WO2019158497A1

WO2019158497A1 - Optical system for processing at least one incident laser beam

Info

Publication number: WO2019158497A1
Application number: PCT/EP2019/053374
Authority: WO
Inventors: Berthold Burghardt; Hans-Juergen Kahlert; Johannes Richter; Sebastian Geburt
Original assignee: Innovavent Gmbh
Priority date: 2018-02-13
Filing date: 2019-02-12
Publication date: 2019-08-22
Also published as: DE102018103131A1; DE102018103131B4

Abstract

The invention relates to an optical system for processing an incident laser beam. The optical system comprises a beam splitting device for splitting an incident laser beam into a first partial beam and a second partial beam, such that a cross-section of the first partial beam corresponds to a first section of a cross-section of the incident laser beam and a cross-section of the second partial beam corresponds to a second section of the cross-section of the incident laser beam, wherein the first section and the second section differ from each other, a re-polarization device, arranged in the beam path of the first partial beam or second partial beam, for rotating a polarization of the first partial beam or of the second partial beam by 90° and a beam combining device for coaxially combining the first partial beam and the second partial beam into a combined laser beam. The invention further relates to an optical system for processing a first incident laser beam and a second incident laser beam and to a corresponding method for processing an incident laser beam and for processing a first incident laser beam and a second incident laser beam.

Description

The invention relates to an optical system for processing at least one incoming laser beam, in particular, for example, for so-called laser lift-off applications or for a system for processing thin-film layers. The invention further relates to a method for processing at least one incoming laser beam.

The technique presented below generally serves to process and improve at least one property of an incoming laser beam for the subsequent further processing of the laser beam, in particular for laser processing technologies in the broadest sense, such as laser lift-off applications or the processing of thin-film layers.

The technique presented below can thus be used, for example, in connection with laser lift-off applications. Laser Lift Off applications dissolve plastic substrates from a glass substrate. In this case, a laser line (ie a lighting line) is focused through a transparent glass onto a plastic substrate. The bond is dissolved with the laser beam and the plastic substrate is thus separated contactlessly from the glass substrate. For example, flexible OLED displays are produced on PI films, which are glued on glass plates for the manufacture ^¬ ment. After the production, the z. For example, by incorporating vapor deposition and photolithography processes, the display substrate is detached from the glass slide using a laser lift-off (LLO) process. For these processes are pulsed Festkör ^¬ perlaser that emit, for example, 343 nm and 355 nm laser light and will be readily absorbed by the polyimide layer and an adhesive layer, are almost transparent but for the glass, are used.

One possible application of an LLO process is, for example, the detachment of flexible OLED display substrates from a glass slide. Here are on a flat glass plate of z. B. 0.5 mm thick polyimide films of several 10-100 pm pasted, on which OLED display structures are built. After completion of the display film, it must be removed from the glass carrier. For this purpose, a laser line is focused by the 343 nm or 355 nm transparent glass on the Kunst ^¬ fabric film. At typical energy densities of 100-500 mJ / cm ² , the bond is released by making a 20-50 pm wide line at a speed of 50-300 mm / s is moved over it. The plastic substrate remains undamaged and the flexible OLED display substrate can be used for further processing z. B. be used in smartphones.

Another application of the technique presented concerns the processing of thin film layers. For the crystallization of thin-film layers, for example for the production of thin-film transistors (in English: Thin Film Transistor, in short: TFT) lasers are used. As the semiconductor to be processed in particular silicon (in short: Si), more precisely a-Si is used. The thickness of the semiconductor layer is z. 50 nm, which is typically on a substrate (eg glass substrate) or other substrate.

The layer is illuminated with the light of the laser, for example a pulsed solid-state laser. In this case, the light with a wavelength of z. B. 532 nm or 515 nm formed into a line of illumination, see, for. B. DE 10 2012 007 601 Al or WO 2013/156384 Al. For several years, lasers with wavelengths of 343 nm and 355 nm have also been used for these processes. By means of a beam shaping device, the laser beam can be shaped such that a beam profile of the laser beam has a long axis and a short axis. Subsequently, the laser beam thus formed can be imaged on the basis of an imaging device arranged downstream in the beam path of the laser beam of the beam shaping device in order to generate the illumination line from the light of the laser beam. A corresponding optical system is described for example in DE 10 2015 002 537.

In detail, the beam-shaping device may, for example, comprise an anamorphic optical system and have different imaging properties with respect to a first and a second imaging axis. In particular, the beam ^¬ shaping means may be arranged to produce a laser beam at a location directly in front of the imaging device from laser light whose beam profile having a long axis and a short axis, wherein the beam profile in the long axis of a (largely) homogenized (or, in substantially homogeneous) In ^¬ tensitätsverteilung has. The imaging device then focused to generate the short axis of the illumination line (insbesonde ^¬ re exclusively) the short axis of the beam profile produced by the beam shaping means directly in front of the imaging device. However, the imaging ^{device has} (in particular) no focusing properties, in particular with ^{respect to} the long axis, so that the long axis of the beam profile generated by the beam-shaping device directly in front of the imaging device remains virtually unchanged by the image. Passing device and thus can correspond to the long axis of the illumination line.

Accordingly, the illumination line, like the previously formed beam profile of the laser beam, has a short axis and a long axis, and for the sake of clarity, the short axis of the beam profile of the laser beam, in particular, corresponds to the illumination line before imaging by the imaging device, and the long axis of the beam profile corresponds to the (homogenized) long axis of the illumination line. The intensity distribution of the illumination line along the long axis is ideally rectangular and has, for example, a length (or full width at half maximum, in short: FWHM) of several 100 mm, eg. B. 750 mm to 1000 mm or longer, on. The intensity distribution along the short axis is typically Gaussian and has a FWHM of about 5 pm to 100 pm. The short and the long axis thus form a relatively high aspect ratio.

The illumination line is s out with a feed rate of about 1 mm / s to 50 mm / s, before ^¬ preferably 10 mm / 20 mm / s in direction of the short axis over the semiconductor layer. The intensity (in the case of continuous wave lasers) or the pulse energy (in the case of pulsed lasers) of the light beam is adjusted such that the half ^¬ conductor layer for a short time (ie, on a time scale of about 50 ns to 100 ps) on ^¬ melts and when solidified crystalline layer with improved electrical properties.

In addition to the above-described fields of application in connection with LLO and the manufacture of thin film transistors, there are a number of other application ^¬ areas in which the generation of a line of illumination having a high aspect behaves ^¬ nis for illuminating a substrate is required.

When generating one of the illumination lines described above, in particular the depth of field of the illumination line with respect to the focusing along its short axis is of great importance. For example, variations in the thickness and / or position of the illuminated substrate may cause the surface of the substrate to be illuminated to no longer be in the focus of the illumination line, resulting in inconsistent or varying illumination intensity and thus in inconsistent quality Lighting can lead. With insufficient depth of field, the quality of the process produced by the illumination, and thus of the final product, can thus suffer significantly. Against this background, it is desirable to provide one or more laser beams which have been processed and improved in such a way that they produce a laser beam (in particular an illumination line) focused at least along one axis, wherein the depth of field of the generated focus is improved and wherein a profile of the focused beam along the short (focused) beam axis is substantially symmetrical.

In particular, it is desirable to generate a laser beam from an incident laser beam whose beam parameter product is reduced along at least one axis and whose beam profile is substantially symmetrical with respect to this axis.

It is therefore an object of the invention to provide an optical system for processing at least one incident laser beam which is adapted to process the at least one incident laser beam to produce an outgoing laser beam whose beam parameter product is reduced along at least one axis and whose beam profile is substantially symmetrical with respect to this axis.

This object is achieved by means of an optical system according to claim 1 and claim 8 and by means of a method according to claim 14 and claim 15.

According to a first aspect, an optical system for processing an incident laser beam is provided. The optical system comprises a beam splitting device for splitting an incident laser beam into a first partial beam and a second partial beam so that a cross section of the first partial beam corresponds to a first section of a cross section of the incident laser beam and a cross section of the second partial beam corresponds to a second section of the cross section of the incident laser beam wherein the first portion and the second portion differ from one another. The optical system further comprises a Umpolarisierungseinrichtung arranged in the beam path of the first sub-beam or the second sub-beam for rotating a polarization of the first sub-beam or the second sub-beam by 90 ° and a beam combining means for coaxially combining the first sub-beam and the second sub-beam to a unified laser beam. The beam splitting device may for example comprise a mirror. The mirror can partially protrude into the beam path of the incident laser beam in such a way that a predetermined component, ie a second component beam with a predetermined cross section, is split off from the incident laser beam. The remaining partial beam of the incident laser beam corresponds in this case to the first partial beam. For example, the first portion and the second portion of the cross section of the incident laser beam deviate from each other such that the cross section of the incident laser beam is composed of the first portion and the second portion, wherein the first portion and the second portion in the incident laser beam no overlap have each other.

The Umpolarisierungseinrichtung includes, for example, a lambda / 2-plate, which is adapted to linearly polarized light of a predetermined wavelength lambda (in particular the wavelength of the incident laser beam) to rotate by 90 °. In particular, the repolarizing means may be adapted to polarize the polarization of a linearly polarized sub-beam (ie to rotate the beam axis) such that it has its polarization with respect to the beam combining means of s-polarized to p-polarized or p-polarized to s. polarized changes.

The beam combining device can be set up, for example, to combine the two partial beams so that a cross section of the first partial beam and a cross section of the second partial beam largely overlap after the connection. In other words, an overlapping area of the cross section of the first partial beam and the cross section of the second partial beam can be selected to be maximum.

By overlaying the first sub-beam with the second sub-beam as described above, a beam parameter product of the merged laser beam can be halved compared to the incident laser beam along a first axis, with the beam parameter product being kept constant along an axis perpendicular to the first axis. When the combined laser beam is subsequently focused along the first axis whose beam parameter product has been halved, the depth of field of that focus is improved as compared to focusing the incident laser beam. Further, a Intensitätsvertei ^¬ development of the combined laser beam can be generated with a low profile or a minimum in the middle, which is especially suitable for further efficient beam parameter product reduction, for example, using a staircase mirror assembly.

The optical system may further comprise a beam generating device for generating the incident laser beam so that the incident laser beam is linearly polarized. The beam combining device may comprise a polarizer (in particular a thin-film polarizer) which is adapted to transmit one of the two partial beams (first partial beam and second partial beam) and to reflect the other of the two partial beams so that the first partial beam and the second partial beam are combined ,

For example, the beam generating device may include a laser beam source and, optionally, a downstream linear polarizer such that the laser beam output from the beam generating device is linearly polarized along a predetermined polarization axis (eg, x-axis or y-axis).

The polarizer of the beam combining device may, for example, be a thin-film polarizer (also: thin-film polarizer). In particular, the polarizer may be configured to transmit p-polarized light relative to the polarizer and to reflect s-polarized light. By convention, p-polarized (parallel polarized) light is linearly polarized light whose electric field (E-field) is in the plane of incidence of the associated light beam with respect to the polarizer. Accordingly, s-polarized (perpendicularly polarized) light is linearly polarized light whose electric field is perpendicular to the above-mentioned plane of incidence.

The Umpolarisierungseinrichtung is thus provided either in the first partial beam or in the second partial beam, so that the original linear polarization of the incident laser beam is rotated in this partial beam by 90 °. Thus, a partial beam which is s-polarized with respect to the beam combining device and a partial beam which is p-polarized with respect to the beam combining device impinge on the beam combining device. The p-polarized partial beam is transmitted by the beam combining device and the s-polarized partial beam is reflected. This results in a unified laser beam whose beam direction extends along the transmitted p-polarized sub-beam.

The optical system may comprise at least one beam deflection device which is adapted to the partial beam which reflects on the polarizer is so directed to the polarizer that this partial beam incident on a Brewster angle of the polarizer (in particular with respect to the wavelength of the sub-beam) on the polarizer. The radiation-deflecting device may comprise, for example, a mirror. The Brewster angle is defined as the angle of incidence of the laser beam with respect to a surface normal of the beam combining device. For example, for synthetic quartz at the wavelength of 343 nm, the Brewster angle is 56 °. Thus, the partial beam can impinge, for example, at an incident angle of 56 ° on the polarizer. Thus, a polarizer can be used which has a coating on only one side.

The beam splitting device may comprise a mirror, which is designed to reflect the second partial beam out of the incident laser beam so that the second partial beam is deflected and a remaining portion of the incident light beam represents the first partial beam.

The mirror may, for example, comprise a straight edge along which the incident laser beam is split.

The beam splitting device may be configured to divide the incident laser beam substantially along a straight line passing through a central beam axis of the incoming laser beam so that the first section and the second section have substantially the same cross-sectional area.

A cross-sectional area of the first partial beam and a cross-sectional area of the second partial beam may thus correspond, for example, to a semicircle or a halved oval (for example a halved ellipse).

The optical system may further comprise a beam generating means for generating the incident laser beam so that the incident laser beam has an oval cross-sectional area with a long axis and a short axis.

The beam splitter may be configured to split the incoming laser beam along its long axis. Alternatively, the beam splitting device can be set up to divide the incoming laser beam along its short axis. According to a second aspect, an apparatus for generating a lighting line is provided. The device comprises the optical system according to the first aspect. The apparatus further comprises a staircase mirror assembly downstream of the optical system arranged to reduce a beam parameter product of the merged laser beam by dividing the merged laser beam into two or more sub-beams, and a staircase optical system downstream lighting line optic adapted to receive the two or more sub-beams using a homogenizing optic and an imaging device as a line of illumination.

"Downstream of the optical system" here means that the staircase mirror assembly is arranged in the beam path behind or behind the optical system.

For example, the stair mirror assembly may be configured as described in any of the following documents: Applied Optics, Vol. 24, 20.08.1997, pages 5873 and 5374, DE 103 31 442 A1 and DE 20 2005 021 171. The staircase mirror arrangement can be designed such that it divides the combined laser beam along an axis which is imaged by the illumination line optical system as a short axis becomes. In other words, the stair mirror assembly may be configured to split the sub-beam along an axis along which it has previously been split by the beam splitter. Thus, the beam parameter product along this axis can be further reduced. The illumination line optical system can, for example, have one or more cylindrical lenses and in particular comprise one or more of the optical elements described in DE 10 2015 002 537 for generating a lighting line.

According to a third aspect, there is provided an optical system for processing a first incoming laser beam and a second incident laser beam. The optical system comprises a first beam splitting device for splitting a first incident laser beam into a first sub-beam and a second sub-beam such that a cross-section of the first sub-beam corresponds to a first portion of a cross-section of the first incident laser beam and a cross-section of the second sub-beam corresponds to a second portion of the cross-section of the first first incoming laser beam corresponds, wherein the first portion and the second portion differ from each other, arranged in the beam path of the first sub-beam or the second sub-beam first Umpolarisierungseinrichtung for rotating a polarization of the first sub-beam or the second sub-beam by 90 °, a first beam combining means for uniting the second partial beam and a second incident laser beam to a first combined laser beam, a second beam splitter for splitting the first merged laser beam into a third beam and a fourth beam so that a cross section of the third beam corresponds to a first portion of a cross section of the first merged laser beam and a cross section of the fourth beam corresponds to a second portion of the cross section of the first merged laser beam wherein the first portion and the second portion deviate from one another and wherein the second partial beam of the first incident laser beam is substantially completely contained in the third partial beam of the first merged laser beam, a second Umpolarisierungseinrich- device arranged in the beam path of the fourth partial beam for rotating a polarization of the fourth Partial beam by 90 ° and a second beam combining device for combining the fourth partial beam and the first partial beam to a second combined laser beam.

The above statements regarding the first aspect may also apply, as far as possible, to the optical system according to the third aspect.

In particular, the first beam splitting device and the second beam splitting device may each comprise, for example, a mirror. The mirror can partially protrude into the beam path of the incident laser beam such that a predetermined component, ie a second partial beam or a fourth partial beam, each having a predetermined cross section, is split off from the incident laser beam or from the first combined laser beam. The remaining part of the beam incident laser beam in this case corresponds to the first part ^¬ beam. The remaining partial beam of the first combined laser beam corresponds to the third partial beam. The first portion and the second portion of the cross section of the incoming laser beam soft, for example, so from each other, that the cross-section of the incident laser beam from the first portion and the two ^¬ th segment composed, wherein the first portion and the second portion having no overlap with one another.

The first Umpolarisierungseinrichtung and the second Umpolarisierungseinrichtung include, for example, each a lambda / 2-plate, which is adapted to linearly polarized light of a predetermined wavelength lambda (in particular the wavelength of the respective incident on the lambda / 2-plate laser radiation) to rotate by 90 ° , In particular, the Umpolarisierungseinrichtungen each be adapted to polarize the polarization of a linearly polarized (partial) beam so that this polarization with respect to the first or second Beam combiner changes from s-polarized to p-polarized or from p-polarized to s-polarized.

The first beam combining device can be set up, for example, to combine the second partial beam and the second incident laser beam such that a cross section of the second partial beam and a cross section of a portion of the second incident laser beam, which corresponds to the third partial beam after the cleavage by the second beam splitter , overlap as far as possible. Furthermore, the second beam combining device can be configured to combine the first partial beam and the fourth partial beam with one another such that a cross section of the first partial beam and a cross section of the fourth partial beam largely overlap.

By means of the above-described superpositions with the aid of the first beam combining device and the second beam combining device, an outgoing third partial beam and an outgoing second combined laser beam are generated. A beam parameter product of these outgoing beams compared to the two incident laser beams may be halved along an axis with the beam parameter product kept constant along an axis perpendicular to the one axis. If the outgoing laser beams are subsequently focused along the one axis whose beam parameter product has been halved, a depth of field of this focusing can be improved in comparison to a focusing of the incident laser beams. Furthermore, an intensity distribution of the outgoing laser beams can be generated, each with a flat profile or minimum in the middle, which is particularly suitable for further efficient beam parameter product reduction, for example by means of a staircase mirror arrangement.

The optical system may further comprise first beam generating means for generating the first incident laser beam so that the first incident laser beam is linearly polarized, and second beam generating means for generating the second incident laser beam so that the second incident laser beam is linearly polarized. The first beam combining device may comprise a polarizer, which is configured to transmit the second incident laser beam and to reflect the second partial beam so that the second incident laser beam and the second partial beam are combined. The second beam combining device may comprise a polarizer, which is adapted to transmit the first partial beam and to the fourth partial beam reflect, so that the first partial beam and the fourth partial beam are combined.

The second incident laser beam may be p-polarized with respect to the polarizer of the first beam combining device. The first incident laser beam may be p polarized with respect to the polarizer of the first beam combining device, wherein the first Umpolarisierungseinrichtung is arranged in the second partial beam. Alternatively, the first incident laser beam may be s-polarized with respect to the polarizer of the second beam combining device, the first repolarizing device being arranged in the first sub-beam. Thus, the repolarizing means may be arranged in the respective sub-beams so that each of a p-polarized laser beam and an s-polarized laser beam impinges on the first beam combining means and the second beam combining means to be united by them. The optical system can be arranged such that the second partial beam strikes this polarizer at a Brewster angle of the polarizer of the first beam combining device. The optical system may further be arranged so that the four ^¬ th partial beam is incident at a Brewster angle of the polarizer of the second Strahlvereini ^¬ restriction device to this polarizer.

The first beam splitting means may comprise a mirror, which is arranged to reflect the second partial beam from the first incident laser beam out so that the second part beam is deflected and a verblei ^¬ bender component of the first incident light beam representing the first partial beam. Further, the second beam splitting device may comprise a mirror, wel ^¬ cher is configured to reflect the fourth sub-beam from the first combined laser ^¬ radiating out, so that the fourth sub-beam is deflected and a remaining portion of the first combined light beam to the third partial beam is ^¬ represents ,

The first beam splitter may be configured to split the first ^incident laser beam substantially along a straight line passing through a central beam axis of the first incoming laser beam so that the first portion and the second portion of the cross section of the first incident laser beam are substantially equal in cross-sectional area respectively. Furthermore, the second beam splitting device may be configured to divide the first combined laser beam substantially along a straight line passing through a central beam axis of the first combined laser beam, so that the The first portion and the second portion of the cross section of the first merged laser beam have a substantially equal cross-sectional area.

According to a fourth aspect, a device for generating a lighting line is provided. The device comprises the optical system according to the third aspect. The apparatus further includes a staircase mirror assembly downstream of the optical system configured to reduce a beam parameter product of the third sub-beam and the second merged laser beam by dividing the third sub-beam and the second merged laser beam into two or more sub-beams, respectively, and one subsequent to the stair-mirror assembly Illumination line optics which is adapted to image the respective two or more sub-beams using a homogenizing optical system and an imaging device as a common illumination line. The stair mirror assembly may be configured to divide the third sub-beam and the second merged laser beam along an axis which is imaged by the illumination line optics as a short axis. In other words, the stair mirror assembly may be configured to split the third sub-beam and the second merged laser beam along an axis along which it has previously been split by the beam splitting devices. Thus, the beam parameter product along this axis can be further reduced.

According to a fifth aspect, there is provided a method of processing an incoming laser beam. The method includes splitting an incident laser beam into a first sub-beam and a second sub-beam such that a cross-section of the first sub-beam corresponds to a first portion of a cross-section of the incident laser beam and a cross-section of the second sub-beam corresponds to a second portion of the cross-section of the incident laser beam Section and the second section differ from each other, turning a polarization of the first partial beam or the second partial beam by 90 ° and coaxially combining the first partial beam and the second partial beam into a combined laser beam. All of the above-described details of the optical system according to the first aspect can be correspondingly applied to the method according to the fifth aspect. The optical system according to the first aspect may be configured to perform the method according to the fifth aspect. According to a sixth aspect, there is provided a method of processing a first incoming laser beam and a second incident laser beam. The method includes splitting a first incident laser beam into a first sub-beam and a second sub-beam such that a cross-section of the first sub-beam corresponds to a first portion of a cross-section of the first incident laser beam and a cross-section of the second sub-beam corresponds to a second portion of the cross-section of the first incident laser beam. wherein the first portion and the second portion deviate from each other, rotating a polarization of the first sub-beam or the second sub-beam by 90 °, merging the second sub-beam and a second incident laser beam into a first merged laser beam, splitting the first merged laser beam into a third sub-beam, and a fourth sub-beam such that a cross-section of the third sub-beam corresponds to a first portion of a cross-section of the first merged laser beam and a cross-section of the fourth sub-beam corresponds to a second portion of Que corresponds to the first section and the second section, wherein the second partial beam of the first incident laser beam is substantially completely contained in the third partial beam of the first merged laser beam, rotating a polarization of the fourth partial beam by 90 ° and merging the fourth sub-beam and the first sub-beam into a second merged laser beam.

All of the above-described details of the optical system according to the third aspect can be applied as appropriate to the method according to the sixth aspect. The optical system according to the third aspect may be configured to perform the method according to the sixth aspect.

Although the arrangement of the optical system according to the first aspect is different from the arrangement of the optical system according to the third aspect, it should be noted that both aspects are based on the same basic idea for solving the same problem, namely a reduction of the beam parameter product along an axis while remaining the same Beam parameter product along an axis perpendicular to the one axis. In both optical systems, a beam parameter product can be halved along an axis, with a constant beam parameter product along an axis perpendicular to the one axis. According to the optical system of the first aspect, this is done by splitting off a partial beam from an incident laser beam and superimposing the split-off partial beam with a remaining partial beam of the incident laser beam. According to the optical System of the third aspect, this is done by splitting a partial beam of a first incoming laser beam and superimposition of the split partial beam with a remaining partial beam of a second incident laser beam, wherein the second incident laser beam as a partial beam is split off and a remaining partial beam of the first incident laser beam superimposed becomes.

The above applies mutatis mutandis to the method according to the fifth aspect and the sixth aspect.

The invention will be further elucidated with reference to the accompanying drawings, of which

1a, 1b show a schematic overview representation of a device for generating a lighting line from different viewing directions, wherein the optical systems described herein can be integrated into this device,

FIG. 2 shows details of the homogenization of the laser beam and the generation of the long beam axis according to FIG.

3 shows a typical focusing of a laser beam with a specific one

Diffraction coefficient and the resulting beam waist at location z = 0,

4a shows the beam propagation, expressed by the beam width (FWHM), as

Function of z for a laser beam with FWHM ₀ = 30 pm and M ² = 25 shows

Fig. 4b shows the beam propagation, expressed by the beam width (FWHM), as

Function of z for a laser beam with FWHM ₀ = 30 pm and M ² = 10 shows

5a shows a schematic cross-sectional view of a laser beam according to a first comparative example, wherein the laser beam is split and the two partial beams are positioned next to each other, 5b shows a perspective view of the beam path according to the first comparative example of FIG. 5a,

5c shows a top view of the beam path according to the first comparison example of FIG. 5a,

6a is a perspective view of the beam path according to a

second comparative example shows

6b shows a schematic cross-sectional view of the laser beam according to the second comparative example according to FIG. 6a,

7a shows a top view of the beam path according to a first embodiment of the present disclosure, wherein a partial beam is branched off from an incident laser beam and, after rotation of the polarization by 90 °, is superimposed on the remaining partial beam of the incoming partial beam with the aid of a polarizer,

7b shows a schematic cross-sectional view of the laser beam according to the first embodiment according to FIG. 7a, wherein the laser beam is split and the two partial beams are superimposed,

Fig. 8 shows a top view of the beam path according to a second embodiment ^¬ form of the present disclosure, wherein a part beam from egg ^¬ nem incoming laser beam is diverted and the remaining portion of beam of the incident sub-beam by rotation of its polarization is superimposed by 90 ° by using a polarizer,

Fig. 9 shows a top view of the beam path according to a third embodiment of the present disclosure, with one partial beam is diverted from two incoming laser beams and the respective remaining sub-beam of the other incoming laser beam are Überla ^¬ Gert,

Fig. 10 shows a plan view of six incident laser beams, with three

Arrangements similar to the third embodiment of Figure 9 are arranged side by side and the outgoing laser beams are respectively expanded, 11 is a perspective view of the beam path according to the third

Embodiment with a downstream stair mirror assembly shows and

12 shows a schematic overview illustration of an apparatus for generating a lighting line according to an embodiment of the present disclosure from different viewing directions, wherein the optical system of FIG. 7a has been integrated into the apparatus of FIG. 1a, 1b.

Figures la and lb show a device for generating a lighting line. The embodiments of optical systems for processing at least one incoming laser beam, which are discussed in detail below, may for example be integrated into the device according to FIGS. 1 a, 1 b, the devices resulting therefrom being part of the present disclosure. A corresponding device is described, for example, below in connection with FIG. 12.

A typical apparatus for generating a line of illumination is shown in FIGS. 1a, 1b and designated generally at 10. The device 10 can be used for example in a system for processing thin-film layers. However, the device 10 may be required ^¬ also be used for any other application for which a line of illumination is required. The apparatus 10 includes a beam shaping device 12, which is adapted to form a laser ^¬ beam 14 such that a beam profile 16 of the laser beam 14 having a long axis and a short axis, and a in the beam path of the laser beam 14, the beam shaping device 12 downstream of the imaging device 18, which is adapted to image the thus-shaped laser beam 14 as a line of illumination 22. The imaging device 18 thus generates the short axis of the illumination line 22 from the short axis of the laser beam 14 formed by the beam shaping device 12.

By convention, in the figures, the short axis parallel to the x-axis, the long axis parallel to the y-axis and the optical axis of the device 10 parallel to the z-axis. In Fig. La, the apparatus 10 is shown seen, for example, from the side (viewed along the x-direction) and in Fig. Lb shown seen in ^¬ game from the top (the viewing direction along the y-direction). The beam shaping device 12 may represent or comprise, for example, the anamorphic optical system 42 shown in FIGS. 4 to 6 of DE 10 2012 007 601 A1. In particular, the beam shaping device 12 may comprise one or more of those shown in FIGS. 4 to 6 of DE 10 2012 007 601 A1 Components 20, 54, 56, 58, 62, 66, 68, 74 include.

In other words, the beam-shaping device 12 can rotate through a first imaging axis x (parallel to the x-axis of the coordinate system), a second imaging axis y (parallel to the y-axis of the coordinate system) to the first imaging axis x, and one to the first and the second Image axis x, y vertical (parallel to the z-axis of the coordinate system) optical axis z described ^¬ who. The beam shaping device 12 (for example as anamorphic optics) has different imaging properties with respect to the first and second imaging axes x, y. The beam shaping device 12 can be adapted on site "16" in front of the imaging device 18 (see, for. Example, Fig. La, lb) of La ^¬ serlicht to generate a laser beam 14, the beam profile 16 has a long axis (y) and a short axis (x), wherein the beam profile in the long axis (y) has a largely homogenized (or substantially homogeneous) intensity distribution.

In detail: The beam shaping device 12 may comprise (in particular as anamorphic optical system) (see FIGS. 1a, 1b):

A first telescope assembly 20, which is optically effective with respect to the short axis x, d. H. has a refractive power with respect to the short axis x.

The first telescope assembly 20 is composed of a first cylindrical lens 23 and a second cylindrical lens 24. The first cylindrical lens 23 receives the laser beam 14 from a laser beam source 26 and focuses it with respect to the short axis x on a first intermediate image 28. The second cylindrical lens 24 is in

Beam path behind the first cylindrical lens 23 is arranged and collimates the light rays of the first intermediate image 28. As shown in Fig. Lb, it is in the first telescope assembly 20 to a 1: 1 telescope, which is designed as a Kepler telescope. Here, the first cylindrical lens 23 and the second cylindrical lens 24 are each a converging lens having substantially the same focal length. The image-side focal point of the first cylindrical lens 23 substantially coincides with the object-side focal point of the second cylindrical lens 24.

A cylindrical lens 30 arranged in the beam path behind the first telescope arrangement 20 and having a refractive power with respect to the long axis y. The Cylindrical lens 30 receives the laser beam 14, which was not influenced by the first telescope arrangement 20 with respect to the long axis y, from the laser beam source 26 and focuses it onto an intermediate image 32.

A cylindrical lens 34 arranged in the beam path behind the cylindrical lens 30 and having a refractive power with respect to the long axis y. The cylindrical lens 34 collimates the light beams of the intermediate image 32. As shown in FIG. 1a, the cylindrical lens 30 and the cylindrical lens 34 form a Kepler telescope which serves to widen the laser beam 14 with respect to the long axis y.

A second telescopic arrangement 36 arranged in the beam path behind the cylindrical lens 34 and optically active with respect to the short axis x, i. H. has a refractive power with respect to the short axis x. The second telescope arrangement 36 is composed of a first cylindrical lens 38 and a second cylindrical lens 40 arranged in the beam path behind the first cylindrical lens 38. The first cylindrical lens 38 widens the laser beam 14 with respect to the short axis x and the second cylindrical lens 40 collimates this expanded laser beam again , As shown in Fig. 1b, the second telescope assembly 36 is a beam-expanding telescope (eg, a 1: 5 telescope) designed as a Galileo telescope. In this case, the first cylindrical lens 38 is a diverging lens and the second cylindrical lens 40 is a converging lens, wherein the focal points of the first cylindrical lens 38 and the second cylindrical lens 40 substantially coincide or lie one above the other. The result is a virtual second intermediate image in the beam path in front of the first cylindrical lens 38 (not shown).

Anamorphotic homogenizing optics 42 arranged in the beam path behind the second telescope arrangement 36 for (largely) homogenizing the laser beam 14 with respect to the long axis y.

An arranged in the beam path behind the anamorphic homogenization optics 42 and with respect to the long axis y refractive power having condenser cylinder lens 44 for superimposing the homogenized laser beams on the illumination line 22nd

In the beam path behind the condenser cylinder lens 44 is the imaging device 18. The imaging device 18 may comprise or represent, for example, the component 66 shown in FIGS. 4 to 6 of DE 10 2012 007 601 A1. In the latter case, the imaging device 18 thus represents, for example, a focusing cylinder lens optics 66 which is arranged in the beam path behind the condenser cylinder lens 44 and serves to focus the laser beam 14 with respect to the axis x onto the illumination line 22. The beam forming device 12 downstream imaging device 18 thus attacks the beam profile 16 in front of the imaging device 18 and images the laser ^¬ beam 14 as the illumination line 22, wherein only (more precisely: exclusively) the short axis x of the beam profile 16, but not the homogenized long Axis y of the beam profile 16 is focused.

The illumination line 22 produced by the optical system 10 can be used for the crystallization of thin-film layers, for example for the production of thin-film transistors (in short: TFT). In this case, a semiconductor layer to be processed is acted upon by the illumination line 22 and guided over the semiconductor layer, wherein the intensity of the illumination line 22 is adjusted such that the semiconductor layer melts for a short time and solidifies again as a crystalline layer with improved electrical properties. As described above, anamorphic optical arrangements are used to generate a laser line beam geometry. This z. B. in the one (long) beam axis y of the laser beam emitted from the laser beam source 26 14 homogenized by means of cylindrical lens arrays. The other (short) axis x is optically processed as a Gaussian beam and the beam waist of the laser beam source 26 is transferred to the plane of homogenization. A typical arrangement is shown in Figs. 1a, 1b and has been discussed in detail above.

In the axis y to be homogenized, the laser beam 14 is cylindrically widened (typically 2 to 4 times) and guided on two successive lens arrays, see FIG. 2. The homogenized long beam axis y arises in the focal length of the condenser cylinder lens 44. With respect to the short axis x, the beam waist of the laser beam 14 formed in the laser beam source 26 is recollimated with a cylindrical 1: 1 telescope 20 and expanded with another telescope 36 to produce a Gaussian small beam axis x of desired width with the focusing lens 18 ,

For the production of line beams with high aspect ratio, as described above with reference to the figures la to 2, and in particular at long (100 mm to 1000 mm and larger, along the long axis y) narrow (10 to 100 pm FWHM (Full Width at Half Maximum) along the short axis x) lines, the depth of field is of great importance. For the Gaussian beam mapping, the beam parameter product or diffraction factor M ^{2 is} critical to the size of the beam waist that produces a lens and thus to the depth of field along the z-axis. The smaller M ² is, the greater the depth of field. The radius w _{0 of} the beam waist of a Gaussian beam in the focal length f of a lens is given by the formula (1):

(1) w ₀ = 4 fl M ² / (pd) w ₀ : radius (1 / e ² ) of the focused laser beam at the height of the beam waist (z = 0) d: beam radius (1 / e ² ) at the height of the lens ( z = -f)

l: wavelength of the laser beam

M ² : diffraction factor of the laser beam

f: focal length of the lens

Fig. 3 illustrates the focusing of a laser beam according to the above formula (1). In the figure, the beam radius d is shown at the level of the lens, the beam radius w ₀ at the height of the focal length of the lens (z = 0) and the development of the beam waist w (z) at an exemplary selected location z. Furthermore, the opening angle theta of the beam is drawn.

The beam waist w (z) develops along the propagation direction z according to the formula (2):

(2) w (z) = w ₀ (1 + (1 M ² z) / (pw ₀ ² )) ^1/2 w (z): radius (1 / e ² ) of the laser beam at the location z

w ₀ : radius (1 / e ² ) of the laser beam in the beam waist (z = 0)

l: wavelength of the laser beam

M ² : diffraction factor of the laser beam

z: propagation coordinate

The development of the beam waist (more specifically, the radius of the beam waist in FWHM) according to the above formula (2) is illustrated in Figs. 4a and 4b. Fig. 4a shows the beam propagation, expressed by the beamwidth (FWHM), as a function of z for a laser beam with w ₀ = 30 pm and M ² = 25. Fig. 4b shows the beam propagation, expressed by the beamwidth (FWHM), as function of z for a laser beam with w ₀ = 30 pm and M ² = 10. As can be seen from the figures easy, the beam with the smaller beam quality factor M ² (Fig. 4b) a interpreting ^¬ Lich better depth of field on, since with increasing distance z from the focus position z = 0, the beam radius w (z) is not increased as much as in the case of the higher diffraction factor (FIG. 4a). The depth of field of a focused laser beam can be defined, for example, by the length along the beam axis (z), up to which the radius w (z) of the laser beam has increased to 10% of its original radius w ₀ . According to this definition, the depth of field for the laser beam shown in FIG. 4a is for example approximately 110 pm and for the laser beam illustrated in FIG. 4b approximately 273 pm.

The beam parameter product (SPP) and the diffraction index M ^{2 of} a laser beam are as follows (Formula (3)):

(3) M ² = SPP [mm mrad] p / l [pm]

The beam parameter product is therefore proportional to the diffraction factor. For example, halving the diffraction index also means halving the beam parameter product (with the same wavelength l). In the following, a halving (or reduction) of the diffraction factor M ² is thus also referred to a halving (or reduction) of the beam parameter product.

The beam parameter product (SSP) is further calculated from the half beam diameter (1 / e ² ) multiplied by half the aperture angle of the laser light, see Fig. 3 (formula (4)):

(4) SPP (ray parameter product) = w ₀ x theta w ₀ : radius or half diameter of the laser beam

Theta: half the opening angle of the light cone with the radius w ₀

The present disclosure refers to reduce the beam parameter product (ent ^¬ speaking M ²⁾ of a laser beam in a beam axis in order to increase the depth of field.

A simple arrangement for reducing the beam parameter product is shown as a first comparative example in FIGS. 5a, 5b and 5c. According to the first comparative example, an incident laser beam 46 is geometrically divided and the resulting partial beams 48 and 50 are deflected by mirrors so that these z. B. next to each other. At this time, the beam parameter product in the divided axis (x) is approximately halved and obtained in the undivided axis (y) in each partial beam. 5a shows the above-described process by the first comparative example on the basis of the cross sections (perpendicular to the beam propagation direction z) by the incident laser beam 46 or by the partial beams 48 and 50. In the left area of the figure, the cross section of the incident laser beam 46 is shown in both axes x and y has the diffraction factor M ² . Then, the incoming laser beam 46 along the y-axis into two partial beams 48 and 50 is allocated among each having along the y-axis of the original beam parameter product corresponding to M ^2, and along the x-axis a halved beam parameter product corresponding to M ^2/2 respectively. Each of the sub-beams has, along the x-axis, the beam parameter product halved corresponding to M ^2/2 and along the y axis, the original beam parameter product corresponding to M ^2. The combined (eg side by side) beams can be assigned a beam parameter product in the y-axis (see FIG. 5a), which is at least twice as large as the original one, depending on how far apart the two partial beams are arranged ,

FIGS. 5b and 5c show the beam path of the first comparative example in a perspective view (FIG. 5b) or in a side view as viewed along the y-axis (FIG. 5c). As shown in FIGS. 5b and 5c, the partial beam 50 is split off and the deflection of this partial beam 50 is effected with the aid of mirrors 52. The mirror 52 for splitting the partial beam 50 from the incident laser beam 46 projects in half (ie up to a central beam axis) of the incoming laser beam 46) into the incoming laser beam 46.

For the division of the raw beam emitted by a laser z. B. from the typical round cross-section of the laser beam, a rectangular or oval cross-section using crossed cylindrical telescopic arrangements generated (see, the oval cross section of the incoming laser beam in Figures 5a and 7b).

Figures 6a and 6b show a second comparative example. The second comparative example is a modification of the first comparative example, and the above description of the first comparative example also applies to the second comparative example. The only difference between the two comparative examples is that the second comparative example additionally has a telescope optics consisting of two cylindrical converging lenses 53. With the aid of this telescope optics (for example, a 1: 1 telescope), it is possible to rotate the profile of the split-off partial beam 50 in such a way that the beam profiles of the two partial beams 48 and 50 in the case of juxtaposition. are aligned as shown in Fig. 6b. In contrast to the alignment of FIG. 5a, in which the two partial beams 48 and 50 have the same orientation, in the second comparative example the orientations of the two partial beams 48 and 50 are rotated or mirrored along the y-axis. An advantage here is that, when viewed along the x-axis, the summed beam intensity of the two partial beams 48, 50 is distributed symmetrically.

The optical systems of the present disclosure realize symmetrization of an incident laser beam 54 and reduction of the beam parameter product in one axis (x). For this purpose, according to a first embodiment of an optical system 55 shown in FIG. 7a, the incident laser beam 54 is geometrically divided along one axis by means of a mirror 56 and deflected twice by 90 ° by means of mirrors 58, 60. A lambda / 2 plate 62 allows the polarization of one of the two partial beams 64, 66 to be rotated through 90 °, so that the two partial beams can be superimposed coaxially again with a thin-film polarizer 68 and form a combined laser beam 70, see FIG. 7a ,

In detail, an incident laser beam 54 linearly polarized along the x-axis impinges on the optical system 55 along the z-axis. In other words, ER- stretches a beam axis of the incoming laser beam 54 along the z-axis and the electric field vectors of the incident laser beam 54 are positioned so ^¬ oriented such that they extend along the x-axis. To generate the laser beam 54 arrive ^¬ a laser beam source (not shown) is used that produces the linearly polarized laser beam 54, optionally with the use of a linear polarizer. As shown in Fig. 7a, the incoming laser ^¬ beam 54 is substantially a Gaussian intensity profile (both along the x-axis and along the y-axis), wherein an intensity maximum in the central beam axis of the incoming laser beam 54 is located. A partial beam 66 (second partial beam) is split off by means of the mirror 56 from the incident laser beam 54 and deflected along the x-direction. The remaining part of the incident laser beam 54 corresponds to a first partial beam 64. In other words, the incident laser beam 54 is split by means of the mirror 56 into a first partial beam 64 and a second partial beam 66. The splitting or splitting takes place along the y-axis, so that two sub-beams are produced whose intensity profiles after mirroring of the second sub-beam 66 on the mirror 56 substantially coincide (when viewing a cross-section through the xy-plane for the first sub-beam 64 or considering a transverse Section through the yz plane for the second sub-beam 66). In other words, the incoming laser beam 54 is halved in the middle, along an axis that passes through the beam maximum parallel to the y-axis. The second partial beam 66 is deflected by two mirrors 58, 60 so that it again meets the first partial beam 64 at a 90 ° angle.

At an arbitrary position after splitting off the second partial beam 66, a lambda / 2 plate 62 is positioned in the second partial beam 66 and arranged such that the linear polarization of the second partial beam 66, which before passing through the lambda / 2 plate 62 is within the xz plane, is rotated by 90 °, that the polarization of the second partial beam 66 after passing through the lambda / 2 plate 62 is perpendicular to the xz plane. In other words, the incident laser beam 54 and thus also the second partial beam 66 were p-polarized directly after being split off with respect to the thin film polarizer 68. After passing through the lambda / 2 plate 62, the second partial beam 66 is s-polarized with respect to the thin-film polarizer 68. The polarization directions of the respective beams are illustrated in the figures by arrows or crosses.

The thin film polarizer 68 is configured to transmit p-polarized light and to reflect s-polarized light. This leads in the arrangement of FIG. 7a to the fact that the first partial beam 64 arriving from the left along the z-axis onto the thin-film polarizer 68, which is p-polarized with respect to the thin-film polarizer 68, transmits through the latter and from above along the x - Axis incident on the thin-film polarizer 68 second partial beam 66, which is s-polarized with respect to the thin-film polarizer 68, is reflected by this. The first partial beam 64 and the second partial beam 66 are transmitted coaxially in the same direction (along the z-axis) and thus form a combined laser beam 70. In other words, the first partial beam 64 and the second partial beam 66 are superimposed with one another. The association is such that an overlap of the two partial beams 64, 66 is maximized. The resulting combined laser beam 70 is thus mirror-symmetric with respect to an axis of symmetry running along the x-axis and mirror-symmetrical with respect to an axis of symmetry running along the y-axis. Details of the cross sections of the respective beams are also illustrated in Fig. 7b.

Fig. 7b describes the above-described first embodiment with reference to the cross sections of the beams involved. Beginning on the left in FIG. 7b, the cross section of the incident light beam 54 and its essentially Gaussian intensity beam are shown in FIG. profile shown. The Gaussian intensity profile is exemplified along the x-axis. Also along the y-axis, the intensity profile of the incident laser beam 54 is substantially Gaussian. As shown in Fig. 7b, although the intensity profile of the incident laser beam is mirror-symmetrical with respect to x-axis reflection and y-axis mirroring, it is not necessarily rotationally symmetric. In the example described in FIG. 7b, the incoming laser beam 54 has already been brought into an elliptical shape by means of suitable cylinder optics, with a long axis along the y-axis and a short axis along the x-axis. The diffraction factor of the incoming laser beam 54 is M ² both along the x-axis and along the y-axis.

After being split by the mirror 56, the diffraction factor of the two partial beams 64, 66 along the y-axis is still M ² , but the diffraction factor of the respective beams perpendicular to the y-axis was halved to M ^{2/2 in} each case. Here, FIG. 7b for the first partial beam 64 and for the second partial beam 66 each symbolically shows a cross section perpendicular to the propagation direction of the respective beam. The right portion of Fig. 7b shows the merged laser beam 70 in cross section through an xy plane. As can be the schematic representation of FIG. 7b entneh ^¬ men, the two sections of the two partial beams 64, were 66 superimposed so that the resulting overall cross section of the combined laser beam 70 having a small area as possible, or that an overlap of the two cross-sections of the partial beams 64, 66 is maximum. The two Teilstrah ^¬ len 64 In other words, 66 superimposed so that an extension of the combined laser beam 70 in a plane perpendicular to the propagation direction (z-axis) substantially coincides with an extension of the first partial beam 64 and second partial beam 66, each in a plane perpendicular to the propagation direction of the respective sub-beam (see Fig. 7b).

At the far right in FIG. 7b is shown an intensity distribution of the combined laser beam 70 along the x-axis. With solid lines, the Intensitätsvertei ^¬ averaging the individual partial beams 64, indicated 66, and the dotted line is does illustrate a summed, superimposed intensity of the combined partial beam 70. Since two halved Gaussian profiles were overlaid, the resultant combined laser beam 70 has an intensity profile on , which - viewed along the x-axis - in each case has a maximum at its edge regions and has a minimum in the middle.

A laser beam in the divided axis (ie, along the x-axis) in about half the beam parameter product has maintaining (corresponding to M ^2/2) and in the other axis the original beam parameter product (M ²⁾ is formed on the above-described manner. In contrast, z. For example, in known staircase arrays, the beam parameter product is reduced in one axis and increased in the other axis perpendicular thereto. In modifications of the first embodiment, the deflection angles of the mirrors 56, 58, 60 can also deviate from 90 ° (compare also the second embodiment according to FIG. 8), whereby, however, the divided partial beams 64,

66 coaxial (in terms of direction and cross section) with the thin-film polarizer 68 are superimposed again. The merged beam 70 then contains both polarization directions in approximately the same intensity (see Fig. 7a).

According to a first modification of the first embodiment, the incident laser beam 54 is s-polarized relative to the thin-film polarizer 68, ie perpendicular to the plane of the figure 7a and thus along the y-axis (ie the laser beam source used is directed to generate such an incoming laser beam 54 ^¬ ). With the arrangement of the remaining elements of the optical system remaining constant (as shown in FIG. 7a), this results in the merged laser beam 70 leaving the optical system not along the z-axis but along the negative x-axis. More specifically, in this case, the first partial beam 64 is s-polarized and the second partial beam 66 is p-polarized after rotation of its polarization by the lambda / 2 plate 62, so that the second partial beam 66 is transmitted through the thin-film polarizer 68 and the first partial beam 64 is reflected ,

According to a second modification of the first embodiment, the incident laser beam 54 is s-polarized with respect to the thin-film polarizer 68, ie perpendicular to the plane of Fig. 7a and thus along the y-axis (ie the laser beam source used is an ^¬ for generating such an incoming laser beam 54 ^¬ directed). Furthermore, the lambda / 2 plate 62 is not arranged in the second partial beam 66 son ^¬ countries in the first partial beam 64 (downstream of the mirror 56). According to this arrangement, the first partial beam 64 is p polarized after reversal of its polarization and the second partial beam 66 is s-polarized. Since the polarization of the respective partial beams 64, 66 when hitting the thin-film polarizer 68 is identical to the polarization of the partial beams 64, 66 of the first embodiment a beam path of the combined laser beam 70 according to the second modification of the course of the combined laser beam 70 of the first embodiment of the Fig, 7a.

According to a third modification of the first embodiment, the incident laser beam is p-polarized, but an arrangement of the other components of the optical system corresponds to the arrangement of the second modification. As described in connection with the first modification, the combined laser beam 70 leaves the optical system along the negative x-axis.

8 shows a second embodiment of an optical system according to the present disclosure. Significant differences of the second embodiment compared to the first embodiment are that on the one hand the deflected second partial beam 66 is transmitted through the thin-film polarizer 68 and the first non-deflected first partial beam 64 is reflected by the thin-film polarizer 68. Another difference is that the angle at which the reflected sub-beam strikes the thin-film polarizer 68 is not 45 ° but 56 °. Details of the second embodiment of FIG. 8 will be described below.

A linearly polarized incident laser beam 54 impinges on the optical system along the z-axis. The incident laser beam 54 is p-polarized with respect to the thin-film polarizer 68 described later (that is, with E ~ Fe! D in the x-z plane). Similar to the first embodiment (only at a different deflection angle), the mirror 56 splits a partial beam 66 (second partial beam) from the incident laser beam 54, the remaining partial beam 64 of the incident laser beam 54 being the first partial beam 64 along the Z-axis , The first partial beam 64 is directed by means of a mirror 72 onto the backside of a thin-film polarizer 68. Likewise, the deflected first partial beam is directed by means of a mirror 74 onto the front side of the thin-film polarizer 68. In the beam path of the first partial beam 64 (i.e., behind the mirror 56 and in front of the thin-film polarizer 68), a lambda / 2 plate 62 is arranged, which can be positioned in front or behind the mirror 72 in the beam path. In the embodiment of FIG. 8, the lambda / 2 plate 62 is positioned between the mirror 56 and the mirror 72.

The lambda / 2 plate 62 is configured to rotate the linear polarization of the first sub-beam by 90 °. In the illustrated second embodiment, the lambda / 2 plate 62 is adapted to the original p-polarization of the first Partial beam 64, which corresponds to the polarization of the incident laser beam 54 to rotate so that the first partial beam 64 is s-polarized behind the lambda / 2 plate 62 with respect to the Dünschichtschichtpolarisators 68. As shown in FIG. 8 by a cross, after rotation of the polarization by the lambda / 2 plate 62, the first partial beam is polarized along the y-axis.

Similarly as described with respect to the first embodiment, in the second embodiment as well, an s-polarized sub-beam and a p-polarized sub-beam impinge on the thin-film polarizer 68, in the case of the second embodiment, the first sub-beam 64 is s-polarized and the second sub-beam p is polarized. The p-polarized second beam component is transmitted by the thin film polarizer 68 along the z-axis and the s-polarized first partial beam 64 is reflected at the Dünnschichtpo ^¬ larisator 68 and runs after reflection also along the z-axis and coaxially to the second part beam. Thus, behind the thin-film polarizer 68, a unified laser beam 70 is formed.

The illustration of FIG. 7b and the cross sections of the respective beams described therein also apply to the second embodiment according to FIG. 8.

The optical system according to the second embodiment of FIG. 8 is designed such that the first partial beam 64, which is reflected at the thin-film polarizer 68, impinges on it at the Brewster angle of the thin film polarizer 68. For synthetic quartz at the wavelength 343 nm Brewster angle at ^¬ example 56 °. If the reflected (first) partial beam 64 already irradiates the thin-film polarizer 68 at its Brewster angle, this has the advantage that a coating of the thin-film polarizer 68 on its rear side is not required and can therefore be omitted.

May alternatively 7a to the configuration of the first embodiment shown in FIG. This also be designed so that an angle at which the second part beam impinges 66 on the thin film polarizer 68, the Brewster angle of the Dünnschichtpoiari ^¬ crystallizer 68 corresponds (for example, 56 °).

Furthermore, as an alternative to the configuration of the second embodiment according to FIG. 8, an angle at which the first partial beam 64 impinges on the thin-film polarizer 68 can also be selected differently (for example 45 °) and the thin-film polarizer 68 can have a corresponding coating on its rear side. According to a first modification of the second embodiment, the incident laser beam 54 is s-polarized with respect to the thin-film polarizer 68, ie perpendicular to the plane of the drawing of FIG. 8 and thus along the y-axis (ie the laser beam source used is for generating such an incoming laser beam 54). directed). With the arrangement of the remaining elements of the optical system remaining constant (as shown in FIG. 8), this results in the merged one

Laser beam 70, the optical system not along the z-axis but in the representation of Fig. 8 leaves obliquely above. More specifically, in this case the first partial beam 64 is p polarized after reversal of its polarization by the lambda / 2 plate and the second partial beam 66 is s-polarized, so that the first partial beam 64 is transmitted through the thin-film polarizer 68 and the second partial beam 66 is reflected ,

According to a second modification of the second embodiment, the incident laser beam 54 is s-polarized with respect to the thin-film polarizer 68, i. H. 8 and thus along the y-axis (i.e., the laser beam source used is configured to produce such an incident laser beam 54). Furthermore, the thin-film polarizer 68 is not arranged in the first partial beam 64 but in the second partial beam 66 (downstream of the mirror 56). According to this arrangement, the second sub-beam 66 is p-polarized after reversing its polarization and the first sub-beam 64 is s-polarized. Since the polarization of the respective partial beams 64, 66 when hitting the thin-film polarizer 68 is identical to the polarization of the partial beams 64, 66 of the second embodiment, a beam path of the combined laser beam 70 according to the second modification corresponds to the course of the combined laser beam 70 the second embodiment of FIG. 8.

According to a third modification of the second embodiment, the incident laser beam is p-polarized, but an arrangement of the other components of the optical system corresponds to the arrangement of the second modification. As described in connection with the first modification of the second embodiment, in this case the combined laser beam 70 leaves the optical system obliquely upwards (in the representation of FIG. 8). 9 shows a third embodiment of the present disclosure wherein, according to the third embodiment, the light of two incident laser beams 76, 78 is mixed with each other in two outgoing laser beams 80, 82. In detail, a first incoming laser beam 76 and a second incident laser beam 78 strike the optical system along the z-axis. Both the first incident laser beam 76 and the second incident laser beam 78 are p polarized with respect to the thin film polarizers 84, 86 used in the optical system, ie, the incident laser beams 76, 78 are polarized parallel to the xz plane.

The first incoming laser beam 76 is split by a first mirror 88 into a first partial beam 90 and a second partial beam 92. The division of the first incident light beam 76 into the first partial beam 90 and the second partial beam 92 is analogous to the division of the incident laser beam 54 into the first partial beam 64 and the second partial beam 66 by means of the mirror 56 in the first embodiment (see FIG. 7a). , The first partial beam 90 is further p-polarized and runs along the z-axis. The second sub-beam 92 is deflected downwards (along the negative X-axis) in the direction of the second incident laser beam 78 and passes through a lambda / 2 plate 94, by which its polarization by 90 ° from the original p-polarization in an s Polarization is rotated.

The thus s-polarized second partial beam 92 is combined with the second incident laser beam 78 by means of the thin-film polarizer 84 and thus forms a first merged laser beam 96 running along the z-axis. More precisely, the second partial beam 92 is superimposed on the second incident laser beam 78, that only one half of the cross section of the second incident laser beam 78 is superimposed by the second partial beam 92, wherein this half is the later-described third partial beam 82, which is not split off by the second mirror 98.

The first combined laser beam is then split by the second mirror 98 into a third partial beam 82 and a fourth partial beam 100. In the third part ^¬ beam 82 is the portion of the second incident laser beam 78, the second beam has been superimposed on the 92nd The third partial beam 82 extends ent ^¬ long the z-axis.

The fourth sub-beam 100 is Reflectors advantage ^¬ from the mirror 98 upwards along the x-axis and passes through a lambda / 2 plate 102, through which its polarization is rotated 90 ° from its original p-polarization to s-polarization. The thus s-polarized fourth partial beam 100 is combined with the first partial beam 90 with the aid of the thin-film polarizer 86 and thus forms a second combined laser beam 80 running along the z-axis. A beam profile or an intensity distribution of the second combined laser beam 80 and of the third Partial beam 82 correspond to the beam profile or the intensity distribution of the combined laser beam 70 of the first embodiment.

According to a first modification of the third embodiment, the first incident laser beam 76 is s-polarized with respect to the thin film polarizer 84, i. H. 9 are thus along the y-axis (i.e., the laser beam source used is arranged to produce such an incident laser beam 76). The second incoming laser beam is still p-polarized. Furthermore, the lambda / 2 plate 94 is not arranged in the second partial beam 92 but in the first partial beam 90 (downstream of the mirror 88). According to this arrangement, after reversing its polarization, the first sub-beam 90 is p-polarized and the second sub-beam 92 is s-polarized. Since the polarization of the respective (partial) beams 90, 100, 92, 78 when hitting the thin-film polarizers 84, 86 is identical to the polarization of the respective beams of the third embodiment (see Fig. 9), a beam trace corresponds to the respective (part -) rays after passing through the thin-film polarizers 84, 86 the course of the illustrated in Fig. 9 rays of the third embodiment.

An advantage of the beam profile generated by the embodiments described above is that the composite laser beam guided to a staircase behind the optical system transports comparable energy components in the axis (x-axis) to be separated externally and internally and thereby along the further division of the beam parameter product This axis is very efficient. In particular, for the production of long lines, it may be necessary to combine the beams of several solid-state lasers to the sum sufficient

Pulse energy and thus energy density in the line to have available. The Ver ^¬ kleinerung the beam parameter product and mixing of individual rays before the homogenization can be of great advantage.

In the above-described FIG. 9, there is correspondingly shown an arrangement which mixes two incident laser beams 76, 78, halves the beam parameter product in one axis and a symmetrical beam 80, 82 with a flat distribution or generated a minimum in the beam center. Thus, there are two combined beams 80, 82 each containing approximately equal s and p polarization components and having a symmetrical intensity profile with a minimum in the center of the beams.

Fig. 10 shows an example of six incident laser beams and a use of thin-film polarizers at an angle not equal to 45 °, z. B. at the Brewster angle (56 ° for synthetic quartz, 343 nm) for the wavelength in question, to dispense with a coating on the back of the Dünschichtschichtpolarisators. In addition, an (optional) telescope expansion after the reduction of the beam parameter product along the x-axis is shown.

In the arrangement according to FIG. 10, substantially three arrangements of the third embodiment according to FIG. 9 are positioned next to each other, but the mirrors and thin-film polarizers are rotated such that entrance angles of the respective partial beams reflected at the thin-film polarizer correspond to the Brewster angle of the respective thin-film polarizer.

The outgoing laser beams 70, 80, 82 corresponding to the above-described embodiments and their modifications produced can reduced beam parameter product be further processed in a staircase mirror assembly 104 to the already (with respect to the x axis) on (with respect to the x-axis) to ver ^¬ smaller. The reduction / enlargement of the beam parameter product, for example in staircase ^{mirror arrangements,} has been described in many cases (see, for example, Applied Optics, Vol 36, No. 24, 20.08.1997, pages 5873 and 5374, DE 103 31 442 A1 and DE 20 2005 021 171) and prior art since the 1990s. For this purpose, the composite beam 70, 80, 82 is focused in a staircase mirror assembly 104 of long focal length and split once more or split several times. The focal length for focusing in the staircase mirror is selected so that the focus width (1 / e ² ) is significantly smaller than the staircase mirror facet.

Similar to the arrangement of FIG. 11, a staircase mirror assembly 104 may also be downstream of all other embodiments of an optical system described herein. The partial beams leaving the staircase ^leveling arrangement 104 can then be shaped into a lighting line, for example with a device 10 according to FIG. 1 a, 1 b. This is illustrated by way of example with reference to FIG. 12, wherein an optical system 55 according to the first embodiment (FIG. 7 a) is integrated in the device 10 of FIGS. 1 a, 1 b. The upper part (a) of Fig. 12 shows a view along the x-axis (on the long beam axis y) and the lower part (b) shows a view along the y-axis (on the short beam axis x).

Specifically, each of the embodiments described herein for an optical system may be integrated into the apparatus 10 of Figs. 1a, 1b, for example, between the cylindrical lenses 34 and 38 as shown in Fig. 12.

In the apparatus of FIG. 12, the beam parameter product is reduced by the optical array 55 along the x-axis, ie along the axis which forms the short axis of the illumination line 22. Further, in Fig. 12, the optional elements 106 and 104 are shown. By the optional telescope optics 106, the beam 14 can be expanded, for example, along the x-axis. The stair mirror assembly 104, as described above in connection with FIG. 11, may further reduce the beam parameter product along the short axis (x-axis) to improve the focus of the illumination line 22. As shown in Figure 12, the laser beam 14 is deflected twice by 90 ° by the stair mirror assembly 104 in both the y-z plane and the x-z plane.

By the technique described herein, beam parameter product reduction of one axis (eg, the x-axis) can be achieved without increasing the other axis (eg, the y-axis), with the ability to mix two or more beams. Furthermore, an intensity distribution with a shallow profile or minimum in the center can be achieved which is particularly suitable for further efficient beam parameter product reduction, e.g. B. with staircase levels. In other words, the optical arrangements described herein have the

Advantage, that a laser beam can be generated which can produce a reduced beam parameter product along at least one axis (short axis). This axis can be focused in a subsequent optics so that a depth of field of the generated focus is improved. Since the generated laser beam is largely symmetrical along the short axis, the beam can be better focused and a symmetrical focus is created which approximates a Gaussian profile. When using an optional staircase mirror arrangement, the generated beam profile along the short axis is particularly well suited for further splitting, since this is symmetrical on the one hand with respect to the short axis and on the other hand has an intensity maximum at its edge regions.

Further, with the above-described technique, it can be achieved that the flanks of the homogenized beam profile become narrower in the long axis, thus improving efficiency. When using multiple lasers, multiple outgoing beams can be placed close together. Without the superposition (union) of the sub-beams described herein, the beam array would be twice as long along the long axis. Thus, the technique described herein can save space and reduce the size of optical components to be used, resulting in cost savings.

Unless expressly stated otherwise, identical reference numerals in the figures stand for identical or identically acting elements. In addition, any combination of the features shown in the figures is conceivable.

Claims

claims

1. An optical system for processing an incoming laser beam, comprising:

a beam splitting device (56) for splitting an incident laser beam (54) into a first partial beam (64) and a second partial beam (66) such that a cross section of the first partial beam (64) corresponds to a first section of a cross section of the incident laser beam (54) and a cross section of the second partial beam (66) corresponds to a second section of the cross section of the incident laser beam (54), wherein the first section and the second section deviate from one another;

a Umpolarisierungseinrichtung arranged in the beam path of the first partial beam (64) or the second partial beam (66) for rotating a polarization of the first partial beam (64) or the second partial beam (66) by 90 °;

a beam combining means (68) for coaxially merging the first sub-beam (64) and the second sub-beam (66) into a unified laser beam.

2. An optical system according to claim 1, further comprising:

a beam generating device for generating the incoming laser beam (54), so that the incident laser beam (54) is linearly polarized,

wherein the beam combining means (68) comprises a polarizer wel ^¬ cher is adapted to one of the two sub-beams, the first partial beam (64) and second partial beam (66) to have transmit and the other to reflect radiation both part ^¬ of, so that the first partial beam (64) and the second partial beam (66) are combined.

3. An optical system according to claim 2, further comprising:

at least one beam deflecting device (72), which is adapted to direct the partial beam, which is reflected at the polarizer, on the polarizer, that this partial beam impinges on the polarizer at a Brewster angle of the polarizer.

4. Optical system according to one of claims 1 to 3,

wherein the beam splitting device (56) comprises a mirror, which is adapted to reflect the second partial beam (66) out of the incident laser beam (54), so that the second partial beam (66) is deflected and a remaining portion of the incoming light beam (54) represents the first partial beam (64).

5. An optical system according to claim 4,

wherein the beam splitter (56) is arranged to divide the incident laser beam (54) substantially along a straight line passing through a central beam axis of the incident laser beam (54) so that the first portion and the second portion are substantially equal have large cross-sectional area.

The optical system of any one of claims 1 to 5, further comprising:

a beam generating device for generating the incoming laser beam (54), so that the incident laser beam (54) has an oval cross-sectional area with a long axis and a short axis,

wherein the beam splitter (56) is arranged to split the incident laser beam (54) along its long axis, or

wherein the beam splitter (56) is arranged to split the incident laser beam (54) along its short axis.

7. Apparatus for generating a lighting line, comprising:

the optical system according to any one of claims 1 to 6;

a staircase mirror assembly (104) disposed downstream of the optical system and configured to reduce a beam parameter product of the merged laser beam (70) by dividing the merged laser beam (70) into two or more sub-beams; and

a lighting-line optical system arranged downstream of the stair-mirror arrangement, which is set up to image the two or more partial beams using a homogenizing optical system (42) and an imaging device (18) as a lighting line.

8. An optical system for processing a first incoming laser beam and a second incident laser beam, comprising:

a first beam splitting device (88) for splitting a first incident laser beam (76) into a first partial beam (90) and a second partial beam (92) so that a cross section of the first partial beam (90) corresponds to a first section of a cross section of the first incident laser beam (76 ) and a cross-section of the second sub-beam (92) corresponds to a second section of the cross-section Section of the first incoming laser beam (76) corresponds, wherein the first section and the second section differ from each other;

a first Umpolarisierungseinrichtung (94) arranged in the beam path of the first partial beam (90) or the second partial beam (92) for rotating a polarization of the first partial beam (90) or the second partial beam (92) by 90 °;

a first beam combining means (84) for combining the second sub-beam (92) and a second incident laser beam (78) into a first merged laser beam (96);

a second beam splitting device (98) for splitting the first combined laser beam (96) into a third partial beam (82) and a fourth partial beam (100) such that a cross section of the third partial beam (82) corresponds to a first section of a cross section of the first combined laser beam (96 ) and a cross section of the fourth partial beam (100) corresponds to a second section of the cross section of the first merged laser beam (96), wherein the first section and the second section deviate from one another and wherein the second partial beam (92) of the first incident laser beam (76) essentially completely contained in the third sub-beam (82) of the first merged laser beam (96);

a second Umpolarisierungseinrichtung (102) arranged in the beam path of the fourth partial beam (100) for rotating a polarization of the fourth partial beam (100) by 90 °; and

a second beam combining device (86) for combining the fourth sub-beam (100) and the first sub-beam (90) into a second merged laser beam (80).

The optical system of claim 8, further comprising:

a first beam generating means for generating the first eintreffen- the laser beam (76) so that the first incident laser beam (76) is linear polari ^¬ Siert; and

second beam generating means for generating the second incident laser beam (78) so that the second incident laser beam (78) is linearly polarized,

wherein the first beam combining device (84) comprises a polarizer which is adapted to transmit the second ^incident laser beam (78) and to reflect the second partial beam (92) so that the second ^incident laser beam (78) and the second partial beam (92) are combined;

wherein the second beam combining means (86) comprises a polarizer adapted to transmit the first sub-beam (90) and to reflect the fourth sub-beam (100) so that the first sub-beam (90) and the fourth sub-beam (100) are merged;

wherein the second incident laser beam (78) is p-polarized with respect to the polarizer of the first beam combining device (84); and

wherein the first incident laser beam (76) is p-polarized with respect to the polarizer of the first beam combining device (84) and the first repolarizing device (94) is disposed in the second beam (92), or

wherein the first incident laser beam (76) is s-polarized with respect to the polarizer of the second beam combining device (86) and the first repolarizing device (94) is disposed in the first sub-beam (90).

10. Optical system according to claim 9,

wherein the optical system is arranged so that the second partial beam (92) meets this polarizer at a Brewster angle of the polarizer of the first beam combining means (84); and

wherein the optical system is arranged so that the fourth partial beam (100) impinges on this polarizer at a Brewster angle of the polarizer of the second beam combining means (86).

11. Optical system according to one of claims 8 to 10,

wherein the first beam splitting means (88) comprises a mirror configured to reflect the second sub-beam (92) out of the first incident laser beam (76) so that the second sub-beam (92) is deflected and a remaining portion of the first incoming beam Light beam (76) represents the first partial beam (90), and / or

wherein the second beam splitting means (98) comprises a mirror configured to reflect the fourth sub-beam (100) out of the first merged laser beam (96) such that the fourth sub-beam (100) is deflected and a remaining portion of the first merged one Laser beam (96) represents the third partial beam (82).

12. Optical system according to claim 11,

wherein the first beam splitting means (88) is arranged to split the first incident laser beam (76) substantially along a straight line passing through a central beam axis of the first incoming laser beam (76) so that the first portion and the second portion of the cross section of the first incoming one Laser beam (76) have substantially equal cross-sectional area, and / or wherein the second beam splitter (98) is configured to split the first merged laser beam (96) substantially along a straight line passing through a central beam axis of the first merged laser beam (96) such that the first portion and the second portion of the cross section of the first merged one Laser beam (96) have substantially equal cross-sectional area.

13. A device for generating a lighting line, comprising:

the optical system according to any one of claims 8 to 12;

a staircase mirror assembly downstream of the optical system, arranged to split a beam parameter product of the third sub-beam (82) and the second merged laser beam (80) by dividing the third sub-beam (82) and the second merged laser beam (80) into two or more sub-beams, respectively to reduce; and

one of the staircase mirror arrangement downstream illumination line optics, which is adapted to each of the two or more partial beams Ver ^¬ using a homogenization (42) and an imaging device (18) as a common illumination line.

14. A method of processing an incoming laser beam, comprising:

Splitting an incident laser beam (54) in a first partial beam (64) and a second partial beam (66) so that a cross section of the first partial beam (64) a first portion of a cross section of the incoming laser beam ^¬ speaks (54) ent and a cross section of the second Partial beam (66) corresponds to a second portion of the cross section of the incident laser beam (54), wherein the first portion and the second portion deviate from each other;

Rotating a polarization of the first sub-beam (64) or the second sub-beam (66) by 90 °;

coaxially combining the first sub-beam (64) and the second sub-beam (66) into a merged laser beam (70).

15. A method of processing a first incoming laser beam and a second incident laser beam, comprising:

Splitting a first incident laser beam (76) in a first partial beam (90) and a second partial beam (92) so that a cross section of the first part ^¬ beam (90) corresponding to a first portion of a cross section of the first incident laser beam (76) and a cross section of the second partial beam (92) one second portion of the cross section of the first incident laser beam (76), wherein the first portion and the second portion deviate from each other;

Rotating a polarization of the first partial beam (90) or the second partial beam (92) by 90 °;

- combining the second partial beam (92) and a second incident laser beam ^¬ (78) to a first combined laser beam (96);

Splitting the first combined laser beam (96) into a third sub-beam (82) and a fourth sub-beam (100) such that a cross-section of the third sub-beam (82) corresponds to a first portion of a cross-section of the first merged laser beam (96) and a cross-section of the fourth Partial beam (100) corresponds to a second portion of the cross section of the first combined laser beam (96), wherein the first portion and the second portion differ from each other and wherein the second partial beam (92) of the first incident laser beam (76) substantially completely in the third partial beam ( 82) of the first merged laser beam is included; - Turning a polarization of the fourth partial beam (100) by 90 °; and

Combining the fourth sub-beam (100) and the first sub-beam (90) into a second merged laser beam (80).