIG. 2 schematically shows a detailed view of the solid-state laser 260 of the laser device 11 from FIG. 1. As can be seen from FIG. 2, the solid-state laser 260 has a laser-active solid, referred to below as a laser crystal 44, which has a crystal called a Q-switch Q-switch 46, visually subordinate. The solid state laser 260 further includes a coupling mirror 42 and a Auskoppelspiegel 48. The components of the solid state laser 260 are monolithic in this example, that is, they are largely non-detachably connected to each other, for example by bonding and / or coating.

To generate a laser pulse, also called a giant pulse, the

Laser crystal 44 is applied through the coupling mirror 42 through pump light 28a, so that there is an optical pumping and the formation of a population inversion in the laser crystal 44. First, the passive Q-switch 46 is in its idle state, in which it has a relatively low transmission for the light to be generated by the laser device 11. In this way, the

Process of stimulated emission and thus the generation of laser radiation initially suppressed. However, as the pumping time increases, that is, when it is exposed to the pumping light 28a, the radiation intensity in the solid-state laser 260 rises, so that the passive Q-switch 46 finally fades. In this case, its transmission increases abruptly, and the generation of laser radiation sets in. This state is symbolized by the double arrow 24 '. During laser operation, due to the effect of the stimulated emission, rapid degradation of the population inversion present in the laser crystal 44 occurs, so that the emission of the solid state laser 260 typically stops after a few nanoseconds, and subsequently the transmission of the Q-switch 46 also returns to its original, low value ,

In the manner described above, a laser pulse 24, also referred to as a giant pulse, which has a relatively high peak power. The laser pulse 24 is, optionally using another light guide (not shown) or directly, coupled through a likewise not shown combustion chamber window of the laser device 11 in the combustion chamber 14 (Figure 1) of the engine 109, so that existing therein fuel 229 or air / Fuel mixture is ignited.

Figures 3a, 3b, 3c and 3d show a schematic view of an embodiment of a light source 10. The diode laser 13 encompassed by the light source 10 has the design of a so-called diode laser bar. It thus has a plurality of juxtaposed emitters 131. The emitters 131 have a side surface 1310 through which the light generated by the emitters 131 exits. This side surface 1310 typically has an approximately rectangular shape with a, referred to as fast axis, short, for example, lμm long, first page 1311 and one, usually referred to as slow axis, longer, for example 10 - 500μm long, second side 1312. Between those in a layer plane in the direction The slow-axis emitters 131 arranged next to one another are areas designated as separating trenches, from which no light is emitted. The light generated by the emitters 131 and emerging from the side surfaces 1310 each has the shape of a cone of light, wherein the half-opening angle of the cone of light in the plane of the fast-axis is typically in the range of 30 ° to 60 ° and generally greater than that Aperture angle of the light cone in the plane of the slow axis, which is typically only a few degrees.

Although in this example the diode laser 13 has the design of a so-called diode laser bar, the invention is not limited to such a design, but also includes, for example, diode laser 13 with other arrangements of emitters 131, for example arrangements having emitters 131 in multiple layer planes, these Layer planes are offset for example in the direction of the fast axis by a few microns to each other, for example, so-called diode laser stacks or nanosticks.

The light guide device 12 likewise encompassed by the light source 10 has a plurality of fibers 121, also referred to as optical fibers 121, the fibers 121 each having a first end 1211 and a second end 1212. The fibers 121 are arranged in the region of their first ends 1211 in a position next to one another. Furthermore, the fibers 121 are arranged in the region of their first ends 1211 such that the end faces 1216 of the fibers 121 associated with the first ends 1211 lie together in one plane. Furthermore, the fibers 121 are arranged in the region of their first ends 1211 along their side surfaces 1217 in abutment, that is arranged so that all fibers 121 or almost all fibers 121, for example, more than 90% of the fibers 121, immediately adjacent fibers 121 in the region touching first ends 1211.

In this example, the end faces 1216 of the fibers 121 have a substantially rectangular shape, likewise, cross-sections of the fibers 121 in the region of their first ends 1211 have a substantially rectangular shape. In this case, the fibers 121 in the region of their first ends 1211 areally contact each other along approximately planar regions of the side surfaces 1217 of the fibers 121. However, the invention is of course not applicable to fibers 121 which are in the region of their first ends 1211 in FIG Have substantially rectangular cross sections, limited. These cross sections may also be trapezoidal or have curved sides, wherein it is preferred that the fibers 121 contact each other flatly along their side surfaces 1217 in the region of their first ends 1211 and that the end faces 1216 of the fibers 121 lie together in one plane, wherein the end faces 1216 of the fibers 121 together as close as possible, that is without inclusions free surfaces lie.

The end faces 1216 of the fibers 121 and cross sections of the fibers 121 have an at least substantially identical surface area, which is preferably between 3000 μm ² and 5000 μm ² . Preferably, the end faces 1216 of

Fibers 121 and cross-sections of the fibers 121, which lie in the region of the first ends 1211 of the fibers 121, the shape of a rectangle whose side lengths form a ratio of about 0.78 or pi / 4, wherein the fibers 121 preferably along the short Touch the sides of the rectangles. In the context of this invention, a cross section of a fiber 121 is to be understood as a cross section perpendicular to the longitudinal axis 1219 of the fiber 121.

The fibers 121 consist of at least one glass, each individual fiber 121 preferably consisting of at least two different glasses. Glass types that are used are, for example, so-called flint glasses and / or soda-lime glasses.

FIG. 4 shows a section of the light-conducting device 12, in particular of the end faces 1216 which are associated with the first ends 1211 of the fibers 121 and which represent cross-sections of the fibers 121 in the region of their first ends 1211. A fiber core 1213 arranged centrally in the fiber 121 and, furthermore, a fiber cladding 1214 surrounding the fiber core 1213 laterally, that is to say perpendicular to the longitudinal axis 1219 of the fibers 121, become visible in cross-section or along the end face 1216 of a fiber 121. In cross-section, or along the end face 1216, of a fiber 121, a fiber sizing 1215 laterally surrounding the fiber cladding 1214 is also visible. Both the end face 1216 of the fiber 121 and cross sections of the fibers 121 in the region of their first ends 1211 have an almost rectangular shape in this example. Likewise, in the region of the first end 1211 of the fibers 121, cross sections of the fiber core 1213 and the structure composed of fiber core 1213 and fiber cladding 1214 and the structure composed of fiber core 1213 and cladding 1214 and fiber sizing 1215 have nearly rectangular cross sections. It is provided that the thickness of the fiber cladding 1214, at least in the region of the first ends 1211 of the fibers 121 compared to the cross-sectional area, in particular compared to the square root of the surface area of the cross-sectional area, of the fiber core 1213 is low, whereby a high proportion of the fibers Emission of the diode laser 13 in fiber cores 1213 coupled, where it can be guided loss.

In order to ensure that the light, which nevertheless couples into the fiber cladding 1214 of a fiber 121, is at least partially guided to the second end 1212 of the fiber 121, it is additionally or alternatively provided that the fiber core 1213 is made of a first material, the fiber cladding 1214 is made of a second material and the fiber sizing 1215 is made of a third material, wherein the first material for the light generated by the diode laser 13, whose wavelength is for example 808 nm, has a refractive index ni, the second material being generated by the diode laser 13 Light has a refractive index n ₂ , and wherein the third material has a refractive index n ₃ for the light generated by the diode laser 13, and where ni> n ₂ > n ₃ > 1.

In this example, the fiber core 1213 has a nearly rectangular shape and edge lengths of 60 μm and 77 μm in the region of the first ends 1211 of the fiber 121, the fiber cladding 1214 forms an approximately 2 μm thick layer and the fiber sizing 1215 is approximately 0.05 μm thick Layer. The first material, the material of the fiber core 1213, is a glass having a refractive index between 1.5 and 1.6, for example, flint glass. The second material, the material of the fiber cladding 1214, is a glass having a refractive index between 1.4 and 1.5, for example soda-lime glass. The third material, the material of the fiber sizing 1215, is a plastic and has a refractive index of between 1.15 and 1.35. The fiber sizing 1215 additionally has the function that

To improve the durability of the fibers 121. The fiber sizing 1215 may be a coating of varnish (acrylate or plastic).

The first ends 1211 and / or the second ends 1212 of the fibers 121 may comprise a polish and / or, as shown in FIG. 4 a, an antireflection layer 15. Such a polish and / or such antireflection layer 15 is designed so that it reduces optical losses on entry / exit in / from the light guide 12.

Alternatively or additionally, it is possible, as shown schematically in Figure 4b, a space between the first ends of the fibers 1211 and the emitters 131 of

Diode laser 13 completely with an optically homogeneous medium 17, for example an optical gel, preferably with a gel that reduces optical losses in coupling the light generated by the emitters 131 of the diode laser 13 into the fibers 121 and / or has a refractive index equal to or about equal to, for example, not more as 15% different, the refractive index of the fiber core is ni.

Alternatively or additionally, it is possible to arrange the first ends 1211 of the fibers 121 at a distance of 1 μm to 10 μm in front of the emitters 131 of the diode laser 13.

As can be seen in FIGS. 3 a, 3 b and 3 c, the fibers 121 are connected to a fiber carrier 20 in the region of their first ends 1211. The fiber carrier 20 used in this example has the shape of a cuboidal disk, extends across the width in which the fibers 121 are arranged, for example, about 20 mm, has a length of 1 mm, oriented in the direction of the longitudinal axes 1219 of the fibers 121 20 mm, for example up to 10 mm. The fiber carrier 20 terminates flush on its side facing the diode laser 13 with the end faces 1216 of the fibers 121. The height of the fiber carrier 20 is in the range of a few tenths of a millimeter to a few millimeters and is typically many times higher than the height of the fibers 121.

The fiber carrier 20 consists of a glass and is bonded to the fibers 121 in the region of their first ends 1211. The fiber carrier 20 is made of a glass which has lower hardness at room temperature, a comparable coefficient of thermal expansion and / or a higher softening temperature compared to the type of glass or the types of glass constituting the fibers 121. Types of glass used are, for example, float glasses.

The region, referred to herein as the region of the first ends 1211 of the fibers 121, is to be understood as the region of the fibers 121 in which the fibers 121 are arranged on the fiber carrier 20.

The composite of fibers 121 and fiber carrier 20 is fixed relative to the diode laser 13, for example by gluing. Another possibility is to fix by clamping so that it can be loosened at a later time, for example, for disassembly or readjustment. A further embodiment is shown in FIGS. 5a, 5b and 5c. This further embodiment differs from the embodiment illustrated in FIGS. 3 a, 3 b and 3 c in that the fibers 121 are arranged not only on a fiber carrier 20 in the region of their first ends 1211 but are arranged between the fiber carrier 20 and a second fiber carrier 21 , The fiber carrier 20 and the second fiber carrier 21 each have the shape of a cuboid glass disc and are, for example, the same size. For example, the fiber carrier 20 and the second fiber carrier 21 have the dimensions given in the preceding example for the fiber carrier 20.

There is a material connection between the fiber carriers 20, 21 and the fibers 121 and both the fiber carrier 20 and the fiber carrier 21 are flush with the end surfaces 1216 of the fibers 121.

On the one hand, it is possible that the surface of the fiber carrier 20 facing the fibers 121 and the surface of the second fiber carrier 21 facing the fibers 121 are parallel to one another, so that the gap remaining between the fiber carriers 20, 21 has a uniform height. Alternatively, the fiber 121 facing surface of the fiber carrier 20 and the fibers 121 facing surface of the second fiber carrier 20 are tilted to each other so that the remaining between the fiber carriers 20, 21 gap in the region of the end faces 1216 of the fibers 121 has a lower height than in the area of the fiber carriers 20, 21 lying opposite the end faces 1216 of the fibers 121. Preferably, a tilting takes place at an angle of 0.1 ° to 2.5 °, for example 0.2 ° to 0.5 °.

According to the shape of the gap between the fiber carriers 20, 21, a continuous taper of the fibers 121 is provided. The continuous transition between a cross-sectional shape useful for coupling into the fibers 121 and a cross-sectional shape useful for the fibers in the fibers 121 avoids abrupt transitions which are potential mechanical weak points.

The two fiber carriers 20, 21 can have similar, in particular identical, properties with respect to their material. The second fiber carrier 21 preferably consists of a glass, which has a lower hardness at room temperature and / or in comparison to the type of glass or to the types of glass which make up the fibers 121 has comparable thermal expansion coefficient and / or a higher softening temperature.

In the following, the production of a light source 10 will be explained by way of example with reference to FIG. The starting point is a fiber carrier 20 with a height of 1 mm, a length of 5 mm and a width of 14 mm. Along the entire width of the fiber carrier 20 optical fibers 121, the round end faces 1216 and circular cross-sectional areas and having a length of about 1000 mm and a diameter of about 70 microns, arranged, the fibers 121 in the region of the fiber carrier 20 in a Layer and lie along their side surfaces 1217 on impact, that is, all fibers 121 or almost all fibers 121, for example, more than 90% of the fibers 121, immediately adjacent fibers 121 in the region of their first ends 1211 along their side surface 1217 touch. It thus comes to the arrangement of about 200 fibers 121st

The fibers 121 are oriented relative to each other and relative to the fiber carrier 20, for example by utilizing a common stop surface (not shown), such that the end surfaces 1216 of the fibers 121 are flush with each other and flush with the fiber carrier 20.

A heating of the arranged on the fiber carrier 20 fibers 121 by means of a heater 70, for example by means of an electrical resistance heater, for example to a temperature of 550 ° C to 800 ⁰ C, wherein the heat generated by the heater 70, the fibers 121 in the example by the Fiber carrier 20 comes through. As a result of the heating of the fibers 121 and the fiber carrier 20, a cohesive connection between the fibers 121 and the fiber carrier 20 is formed.

In an alternative embodiment of the method, as illustrated in FIGS. 7a and 7b, the formation of a connection between the fiber carrier 20 and the fibers 121 is promoted and accelerated by a counter-surface 22 of a tool 200 on the side of the fibers 121 facing away from the fiber carrier 20 is brought into contact with the fibers 121 under the action of a force F. Thus, a force is also generated between the fiber carrier 20 and the fibers 121. In order to avoid that a compound also forms between the fibers 121 and the counter-surface 22, the latter is made of at least one heat-resistant material, which also under the action of heat and pressure does not connect with glass, for example, SiC, form.

Alternatively, the formation of a connection between the mating surface 22 and the fibers 121 may also be desirable, in particular if the mating surface is part of a second fiber carrier 21, as shown in FIGS. 7c and 7d. In this case, by means of a second heating device 71, for example by means of a second electrical resistance heater, which is arranged on the side facing away from the first electrical resistance heater 70 side of the composite of fibers 121 and fiber carriers 20, 21, the heat supply can be improved.

In an alternative embodiment of the method, the continued heating of the fibers 121 is associated with a softening of the fibers 121 and / or under the action of force applied by the mating surface 22, the fibers 121 deform in the region of their first ends 1211 As shown in FIG. 7e, it can be observed that the initially round cross-sectional areas of the fibers 121 in the regions in which the fibers 121 contact one another or the fiber carrier 20 or the counter surface 22 flattened the curvature of the side surfaces 1217 of the fibers 121 in FIG thus decreases these areas (increase in the radius of curvature), while the curvature in still free areas of the side surfaces 1217 of the fibers 121 increases (reduction of the radius of curvature). If the action of the heat and the force continues, the fibers 121 are further deformed in the region of their first ends 1211 until the space between the fiber carrier 20 and the mating surface 22 is at least substantially completely filled by the fibers 121 (FIG. 7e). , The fibers 121 then have in the region of their first ends, for example, rectangular cross-sections, in particular with an aspect ratio of Pi to 4, on the other hand, less regularly shaped cross-sectional areas of the fiber 121, such as trapezoidal cross-sections or curved cross sections, result (Figure 7f).

In another embodiment it is provided that, as can be seen in FIGS. 7g, 7h and 7i, the fibers 121 are pressed more strongly in a first subregion 121a, which comprises the end faces 1216 of the fibers 121, than in a second subregion 121b second portion 121 b is spaced from the end faces 1216 of the fibers 121. For example, the fibers 121 in the first subregion 121a are pressed so strongly that they have almost rectangular end faces following the pressing 1216 (Figure 7h). In this example, the fibers 121 in the second subregion 121b are pressed so little that they maintain a virtually round cross-sectional area in the second subregion 121b (FIG. 7i).

For this purpose, it is provided that the counter surface 22 forms an angle of 0.1 ° to 2.5 ° to the support surface of the fibers 121 on the fiber carrier 20. Alternatively or additionally, it is provided that the force acting on the fibers by the opposing surface 22 to the normal force of the support surface of the fibers 121 on the fiber carrier 20 forms an angle of 0.1 ° to 2.5 °, so that there is an uneven compression of the fibers 121 is coming.

The production of a single light source 10, in particular the production of a single light guide 12, has been described above. It is, as described below by way of example, additionally or alternatively possible, in a single operation in each case a plurality of light sources 10, in particular in each case a plurality of light-conducting devices 12 to produce.

For this purpose, for example, as shown in FIGS. 8a and 8b, a multiplicity of fibers 121, in particular a very large number of fibers 121, for example 1000 or more fibers 121, are arranged next to each other so that the fibers 121 in a fiber section 1218 are along their side surface 1217 in abutment, that is to say arranged so that all the fibers 121 or almost all the fibers 121, for example more than 90% of the fibers 121, touch immediately adjacent fibers 121 in the region of their first ends 1211 along their side surfaces 1217 in the fiber section 1218.

The fibers 121 are arranged so that the fiber section 1218 lies in the longitudinal direction of the fibers 121 at least approximately in the middle of the fibers 121. The fibers 121 are also located in the fiber section 1218 on a fiber carrier 20 which is, for example, a glass plate and has a height of about one millimeter, a length of several millimeters and a width of 50 mm to 200 mm or more. In this

For example, a second fiber carrier 21, whose properties in terms of geometry and material with those of the fiber carrier 20 match, compared to the first fiber carrier 20 is placed on the fibers 121.

In the figure 8c, the following process steps are shown schematically. These process steps include heating the fiber carrier 20 and the fiber carrier 21 Two designed as electric resistance heating heaters 70, 71. Indirectly, the fibers 121 are thus heated, in this example, on 550 to 850 ⁰ C. Further, these method steps comprising the application of a force F to the fiber carrier 20 and the action of a force F ' on the second fiber carrier 21. The forces F and F 'are opposite to each other and oriented so that a total of the two fiber carriers 20, 21, a pressure on the fibers 121 is applied, for example, a pressure of 0.5 N / cm ² to 50 N / cm ² .

Due to the action of the pressure, a deformation of the fibers 121 occurs in the region between the fiber carrier 20 and the second fiber carrier 21, wherein the fibers 121 in the region between the fiber carrier 20 and the second fiber carrier 21 initially have round cross-sectional areas and these round cross-sectional areas due deform the deformation of the fibers 121 as described above.

An example of correspondingly deformed fibers 121 is further shown in Figure 8d wherein the cross-sectional areas of the fibers 121 have flattenings in the regions where the fibers 121 contact the fiber carriers 20, 21 or each other. FIG. 8 e shows a further example in which the fibers 121 largely fill the area between the fiber carrier 20 and the second fiber carrier 21 so that the entirety of the fibers 121 largely completely fill the space located between the fiber carriers. The cross sections of the individual fibers 121 in the region between the fiber carriers 20, 21 may be rectangular or trapezoidal.

Subsequently, a cooling of the fibers 121 and the fiber carrier 20, 21, wherein it comes to solidification of the fibers 121 and wherein between fibers 121 and the fiber carriers 20, 21 forms a material connection.

As shown schematically in FIG. 9 a, in this example it is provided that subsequently the composite of fiber carrier 20, fibers 121 and second fiber carrier 21 by means of a section 55 which is approximately perpendicular to the longitudinal axes 1219 of the fibers 121 in the region of the fiber section 1218 of the fibers 121 is made into two approximately equal parts 301, 302 is separated. The cut 55 can be carried out, for example, in a manner known per se by means of a diamond saw or by means of scribing and breaking or with the aid of a laser beam, for example infrared laser, in particular CO ₂ laser. It is optionally possible to stack the two parts 300, 301 thus obtained or a plurality of parts 301, 302 thus obtained on each other and to polish together and / or provided with an antireflection layer.

The obtained parts 301, 302 can be considered as two light-guiding devices 12, which were manufactured together.

Optionally it is also possible, as shown schematically in Figure 9b, the parts 301, 302 individually or jointly by one or more second cuts 56, which are performed in the region of the fiber portion 1218 of the fibers 121 along the longitudinal axes 1219 of the fibers 121 on to divide and so to produce a plurality of light-conducting devices 12. The second cuts 56 can be made flexible, in particular so that the width of the light guides 12 produced correspond to the width of the diode lasers 13 with which they cooperate.

The second cuts 56 can be made as well as the cuts 55, for example by means of a diamond saw or by means of scribing and breaking or with the aid of a laser beam, for example infrared laser, in particular CO ₂ laser.

In particular, it is possible, in order to carry out the second cuts 56, to stack the parts 301, 302 or a multiplicity of parts 301, 302, so that a plurality of light-conducting devices 12 are separated every second cut 56.

As discussed above, the fabrication of a light source 10 may provide for deformation under the application of a force F to the heated fibers 121 in the region of the first ends 1211 of the fibers 121 or in, for example, approximately the center, fiber portion 1218 of the fibers 121 the heated fibers 121 come, for example, so that the entirety of the deformed fibers 121 completely fills a region between a fiber carrier 20 and a second fiber carrier 21. Of course, it is also possible to replace the fiber carrier 20 and / or the second fiber carrier 21 by a tool 200, for example made of SiC, which does not bond to the fibers 121 and which is removed after deformation of the fibers 121. It is essential that the fibers 121, as shown in Figure 10, between two pressing surfaces 201, 202 are arranged, through which the force F and the counterforce F 'acts on the fibers 121. In this case, the manufactured device does not have two fiber carriers 21, 22, but instead at most one fiber carrier 21. It is particularly preferred in this case to introduce the first and / or second cuts 55, 56 by scribing and breaking.

In the following example, the forces F and F 'are selected so that, although a deformation of the fibers 121 occurs, this deformation comes to a standstill when the fibers 121 at least largely cover a region between the pressing surfaces 201, 202 for the first time (for example> 99, 5% of the cross section). In this case, both an insufficient force F, which would not be sufficient for deforming the fiber 121, and an excessive force, which would lead to the lateral emergence of the fibers 121 from the area between the pressing surfaces 201, 202, is avoided.

Specifically, 140 fibers of flint glass / soda lime glass between two pressing surfaces 201, 202 sized 15mm * 8mm were arranged and heated to about 630 ⁰ C, ie above the softening temperature of the fibers 121. Subsequently, the fibers 121 were subjected to a force F. The desired behavior was observed for forces between IN and 35 N.

Of course, it is within certain limits possible to heat the fibers 121 to a higher or lower temperature, resulting in an increased or decreased flowability of the fibers 121 results. The area of the force F in which the behavior that deformation of the fibers 121 comes to a standstill but this deformation comes to a standstill when the fibers 121 at least largely cover a region between the pressing surfaces 201, 202 for the first time (for example> 99.5%). of the cross-section) occurs, shifts in this case and can be found by experimentation. In the present example, the desired behavior for forces F between 10 N and 20 N and fiber temperatures between 590 ⁰ C and 690 ⁰ C was achieved.

In another embodiment, it is additionally or alternatively provided that the height of the gap remaining between the pressing surfaces 201,202 is determined, whereby the exertion of the force F is terminated when the determined value reaches or exceeds a predetermined value, ie when the height of the between the pressing surfaces 201, 202 remaining gap reaches or exceeds a predetermined height.

The exercise of the force can be stopped on the one hand, when the fibers 121 a

Range between the pressing surfaces 201, 202 at least largely (for example,> 99% the cross-sectional area), on the other hand, another height can be selected. In the embodiment shown in FIG. 11, fibers 121 of first round cross-section and diameter D, which in this example is 100 μm, are single-layered and inserted along the side surfaces 1217 of the fibers 121 between two pressing surfaces 201, 202. The pressing surfaces 201, 202 are each either part of a fiber carrier 20, 21, which connects to the fibers 121 or a tool 200, for example of SiC, which does not enter into communication with the fibers 121.

The pressing surfaces 201, 202 are on actuators 60, here for example via piezoelectric actuators, displaced, wherein the displacement of the pressing surfaces 201, 202 by a to the

Actuators 60 applied signal, for example, by a voltage is triggered. It is provided that the actual distance of the pressing surfaces 201, 202 from each other is detected, for example on the basis of the signals applied to the actuators or by an optical system.

In this example, the position of the pressing surfaces 201, 202 relative to each other before application of a voltage to the piezoactuator is referenced in that the pressing surfaces 201, 202 are brought into contact with the not yet softened fibers 121. Subsequently, the voltage applied to the piezo actuators is increased stepwise or continuously until the applied voltage corresponds to a length expansion of the piezo actuators of 22 μm. At this time, the space located between the pressing surfaces 201, 202 is at least substantially completely filled by the deformed fibers 121.

Claims

claims

1. A method for producing a light source (10), in particular a light source (10) for the optical excitation of a laser device (11), for example a

A laser device (11) of a laser ignition system of an internal combustion engine (109), comprising a diode laser (13) having a plurality of emitters (131) and a light guide (12), wherein the light guide (12) comprises a plurality of optical fibers (121) and each optical Fiber (121) has a first end (1211) and a side surface (1217), the first ends (1211) being to the emitters in such a manner

(131) are arranged such that light generated by the emitters (131) couples into the first ends (1211) of the optical fibers (121), wherein the optical fibers (121) at least in the region of their first ends (1211) along their side surfaces (12). 1217) are arranged in abutment, characterized in that the method comprises the following steps

Arranging a multiplicity of optical fibers (121) which in one partial region form a fiber section (1218) which is arranged between two pressing surfaces (201, 202) lying opposite one another, heating the fiber section (1218),

Deforming the fiber portion (1218) by applying a force to the heated fibers (121) through the pressing surfaces (201, 202), wherein during the application of the force, the height of the gap remaining between the pressing surfaces (201, 202) is determined, and wherein the exercise the force is terminated when the determined height of the gap remaining between the pressing surfaces (201, 202) reaches or exceeds a predetermined value.

A method according to claim 1, characterized in that the optical fibers (121) are butted along at least the fiber portion (1218) along their side surfaces (1217).

3. The method of claim 1 or 2, characterized in that the predetermined value of the height is chosen so that at the end of the exercise of the force, the fibers (121) at least largely fill a region between the pressing surfaces (201, 202).

4. The method according to any one of the preceding claims, characterized in that for the deformation of the optical fibers (121), the pressing surfaces (201, 202) a defined path length are moved towards each other.

5. The method according to claim 4, characterized in that the method the

Depositing or measuring the distance between the pressing surfaces (201, 202) when placing the pressing surfaces (201, 202) on the optical fibers (121) and further depositing or measuring the proportion of the free cross-sectional area between the pressing surfaces (201, 202 ) in the region of the optical fibers (121) when the pressing surfaces (201, 202) are placed on the optical fibers (121) and that the path length is given by the product of the two stored or measured quantities.

6. The method according to claim 5, characterized in that the distance between the pressing surfaces (201, 202) at the beginning of the deformation of the fibers (121) is characterized in that the fibers (121) are arranged in one layer and a round cross-section with have a known diameter.

7. The method according to claim 6, characterized in that the optical fibers (121) are arranged in a layer and have a round cross-section with a known diameter and the distance at least about the product of the diameter of the fibers (121) with the factor ( l-pi / 4) is the same.

8. The method according to any one of the preceding claims, characterized in that the pressing surfaces (201,202) are moved towards each other via a high-precision drive, in particular via a piezo-driven drive.

9. The method according to any one of the preceding claims, characterized in that at least one of the pressing surfaces (201) is part of a fiber carrier (20), and that for forming a compound, in particular for forming a material connection, between the heated fibers (121). and the fiber carrier (20) comes.

10. The method according to claim 9, characterized in that one of the pressing surfaces (201, 202) is part of a fiber carrier (20) and one of the pressing surfaces (201, 202) is part of a second fiber carrier (21) and that it is for forming a connection . in particular for the formation of a cohesive connection, between the heated fibers (121) and the fiber carrier (20) and the second fiber carrier (21) comes.

11. The method according to claim 9 or 10, characterized in that a material bond between the fibers (121) is avoided.

12. The method according to any one of claims 9 to 11, characterized in that the fibers (121) consist of one or more first glasses and the fiber carrier (20) or the fiber carrier (20,21) consist of one or more second glasses and that the softening temperature of the second glass or the softening temperatures of the second glasses are higher than Ha1 / softening temperature of the first glass or softening temperatures of the first glasses.

13. The method according to any one of claims 9 to 12, characterized in that the softening temperature of the second glass or the second glasses has a value of 20 to 250 K, in particular 20 to 150 K higher than the softening temperature of the first glass or the first glasses.

14. The method according to any one of claims 9 to 13, characterized in that the fibers (121) consist of one or more first glasses and the fiber carrier (20) or the fiber carrier (20,21) consist of one or more second glasses and that the hardness at room temperature of the second glass or the room temperature hardnesses of the second glasses are higher than ha1 / ha

Room temperature of the first glass or the room temperature curing of the first glasses.

15. The method according to claim 1 to 9 or 11 to 14, characterized in that at least one of the pressing surfaces (201, 202) consists of a heat-resistant material which does not enter into communication with the fibers (121) even at temperatures of 800 ⁰ C, for example from SiC.

16. The method according to any one of claims 1 to 8, characterized in that both pressing surfaces (201, 202) consist of at least one heat-resistant material, with the fibers (121) even at temperatures of 800 ⁰ C no connection received, for example from SiC.

17. The method according to any one of the preceding claims, characterized in that the heating of the arranged fibers (121) within the fiber portion (1218) takes place by the fibers over at least one, in particular both of the

Pressing surfaces (201, 202), in particular by means of an electrical resistance heater or by means of an induction heater, are heated.