WO1996034440A1

WO1996034440A1 - Process and device for forming and guiding the radiation field of one or several gas lasers

Info

Publication number: WO1996034440A1
Application number: PCT/EP1996/001250
Authority: WO
Inventors: Keming Du; Dietmar Ehrlichmann; Uwe Habich; Peter Loosen
Original assignee: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
Priority date: 1995-04-26
Filing date: 1996-03-22
Publication date: 1996-10-31
Also published as: DE19514624C2; DE19514624A1

Abstract

A process and device for forming and guiding the radiation field of one or several gas lasers, in particular the radiation field of an array or field arrangement of several gas lasers, wherein radiation transformation optics with reflecting elements generate a defined radiation field. The device is characterised in that the radiation field (7) is subdivided into at least two radiation fractions according to predetermined data. Each radiation fraction is directed to a first reflecting element with a first reflecting surface (9, 14, 19, 23, 27). The first reflecting surfaces (9, 14, 19, 23, 27) are arranged in planes that are mutually offset and/or inclined so that the radiation fractions are irradiated from the first reflecting surfaces (9, 14, 19, 23, 27) with relative output co-ordinates, relative propagation directions and/or relative output orientations modified with respect to their relative lateral input co-ordinates of incidence on the first reflecting elements. The reflected radiation fractions are grouped and each radiation group is directed to an associated second reflecting element with a second reflecting surface (12, 14, 20, 23, 27). The second reflecting surfaces are arranged in planes that are mutually offset and/or inclined so that the radiation groups are irradiated by the first reflecting surfaces (9, 14, 19, 23, 27) with relative output coordinates, relative propagation directions and/or relative output orientations modified with respect to their relative lateral input co-ordinates of incidence on the corresponding second reflecting elements.

Description

P a t e n t a n m e l g

"Arrangement and method for shaping and guiding a radiation field of one or more gas lasers

The present invention relates to an arrangement and a method for shaping and guiding a radiation field of one or more gas lasers, in particular a radiation field of an array or a field arrangement of several gas lasers, with a radiation transformation optics for generating a defined radiation field , the optics having reflective elements.

Individual laser radiation sources can only be scaled to higher powers to a limited extent. This applies in particular to gas lasers.

In order to achieve extensive radiation fields with a high power density with the gas lasers mentioned, in particular in those of a low power class, while maintaining a high beam quality, it is necessary to combine several gas lasers to form arrays or field arrangements.

An important task that arises in the development and construction of gas laser radiation sources is the scaling of the laser radiation power while achieving a high beam quality. Various measures can be taken to achieve this. One possibility is to scale the laser power by scaling the laser oscillator volume. When enlarging the laser oscillator volume, however, it must always be taken into account that the axial dimension, ie the resonator length, and the lateral dimensions are related to one another in such a way that the Fresnel number of the oscillator does not become significantly greater than 1, so that a high beam quality is guaranteed. These boundary conditions considerably limit the design of a high-performance oscillator with high beam quality. In order to achieve the required resonator lengths while maintaining a compact size of the resonator, the oscillator is often folded several times. Such folding is always associated with technical complications, since, for example, segmented resonator mirrors with individually curved mirror surfaces have to be used in order to compensate for a thermal lens effect. Furthermore, the decoupling window of a long oscillator is heavily loaded due to the relatively small aperture, which in turn leads to a reduction in the beam quality with regard to the decoupled beam.

Another possibility of scaling the laser radiation power is to use a so-called oscillator amplifier. In this case, a laser oscillator with a relatively low power but high beam quality is first set up. The laser radiation emerging from the laser oscillator is then fed into a downstream power amplifier and amplified to the desired high power. Such a laser oscillator-amplifier principle is mostly used in pulsed lasers. With such a laser oscillator-amplifier principle, several hundredfold amplifications can be achieved. In contrast, the gain in connection with continuously operated lasers is only a few hundred percent, taking into account that the efficiency of the entire laser (laser oscillator and amplifier) does not become too low.

A third alternative for scaling a laser radiation source is the laser array. These are several laser oscillation ren, which are arranged spatially side by side in a field arrangement or an array and operated in parallel. In such a laser array, the total laser radiation power is consequently the sum of the power of the individual oscillators. A central problem that arises in connection with this scaling principle is the coherent coupling of the oscillators with one another. It must be taken into account that a periodic field distribution is reproduced in equidistant planes when spreading in amplitude and phase, so that measures must be taken to bring these beams of the individual laser oscillators together in a common plane or in a common focal point, which requires a high optical effort. Furthermore, in order to achieve a coherent coupling of the oscillators, it must be ensured that the natural frequencies of the individual oscillators do not deviate too much from one another. Furthermore, imaging errors in two-dimensional laser oscillator arrays with free propagation lead to losses which typically reach values of 401 compared to one-dimensional arrays composed of eight oscillators. The high losses consequently lead to low efficiency. Due to the measures required to bring the beams together, justification problems arise, so that, conversely, such a laser arrangement shows a high sensitivity. Furthermore, no spherical mirrors should be used in such an arrangement, since this results in different lengths of the individual oscillators, but this is especially necessary for stable laser operation. Furthermore, in order to implement such arrangements, the distances between adjacent, individual laser oscillators would have to be maintained, which are so small with a realistic oscillator length that they are practically impossible to relate and technically controllable.

Another problem that also arises with large field arrangements of lasers is the dissipation of the heat generated during the laser, which in turn requires appropriate cooling measures, so that distances must remain between the individual radiation sources in order to be able to take cooling measures. Such cooling measures naturally limit the Packing density with which the lasers can be combined into laser arrays or field arrangements.

Finally, for such radiation fields, which are generated by arrays or field arrangements composed of individual radiation sources, in the imaging plane, i.e. For example, certain beam geometries and power densities are required on the workpiece surface so that the radiation which is emitted by each individual radiation source is guided and shaped accordingly.

Based on the above-mentioned prior art and the problem described, the present invention is based on the object of specifying an arrangement and a method with which the radiation emitted in particular by several gas lasers, but also the radiation emitted by a gas laser (correspondingly divided into radiation components) can be transformed with simple and inexpensive measures to form radiation fields of a desired arrangement and distribution of the power density and beam quality and can be adapted to the respective requirements.

The above object is achieved in connection with an arrangement of the type specified at the outset in that the radiation field is grouped into at least two radiation components in accordance with a specification, that each radiation group is directed to a first reflective element with a first reflection surface and the first reflection surfaces are arranged in planes which have an offset and / or a tilt in relation to one another such that the radiation groups with output coordinates changed relative to their relative lateral input coordinates with which they strike the first reflective elements and / or the output propagation directions changed relative to each other and / or the output orientations changed relative to each other are emitted by the first reflection surfaces, that the emitted radiation groups are grouped and each radiation group is each assigned to a second reflective element assigned to it r second reflection surface is directed, the second reflection surfaces being arranged in planes which are offset and / or tilted relative to one another in such a way that the radiation groups with their relative lateral input coordinates with which they point to the respective second reflective element are incident, the output coordinates changed relative to one another and / or the output propagation directions changed relative to one another and / or the output orientations changed relative to one another are emitted by the first reflection surfaces.

According to the method, the above object is achieved, starting from a method of the type described at the outset, in that the radiation field is grouped into at least two radiation components in accordance with a specification that each radiation group formed is directed onto a first reflective element with first reflection surfaces, whereby the first reflection surfaces, which are arranged in planes that are offset and / or tilted relative to one another, change the radiation groups with respect to one another with respect to their relative lateral input coordinates with which they are incident on the first reflective element most of the output coordinates and / or the output propagation directions changed relative to one another and / or the output orientations changed relative to one another are emitted by the first reflection surfaces, that the radiation groups emitted by the first reflective elements group and each of these radiation groups is directed onto a second reflective element assigned to it with a second reflective surface, the second reflective surfaces, which are arranged in planes that are offset and / or tilted relative to one another, causing the radiation groups to have relative lateral inputs with respect to them path coordinates with which they fall on the second reflective element, output coordinates changed relative to one another and / or output propagation directions changed relative to one another and / or output orientations changed relative to one another are emitted from the second reflection surfaces.

With such an arrangement in its simplest design, you can use a minimal number of reflective elements with a high power transmission coefficient, the radiation components are imaged in the form of a desired radiation field in an imaging plane. With the specified arrangement or the method, it is possible to first generate a defined offset by means of first reflective elements which hit the individual radiation groups, so that the respective radiation groups with output coordinates and / or output coordinates changed relative to one another Direction of propagation and / or exit orientations emerge. The emerging radiation components or the radiation field composed of them are then re-grouped and each radiation group leads to a second reflective element assigned to it. This grouping can be changed compared to the first grouping with which the individual radiation components enter the reflective elements, or the original grouping can be retained, ie a second reflective element is then assigned to each first reflective element. that strikes those radiation components that were also transformed by the respective first reflective element. The respective radiation group is then reflected on the respective second reflective elements in such a way that the radiation group with output coordinates changed relative to one another relative to its input coordinates and / or output propagation directions changed relative to one another and / or output orientations changed relative to one another from the reflective elements Elements exit. This means that on the exit side of the reflective elements, the emerging radiation groups spread in their relative coordinates to one another with a directional component that is different from the first reorientation. In other words, the radiation which is emitted by a field arrangement composed of individual lasers is initially irradiated onto the first reflective elements with an extent perpendicular to the beam propagation direction, ie in the xy direction, in such a way that the individual radiation groups are reflected differently and an offset is first achieved after the first reflective element in one direction of propagation, ie, for example in the y direction, which is preferably perpendicular to the greatest extent of the Radiation field. On the exit side of the reflective element, the individual radiation groups are adjacent to one another in this x-direction and offset from one another in the y-direction like steps. For example, while maintaining this grouping, the offset radiation groups then each enter a second reflective element at a defined angle and / or a direction which has a directional component changed to the direction of incidence of the first element, so that the individual radiation groups are reflected on the respective second reflective elements in such a way that they have a different offset and / or a different direction of propagation, now in the x direction, on the outlet side than in the inlet side. This in turn means that in an imaging plane the radiation components which are offset in a step-like manner on the exit side of the first reflective element are then pushed together and form, for example, a closed radiation field. It can be seen from this example that from any number of individual radiation sources, optionally grouped, using a number of first and second reflective elements corresponding to the number of radiation groups, a reorientation and / or regrouping of the radiation components in the two spatial directions perpendicular to the original Sprung expansion direction of the radiation field can be achieved. Here, a high efficiency of power effectiveness, a compact structure using a minimal number of optical components and a high degree of freedom in the order and reorientation of the radiation components are achieved.

Although the individual radiation sources and thus their radiation cross sections are at a certain distance from one another, these measures not only allow the position of the individual radiation fields to be reoriented on the exit side of the second element, but it is also possible in a simple manner to separate the individual elements To bring radiation fields closer together and thus increase the power density per unit area. It can be seen that for such a reorientation and change in the power density distribution, only a minimal number of optimal shear components is required, which in turn results in a compact construction. Furthermore, with the relative position of the reflection surfaces of the reflective elements to the individual gas lasers and the expansion of the reflective elements transversely to the direction of propagation of the radiation, a grouping corresponding to the desired image and power density distribution can be carried out. This means that, for example, the radiation from one or more lasers (single radiation source) of the field arrangement is radiated into one and / or the other reflective element, ie the radiation components of the radiation field are already grouped on the input side of the reflective elements. The arrangement is suitable for arbitrarily grouped and structured field arrangements from individual radiation sources, ie for linear field arrangements or arrays or, for example, for a field arrangement with several, stacked, linear laser arrays composed of several individual gas lasers (individual radiation sources) that are perpendicular generate two-dimensional radiation field to the direction of propagation.

An orientation is to be understood to mean that the beam cross-section is rotated, for example, by 180 ° in relation to the beam axis in relation to the orientation before it hits the mirror surface in an imaging plane. Such a reorientation can also serve to uniform the radiation field generated from the individual lasers.

If necessary, additional imaging optics are used in order to image the radiation emitted by the individual radiation sources onto the elements, also as part of a grouping.

In a further embodiment of the arrangement, the individual reflection surfaces of the reflective elements are each at a different distance from the beam exit surfaces of the lasers or the respective laser group of the array assigned to them, the radiation of which is incident thereon, the changing distance sequentially in the order of the Grouping of the array corresponds; this makes it possible for the beam Distribution components on the output side of the elements has an approximately parallel direction of expansion.

In accordance with the choice of the distance between the individual beam exit surfaces of the individual radiation sources of the array or their grouping with respect to one another, the distance between the reflection surfaces and the offset of the reflection surfaces to one another are preferably selected and adapted to the requirements.

However, the centers of the irradiated reflection surface areas of the individual reflection surfaces, on which the respective beams of the individual individual radiation sources impinge, preferably lie on a straight line, preferably at equal distances from one another, i.e. these reflection surfaces then have the same offset to one another and a distance to the exit surfaces of the individual radiation sources that changes by the same amount in each case.

As a simple, reflective element by means of which the individual reflection surfaces can be formed and shaped, a mirror constructed in the manner of steps has proven to be advantageous. Such a stair-step-like mirror can be provided in the form of a substrate carrier correspondingly coated with a mirror surface, for example by vapor deposition. However, it is also possible to grind in such a step mirror on a glass substrate by means of diamond tools, such a step mirror having the advantage that it is extremely stable and free from distortion. The reflective elements, as shown above, can also be applied to easily producible carrier bodies made of plastic. Particularly with regard to such plastic carriers, which can be produced, for example, by means of injection molding techniques, there is a very inexpensive arrangement.

The arrangement according to the invention also has the advantage that the reflection surfaces can be formed by flat mirror elements, ie are very easy to manufacture and are particularly advantageous in connection with gas lasers. However, the individual reflection surfaces can also be concave or convex curved surfaces in order to additionally widen or focus the beam cross sections of the radiation components from which the radiation field is composed. Curvatures in the form of cylinder jacket segment surfaces are preferred in order, for example, to achieve focusing only in one direction which is to be influenced.

To achieve a reorientation or mirroring of the respective individual radiation cross section or the beam cross sections of the radiation field, the radiation field is guided with the first and second reflective elements (possibly using additional reflective elements) that the direction of that of the last reflective element emitted radiation groups in the direction of the radiation group directed at the first reflective element. The surfaces of the first and second reflective elements or the surface normals preferably form an angle of 90 ° to one another, so that an image rotation with a symmetrical beam cross section of exactly 180 ° can be achieved. Such an arrangement can be realized, for example, by applying the first and second reflective elements on a sawtooth-shaped carrier in cross section, the mirror surface then corresponding to the sawtooth profile in one direction (first reflective elements) and are aligned in a second direction (second reflective elements), so that the respective radiation group is directed from the respective first reflective element to the immediately adjacent second reflective element which is oriented at an angle thereto and thus radiates in one direction from the second reflective element is, which is opposite to the direction of radiation onto the first reflective element.

In order to give the radiation emitted by a reflective element an additional directional component in addition to the direction in which the radiation impinges on the reflective element, those reflective elements are advantageous in which the reflective elements Surfaces are perpendicular to a common plane on the one hand, but on the other hand are pivoted relative to one another about axes which run in the plane of these surfaces and parallel to one another. In addition, there is the possibility of arching these surfaces slightly concave or convex in order to widen or focus the respective radiation of the radiation groups. A further, simple possibility of expanding a radiation field in a directional component is provided when the reflection surfaces of the reflective elements are each perpendicular to a common plane and are pivoted relative to one another about axes which run in the plane of these surfaces and parallel to one another .

In order to either produce uniform radiation fields with a relatively large expansion or to obtain a small radiation spot with a high radiation density in the working plane, a plurality of strip-shaped radiation fields which are constructed from individual lasers are aligned parallel to one another so that the output radiation is emitted by a laser field arrangement, which is composed of a predetermined number of linear laser arrays, each linear laser array being constructed from a number of individual lasers.

As already mentioned, a fundamental disadvantage of a field arrangement or an array of individual radiation sources is their low fill factor. The fill factor is, for example, the sum of the cross-sectional areas of the individual laser beams in an exit plane in which the exit windows of the individual lasers lie in relation to the total area that is spanned by the exit windows of the field arrangement. In many applications it is desirable, on the one hand, to achieve a very uniform fill factor, ie the surface irradiated with the laser radiation should be irradiated with a uniform intensity in all surface areas, a measure then having to be applied such that when the cross-sectional dimensions of the radiation components of individual radiation groups is smaller than the width of the assigned reflective element, the respective radiation group in the reflection area of the respective reflective element under one Angle of incidence not equal to O ^β occurs in such a way that almost the entire width of the reflective surface of the reflective element is illuminated.

With regard to a compact structure of the arrangement, the first and / or the second reflective elements are combined into a respective first and second element, for example in the form of a stair mirror. Such arrangements from only one body have the advantage that after the manufacture of the body no further adjustment measures of the respective reflective elements are required, but the adjustment of such an arrangement is only necessary relative to the laser field arrangement.

In the context of the radiation transformation according to the invention, the aim is in each case that after the last transforming element — if necessary, transformations can be carried out with more than two elements that have radiation directions emerging or reflected from the last element that have mutually parallel directions of propagation or a common intersection .

The reflective elements, as they are used in accordance with the arrangement according to the invention, have their specific advantages. Reflective elements are distinguished by the fact that only one surface element is required in order to achieve the desired transformation. They are inexpensive to manufacture. They can also withstand high loads.

In order to clarify the advantages, which are better illustrated with the measures according to the individual claims, which are explained above, and to show further features of the invention, various exemplary embodiments of the invention will now be described with reference to the drawings.

The drawings show:

Figures 1A to 1E schematically different one and two-dimensional Laser arrays, in conjunction with which the arrangements according to the invention can be used,

FIGS. 2A, 2B and 2C show schematic representations of different gas-1aser field arrangements,

3A 3B shows a first embodiment of the arrangement according to the invention for shaping and guiding a radiation field of a one-dimensional, straight-line laser array, which is shown in FIGS. 1A or 1B, using a first element (FIG. 2A) and a downstream second element ( Figure 2B),

FIG. 4 shows an embodiment of a stair step mirror in which the individual mirror surfaces have a different offset from one another and with which the fill factor is increased,

5 shows a further embodiment similar to the embodiment of FIG. 4 with a different grouping of the radiation field on the output side of the mirror surfaces,

FIG. 6 shows the arrangement of FIG. 4, a linear laser array being associated with each mirror surface of the stair step mirror,

FIG. 7 shows the arrangement according to FIG. 6, the one step-shaped mirror element having a further gradation,

FIG. 8 shows a sectional illustration of a first and a second reflective element, which are arranged at an angle of 90 ^β to one another, the right illustration showing a top view of the reflection surface orientation of the arrow VIII,

FIG. 9 shows the arrangement according to FIG. 8, four individual beams being assigned to the reflective elements, the right representation again representing a view of the mirror surface orientation of the arrow IX; FIG. 10 shows a perspective illustration of a stair-stepped mirror with reflection surfaces running in a sawtooth cross section,

11 and FIG. 12 each have a stair mirror with concave curved mirror surfaces,

FIG. 13 shows a stair-step mirror in which the individual mirror surfaces are each pivoted about a common axis by the same angle to one another, and

FIG. 14 shows a further embodiment of a stair step mirror in which the individual mirror surfaces have a different offset from one another and are inclined differently to one another.

The arrangement according to the invention in the various possible embodiments is suitable for shaping and guiding a radiation field of an array or a field arrangement which is composed of several individual radiation sources. However, it is also suitable for shaping a radiation field which is emitted by a single laser, for example for the radiation of a gas laser with a slab geometry with an elongated radiation field which is to be rearranged or transformed.

Since individual laser radiation sources in the form of gas lasers can only be scaled to higher powers to a limited extent, a greater number of individual laser radiation sources are combined into different arrays or field arrangements in order to achieve higher laser powers and power densities. Various of these field arrangements are shown in FIGS. 1A to 1E.

Here, linear field arrangements, as shown in FIGS. 1A and IC, double-linear field arrangements, such as as shown in FIG. 1B, distinguish radial field arrangements in accordance with the schematic representation of FIG. 1D and two-dimensional arrays in accordance with the schematic representation in FIG. 1E.

A linear array, as shown in FIG. 1A, has N individual radiation sources, so that there is an elongated, linear radiation distribution. The linear geometry is disadvantageous for cases in which circular or square radiation surfaces with a high fill factor are to be achieved in an imaging or processing plane.

Insofar as the term “fill factor” is used in the context of this description, this is to be understood to mean the beam cross-sectional area of the individual radiation sources, designated by the reference number 1 in FIGS. 1, to the total area spanned by the individual radiation sources 1.

A disadvantage of a linear array according to FIG. 1A from single radiation sources is that the beam quality is reduced in the longitudinal direction by at least a factor N compared to the single radiation source. In the case of a one-dimensional, linear arrangement, there is therefore a certain asymmetry in the emission of the radiation field with respect to the cross-sectional geometry and the beam quality, which increases to an extent as is attempted to increase the number of individual radiation sources and thus the total power. Two-dimensional arrays corresponding to FIG. 1B, or in particular arrays, which are composed of more than two linear individual arrays, as shown in FIG. 1E, have the disadvantage of the low accessibility of the internal single radiation sources, for example in order to cool them. In order to meet the cooling measures and the necessary measures for excitation, the distances D (see FIG. 1A) of the individual radiation sources 1 from one another must be increased, which of course reduces the fill factor at the location of the radiation emission. Another embodiment of an arrangement is shown in Figure ID. The individual sources 1 have a circular cross-section-shaped emission cross section, which are arranged around a central axis.

As illustrated in FIGS. 1A to 1E, it is not sufficient for high radiation power and high radiation densities and large fill factors alone to increase the number of individual radiation sources, since a multidimensional arrangement of individual radiation sources also has its limits. Larger field arrangements require, for example, larger distances D between the individual radiation sources in order to supply the internal radiation sources accordingly.

In order to be largely independent of the arrangement of the individual radiation sources, it is therefore necessary to coordinate the radiation of the individual radiation sources 1 by means of downstream optical arrangements in relation to one another and / or in the direction of propagation of the individual beams and / or the orientation of the individual beam to be changed in such a way that defined radiation fields can be generated in one imaging plane from a plurality of individual radiation sources, given the structure of a field arrangement.

Diffusion-cooled CO ₂ lasers are preferably used in connection with the arrangement according to the invention as single radiation sources, in which the heat loss is dissipated to cooled outer surfaces by heat diffusion, which is why, in contrast to convectively cooled CO ₂ lasers for heat dissipation, there is no gas circulation and gas flow guidance For this reason, they are particularly compact and also inexpensive to manufacture. The disadvantage is their limited scalability, so that these diffusion-cooled CO ₂ lasers have to be put together to form field arrangements, for which their low price is again advantageous.

The excitation of a CO ₂ laser is carried out particularly expediently by metallic electrodes, which are identified by the reference number _{2 in} FIGS. 2A, 2B and 2C, between which an electrical high-frequency alternating Seifeid a gas discharge (gas discharge space 3) supplies energy. However, the gas laser can also be excited by medium-frequency, low-frequency or direct-voltage gas discharges. The metallic electrodes 2 can be replaced by dielectric electrodes, in particular Al ₂ O ceramic. Furthermore, the metallic electrodes 2 can be made cooled and then represent a heat sink for the heat loss.

The lateral resonator dimensions of a single radiation source can differ depending on the direction. The small dimensions result in radiation guidance through the reflection at the lateral boundaries of the resonator (waveguide). Typical waveguides range up to 4 mm.

In addition to the type of radiation propagation, the resonator is also characterized by the type of stability. Each resonator direction can be made stable or unstable independently of the other. A stable resonator is characterized in that a geometrical beam, the course of which differs infinitesimally from the optical axis, remains in an infinitesimally small environment of the optical axis even after repeated circulation in the resonator. Otherwise the resonator is unstable. The stability properties can be directional. Then the infinitesimal quantities should only be considered in one direction. In the case of stable resonators, the beam is decoupled by a partially transmissive mirror, and in the case of the unstable resonator, diffraction is decoupled by an aperture, designated by reference numeral 4, which is located in at least one of the two resonator mirrors.

The execution of a linear array according to FIGS. 1A and IC or of an array of several linear arrays arranged parallel to one another, as shown in FIGS. 1B and 1E, is particularly advantageous if the individual sources have a stable resonator. The stable direction corresponds to the array or field arrangement direction and the unstable direction, as indicated on the right in FIG. 23 is perpendicular to it. In the unstable direction, in which no lateral size restriction is imposed on the single radiation source, the unstable resonator can be used to utilize a laser medium of large lateral dimensions, which has a large coolable surface, as shown in FIG. 2B.

The cheapest embodiment, which can be used in conjunction with the arrangement according to the invention, which is described below, is a double-linear field arrangement according to FIG. 1B, the construction of which is shown schematically in FIG. 2C. The respective exit windows lie in a central area, while the resonator or gas discharge spaces 3 extend upwards and downwards.

According to a first embodiment of the invention, which is shown in FIGS. 3A and 3B, the radiation 7 emanating from a radiation source, which is a linear arrangement of seven individual radiation sources 1, as is also shown enlarged in FIG. 1A, is first Element 8 directed, which is made up of individual first reflective elements or reflection surfaces 9, in the form of a stair mirror. The individual beams 7 are reflected on the individual reflection surfaces 9 of the first element or of the stair step mirror 8. The angle of incidence on the reflection surfaces 9 and the step height, i.e. the lateral offset of the individual reflection surfaces 9 to one another and, if appropriate, the distance of the reflection surfaces 9 from the beam exit plane of the laser field arrangement are coordinated in such a way that the reflected radiation groups 10, as shown in FIG .

The individual second reflective elements 12 of the second element 11 run in a direction that is rotated by 90 * with respect to the first reflective elements 9 of the first element such that the individual radiation components or radiation groups are in a direction opposite to the initial direction of propagation emerge from the first elements 8 in the direction rotated by 90 °, as is shown by reference numeral 13. The distances between the individual second reflective elements 12 and the first reflective elements 8 are selected such that the individual radiation groups are transformed by means of the second element 11 in such a way that the radiation cross sections are in an imaging plane which is shown on the left in FIG. 3B two-three-two radiation fields are pushed together in the grouping, so that an approximately circular radiation field is formed.

The radiation groups 10 reflected on the reflective elements 9 can then be regrouped, although this is not shown in the figures, and in accordance with the specifications, each radiation group 10 is irradiated into a second reflective element 12 of a second element 11 assigned to it. In the embodiment shown in FIG. 3B, the second element 11 is composed of three individual second reflective elements 12.

As FIGS. 3A and 3B show, the radiation elements are transformed twice by the two elements 8 and 11 or their first reflective elements 9 and their second reflective elements 12 in such a way that on the one hand they are perpendicular to the reflective elements 9 in one direction Direction of propagation are offset differently, while they are pushed over each other again by the second reflective elements 12 in the direction which is both perpendicular to the direction of propagation of the radiation components 10 and perpendicular to the first change of direction, so that the radiation cross sections proceed from a linear arrangement , can be brought together to form a dense radiation field of high radiation intensity. Based on the principle as shown in FIGS. 3A and 3B, other beam geometries can be formed starting from a linear arrangement.

For example, square radiation fields can be generated from a linear radiation source, which is composed of nine radiation components, by the double transformation, as explained with reference to FIGS. 3A and 3B, by first grouping into three Radiation groups with three radiation components each take place, which are offset in the first transformation on the first element 8 like steps in the y direction, while in the x direction they maintain their respective spacing from one another, while then in the context of the second transformation ( 3B) by means of the second element 11, the radiation groups offset from one another are pushed one under the other, so that a dense radiation field arises which is built up from the three times three radiation components of the three radiation groups. A further possibility is, for example, that ten individual radiation components are grouped twice, these groups of two radiation components are offset from one another like steps, so that they can then be exactly aligned with one another in the second transformation on the second element 11 to form an elongated rectangular radiation field push.

It can also be seen from FIGS. 3A and 3B that, depending on which radiation pattern is to be generated from the individual radiation cross sections, the steps can also be graded in a different way, for example also in such a way that, for example, the second reflective elements 12 of the first Element 8 analog of the second element 11 with the largest or smallest distance from the radiation sources 1 in the beam direction can be arranged in the middle.

At this point it should be noted that in the individual figures of the various embodiments, identical or comparable components are identified by the same reference numerals. A repetitive description of these parts is not carried out, so that the description of these parts based on the one embodiment can be applied analogously to the other embodiment.

Regarding the radiation fields generated in each case, it must be stated that in order to clarify the respective change in the direction of propagation of the radiation surfaces, the individual radiation cross sections are shown at a corresponding distance from one another; however, the rays can are brought together in such a way that a coherent radiation field is generated in the desired imaging plane in order to increase the fill factor.

If one considers field arrangements which are made up of laser arrays, for example in the form as shown in FIGS. IB and 1E, the fill factor is thermally less than 1. This reduces the beam quality compared to a theoretical case of occupancy density of 1001. In order to increase the fill factor and thus maintain a high beam quality, an arrangement of reflective elements 14, which is shown in FIG. 4, is advantageous.

In this example, the radiation components 7 are incident on tilted respective reflective surfaces 14 of a stair mirror 15, so that, compared to the width of the respective radiation components, a larger area of the reflective surfaces 14 is irradiated; As a result, the relative coordinates of the individual radiation components 10 are changed on the output side in such a way that they have a fill factor of approximately 1001, as is indicated by the connected radiation cross sections on the side of the exit beams 10. Such a measure can be implemented, for example, in the embodiment shown in FIGS. 3A and 3B for the first element 8 and / or the second element 11 in order to compare the fill factor of the rays reflected by the mirror surfaces with the Increase entry rays.

While the increase in the fill factor is shown only schematically with reference to FIG. 4, the offset of the emerging radiation components with respect to the radiation can also be adjusted by suitable selection of the direction of incidence of the radiation components on the reflection surfaces 14 and by suitable selection of the position of the surfaces according to FIG incoming radiation components to each other are changed so that a desired transformation occurs, diagonally in the example shown.

With this arrangement, on the output side, compared to the entry side, the fill factor also increased, but at the same time an offset was reached (see Figure 5).

Since high power densities are required in certain applications and e.g. If several gas laser field arrangements are stacked on top of one another in the unstable direction, the above measures for increasing the fill factor can be repeated for such cases.

FIG. 6 shows a schematic structure of a reflective element or a stair mirror 16 with three reflective surfaces 14 (corresponding to FIGS. 4 and 5). In this case, in contrast to the embodiment, as shown, for example, in FIG. 4, each individual reflective surface 14 is assigned a linear field arrangement 17, with each linear field arrangement 17 in this schematic representation being composed of three individual radiation sources 18. The radiation components of each linear field arrangement 17 each fall on a reflective surface 14 of the stair mirror 16 at a previously selected angle of incidence, as a result of which the individual linear field arrangements 17 are pushed closer to one another on the output side due to the inclination of the mirror surfaces. as a comparison of the respective radiation field 4, 8 shows on the incidence side and the exit side of the staircase mirror 16. With this simple measure, the fill factor can also be increased, in the embodiment shown in FIG. 6 only in one direction.

In Figure 7, the upper part of the stair mirror 16 of Figure 6 is shown enlarged. While the individual reflective surfaces 14 of the stair mirror 16 of FIG. 6 assigned to each step lie in one plane, in the embodiment of FIG. 7 a reflective surface is additionally graduated, so that the individual radiation components of a linear field arrangement 17 from individual radiation sources 18 are thereby achieved receive a corresponding offset on the performance side. FIGS. 8 to 10 show arrangements with which the individual radiation cross sections of a radiation component or of a radiation group can be reoriented or mirrored by 180 °. For this purpose, the respective first and second reflective elements, designated by the reference numerals 19 and 20, are each put together in pairs such that a first reflective element 19 and a second reflective element 20 enclose an angle of 90 °. The respective radiation group that strikes the first reflective element 19 is unguided from there by 90 ° and impinges on the reflection surface of the immediately adjacent second reflective element 20, so that the output radiation 10 from the second reflective element 20 counteracts the direction of incidence of the entrance radiation 7 is directed onto the first reflective element 19 and parallel thereto. This results in a rotation or reflection of the respective radiation cross-section, as is illustrated by the two top views of the elements 19, 20 on the right in FIGS. 8 and 9.

Based on such first and second reflective elements 19 and 20, an element can be constructed, as shown in FIG. 10, in accordance with the stair-step mirrors described above. This double element 21 has a plurality of first elements 19 and a plurality of second elements 20 (a double element 21 with two of these reflective elements 19, 20 is shown in FIG. 10), the respective first reflective elements 19 and the respective second reflective elements 20 run parallel to each other with their reflective surfaces. As is made clear on the basis of the radiation groups which strike these respective reflective elements 19 and are emitted by the second reflective elements 20, the beam cross sections are reoriented here, which can serve to homogenize and homogenize a radiation field.

In order to additionally focus the individual radiation components that strike the reflective elements described above, the individual radiation entry surfaces of the second reflective elements can be used Elements or else the mirror surfaces of the reflective elements are concavely curved in different directions, preferably in the shape of a cylinder segment, as shown in FIGS. 11 and 12.

Various embodiments have been explained above in order either to group and rearrange the individual radiation components or to increase the fill factor of a radiation group. It is understandable that the respective measures, which are outlined for regrouping and increasing the fill factor, can be carried out in a different order and in a different number of steps.

FIG. 13 shows a further embodiment of a stair step mirror 22 with six mirror surfaces 23, each mirror surface 23 being assigned to a radiation group. The individual mirror surfaces 23 are on the one hand perpendicular to a plane which corresponds to the surface 24 of the stair mirror 22, and on the other hand they are around an axis 25, which is indicated by a broken line in FIG panned. On the basis of this measure, a double offset or a double transformation of the individual radiation components between the entry side and on the radiation exit side can be achieved.

Furthermore, in contrast to the illustration in FIG. 13, the individual mirror surfaces 23 can have an additional offset such that the individual axes 25, about which the individual mirror surfaces 23 are pivoted towards one another, are aligned parallel to one another at a distance.

FIG. 14 shows an example of a further staircase mirror 26 with six mirror surfaces 27, each of which is assigned to a radiation group. The individual stair-step mirror surfaces 27 are perpendicular to a surface 28 which corresponds to the one side surface of the stair-step mirror 26 in FIG. 14, but they are slightly tilted at an angle to one another, transversely to their longitudinal extent, the longitudinal edges which are on the Surface 28 are perpendicular, parallel to each other are aligned. The respective offset of adjacent mirror surfaces 27 is enlarged from right to left. This arrangement ensures that, starting from incident radiation groups which are spatially separated and whose directions of propagation are different, these are reflected in such a way that the radiation groups are stacked one above the other and spread in a common direction or have a common intersection.

Claims

P a t e n t a n e l g

"Arrangement and method for shaping and guiding a radiation field of one or more gas lasers (s)"

P a t e n t a n s r u c h e

Arrangement for shaping and guiding a radiation field of one or more gas lasers, in particular a radiation field of an array or a field arrangement of several gas lasers, with radiation transformation optics for generating a defined radiation field, the optics having reflective elements, characterized in that that the radiation field (7) is grouped into at least two radiation components in accordance with a specification, that each radiation group is directed at a first reflective element with a first reflection surface (9; 14; 19; 23; 27;) and the first reflection surfaces (9; 14; 19; 23; 27;) are arranged in planes which are offset and / or tilted relative to one another in such a way that the radiation groups with respect to their relative lateral input coordinates with which they refer to the first reflective elements occur, output coordinates changed relative to one another and / or outputs changed relative to one another ngs propagation directions and / or starting orientations of the first reflection surfaces (9; 14; 19; 23; 27;) are emitted. that the emitted radiation groups are grouped and each radiation group is directed in each case to an associated second reflective element with a second reflective surface (12; 14; 20; 23; 27), the second reflective surfaces being arranged in planes that one Have offset and / or tilt to one another such that the radiation groups with their output coordinates and / or output outputs changed relative to their relative lateral input coordinates with which they strike the respective second reflective element, Directions of propagation and / or output orientations changed relative to one another are emitted by the first reflection surfaces (9; 14; 19; 23; 27).

2. Arrangement according to claim 1, characterized in that the offset of the reflection surfaces (12; 14; 20; 23; 27), which are assigned to a reflective element, corresponds sequentially to the order of the radiation groups.

3. Arrangement according to claim 1, characterized in that the reflecting surfaces (9; 14; 19; 23; 27) are each at a different distance from the radiation exit surfaces of the lasers (1) assigned to them.

4. Arrangement according to one of claims 1 to 3, characterized in that the centers of the irradiated reflection surfaces (9; 14; 19; 20; 23; 27) lie on a straight line.

5. Arrangement according to one of claims 1 to 4, characterized in that the respective offset and the respective change in distance between neighboring reflection surfaces (9; 14; 19; 20; 23; 27) which are assigned to a reflective element of are the same size.

6. Arrangement according to one of claims 1 to 5, characterized in that the reflection surfaces associated with a reflective element are formed by a mirror (9; 11; 15; 16; 21; 22; 26) constructed like a stair step,

7. Arrangement according to one of claims 1 to 6, characterized in that the reflection surfaces (9; 12; 14; 19; 20; 23; 27) are flat areas areas.

8. Arrangement according to one of claims 1 to 6, characterized in that the reflection surfaces are concave or convex curved areas.

9. Arrangement according to claims 1 to 8, characterized in that the reflective elements (19, 20) are arranged such that the direction of the radiation groups (10) emitted by the last reflective element corresponds to the direction of the first reflective Element (19) directed radiation group (7) runs counter.

10. Arrangement according to one of claims 1 to 9, characterized in that the reflection surfaces (27) of the individual reflective elements are perpendicular to a common plane (28) and are inclined to each other.

11. Arrangement according to one of claims 1 to 9, characterized in that the reflection surfaces (27) of the individual reflective elements about a common axis (25) which extends in the plane of these surfaces (23) are pivoted to each other.

12. Arrangement according to one of claims 1 to 11, characterized in that the radiation groups (19) form a strip-shaped radiation field (18).

13. The arrangement according to claim 12, characterized in that the radiation groups (19) have the same size.

14. Arrangement according to claim 12 or 13, characterized in that the radiation groups (19) are arranged at the same distance from each other.

15. The arrangement according to claim 12 to 14, characterized in that the radiation groups (18) are aligned parallel to one another lying transversely to the direction of propagation of the radiation in one plane.

16. Arrangement according to one of claims 12 to 15, characterized in that a plurality of strip-shaped radiation fields (17) are arranged parallel to one another.

17. The arrangement according to claim 16, characterized in that the strip-shaped radiation fields (17) have the same distance from one another.

18. Arrangement according to one of claims 12 to 17, characterized in that each strip-shaped radiation field (17) is formed from an equal number of radiation groups (18).

19. Arrangement according to one of claims 1 to 18, characterized in that in the case of radiation groups whose respective cross-sectional dimensions of their radiation components are smaller than the width of the assigned reflective element, the respective radiation group onto the reflection surface (14) of the respective reflective element strikes at an angle of incidence not equal to 0 * in such a way that approximately the entire width of the reflection surface (14) of the reflective element is illuminated.

20. Arrangement according to one of claims 1 to 19, characterized in that the first reflective elements (9) are combined to form a first element (8) and / or the second reflective elements (12) are combined to form a second element (11) .

21. The arrangement according to claim 20, characterized in that the reflection surfaces are each applied to a common carrier.

22. A method for shaping and guiding a radiation field of one or more gas lasers, in particular a radiation field of an array or a field arrangement of several gas lasers, with a radiation transformation optics for generating a defined radiation field, the optics having reflective elements, characterized in that the radiation field is grouped into at least two radiation components in accordance with a specification that each radiation group formed is directed onto a first reflective element with first reflection surfaces, with the first reflection surfaces arranged in planes, which have an offset and / or a tilt to one another, the radiation groups with respect to their relative lateral input coordinates with which they are incident on the first reflective element, output coordinates changed relative to one another and / or output propagation directions changed relative to one another and / or the starting orientations changed relative to one another are emitted by the first reflection surfaces,

that the radiation groups emitted by the first reflective elements are grouped and each of these radiation groups is directed to a second reflective element assigned to them with a second reflective surface, the second reflective surfaces being arranged in planes which have an offset and / or have tilting to one another, the radiation groups with respect to their relative lateral input coordinates with which they are incident on the second reflective element, output coordinates changed relative to each other and / or output propagation directions changed relative to each other and / or changed relative to each other Output orientations are emitted from the second reflection surfaces.

23. The method according to claim 22, characterized in that the radiation groups reflected by the second reflection surfaces receive a Ver¬ offset with a directional component perpendicular to the direction of the radiation groups reflected by the first reflection surfaces.

24. The method according to claim 22 or 23, characterized in that the radiation groups are reflected by the reflective elements in a direction which has an essential directional component perpendicular to the greatest extent of the field arrangement or the radiation field.

25. The method according to any one of claims 22 to 24, characterized in that the radiation groups are transformed such that the radiation groups emerging from the last reflective element have mutually parallel directions of propagation.

26. The method according to any one of claims 22 to 25, characterized in that the radiation components are transformed such that the radiation groups emerging from the last reflective element have a common intersection.

27. The method according to any one of claims 22 to 26, characterized in that the reflective elements are arranged in such a way that the direction of the radiation groups emitted by the last reflected element is set such that it corresponds to the direction of the radiation group directed at the first reflective element runs against.