Device and method for machining a workpiece

Abstract

The present invention relates to a method and apparatus for processing a workpiece (4), in particular to a method and apparatus for imprinting an anti-glare function through a laser pulse (100) of a laser (1), wherein the apparatus comprises: a laser (1), in particular a short pulse laser or an ultrashort pulse laser, configured to provide a laser beam (10) including a laser pulse (100); a first diffusion lens (2) and a second diffusion lens (2'), each configured to scatter the laser beam (10) and imprint a locally randomized intensity distribution on the laser beam (10) at a focal plane (12), wherein the first diffusion lens (2) and the second diffusion lens (2') sequentially scatter the laser beam (10); and at least one optical focusing system (3) configured to focus the laser beam (10) onto a focal area (120) within a focal plane (12) on the workpiece (4), wherein the laser beam (10) is applied to the workpiece (4) and consequently the workpiece is processed. The invention includes a progression device (5) configured to move a laser beam (10) and a workpiece (4) by one step (V) relative to each other, wherein the progression device includes a scanner device (50) having a first scanner element (500) and a second scanner element (502), the movement of the scanner elements (500, 502) generates one step, the second scanner element (502) includes a second diffusion lens (2'), and the movement of the scanner elements changes a locally randomized intensity distribution.

Description

Technology Field

[0001] The present invention relates to an apparatus and method for processing a workpiece. Background Technology

[0002] It is known that during laser material processing, the material of a workpiece can be removed by vaporizing or compressing the material through strong light-matter interactions within the focal region of the laser beam. The resulting structure is referred to as a dimple. In this regard, dimples are suitable for functionalizing the surface of components and can particularly affect optical and frictional properties.

[0003] However, when processing materials with a pulsed laser, regular structures, particularly regularly arranged dimples, are often generated, for example, due to the interaction between the beat frequency of the laser system and other process parameters, such as the travel speed and the number of times the material passes through. For example, these regular structures can induce interference effects that interfere with the visual impression of the processed material from a visual perspective.

[0004] U.S. Patent No. 2017 / 0368638 A1 relates to the processing of materials using a high-power laser having shape-adjustable beam and / or variable beam polarization.

[0005] The present invention aims to provide an improved device for material processing and a corresponding method based on known prior art.

[0006] The present objective is achieved through a material processing apparatus having the features of claim 1. Additional advantageous developments are evident from the dependent claims, description, and drawings.

[0007] Accordingly, an apparatus for processing a workpiece, in particular for imprinting an anti-glare function through a laser pulse, is proposed and comprises: a laser configured to provide a laser beam including a laser pulse, in particular a short pulse laser or an ultrashort pulse laser; a first diffusion lens and a second diffusion lens configured to scatter the laser beam and imprint a locally randomized intensity distribution on the laser beam at a focal plane, respectively, and sequentially scatter the laser beam; at least one optical focusing system configured to focus the laser beam onto a focal zone within a focal plane on the workpiece, wherein the laser beam is applied to the workpiece and consequently the workpiece is processed; a progress device configured to move the laser beam and the workpiece in a step forward relative to each other, wherein the progress device comprises a scanner device having a first scanner element and a second scanner element, and the movement of the scanner element creates a step forward. According to the present invention, the second scanner element is designed as a second diffusion lens, and the movement of the scanner element changes the locally randomized intensity distribution.

[0008] In the present invention, the material of the workpiece may be, for example, a polymer or plastic. The material to be processed may be a semiconductor, for example, an elemental semiconductor such as silicon or germanium, a III-V semiconductor such as gallium arsenide, an organic semiconductor, or another type of semiconductor. For example, the material may be a silicon wafer. However, the material may be composed of any metal such as aluminum, magnesium, titanium, iron, or steel alloy. In particular, the material may be a layer system, and each layer may be selected from the group of any metal, polymer, plastic, or semiconductor. In particular, the material may also be glass, for example, sapphire or quartz glass.

[0009] The laser provides laser pulses of a laser beam, and individual laser pulses form a laser beam in the direction of beam propagation. The duration of the laser pulses may be in the range of 100 fs to 100 ps. The wavelength of the laser pulses is 300 nm to 3000 nm, preferably 900 nm to 2200 nm.

[0010] Instead of individual laser pulses, the laser may provide laser bursts, wherein each burst comprises the emission of multiple laser pulses. In this case, the laser pulses may be emitted at very short intervals from each other, separated by a specific time interval of several picoseconds to nanoseconds. In particular, the laser burst may be a GHz burst, wherein the successive sequence of laser pulses in each burst occurs in the GHz range. For example, the burst may comprise 2 to 20 laser pulses, preferably 2 to 10 laser pulses, with a time interval between laser pulses of 10 ns to 50 ns. However, the burst may comprise 30 to 300 laser pulses, with a time interval between laser pulses of 100 ps to 1000 ps.

[0011] The repetition rate of the laser pulse and / or laser burst may be greater than 1 kHz, preferably greater than 10 kHz. For example, the repetition rate may be 100 kHz or more. For example, the laser emits more than 1,000 pulses per second or more than 10,000 pulses per second.

[0012] The pulse energy of the laser pulse can exceed 1 μJ, and for example, can be 2 μJ.

[0013] The diameter of the laser beam emitted from the laser can be larger than 0.1 mm, and, for example, 1 mm or 5 mm.

[0014] The laser pulse passes through the rest of the device and is introduced into the material, where the energy of the laser beam is absorbed at least partially by the material, for example, by nonlinear interactions, particularly multiphoton processes.

[0015] The incident laser beam first passes through a first diffusion lens and then through a second diffusion lens. These diffusion lenses are designed to scatter the laser beam. In particular, this may mean that the laser beam is converted into multiple partial laser beams, each of which may have a unique propagation direction and / or unique intensity and / or unique in-phase wavefront. In particular, the propagation direction of the partial laser beams may differ from the propagation direction of the incident laser beam.

[0016] The scattering of the laser beam depends on both the point of incidence on the first diffusion lens and the point of incidence on the second diffusion lens.

[0017] Multiple partial laser beams are superimposed on the focal area of ​​the focal plane by an optical focusing system, e.g., a 2f optical system. In the present invention, the focus of the scattered laser beam may be located on the workpiece in the direction of beam propagation. In this case, the focus is aligned exactly with the surface of the workpiece and the focal plane, or is aligned with the workpiece located above or below the surface in the direction of beam propagation, while the surface is still being processed. In particular, the focus position may be within 10 times the Rayleigh length from the surface, where the Rayleigh length is the distance along the optical axis required for the laser beam until the cross-sectional area of ​​the laser beam doubles starting from the beam waist or focus.

[0018] In particular, the term "focus" can generally be understood as a targeted intensity increase, where the laser energy converges in the "focus region." Specifically, the term "focus" is therefore used below regardless of the actual beam shape used and the method used to achieve the intensity increase. The location of the focus region along the beam propagation direction can also be influenced by the "focus." For example, the focus region can be virtually point-shaped and can have a Gaussian intensity cross-section, as provided by a Gaussian laser beam. However, the focus region can be designed in the shape of a line or rectangle, or take the form of an Airy distribution. Furthermore, other more complex beam shapes are possible, and the focus location can be extended to three dimensions, allowing, for example, multi-spot profiles of a Gaussian laser beam and / or non-Gaussian intensity distributions.

[0019] As a result of the energy absorbed from the laser beam within the focal region, the material is heated and / or transitions into a transient plasma state due to electromagnetic interactions between the laser and the material. In particular, in addition to linear absorption processes, non-linear absorption processes can also be utilized, which is possible by using high laser energy or laser intensity. Consequently, the material is deformed, particularly in the laser focal region where the laser beam intensity is greatest. This allows for the emission of some material from the material composite of the workpiece, for example, by melting or evaporating the material. Thus, machining processes known in themselves in relation to the interaction between the laser beam and the material of the workpiece to be processed are possible, and these methods are known, for example, as laser drilling, impact drilling, laser fusion, blasting, or compaction.

[0020] When a laser pulse interacts with the material of a workpiece to be processed, it causes corresponding material deformation on the surface of the workpiece. In particular, material deformation can be induced using laser pulses or laser bursts.

[0021] This material deformation is generated as the material on the workpiece surface evaporates due to the irradiated laser intensity. In particular, if the laser beam intensity exceeds the critical processing threshold for each material, the material evaporates. Therefore, the shape and form of the laser beam, especially the intensity distribution at the focal plane, are critical to the shape and form of the material deformation.

[0022] For example, without a diffusion lens, the laser beam has only a Gaussian beam profile. A specific spatial region is formed around the focal point where the laser energy exceeds a critical processing threshold. That is, at the focal point where the material can be vaporized, there is a region of uniform intensity in the laser beam intensity distribution. The shape and form of the material deformation are determined from this region of uniform intensity. In particular, the material deformation can have a circular or elliptical cross-section in the plane of the material surface, and the depth of the material deformation increases from the edge to the center. Specifically, the cross-section of the material deformation in the plane perpendicular to the surface may be circular or rounded. However, while it is possible for the material deformation to have an elliptical or circular cross-section in the plane of the surface, if the edge slope is steep, it may have a substantially rectangular cross-section in the plane perpendicular to the material surface. For example, such material deformation may have a uniform depth.

[0023] However, when the first and second diffusion lenses are placed in the beam path of the device, the laser beam is scattered randomly, resulting in a locally random intensity distribution at the focal plane. Therefore, the laser beam incident on the first diffusion lens is scattered into multiple partial laser beams, and the intensity and propagation angle of these beams are distributed randomly or statistically, for example, corresponding to a normal distribution or a Gaussian distribution. Since the intensity and propagation angle may be statistically distributed in a band-limiting manner, the maximum and minimum propagation angles of the partial laser beams are determined by the shape and form of the diffusion lens.

[0024] When a partial laser beam generated by the first diffusion lens is incident on the second diffusion lens and scattered there, scattering occurs again. The scattering at the second diffusion lens depends on the position where the laser beam is incident on the second diffusion lens after the first scattering.

[0025] This imprints a dual random or statistical element on the intensity profile of the focal plane, exhibiting locally randomly distributed peaks and troughs of intensity, each peak and trough making the processing intensity of the material particularly strong or weak. In particular, such scattering can imprint a kind of speckle pattern on the laser beam of the focal plane, as defined, for example, in Goodman's "Speckle phenomena in optics: theory and applications", Roberts and Company Publishers, 2007. This locally randomized intensity distribution enables non-uniform processing of the material, thereby preventing regular and / or smooth processing patterns in individual material deformations.

[0026] By introducing such non-uniform material deformation by introducing a locally randomized intensity distribution on the surface of the material, the optical properties of the material can be determined, for example, light passing through a transparent material is scattered in these material deformation areas, causing the material to appear diffuse and / or matte. In particular, applying such material deformation to the surface of a workpiece can reduce the reflection of the material.

[0027] For example, tactile sensation or roughness can be controlled by the type and shape of material deformation and the distribution of material deformation on the surface of the component. However, it is also possible to change the optical properties of the material by controlling light scattering.

[0028] In particular, anti-glare functions can be implemented through material deformation. Furthermore, the anti-glare function can be composed of incident rays that are not solely reflected from the surface at the reflection angle according to Snell's law of refraction. Specifically, this may occur when incident rays are reflected or scattered from the surface at different angles. In particular, since incident rays are induced in different spatial directions, precise reflection does not occur in the sense that the total energy of the incident rays can be detected at a specific reflection angle. Rather, the energy of the incident light is distributed across a spatial region, allowing the energy of the incident rays to be detected at various reflection angles.

[0029] A progression device may be configured to move a laser beam and a workpiece by one step relative to each other, and the progression device includes a scanner device having a first scanner element and a second scanner element, wherein the movement of the scanner element generates one step.

[0030] “Displaceable relative to each other” means that the laser beam can be displaced by translation relative to a fixed material, and the material can be displaced relative to the laser beam, or both the material and the laser beam can move.

[0031] In particular, this allows laser pulses to be introduced by positioning the focal region of the laser beam at various locations on the material. In this case, the laser pulses are positioned specifically along a so-called propagation trajectory. For example, the propagation trajectory can be a straight line or a curve. In particular, the local propagation direction is always the y-direction, the z-axis is parallel to the surface normal, and the x-axis is aligned perpendicular to the y-axis which is parallel to the surface of the material.

[0032] For example, the laser beam can move along with the laser pulse while it is emitted inside or on the material, thereby arranging different focal zones side by side or even overlapping them to enable uniform and flat processing of the workpiece.

[0033] Therefore, the advance device can change the position of the laser, particularly relative to the workpiece, so that continuously emitted laser pulses process the workpiece at different locations. Consequently, since the laser beam can cover the entire surface of the workpiece, processing of flat materials can be performed.

[0034] Scanner elements of a scanner device can be configured to displace a laser beam along several axes of a workpiece. For example, a first scanner element can generate displacement in the x-direction, and a second scanner element can generate displacement in the y-direction. By superimposing the two displacements, the scanner elements can be used to displace the laser beam in the xy plane.

[0035] According to the present invention, the second scanner element is designed as a second diffusion lens. Therefore, since the second diffusion lens already provides scattering based on the point of incidence of light scattered by the first diffusion lens, generating a step forward can also change the locally randomized intensity distribution.

[0036] In this context, the phrase “the scattering element includes the following” may mean that the second scanner element itself possesses both beam deflection and scattering effects, that is, that the second scanner element and the second scattering element are designed as a single unit. For example, the second scanner element may have a coating having the corresponding scattering and deflection effects. However, the second scattering element and the second scanning element may also be designed as a single functional unit, for example, when the second diffusion lens is located immediately behind the scanner element. In particular, the second diffusion lens and the second scanner element may be mechanically connected so that the second diffusion lens moves in accordance with the movement of the second scanner element. However, the second scanner element may also move independently of the second diffusion lens.

[0037] By displacing the second scanner element, the point at which the laser beam scattered by the first diffusion lens enters the second diffusion lens can be changed. Since the scattering characteristics at different points of incidence change, the first laser pulse may have a locally randomized first intensity distribution, and the second laser pulse may have a locally randomized second intensity distribution, and these two intensity distributions are different from each other. This allows periodic and repetitive patterns in material deformation to be avoided, thereby enabling high-quality material processing in particular.

[0038] In particular, an advantage is that due to double scattering in the first and second diffusion lenses, even small changes in the second scanner element can have a significant difference in the local randomization of the intensity distribution.

[0039] In particular, if the scanner device is used as a scattering device, a separate second scattering device may not be necessary.

[0040] Since the intensity distribution can be randomized using scanning motion, this device is particularly suitable for imprinting anti-glare functions using high laser energy. For example, according to conventional technology, rapid redeployment of the laser beam is required to obtain a random intensity distribution. However, high laser output requires thick optical elements, which consequently results in high inertia. By randomizing the intensity distribution within a scanner device, which may have a low dynamic range, optical elements suitable for high laser output can be used.

[0041] The first scanner element can be placed in front of or behind the first diffusion lens.

[0042] If the first scanner element is placed behind the first diffusion lens, the laser incidence point on the first diffusion lens is not displaced by the scanner element, thereby preventing variable randomization of the intensity distribution from occurring in the first diffusion lens. However, the scattered laser beam is displaced by the first scanner element and changes the incidence point of the scattered laser beam incident on the second diffusion lens. Therefore, the advancement of the first and second scanner elements variably randomizes the intensity distribution.

[0043] When the first scanner element is placed in front of the first diffusion lens, multiple incident points on the first diffusion lens individually result in already variable and randomized scattering.

[0044] The first scanner element may include a first diffusion lens as described above. Consequently, the first and second scanner elements can be designed to be identical, in particular. In particular, this provides the same technical advantages as described above.

[0045] At least one diffusion lens can be configured to scatter the laser beam by transmission or reflection. In particular, both diffusion lenses can also be configured to transmit or reflect the laser beam.

[0046] For example, a diffusion lens can transmit an incident laser beam and cause the laser beam to scatter as it passes through the diffusion lens. For example, the laser beam can be scattered on the diffusion lens and reflected without passing through it. For example, the diffusion lens can be a mirror with an irregular pattern rather than a planar pattern.

[0047] At least one diffusion lens has a phase pattern, in particular a binary phase pattern, configured to imprint a position-dependent phase difference on a laser beam, and in particular, said phase pattern can be defined as one-dimensional or two-dimensional.

[0048] In this context, the diffusion lens has scattering regions that may or may not locally affect the phase of the incident laser beam. Here, various scattering regions are randomly distributed throughout the diffusion lens, so that the scattering of the laser beam depends on the point where it is incident on each diffusion lens. For example, after being scattered by the first diffusion lens, the first partial laser beam may exhibit a phase shift relative to the second partial laser beam in the first scattering region. This phase shift may deflect a portion of the laser beam from its original direction of propagation.

[0049] The number of different phase shifts that can be generated using a diffusion lens is determined by what is known as the phase quantization of the diffusion lens. When the phase quantization is 2, the diffusion lens exhibits a binary phase pattern. Using a binary phase pattern, only two phase shifts, such as 0° and 180°, can be generated between partial laser beams. When the phase quantization of the diffusion lens is 4, four different phase shifts, such as 0°, 45°, 90°, and 180°, can be generated. However, the diffusion lens may also allow, for example, eight or sixteen different phase shifts between partial laser beams.

[0050] For example, the first scattering region of the diffusion lens may have a first material thickness, and the second scattering region may have a second material thickness. When the diffusion lens is designed as a reflective type, the first and second thicknesses can be selected such that the path difference of the reflected partial laser beam corresponds to half the wavelength. Accordingly, adjacent partial laser beams in the scattering region have a phase difference of 180°.

[0051] However, a laser beam may pass through a diffusion lens having scattering regions of different thicknesses, in which case it provides different optical path lengths due to the difference in thickness of the scattering regions. If the optical path lengths differ by half the wavelength, the partial laser beams will have a phase difference of 180°.

[0052] If a diffusion lens has a binary pattern, this may mean that the diffusion lens provides only two different optical path lengths. Since this pattern can be distributed across the geometric range of the diffusion lens, the diffusion lens has, for example, statistically distributed regions of a first thickness and a second thickness.

[0053] If a diffusion lens exhibits a binary pattern in two dimensions, this may mean that the diffusion lens has a scattering region randomly distributed in both height and width. However, if a diffusion lens exhibits a binary pattern in only one dimension, this may mean that the diffusion lens has a scattering region randomly distributed only in the height or width direction. For example, a binary pattern corresponds to a striped pattern.

[0054] In particular, the spatial frequency of the locally randomized intensity distribution can be controlled by varying the size of the scattering region of each diffusion lens. The spatial frequency can be understood as the reciprocal of the period length of the scattering region. For example, if a diffusion lens has a small rectangular scattering region, this increases the spatial frequency of the locally randomized intensity distribution and consequently results in a particularly non-uniform intensity distribution.

[0055] For example, the side length of a pixel can be greater than 1 μm, for example, 20 μm or 100 μm.

[0056] A diffusion lens can be a spatial light modulator or a diffractive optical element.

[0057] For example, a spatial light modulator can be a nanolattice or a hybrid element, which can imprint a specific phase distribution on a laser beam through its unique structure or configuration. For instance, the light modulator may be a spatial light modulator, and the cells or pixels of this modulator modulate the laser beam through tunable birefringence properties. Thus, a spatial light modulator can be implemented, for example, as an LCD (Liquid Crystal Display).

[0058] Similar to optical modulators, diffractive optical elements are designed to influence one or more properties of an incident laser beam in two-dimensional space. Unlike LCD-based spatial optical modulators, diffractive optical elements are stationary components that can be used to generate exactly one beam shape from an incident laser beam. Typically, a diffractive optical element is a specially formed diffraction grating in which the laser beam is diffracted to form the desired beam shape.

[0059] A diffractive optical element can be implemented as a geometric phase hologram in which the diffraction effect exhibits polarization dependence. See Kim et al., “Fabrication of an Ideal Geometric Phase Hologram with Arbitrary Wavefronts”, Optica 2, 958-964 (2015). Additionally, the geometric phase hologram can be designed as a switchable element, particularly a binary switchable element.

[0060] The progression device may include an axis device.

[0061] For example, a material can be mechanically moved using an axis device. In particular, the axis device may be an XYZ table with stepper motor control. However, to achieve the fastest possible adjustment, the axis device may also be designed as a piezoelectric control device.

[0062] For example, an axis device can be used to perform approximate positioning of a workpiece, and a scanner device scans the workpiece against the axis device along a travel trajectory.

[0063] The scanner device may include a galvanometer scanner and / or a polygon scanner.

[0064] In a galvanometer scanner, the laser beam is repositioned with high precision and repeatability. In particular, a 1D galvanometer scanner deflects the laser beam in only one direction, whereas a 2D galvanometer scanner deflects the laser beam in two mutually orthogonal directions.

[0065] In a polygon scanner, a laser beam is projected onto a rotating polygon, and this mirror periodically deflects the laser beam onto the workpiece. The polygon mirror consists of various faces, and each face may include a self-diffusing lens.

[0066] Because these components move relatively slowly, materials can be processed using particularly high laser energy, making them suitable for high-load and high-performance components.

[0067] The optical focusing system may include a diffusion lens. In particular, the surface facing the workpiece may include a diffusion lens or be designed as a diffusion lens. This allows for further randomization of the intensity distribution on the workpiece surface.

[0068] A beam shaping device can be configured to imprint a specific beam shape, particularly a flat-top beam shape, onto a laser beam, and it is preferable that the beam shaping device be positioned in front of a scanner device.

[0069] For example, a beam shape adjustment optical device, such as a commercially available Pi-Shaper, imprints a flat-top beam shape onto the laser beam. Compared to a Gaussian laser beam, a flat-top laser beam has uniform intensity across the entire beam cross-section, and the intensity decreases sharply after reaching the beam diameter. In a sense, a flat-top laser beam generally has a rectangular intensity profile, whereas the intensity distribution of a Gaussian laser beam has a Gaussian intensity profile.

[0070] Flat-top laser beams provide particularly simple beam shapes. For example, because flat-top laser beams do not require correction for intensity variations at the edges of Gaussian laser beams, they can particularly easily generate multiple adjacent material deformations that are adjacent to each other or partially overlapping.

[0071] An aperture can also be placed in the beam path. The beam profile can be adjusted through the aperture. This allows for the creation of a beam profile with a desired length and radial intensity distribution.

[0072] This creates a uniform deformation area where the deformation is inconspicuous when material deformation is introduced into an adjacent area.

[0073] The above-mentioned objective is also achieved by a method for processing a material having the features of claim 11. Advantageous additional developments of the method can be found in the dependent claims, this description, and the drawings.

[0074] Accordingly, a method for processing a workpiece by a laser pulse, particularly a single-pulse laser or an ultrasingle-pulse laser, is proposed, in particular a method for imprinting an anti-glare function, wherein a laser beam is scattered by a laser pulse passing through a first diffusion lens and a second diffusion lens, and a locally randomized intensity distribution is imprinted on the laser beam within the focal plane by the diffusion lens, and the workpiece and the laser beam are displaced relative to each other along a propagation trajectory, wherein propagation is generated by the movement of a first scanner element and a second scanner element of a scanner device, and the scattered laser beam is focused by an optical focusing system into a focal area of ​​the focal plane on the workpiece, wherein the laser beam is applied to the workpiece and consequently the workpiece is processed. According to the present invention, the second scanner element is designed as a second diffusion lens, and the relative movement of the scanner element modifies the locally randomized intensity distribution.

[0075] The first scanner element may be positioned in front of or behind the first diffusion lens, and / or the first scanner element may include the first diffusion lens.

[0076] The focal regions of different, especially continuous, laser pulses can overlap.

[0077] A continuous machined surface of a workpiece can be formed by overlapping material deformations. This method has a particular advantage in that it can prevent regular patterns caused by, for example, the uniform offset of the laser beam depending on the propagation speed between two laser pulses.

[0078] In particular, the focus zone can machine a planar section of the workpiece. It is also possible to machine the entire surface of the workpiece.

[0079] In this document, "planar section" refers to a continuous area corresponding to the range of at least two machined focal zones, and front machining of the workpiece surface means machining at least the side facing the laser beam. Brief explanation of the drawing

[0080] Preferred additional embodiments of the present invention are described in more detail through the description of the following drawings. In the drawings: FIGS. 1a, b, c, d, e and f show schematic representations of the device of the first embodiment. FIGS. 2a, b, c, and d show schematic representations of the device of the second embodiment. Figures 3a, b, and c schematically illustrate the operating principle of the beam shaping device. FIG. 4 shows a schematic representation of the device of the third embodiment. Figure 5 shows a schematic diagram of a scanner device. Figures 6a and 6b show schematic diagrams of a method according to the present invention. Specific details for implementing the invention

[0081] Preferred embodiments will be described below with reference to the drawings. In this case, elements having the same, similar, or identical effects are indicated by the same reference symbol in different drawings, and repeated descriptions of these elements have been omitted in some cases to avoid duplication.

[0082] FIG. 1a schematically illustrates an apparatus according to a first embodiment. The apparatus comprises a laser (1), in particular a short pulse laser or an ultrashort pulse laser, which provides a laser pulse (100) that forms a laser beam (10). The laser beam (10) passes through a first diffusion lens (2) and then through a second diffusion lens (2'), each of which scatters the laser beam (10) to form a plurality of partial laser beams, the intensity and propagation direction of which are randomized by scattering. The partial laser beams scattered by the second diffusion lens (2') are randomized therein again. An optical focusing system (3) consisting of an excitation lens (30) focuses the scattered laser beam (10) or the plurality of partial laser beams into a focal area (120) within a focal plane (12), which coincides, for example, with the surface (40) of a workpiece (4). Accordingly, the focused and double-scattered laser beam (10) exhibits a locally randomized intensity distribution at the focal plane (12), thereby creating non-uniform material deformation by applying it non-uniformly to the surface (40) of the workpiece (4) at the focal area (120).

[0083] FIG. 1b shows a schematic diagram of the first diffusion lens (2). The diffusion lens has various scattering regions, which are arranged in a grid pattern and have a shape similar to, for example, rectangular pixels. The white scattering region does not cause a phase shift here, but the black scattering region causes a phase shift of 180° compared to the white scattering region. Due to the random scattering region, that is, the random arrangement of scattering regions that cause or do not cause a phase shift, the laser beam (10) passing through the diffusion lens (2) can be imprinted with a random intensity distribution at the focal plane (12). The second diffusion lens (2') has the same shape but has different randomly distributed scattering regions.

[0084] The locally randomized intensity distribution generated by the device shown in FIG. 1a is shown in FIG. 1c and FIG. 1d. FIG. 1c shows the intensity distribution of the laser beam (10) at the focal plane (12) after it first passes through the diffusion lens (2) at the first incident point, and FIG. 1d shows a different intensity distribution while it passes through the diffusion lens (2) a second time at the second incident point. Since the intensity distributions are different, they produce different material deformations on the surface (40) of the workpiece (4).

[0085] The intensity distribution has a somewhat coarse structure depending on the shape of the scattering region of the pixel. For example, diffraction in a rectangular pixel is a sinc² where random intensity profiles are superimposed. 2 - Generates an envelope of shape. The randomized intensity profile reflects the influence of various scattering regions on the laser beam (10).

[0086] According to the present invention, a plurality of scattered partial laser beams are directed toward a second diffusion lens (2') and scattered once again there. Since the scattering by the second diffusion lens (2') also depends on the incident point of the partial laser beams, the already randomized intensity distribution is randomized once again.

[0087] The device shown in FIG. 1a also has a propagation device (5) comprising a scanner device (50) having a first scanner element (500) and a second scanner element (502). The scanning device (50) may be designed to deflect a laser beam (10) and displace the laser beam along a propagation trajectory on a workpiece (4). To this end, the laser beam (10) is incident on the first scanner element (500), and the laser beam (10) is deflected, for example, in a first direction. The laser beam (10) is then incident on the second scanner element (502), and the laser beam (10) is then deflected in a second direction. The point of incidence of the laser beam on the second scanner element (502) depends, in particular, on the deflection and point of incidence of the laser beam on the first scanner element (500).

[0088] According to the present invention, the first scanner element (500) includes a first diffusion lens (2), and the second scanner element (502) includes a second diffusion lens (2'). Accordingly, the movement of the first scanner element (500) and the second scanner element (502) results in not only displacing the laser beam (10) along a forward trajectory across the workpiece (4), but also introducing a locally randomized intensity distribution to the workpiece (4) while advancing. Thus, the process along the workpiece surface (40) is automatically connected to a locally randomized intensity distribution without additional means for randomizing the intensity distribution.

[0089] FIGS. 1e and 1f show other embodiments of the first scanner element (500) and the first diffusion lens (2). Unlike FIG. 1a, the first scanner element (500) does not include the diffusion lens (2), but rather the diffusion lens (2) is designed to be spatially separated from the first scanner element (500).

[0090] In FIG. 1e, a diffusion lens (2) is positioned in front of the scanner element (500) in the direction of beam propagation. The scanner element (500) receives the already scattered laser beam. Thus, the scanner element (500) sends the scattered laser beam (10) to a second scanner element (not shown), where it is scattered again.

[0091] In FIG. 1f, the diffusion lens (2) is positioned behind the scanner element (500) in the direction of beam propagation. Thus, the scanner element (500) directs the unscattered laser beam (10) toward different incident points of the diffusion lens (2), causing the laser beam to scatter differently at each incident point. In this case as well, the scattered laser beam is directed toward a second scanner element (not shown) and scattered again there. Thus, FIG. 1e and 1f also illustrate double randomization of the intensity distribution.

[0092] FIG. 2a illustrates an additional embodiment of the device according to the present invention. Unlike FIG. 1a, the laser beam (10) is further shaped by a beam shaping device (6). For example, a so-called flat-top beam is formed from a Gaussian laser beam of the laser, so that the envelope of the intensity distribution of the focal region (12) becomes more uniform; see FIG. 2b.

[0093] This device also has two diffuser plates (2, 2') through which a laser beam (10) passes in sequence. Here, the laser beam (10) scattered by the first diffuser plate (2) is scattered again by the second diffuser plate (2'). As a result, different laser pulses (100) of the laser (1) undergo different scattering, and as a result, the laser pulses continuously introduced into the material of the workpiece (4) cause material deformation of different shapes.

[0094] FIG. 2b shows the first intensity profile of a laser beam (10) scattered from the focal plane (12). The intensity profile of the flat-top laser beam (10) irradiates a specific area uniformly, and the intensity distribution becomes abruptly restricted toward the edges of the area. The dual scattering process creates a locally randomized intensity distribution in that area, which is similar to laser speckle. For example, the locally randomized intensity distribution exhibits more than 100 local intensity maximums, which leads to very non-uniform and irregular material deformation.

[0095] Figure 2c shows a comparison of the envelopes of the intensity distributions in Figure 1c (dotted line) and Figure 2b (solid line). sinc of the Gaussian raw beam 2 - It is evident that while the shape intensity profile concentrates a significant portion of the intensity into a small spatial area, using a flat-top laser beam significantly simplifies the planar processing of the workpiece (4).

[0096] FIG. 2d illustrates another intensity distribution generated when the first diffusion lens (2) is displaced relative to the second diffusion lens (2') during the scanning process. Because the first diffusion lens (2) and the second diffusion lens (2') scatter the laser beam (10) differently at the displaced positions, spatially randomized intensity profiles are generated differently at the focal plane (12). This allows for avoiding repetitive random intensity distributions on the surface (40) of the workpiece (4). In FIG. 2b and 2d, since the diameter of the focal area is about 1 mm, the laser output is about 0.8 mm 2 It is distributed across the region.

[0097] FIG. 3a schematically illustrates the operating principle of a flat-top beam shaping device (6). A laser beam (10) incident on the beam shaping device (6) and operating on the optical axis is, for example, 1 / e of the maximum intensity value of the laser beam (10). 2It has a first diameter associated with the reduction in intensity of the laser. In the beam shaping device (6), the laser beam (10) can be reshaped by a combination of a phase plate, a spherical lens, and an aspherical lens. For example, the partial laser beam forming the intensity maximum of the incident laser beam (10) can be distributed far from the optical axis, so that the maximum intensity on the optical axis is low but a uniform intensity profile is formed over a wider area. The partial laser beam can be parallelized again to form a flat-top laser beam (10'). The diameter of the flat-top laser beam can be larger than the diameter of the Gaussian laser beam.

[0098] Depending on the beam diameter of the incident laser beam (10), various beam shapes can be generated using the same beam shaping device (6). For example, Laskin et al., “Variable beam shaping using the same field mapping refractive beam shaping device” Laser resonator, microresonator and beam control XIV. Vol. 8236. SPIE, 2012. In FIG. 3b, the incident laser beam (10) has a larger diameter than in FIG. 3a. As a result, an edge peak is formed in the intensity profile of the flat-top laser beam after the beam shaping device (6). In FIG. 3c, the incident laser beam (10) has a smaller diameter than in FIG. 3a. Consequently, the flat-top laser beam (10') has a lower edge slope.

[0099] FIG. 4 shows an additional embodiment of the device. In contrast to FIG. 2a, an additional diffusion lens (2'') is arranged behind the optical focusing system (30). The additional diffusion lens (2'') allows the intensity distribution in the focusing area (120) to be further randomized.

[0100] FIG. 5 illustrates an additionally possible embodiment in which both scanner elements (500 and 502) include diffusion lenses (2 and 2') designed to be reflective. For example, a laser beam (10) is incident on the first diffusion lens (2) at a certain angle and then reflected on the diffusion lens (2'), thereby being scattered. This process may be repeated several times until the scattered laser beam (10) is scattered toward the focusing device (3) by the second diffusion lens (2'). Here, the two diffusion lenses (2, 2') are designed as scanner elements (500, 502) so that the laser beam (10) is incident on each of the diffusion lenses (2, 2') at different points along its trajectory, thereby further randomizing the intensity distribution in the focal plane (12).

[0101] FIG. 6a illustrates a method for processing a workpiece (4). Here, a laser pulse (100) forming a laser beam (10) is emitted as a laser (1). Using a scanner device (50) of a propulsion device (5), the laser beam (10) is guided across the surface of the workpiece (4) along a propulsion trajectory. To this end, the laser beam (10) is deflected by scanner elements (500 and 502) and scattered at each of the scanner elements (500 and 502) designed as scattering elements (2 and 2'). The laser beam (10) is then focused onto the surface (40) of the workpiece (4) using an optical focusing system (3). The laser beam (10) is processed by being applied to the workpiece (4) at a focal plane (12). Since the intensity distribution of the laser beam is locally randomized at the focal plane (12), the surface (40) of the workpiece (4), for example, can be functionalized, and in particular, an anti-glare function can be provided.

[0102] The workpiece (4) can also be displaced using an axis device (504) so ​​that the focal area (120) of the laser beam (10) continuously scans the entire surface (40) or a portion of the surface (40) of the workpiece (4). Here, the focal areas (120) of different laser pulses (100) may overlap. This means, in particular, that the first laser pulse (100) is introduced into the first focal area (120) at the first position x within the material of the workpiece (4), while the second laser pulse (100') is introduced into the second focal area (120') at the second position x' within the material of the workpiece (4).

[0103] By moving the scanner elements (500, 502) relative to each other, different random intensity distributions are generated in various focal zones (120, 120'). As a result, even with uniform one-step movement, no uniform material deformation occurs on the surface (40) of the workpiece (4), thereby preventing the formation of interfering interference or diffraction patterns when viewing the surface.

[0104] FIG. 6b shows that different focal regions (120, 120') of laser pulses (100, 100') introduced continuously at time pulse intervals t0 overlap to process the workpiece (4) as flatly as possible. Between laser pulses (100, 100'), scattering of the laser beam (10) is altered by the corresponding relative movement of the diffusion lenses (2, 2') to achieve non-uniform material processing. For example, the distance between laser pulses can vary from 10 μm to 30 μm.

[0105] Where applicable, all individual features presented in the exemplary embodiments may be combined with and / or exchanged with one another without departing from the scope of the invention. Explanation of the symbols

[0106] 1 laser 10 laser beam 12 focal plane 120 focal area 100 laser pulse 102 partial laser beam 2 First diffusion lens 2' Second diffusion lens 3 Optical focusing system 30 First lens 4 Work 40 Workpiece surface 5 Progress device 50 Scanner device 500 First scanner element 502 Second scanner element 52 Axis system 6 Beam shaping device V progress

Claims

Claim 1 A device for processing a workpiece (4), in particular a device for imprinting an anti-glare function through a laser pulse (100) of a laser (1), wherein the laser (1) is configured to provide a laser beam (10) having a laser pulse (100), in particular a short pulse laser or an ultrashort pulse laser, wherein a first diffusion lens (2) and a second diffusion lens (2') are each configured to scatter the laser beam (10) and imprint a locally randomized intensity distribution on the laser beam (10) at a focal plane (12), wherein the first diffusion lens (2) scatters the laser beam (10) and the second diffusion lens (2') scatters the scattered laser beam (10), wherein at least one optical focusing system (3) is configured to focus the laser beam (10) onto a focal zone (120) within a focal plane (12) on the workpiece (4) such that the laser beam (10) is applied to the workpiece (4) and consequently the workpiece is processed, and the laser beam (10) and A device comprising a progression device (5) configured to move workpieces (4) by one step forward (V) relative to each other, wherein the progression device comprises a scanner device (50) having a first scanner element (500) and a second scanner element (502), wherein the movement of the scanner elements (500, 502) generates one step forward, the second scanner element (502) includes a second diffusion lens (2'), and the movement of the scanner elements changes a locally randomized intensity distribution. Claim 2 A device according to claim 1, wherein the first scanner element (500) is positioned in front of or behind the first diffusion lens (2) and / or the first scanner element (500) includes the first diffusion lens (2). Claim 3 The device according to claim 1, characterized in that at least one diffusion lens (2, 2') is configured to scatter the laser beam (10) by transmitting or reflecting it. Claim 4 An apparatus according to any one of claims 1 to 3, wherein at least one diffusion lens (2) has a phase pattern, particularly a binary phase pattern, configured to imprint a position-dependent phase difference on a laser beam (10), and in particular, said phase pattern is defined as one-dimensional or two-dimensional. Claim 5 A device characterized in that, in any one of claims 1 to 4, the diffusion lens (2) is a spatial light modulator or a diffractive optical element. Claim 6 A device characterized in that, in any one of claims 1 to 5, the progression device (5) includes an axis system (52). Claim 7 A device according to any one of claims 1 to 6, wherein the scanner device comprises a galvanometer scanner and / or a polygon scanner. Claim 8 A device characterized in that, in any one of claims 1 to 7, the optical focus system (3) includes an additional diffusion lens. Claim 9 A device characterized by a beam shaping device (6) configured to imprint a beam shape, particularly a flat-top beam shape, on a laser beam (10) in any one of claims 1 to 8. Claim 10 In claim 9, the device is characterized in that the beam shaping device (6) is positioned in front of the scanner device (50) in the direction of beam propagation. Claim 11 A method for processing a workpiece (4) by a laser pulse (100) of a laser (1), particularly a single pulse laser or an ultra-single pulse laser, in particular a method for imprinting an anti-glare function, wherein a laser beam (10) is scattered by a laser pulse passing through a first diffusion lens and a second diffusion lens, and a locally randomized intensity distribution is imprinted on the laser beam (10) within a focal plane (12) by a diffusion lens (2), and the workpiece (4) and the laser beam (10) are displaced relative to each other along a propagation trajectory, said propagation is generated by the movement of a first scanner element (500) and a second scanner element (502) of a scanner device (50), and said scattered laser beam is focused by an optical focusing system (3) into a focal area (120) within a focal plane (12) on the workpiece (4), wherein the laser beam (10) is applied to the workpiece (4) and consequently the workpiece is processed, and the second scanner element is designed as a second diffusion lens. A method in which the relative movement of the above scanner element modifies a locally randomized intensity distribution. Claim 12 A method according to claim 11, wherein the first scanner element (500) is positioned in front of or behind the first diffusion lens (2) and / or the first scanner element (500) includes the first diffusion lens (2). Claim 13 A method according to claim 11 or 12, characterized in that the focal regions (120) of different, particularly continuous laser pulses (100) overlap. Claim 14 A method characterized in that, in any one of claims 11 to 13, the focal area (120) covers a surface section of the workpiece (4).

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