Apparatus for producing a defined laser line on a work plane

Abstract

An apparatus for generating a defined laser line (12) on a working plane (14) has a laser source (16) for generating a raw beam (18) and an optical assembly (20) that receives the raw beam and deforms it into an irradiation beam (22) illuminating the working plane. The irradiation beam (22) defines a beam direction intersecting the working plane (14) and has a transverse beam profile (28). The beam profile (28) has a major axis (30) perpendicular to the beam direction with a major axis beam width and a minor axis (32) with a minor axis beam width. The optical assembly (20) has a plurality of optical elements (36, 38, 40) that focus the beam profile (28) at a defined position (42) in a region of the working plane (14). The defined position (42) may be shifted by a drift length (50) due to the temperature rise of the optical elements (36, 38, 40) depending on the operating power and / or operating time of the laser source (16). The short-axis beam width of the beam profile (28) varies along the beam direction and defines the available process window. The optical assembly (20) is configured to generate an available process window with a depth of field (46) in the beam direction, which is greater than the drift length (50).

Description

Technical Field

[0001] The present invention relates to an apparatus for generating a defined laser line on a working plane, the apparatus comprising: a laser source configured to generate a raw beam; and an optical assembly receiving the raw beam and deforming it into an irradiation beam that illuminates the working plane, wherein the irradiation beam defines a beam direction intersecting the working plane, and wherein the irradiation beam has a beam profile having a major axis having a long axis beam width perpendicular to the beam direction and a minor axis beam width, wherein the optical assembly has a plurality of optical elements that focus the beam profile at a defined position in a region of the working plane, wherein the defined position is shifted by a drift length due to the heating of the optical elements depending on the operating power and / or operating time of the laser source. Background Technology

[0002] For example, such a device is disclosed in DE 10 2018 200 078 A1.

[0003] Such equipment generates defined linear laser irradiation at a defined area of ​​the work surface, particularly for machining workpieces. The workpiece can be, for example, a plastic material on a glass plate used as a carrier material. The plastic material can be, in particular, a thin film on which organic light-emitting diodes (so-called OLEDs) and / or thin-film transistors are fabricated. OLED films are increasingly used in displays in smartphones, tablets, televisions, and other devices with screen displays. After the electronic structure is fabricated, the film must be released from the glass carrier. This can be advantageously achieved by laser irradiation in the form of a fine laser line, which moves relative to the glass plate at a defined speed and penetrates the entire glass plate, breaking the adhesive bonds of the film. Such applications are commonly referred to in practice as LLO or Laser Lift Off (LLO) technology.

[0004] Another application of using a defined laser line to irradiate a workpiece is to melt amorphous silicon row by row on a carrier plate. Here, the laser line is again moved relative to the workpiece surface at a defined speed. Melting allows relatively cost-effective amorphous silicon to be converted into more valuable polycrystalline silicon. Such applications are commonly referred to in practice as Solid State Laser Annealing (SLA).

[0005] Such applications require a laser line on the working plane that is as long as possible in one direction to cover the widest possible working area, while being very short in another direction to provide the required energy density for the corresponding process. Therefore, a long, thin laser line parallel to the working plane is desired. The direction in which the laser line extends is generally referred to as the major axis of the so-called beam profile, and the linewidth is referred to as the minor axis. Typically, the laser line should have defined intensity profiles on both axes. For example, it is desirable for the laser line to have an intensity profile that is as rectangular as possible, or practically trapezoidal, on the major axis, where a trapezoidal intensity profile can be advantageous if multiple such laser lines are to be joined together to form a longer, continuous line. Depending on the application, a rectangular intensity profile (so-called top hat profile), a Gaussian profile, or other intensity profiles are desired on the minor axis.

[0006] WO 2018 / 019374 A1 discloses a device of the type described at the outset, and numerous details of optical elements relating to an optical assembly. A laser source generates a raw laser beam, which is fanned out very wide in a first spatial direction by means of an optical assembly to obtain a long axis. The laser beam is focused in a second spatial direction perpendicular to the first spatial direction to obtain a short axis. The first and second spatial directions are typically perpendicular to the beam direction in which the laser beam irradiates the working plane. The optical assembly of the device from WO 2018 / 019374 A1 has a collimator for collimating the raw laser beam, as well as a beam deformer, a homogenizer, and a focusing stage. The beam deformer receives the collimated raw beam and expands it along its long axis. In principle, the beam deformer can also receive multiple raw laser beams from multiple laser sources and combine them into a common, expanded laser beam with higher power. The homogenizer produces desired beam profiles along the long and short axes, i.e., for example, top hat profiles. The focusing stage focuses the deformed laser beam onto a specific location within the working plane.

[0007] The opening patent DE 10 2018 200 078 A1 discloses an optical assembly for generating an illumination line, which includes a telescope assembly having optical refractive power relative to the minor axis. The telescope assembly comprises a first lens group and a second lens group movable relative to each other along the optical axis. During laser beam generation by a laser beam source, a control unit controls the aforementioned movement so that the intensity of the illumination line and its so-called full width at half maximum (FWHM) remain as constant as possible over time. It has been shown that the characteristics of the optical assembly can change during laser beam generation. In particular, the heating of the optical elements by the laser beam can create so-called thermal lenses, which alter the optical properties of the assembly. DE 10 2018 200 078 A1 proposes to compensate for or at least reduce the resulting focal position changes by shifting the telescope lenses relative to each other.

[0008] The drawback of this solution is the mechanical expense required to adjust the position of the telescope lens. This movement can lead to wear and / or misalignment of optical components. Therefore, the object of this invention is to describe a device of the type described at the outset, which, in an alternative manner, helps to keep the working plane within the working area of ​​the device. Summary of the Invention

[0009] Here, according to one aspect of the invention, a device of the type described at the outset is described, wherein the short-axis beam width of the beam profile varies along the beam direction and thus defines the available process window, and wherein the optical components are arranged to produce a depth of field in the beam direction. The available process window has a depth of field greater than the drift length.

[0010] This novel device eliminates the need for mechanical adjustments of optical components or elements relative to each other to focus the beam profile on the minor axis. Therefore, preferably, the optical elements having optical refractive power about the minor axis of the beam profile and positioned in a defined area within the working plane for focusing the beam profile have a fixed distance relative to each other. In a preferred embodiment, the optical elements are individually fixed. This reduces mechanical wear and the risk of misalignment of the optical components due to mechanical movement. Instead, this novel device is based on the concept of intentionally increasing the depth of field of the components in the beam direction (hereinafter referred to as longitudinal) so that the defined position on which the beam profile is focused remains within the depth of field even when shifted due to thermal lensing. In other words, this novel device consciously takes into account focus drift caused by the heating of the optical elements depending on the operating power and / or operating time of the laser source. However, the optical components are intentionally configured to reduce beam quality, particularly on the minor axis, so that the beam profile remains within the process window even in the event of focus position drift. Instead of subsequent mechanical adjustments, the optical components are designed to specifically achieve greater depth of field through additional optical elements and / or amplified illumination of optical elements and the utilization of associated aberrations.

[0011] Therefore, this novel device features optical components in which the relationship between depth of field and focus shift is positively influenced. Consequently, the process window of this device is increased compared to existing devices, avoiding subsequent mechanical adjustments and related drawbacks. Correspondingly, the aforementioned objectives are fully achieved.

[0012] In a preferred configuration, the short-axis beamwidth has a maximum value along the beam direction, and the process window has a front end and a rear end in the beam direction, wherein the short-axis beamwidth is at the front end and the rear end that is up to 10% smaller than the maximum value, preferably up to 5% smaller than the maximum value, and particularly preferably 1% smaller than the maximum value, respectively.

[0013] In this configuration, the optical components are arranged to generate a beam profile, thereby producing a process window with given parameters. The short-axis beamwidth can be specifically determined here as the full width at half maximum (FWHM), i.e., the difference between two intensity values ​​of the beam profile on the short axis that have 50% of the maximum intensity of the beam profile at corresponding positions along the beam direction. Alternatively, the short-axis beamwidth can be given here as the difference between two intensity values ​​of the beam profile on the short axis that have 90% of the maximum intensity of the beam profile at corresponding positions along the beam direction (90% peak full width). The given values ​​provide a favorable increase in depth of field while maintaining beam quality on the short axis at levels well-suited for typical LLO and SLA applications.

[0014] In another configuration, the irradiation beam has a strahltaille in the beam direction, wherein the optical components are configured to generate the strahltaille in a region of the working plane.

[0015] Every real laser beam has a so-called waist. The waist is the position in the direction of propagation or beam direction where the laser beam has its minimum diameter or radius. In other words, the diameter or radius of a real laser beam varies along the beam direction. As the distance from the waist increases, the beam diameter also increases. The extent of the waist's extension along the beam direction can be quantified, for example, by means of the so-called Rayleigh length. The Rayleigh length is the distance w0 from the center of the waist, where the beam radius (usually measured in an electric field) increases. times, because it satisfies

[0016]

[0017] Where z R Let w(z) represent the Rayleigh length, and w(z) be the beam radius on the minor axis. In this configuration, the optical components are arranged to place the beam waist in the region of the working plane, preferably in the working plane. This configuration is particularly advantageous when the beam profile on the minor axis is a Gaussian profile. This configuration can achieve high energy density in the workpiece area in a highly efficient manner.

[0018] In another configuration, the optical assembly has an optical phase element that applies an axially conical phase front to the irradiated beam on its short axis.

[0019] A true axial cone is a conical lens that images a point source onto a line or transforms a laser beam into a ring along the optical axis. The term "axial cone" usually refers to a rotationally symmetric case or element. However, in the current case, the phase element affects the minor axis; that is, when observing an optical component with respect to the minor axis, the phase element produces an axial cone-shaped phase front with respect to the minor axis. The major axis is essentially unaffected. Therefore, rotational symmetry is not implied. The axial cone-shaped phase front produced by the phase element in this configuration manifests as a ring-shaped portion of the laser beam with respect to the minor axis, transverse to the component's optical axis, when the beam path is observed. A portion of the laser is "scattered outwards" by means of the phase element. This portion contributes to an increased depth of field in a relatively simple and cost-effective manner. Correspondingly, this configuration allows for the very simple and cost-effective implementation of this novel device.

[0020] In another configuration, the optical phase element includes refractive optical elements, particularly prismatic or non-cylindrical ground lenses.

[0021] This configuration allows for the implementation of this novel device in a particularly simple and cost-effective manner. In particular, this novel device can be obtained by modifying the optical components corresponding to the prior art mentioned at the beginning by introducing such refractive optical elements (e.g., non-cylindrical lenses with wedge-shaped profiles).

[0022] In another configuration, the optical phase element comprises a diffractive optical element.

[0023] In this configuration, a cone-shaped phase front is generated on the short axis by means of diffraction effects. In some embodiments of this configuration, the optical phase element comprises an irregular grating. This configuration enables the production of implementations with low optical loss and large tolerances regarding the position of the phase element in the beam path of the optical assembly.

[0024] In another configuration, the optical phase element includes a spatial light modulator (SLM).

[0025] A spatial light modulator is a device that applies spatial modulation to light. This device may, in particular, comprise a micromirror assembly and / or one or more deformable mirrors. Such a light modulator can produce highly personalized phase fronts and thus allow for optimal beamforming.

[0026] In another configuration, the optical assembly has a telescope assembly having at least two optical elements spaced apart from each other, which have optical refractive power about the short axis of the beam profile, wherein the optical phase element is arranged in front of the telescope assembly when viewed in the beam direction.

[0027] This configuration allows for a very simple and cost-effective way to increase the depth of field by approximately 2 times. This configuration is particularly advantageous for LLO applications and other applications using Gaussian beam profiles on the minor axis, as the influence of the phase element on the beam profile can be easily tolerated here.

[0028] In another configuration, the optical assembly has a telescope assembly having at least two spaced-apart optical elements that have optical refractive power about the minor axis of the beam profile, wherein the optical phase element is arranged between the at least two spaced-apart optical elements of the telescope assembly.

[0029] In this configuration, the optical phase element is advantageously arranged in the far-field plane of the minor axis. Here, the far field can be defined with respect to the output of the beam converter and can be achieved optically (focusing) or by observing a plane far from the exit aperture. Typically, the path length here is much greater than the Rayleigh length of the exit beam from the beam converter. This configuration is particularly suitable for applications with a top-hat beam profile on the minor axis, such as, especially, SLA applications.

[0030] In another configuration, the optical component has an objektiv lens that has aberrations in the edge region, wherein the illuminating beam includes a portion of the beam from the edge region.

[0031] In this configuration, the device advantageously utilizes diffraction-unrestricted optical components. This configuration effectively takes advantage of aberrations in the peripheral regions of the lens. Its advantage lies in reduced localized heating of the optical elements due to the large illumination area. This reduces thermal drift at the focal position, which is already an advantage. Furthermore, the increased depth of field due to the incorporation of the beam portion from the peripheral regions combines these two advantageous effects. This configuration can be implemented with a smaller number of optical elements, thus allowing for long-term cost-effective implementation of this novel device. This configuration is particularly advantageous for SLA applications and other applications with a top-hat beam profile on the short axis.

[0032] In another configuration, the optical component has at least one plano-convex lens having a first plane and a second convex surface, wherein the convex surface points toward the working plane.

[0033] Particularly advantageously, a plano-convex lens is arranged at the optical output end of the device. The plano-convex lens can be, in particular, the last optical element in the beam direction of the optical assembly. Typically, such a plano-convex lens is placed inverted in this type of device so that its plane points towards the working plane. The preferred arrangement has the advantage of more effectively utilizing aberrations from the edge regions of the lens. In some embodiments, the at least one lens may comprise a plurality of individual lenses, at least one of which is a plano-convex lens and arranged in the aforementioned orientation.

[0034] It goes without saying that the features mentioned above, as well as those described below, can be used not only in the combinations described separately, but also in other combinations or individually, without departing from the scope of the invention. Attached Figure Description

[0035] Embodiments of the invention are illustrated in the accompanying drawings, which are described in detail in the following description. In the accompanying drawings:

[0036] Figure 1a and Figure 1b A schematic diagram showing a first embodiment of this novel device is provided.

[0037] Figure 2 Simplified illustrations of the beam profiles used to illustrate the first and other embodiments are shown.

[0038] Figure 3 Simplified illustrations of the waistband and waist length according to some embodiments of this novel device are shown. Figure 4a and Figure 4b A schematic diagram showing a second embodiment of this novel device, and

[0039] Figure 5a and Figure 5b A schematic diagram showing another embodiment of this novel device is provided. Detailed Implementation

[0040] exist Figure 1a and Figure 1b In the figure, the first embodiment of this novel device is indicated by reference numeral 10. Figure 1a The device 10 is shown in a simplified diagram as viewed from above, with the laser line 12 positioned within the area of ​​the working plane 14. The device 10 has a laser source 16, which may be, for example, a solid-state laser that generates laser light in the infrared or ultraviolet range. For example, the laser source 16 may comprise an Nd:YAG laser with a wavelength in the 1030 nm range. In other examples, the laser source 16 may comprise a diode laser, an excimer laser, or a solid-state laser that generates laser light with wavelengths between 300 nm and 350 nm, between 500 nm and 530 nm, or between 900 nm and 1070 nm.

[0041] Figure 1b The device 10 is shown from the side, that is, with a line of sight toward the minor axis of the laser line 12. In the following text, the beam direction of the laser beam is described using the z-axis. The laser line 12 extends in the x-axis direction, and its linewidth is observed in the y-axis direction. Correspondingly, in the following text, the x-axis represents the major axis of the beam profile, and the y-axis represents the minor axis of the beam profile.

[0042] Laser source 16 generates a raw laser beam 18, which, in a further process, is deformed into an illumination beam 22 having a beam direction 23 using optical assembly 20. Here, optical assembly 20 includes a beam guiding unit 24, which in some embodiments may include a collimator for collimating the raw laser beam 18, as well as a beam deformer and homogenizer, both of which are simplified here and commonly referred to by reference numeral 26. The beam deformer and homogenizer 26 expands (collimated) the raw laser beam 18 along the x-axis to produce the major axis of the laser line 12. Furthermore, the beam deformer and homogenizer 26 produces a transverse beam profile 28, as shown in… Figure 2As shown in the simplified illustration, the beam profile 28 has a major axis 30 with a major axis beam width 31 in the x-direction and a minor axis 32 with a minor axis beam width 33 in the y-direction. Here, the intensity I of the laser beam is illustrated on the ordinate axis. The minor axis beam width 33 is exemplarily shown here as full width at half maximum (FWHM). Unlike the trapezoidal intensity curve shown in the simplified illustration, the beam profile can be a Gaussian profile or a top hat profile, but with a finite side slope.

[0043] For machining a workpiece (not shown here), the beam profile 28 can move with the device 10 relative to the working plane 14, for example, in the y-direction. For further details of the device 10, refer to WO 2018 / 019374 A1, mentioned at the outset, which is incorporated herein by reference. In some advantageous embodiments, the beam deformer and homogenizer 26 are implemented, in particular, as described in WO 2018 / 019374 A1. For example, the beam deformer and homogenizer 26 may accordingly comprise transparent, monolithic, plate-like elements having front and back faces arranged generally parallel to each other and at an acute angle (not shown here) to the optical axis 34 of the optical assembly 20. The front and back faces may each have a reflective coating such that the collimated original beam 18 is incident obliquely into the plate-like element at the front face and undergoes multiple reflections therein, then exits fan-shaped at the back face and is homogenized. The beam deformer and homogenizer 26 may include additional optical elements (not shown here) having multiple lenses, which form a fan-shaped illumination beam, particularly along the long axis 30. Alternatively, the beam deformer and homogenizer 26 may be implemented as described in DE 10 2018 200 078 A1, mentioned in the opening, which is also incorporated herein by reference. Correspondingly, the optical assembly may include additional optical elements, which are not shown here for clarity and are particularly used for shaping the beam along the long axis.

[0044] Here, the optical assembly 20 includes a telescope assembly having a first optical element 36 and a second optical element 38. The telescope assembly has optical refractive power that particularly affects the minor axis 32 of the beam profile 28. The telescope assembly is configured to form the beam profile 28 on the minor axis 32. The laser beam thus shaped here illuminates the lens 40, which then focuses the beam profile 28 at a defined position 42 in the region of the working plane 14 by means of the illuminating beam 22.

[0045] like Figure 1b As shown, the irradiation beam 22 has an object-side waist 44 in the beam direction, which is positioned in the region of the working plane 14 (see Figure 14). Figure 3However, the waist can also be located in front of or behind the working plane. The waist 44 has a waist length, which can be quantified, for example, by means of the Rayleigh lengths on both sides.

[0046] In some embodiments, the waist length can be quantified by a percentage increment 48, i.e., the waist length corresponds to the longitudinal distance at points where the beam diameter in the y-direction increases by a defined percentage compared to the minimum beam diameter on the minor axis. In some embodiments, this defined percentage can be less than or equal to 10%. In some embodiments, the waist length can correspond to the depth of field 46.

[0047] Due to irradiation with a high-energy laser beam, optical elements 36, 38, and 40 heat up. This heating can lead to the formation of thermal lenses. Thermal lenses are generated due to the absorption of laser light within the optical components. Localized temperature rises can be significant, especially when using laser sources with power in the kilowatts. The low thermal conductivity of the optical materials results in large temperature gradients. Consequently, the resulting refractive index gradient and thermal expansion of the material act as additional lenses. These thermal lenses cause a shift in the defined position 42 or focal position of the irradiated beam 22 by a drift length 50. This shift in the defined position is particularly likely to occur when the optical elements are first subjected to a laser beam after a prolonged interruption, and when the operating power of the laser source 16 changes, especially after the laser source 16 is switched on, for example, by switching from low-power operation to higher-power operation.

[0048] For this reason, according to Figure 1a and Figure 1b The device 10 has an optical phase element 52 in the beam path. According to... Figure 1a and Figure 1b In one embodiment, phase element 52 is arranged in front of the short-axis telescope assembly having optical elements 36, 38. Phase element 52 applies an axially conical (but not rotationally symmetric) phase front regarding the laser beam illuminating lens 40 along the short axis. As a result, the laser beam acquires an annular portion transverse to the optical axis 34 of assembly 20. Furthermore, these annular portions cause the short-axis profile to be imaged multiple times sequentially in the working plane 14 along the beam direction z. Thus, the depth of field in the beam direction is specifically extended. In a preferred embodiment, as in Figure 3 As simplified in the illustration, the depth of field 46 is sized to be greater than the drift length 50. Here, the depth of field corresponds to the waist length 46; however, this is not necessarily the case in all embodiments.

[0049] In some advantageous embodiments, the depth of field 46 is defined based on the varying short-axis beamwidth 33 along the beam direction 23. The short-axis beamwidth 33 varies along the beam direction and has a maximum value at a point, which... Figure 3The center of the beam is exemplarily aligned with the center of the beam waist. The depth of field defines the available process window in the beam direction. At the front and rear ends of the process window, the short-axis beam width is 10% smaller than the maximum value of the short-axis beam width, preferably 5% smaller, and particularly preferably 1% smaller, respectively. Since the drift length 50 is less than the depth of field 46, the beam profile 28 for machining the workpiece remains within the process window even if the focal plane is displaced due to thermal lenses. Placing the phase element 52 in the beam path in front of the telescope assembly for the short axis 32 is particularly advantageous for LLO applications and other applications with a Gaussian beam profile on the short axis 32.

[0050] According to Figure 4a and Figure 4b In this embodiment, the phase element 52 is arranged between the optical elements 36, 38 of the telescope assembly for the minor axis. In this case, the phase element 52 particularly affects the far field of the minor axis 32 of the beam profile 28. Such placement of the phase element 52 is advantageous for SLA applications and other applications with top-hat beam profiles.

[0051] exist Figure 1a and Figure 1b as well as Figure 4a and Figure 4b In some embodiments, the phase element 52 may be implemented using one or more refractive optical elements, one or more diffractive optical elements and / or a spatial light modulator.

[0052] according to Figure 5a and Figure 5b This embodiment does not require a dedicated phase element 52. Instead, a greater depth of field 46 is achieved by specifically utilizing the aberrations of the optical elements, particularly those from the edge regions of the lens 40. In principle, a dedicated phase element (not shown here) could also be used in combination. In this embodiment, the optical assembly 20 advantageously has no diffraction limitation. Here, the fan-shaped laser beam illuminates the lens 40 until it enters the edge regions, for example, until the edge regions extending to the outer 20% of the lens radius in a minor axis view. This already has the advantage that the radiated power of the laser beam is distributed over a larger lens surface and the lens 40 experiences less localized heating. For this reason, this embodiment advantageously reduces the drift length. Furthermore, the aberrations from the edge regions of the lens increase the depth of field. The quotient of drift length 50 and depth of field 46 is advantageously affected. In many applications, a decrease in beam quality on the minor axis associated with this can be tolerated.

[0053] In a preferred embodiment, lens 40 comprises a plano-convex lens with its convex surface 54 pointing toward the working plane 14 and its plane 56 pointing toward the telescope assemblies 36, 38. This orientation of the lens is quite unusual for the optical components of such a device. However, it enhances the effect of spherical aberration from the edge regions of lens 40.

[0054] The design criteria for a lens element depend on the desired longitudinal displacement. Wavefront aberration W(y) p This can be converted into longitudinal aberration.

[0055]

[0056] Where Δs′ is the longitudinal displacement, n′ is the refractive index on the image side, R is the radius of the reference sphere, and y p These are the pupil coordinates.

[0057] In the case of a cylindrical lens, the wavefront aberration is W. sph (y p )∝y p 4 Correspondingly, the total longitudinal displacement in the air is Δs′=αR 2 y p 2 Here, α measures the degree of spherical aberration and depends on the lens design.

[0058] Gaussian illumination of a lens with a characteristic focal length f. p In the middle, the thermal refractive power is from

[0059] (1)

[0060] Generation. Here, α is the absorptivity of the workpiece, κ is the thermal conductivity of the material, and L... x It is the line length along the major axis and y p This is the radius of the illumination beam. The change in refractive index and the expansion of the glass are summarized by the constant γ.

[0061] (2)

[0062] P0 here represents the laser power. Thermal lensing causes a focal displacement of this magnitude.

[0063] (3)

[0064] Meanwhile, the characteristic of a beam incident on the working plane along its minor axis is its depth of field, which is related to the illumination y p The beam diameter FW of the minor axis in the working plane is approximately proportional to the beam diameter FW.

[0065] (4)

[0066] Increasing the width of the minor axis (FW) increases the depth of field. Lower illumination results in a greater depth of field. Correspondingly, the following relationship can be derived:

[0067] (5)

[0068] The power density P0 / FW is constant and predetermined by the process. The focal length f is derived from the working distance. That is, under diffraction-limited conditions, the focal displacement is independent of the quotient of the depth of field y under illumination. p Conversely, in embodiments of this novel device, the depth of field decreases less with illumination. Correspondingly, quotient Q is y p The function is no longer independent of it. Therefore, the quotient Q is less than 1, preferably much less than 1.

Claims

1. An apparatus for generating a defined laser line (12) on a working plane (14), the apparatus comprising: a laser source (16) configured to generate a raw beam (18); and an optical assembly (20) receiving the raw beam (18) and deforming the raw beam into an irradiation beam (22) that irradiates the working plane (14), wherein, The irradiation beam (22) defines a beam direction (23) intersecting the working plane (14), wherein the irradiation beam (22) has a beam profile (28) perpendicular to the beam direction (23) having a major axis (30) having a major axis beam width (31) and a minor axis (32) having a minor axis beam width (33), wherein the optical assembly (20) has a plurality of optical elements that focus the beam profile (28) onto a defined position (42) in the region of the working plane (14), wherein the optical elements depend on the laser source (16) The defined position (42) is shifted by a drift length (50) due to the increase in operating power and / or operating time of the beam profile (28), characterized in that the short-axis beam width (33) of the beam profile (28) varies along the beam direction (23) and here defines an available process window, wherein the optical assembly (20) has an optical phase element (52) that applies an axially conical phase front to the irradiated beam (22), wherein the optical assembly (20) is configured to generate the available process window in the beam direction having a depth of field (46) greater than the drift length (50).

2. The device according to claim 1, characterized in that, The short-axis beam width (33) has a maximum value along the beam direction (23), the process window has a front end and a rear end in the beam direction, wherein the short-axis beam width (33) is at the front end and the rear end respectively smaller than the maximum value by up to 10%, or smaller than the maximum value by up to 5%, or smaller than the maximum value by 1%, respectively.

3. The device according to claim 1 or 2, characterized in that, The optical elements have optical refractive power about the minor axis (32) of the beam profile (28) and are fixed relative to each other.

4. The device according to claim 1 or 2, characterized in that, The irradiation beam (22) has a waist (44) in the beam direction, wherein the optical component (20) is configured to generate the waist (44) in the region of the working plane (14).

5. The device according to claim 1 or 2, characterized in that, The optical phase element (52) includes a refractive optical element.

6. The device according to claim 1 or 2, characterized in that, The optical phase element (52) includes a diffractive optical element.

7. The device according to claim 1 or 2, characterized in that, The optical phase element (52) includes a spatial light modulator.

8. The device according to claim 1 or 2, characterized in that, The optical assembly (20) has a telescope assembly having at least two optical elements spaced apart from each other, the optical elements having optical refractive power about the minor axis (32) of the beam profile (28), wherein the optical phase element (52) is arranged in front of the telescope assembly when viewed in the beam direction.

9. The device according to claim 1 or 2, characterized in that, The optical assembly (20) has a telescope assembly having at least two optical elements spaced apart from each other, the optical elements having optical refractive power about the minor axis (32) of the beam profile (28), wherein the optical phase element (52) is arranged between the at least two spaced apart optical elements of the telescope assembly.

10. The device according to claim 1 or 2, characterized in that, The optical component (20) has a lens with aberrations in the edge region, wherein the illumination beam (22) includes a portion of the beam from the edge region.

11. The device according to claim 1 or 2, characterized in that, The optical component (20) has at least one plano-convex lens having a first plane (56) and a second convex surface (54), wherein the convex surface (54) points toward the working plane (14).

12. The device according to claim 11, characterized in that, The at least one plano-convex lens is the termination element of the optical assembly (20) in the beam direction.

13. The device according to claim 5, characterized in that, The refractive optical element is a lens that has been ground in a prismatic or non-cylindrical shape.

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