Method and device for correcting the shape of an optical component by means of laser radiation

Abstract

The present invention relates to a method and to a device for correcting the shape of an optical component (1) using pulsed laser radiation. For this purpose, the component (1) is measured and excess material (7) is determined by way of comparison with a target geometry (6) and is at least partially removed by machining using at least one pulsed laser beam (4) with pulse durations of > 1 μs in order to at least approximate the actual geometry (5) to the target geometry (6). During machining, the component (1) is rotated at a rotational speed about an axis of rotation, wherein the distance of the laser beam (4) to the axis of rotation is changed at least temporarily. The rotational speed, the beam diameter of the laser beam (4) on the component (1) and the temporal pulse interval between the pulses of the laser beam (4) are selected such that material regions of the component (1) removed by successive pulses of the laser beam (4) do not overlap.

Description

[0001]Method and device for shape correction of an optical component using laser radiationTechnical field of application The present invention relates to a method for shape correction of an optical component using pulsed laser radiation, in which the component is measured in order to obtain an actual geometry of the component, and by comparison with a predetermined target geometry of the component, excess material is determined and at least partially removed by processing with at least one pulsed laser beam in order to at least approximate the actual geometry to the target geometry. The invention also relates to a device designed to carry out the method. In the manufacture of many components, a shape correction is often necessary at the end of the production process. In particular, the production of optical components from quartz glass requires a maximum degree of precision and reliability.Although machines for processing optical materials have advanced in terms of dimensions and precision over the past two centuries, the fundamental principle of subtractive material removal remains constant. Using conventional processes such as grinding and polishing, the glass material is gradually transformed into the desired shape, surface roughness is minimized, and subsurface damage (SSD) is successively eliminated. While flat and spherical optical components can be produced in high quality using kinematic control of the processing machines and are inexpensive and widely available as standard components, aspheric and freeform optics require a more complex machining process that involves line or point contact. The production times and costs for aspheric lenses significantly exceed those of spherical lenses, while simultaneously reducing precision.Particularly in the field of precision and ultra-precision manufacturing, as well as for numerous aspheres with medium requirements for dimensional accuracy, an additional manufacturing step for shape correction is required after shaping (usually by grinding) and polishing, as schematically illustrated in Figure 1, which shows a process chain for the production of optical components. This involves removing any final deviations between the actual and target geometry in the micrometer to nanometer range. This manufacturing step of precision shape correction is time-consuming and costly. State of the art: Magnetorheological Finishing (MRF) and Ion Beam Figuring (IBF), among others, are currently used for precision and ultra-precision shape correction of optics. Key target parameters are removal rate (and thus process time) and the vertical (^z) and lateral resolution of the material removal.The lateral resolution (spatial resolution) can be characterized by the smallest spatial wavelength to be corrected ^. OIn MRF, a magnetic fluid containing abrasive particles is continuously applied to a magnetic carrier wheel and then guided into the effective gap between the workpiece and the tool. The size of the carrier wheel limits the spatial resolution of MRF shape correction to approximately 2000 µm < ^O < 3000 µm. Concave surfaces with small radii of curvature cannot be machined due to the nature of the process. Particles of the polishing agent (cerium oxide, aluminum, carbonyl iron, and / or diamond nanoparticles) can be introduced into the optical surface and negatively impact the damage threshold of the optics in high-power laser applications. In IBF, the surface material is removed locally by ion bombardment. Similar to other subaperture methods (e.g., MRF), the workpiece shape correction is achieved via dwell times calculated based on the actual and target shape.Disadvantages of IBF include the expensive system technology with vacuum atmosphere and the low removal rates (Vab = 0.1 – 10 mm³ / h) and thus long processing times. Typically, spatial wavelengths of 0 > 3000 µm are corrected using IBF. Correction of smaller spatial wavelengths down to 0 > 1000 µm is possible in principle. However, with decreasing spatial wavelengths, the removal rate decreases significantly, making IBF uneconomical in this case. Other well-known processes for improving surface quality are computer-controlled polishing (CCP), plasma-assisted etching (RIBE), plasma chemical vaporization machining (PCVM), and elastic emission machining (EEM). For all correction processes, the actual shape must be measured before machining in order to determine the excess material to be removed.This is done in separate measuring machines, as the measuring technology is generally not vacuum-compatible (IBF). All other correction methods mentioned require a cleaned surface, meaning that measurements taken directly in the processing machine also require at least manual user intervention after machining. Laser-based shape correction (LBF; Laser Beam Figuring) is currently being researched. This involves focusing laser radiation with a wavelength of typically 10.6 µm onto a quartz glass surface and removing material in a location-selective manner from a few nanometers to several hundred nanometers. The laser radiation can be applied in either pulsed or modulated form. Modulation in the form of rectangular pulses can be generated using an acousto-optical modulator (AOM). The AOM acts as a fast optical switch.This allows the laser source to operate continuously at a stable operating point. Previous experiments and publications have demonstrated that rectangular-wave modulated pulses can be used to selectively remove material from the component's surface in a range of just a few nanometers. LBF is still in the research and development phase and still has significant shortcomings. These shortcomings include, in particular, low processing speed and difficult-to-control process accuracy, which are caused by thermal effects when processing with overlapping pulses in the nanometer range. The higher the pulse frequency (and thus the processing speed), the greater this problem becomes. According to the current state of science and technology, LBF pulses are arranged in an overlapping manner to achieve surface processing.WO 2012 / 119761 A1 describes a method for manufacturing optical components by processing with energetic radiation, in particular laser radiation. The optical component is manufactured from a blank by coarse ablation, polishing, and fine ablation. The fine ablation is performed with a laser beam by varying the speed of movement of the laser beam over the material. The laser beam is guided over the surface of the component using a scanner or an axis system. DE 102018 005 218 A1 discloses a method and a device for modifying a material in a solid body, in which the focus of a laser beam is guided through a scanning movement in a solid body in order to write at least one path into the solid body with the laser beam. In one embodiment, the solid body is guided using a polar movement on an ultra-precision machine.The method is used to generate shapes, but is not suitable for shape correction. DE 102017 002 986 B4 describes a method for producing a transmissive optic and intraocular lens, in which a plastic blank is suitably ablated with an ablation laser and further processed with a polishing laser. Shape correction is not addressed in this document. The object of the present invention is to provide a method and a device for shape correction of an optical component that enables increased process speed and improved and reproducible process accuracy during shape correction. Optical components are understood to be elements that are used for the transmission or reflection of optical radiation in optical applications, such as optical lenses or mirrors.Description of the invention The object is achieved with the method and device according to claims 1 and 15. Advantageous embodiments of the method and device are the subject of the dependent claims or can be derived from the following description and the exemplary embodiments. In the proposed method, the technique of laser-based shape correction (LBF) with pulsed laser radiation is used for the shape correction or change of an optical component. This technique is based on heating the material and removing material in the range of the evaporation temperature. The component is first measured to obtain the actual geometry of the component, and excess material is determined by comparison with a predetermined target geometry of the component and then at least partially removed by processing with at least one pulsed laser beam in order to at least approximate the actual geometry to the target geometry.A pulsed laser beam is understood not only to mean the beam of a pulsed laser beam source, but also a pulse-shaped, amplitude-modulated laser beam, where the minimum amplitude during modulation is less than 20% of the maximum amplitude, preferably zero. The modulation can be achieved, for example, by an acousto-optical modulator (AOM) in the beam path of the laser beam. The proposed method is characterized by the fact that the processing is carried out with pulse durations of the laser beam pulses of > 1 s, and the component is rotated during processing with the laser beam at a (constant or varying) speed about a rotational axis running through the component, for example, by mounting it on a motor-driven rotary spindle, whereby the distance between the laser beam and the rotational axis is changed at least temporarily.For this purpose, the laser beam is preferably moved radially relative to the rotation axis, for example, by a suitable linear movement of the laser optics. For a rotationally symmetrical component, the component's axis of symmetry is preferably selected as the rotation axis. The rotational speed, the beam diameter of the laser beam on the component, and the temporal pulse spacing of the laser beam pulses are selected such that material areas of the component removed by successive pulses of the laser beam do not overlap. The rotation of the component, which is preferably carried out using an ultra-precision lathe (UP lathe) with a repeatability of < 200 nm, preferably < 50 nm, and the selected pulse spacing enable an increased process speed and improved and reproducible process accuracy.It was recognized that with the previous use of the LBF, the problems of thermal interaction between the pulses due to thermal effects lead to difficult-to-control process accuracy, since the heat from previous pulses increases the ablation depth of subsequent pulses. The spacing of the pulses chosen in the proposed method, in which each subsequent pulse strikes the component so far from the previous pulse that it is not, or only slightly, within the temperature field of the previous pulse, at least reduces the thermal interaction between successive pulses, allowing ablation to be performed with greater precision. Due to the rotation of the component, processing is carried out using polar coordinates.The preferred use of a submerged arc lathe enables fast and precise guidance of the laser beam, preferably a focused laser beam, over rotationally symmetrical components or surfaces, and – when using a fast tool system – also over free-form surfaces. By implementing a high spindle speed, e.g., 3,000 revolutions per minute, it is possible to sufficiently separate the heat-affected zones of the individual laser pulses, even at significantly increased pulse frequencies. This results in both increased machining speed and more precise shape correction. Furthermore, a submerged arc lathe allows for measurement of the actual shape without user intervention. This allows iterative measurement and processing, and the machine can independently process a component until the desired shape accuracy is achieved.For precision laser processing, ultrashort pulse lasers with pulse durations in the ps and fs range (UKP laser radiation) are used according to the state of the art. However, when processing already polished glass surfaces, UKP laser radiation always significantly increases the roughness, causes subsurface damage, and thus destroys the polish. In the process proposed here, the shape correction of polished glass surfaces is achieved through thermal ablation with pulse durations in the µs range, i.e., by a factor of approximately 10. 6greater than with USP lasers, whereby the glass is also strongly heated and softened below the volume to be ablated. Therefore, the roughness does not increase significantly during thermal ablation. However, with this thermal ablation with pulse durations > 1 µs, the centrifugal forces can lead to undesired material flow and thus to a deformation of the surface of the component when the process is carried out on a lathe. In the proposed process, the type of glass of the component and the parameter space, in particular speed and pulse duration, are therefore preferably selected so that the process can be advantageously carried out on a submerged arc lathe without undesired deformation of the surface (> 10 nm) due to material flow. The process can therefore be carried out in such a way that the deformation caused by centrifugal forces is less than 10 nm.The proposed method can be used particularly advantageously for rotationally symmetric optical components, where the component's axis of symmetry is selected as the axis of rotation. The proposed method is particularly advantageous for correcting the shape of optical components made of quartz glass, since, especially with quartz glass, very small amounts of material can be removed using pulsed laser radiation by LBF, and even at very high rotational speeds, centrifugal forces do not deform the softened material, or only slightly. To achieve the highest possible precision in the shape correction, the actual geometry of the component is preferably measured with an accuracy of < 500 nm, particularly preferably < 100 nm. Known optical measuring methods, in particular interferometric measuring methods, can be used for this purpose. When using a submerged arc lathe, a measuring device already present on the lathe can also be used if necessary.The component to be processed preferably already has a polished surface, as is usually the case, for example, when the proposed method is used at the end of a production chain for manufacturing the optical component. In a particularly preferred embodiment of the method, the optical component is subjected to another mechanical polishing after processing with the pulsed laser beam in order to reduce roughness for spatial wavelengths 0 < 100 µm resulting from processing the optical component with the laser radiation. Furthermore, it is advantageous to temper the component after the shape correction in order to eliminate any shape deviations resulting from compaction caused by the processing.In the proposed method, the spatial offset between successive pulses is preferably selected such that it corresponds to at least half the beam diameter of the laser beam on the component, preferably at least the full beam diameter of the laser beam on the component. The beam diameter of the laser beam on the component is generally the focus diameter, since the laser beam is focused on the component or the surface of the component for material ablation. The beam diameter of the laser beam or the focus diameter is defined as 1 / e. 2 -diameter, i.e. the diameter at which the intensity in the beam profile is 1 / e 2of the maximum. The diameter of the material region of the component removed by a pulse should preferably be smaller than half the beam diameter of the laser beam on the component. In an advantageous embodiment, the parameters for the laser beam pulses are selected such that both material is removed and the underlying material is heated to a temperature above the softening temperature and smoothed under the influence of surface tension, so that the roughness of the component, measured in Sa, increases by a maximum of 5 nm over an area of ​​100 x 100 m². In the proposed method, machining for shape correction is preferably carried out with a CO2 laser or a UV laser. The laser radiation preferably has a wavelength in the range of 9 - 11 nm or < 180 nm.The pulse frequency of the laser radiation is preferably selected in the range of 1 - 100 kHz, particularly preferably in the range of 10 - 100 kHz, and the pulse duration is preferably in the range between 1 and 50 s. The parameters for the shape correction are preferably selected such that the ablation depth per pulse is < 100 nm, preferably < 50 nm. Preferably, each pulse of the laser beam is assigned an individual pulse energy to enable optimal local adaptation of the ablation depth to the excess material determined by the target / actual comparison. This is particularly advantageous when generating the pulsed laser beam by modulating continuous laser radiation with an acousto-optical modulator (AOM), since by appropriately controlling the AOM, the pulse duration and pulse amplitude can be changed from pulse to pulse, as well as the pulse frequency over several pulses.This also enables operation of the laser source in a thermal equilibrium state, which is very advantageous in terms of ablation accuracy. In a further advantageous embodiment, the machining of the outer or more peripheral regions of the component relative to the rotation axis takes place at a constant path speed by adjusting the rotational speed to the machining radius, and toward the center or rotation axis at a constant (as high as possible) rotational speed and adjusting the pulse frequency to the machining radius. This allows the selection of a high rotational speed even for machining the outer regions. The advantageous embodiments described in this application can, of course, also be combined with one another.The proposed device is designed as an ultra-precision lathe, on which a laser beam source with corresponding laser optics, in one embodiment also a modulation device for modulating the laser beam, and an adjustment device for varying the focus position in the beam direction and for shifting the laser beam radially relative to the rotation axis of the lathe are arranged. Furthermore, the device also includes a measuring device for precisely measuring the actual shape of the component and a control device designed to control the lathe, the adjustment devices, the modulation device, and the laser beam source to carry out the proposed method.The proposed method and the associated device can be advantageously used for the shape correction of polished glass surfaces, particularly of optics such as lenses or mirrors, and can either be performed in addition to or replace other surface finishing processes. The main area of ​​application is the shape correction of precision optics, e.g., for applications in lithography, metrology, laser technology, or fusion technology. The proposed method enables the controlled removal of glass material in layers of preferably 1–100 nm for the precision shape correction of optics. The method achieves deterministic removal because the laser beam tool does not wear mechanically. High rotation or peripheral speeds allow the heat-affected zones of the individual pulses to be separated from one another. This increases both the precision and the possible processing speed.The process can potentially increase processing speed by a factor of > 10 compared to known correction methods using LBF, which are around 1 kHz. When using a lathe, 10 to 100 kHz are possible. When using a submerged arc lathe, the lathe's measuring technology, if available, can be used to measure the component's geometry, allowing measurements, machining, and re-measurements without user intervention. Furthermore, problems that arise when measuring outside the machine are avoided, particularly the necessary alignment of the coordinate systems between the measuring machine and the machine. The process allows spheres and aspheres to be machined with virtually identical processing times. The shape correction also occurs, but not only, in the MSFE (Mid-Spatial Frequency Error) range, so that even shorter spatial wavelengths than with IBF and MRF are economically and technically feasible.Brief Description of the Drawings The proposed method is explained in more detail below using exemplary embodiments in conjunction with the drawings. These show: Fig. 1 shows a process chain for manufacturing optical components; Fig. 2 shows a schematic representation of the shape correction of a component using laser radiation according to the proposed method; Fig. 3 shows a schematic representation of a top view of a surface of an optical component to be corrected, in which the position of the individual pulses during a first revolution is indicated; Fig. 4 shows a schematic representation of a top view of a surface of the optical component to be corrected, in which the position of the individual pulses during the first and second revolutions is indicated; and Fig. 5 shows a schematic representation for defining the distance between two pulses within a revolution on a processing radius without thermal interaction.Ways of Implementing the Invention: The proposed method enables a shape correction of, for example, an optical component, as obtained from a blank after shaping and polishing. Fig. 1 shows a typical process chain for the production of optical components, as already described in the introductory section. The precision shape correction enabled by the present method after shaping and polishing can be used to manufacture precision optics. The present method, in which successive pulses are distributed over the surface to be machined, i.e., are spaced sufficiently apart in time so that the heat-affected zones of two consecutive pulses do not overlap, allows the precision of the removal to be significantly increased.By using a rotating component with a submerged arc lathe, higher pulse frequencies and thus greater processing speeds can be achieved simultaneously, as with previously known techniques. The proposed method and the associated device thus also enable more efficient and cost-effective shape correction of precision aspheres and freeform optics, which fulfills a key requirement in the photonics industry. In contrast to the previously performed processing using a scanner, in which the laser radiation is guided by deflecting mirrors and focused onto the surface of the component 1, the proposed method, as illustrated by way of example in Figure 2, dispenses with a scanner. In the present example, the component 1 whose shape is to be corrected is rotated on an ultra-precision lathe (submerged arc lathe) 2. The feed motion 8 of the laser optics 3 is varied over a full rotation (360°).Machining can take place on multiple circular paths or on a spiral path on the surface of component 1. The beam guidance is thus realized via a polar motion with a synchronized guided feed axis 8 (focus position, focus depth) on a submerged arc lathe. Due to the rotational movement, this kinematics enables high precision on large surfaces without stitching and a high process speed. In contrast to a linear scan with a scanner, no artifacts occur due to approach and retraction movements. With this kinematics, both rotationally symmetrical and non-rotationally symmetrical components can be corrected in shape by suitably varying the feed movement over a full rotation. Pulsed laser radiation or a pulsed laser beam 4 is used for machining, which can be generated, for example, by suitable modulation of continuous laser radiation.The wavelength of the laser radiation must be absorbed close to the surface in the material to be processed, as is the case, for example, when using infrared laser radiation (CO2 laser radiation) when processing quartz glass. The laser radiation is directed onto the material surface, preferably vertically. However, oblique irradiation is also possible. The beam diameter can be in the range from 1 µm to 1 mm, preferably in the range from 100 µm to 500 µm. The method is intended to correct an existing actual shape 5 of the component 1 to a target shape 6 in the nanometer range for high-end optics. The method is particularly suitable for lenses with spherical, aspherical, or freely formed contours. Figure 3 shows an example of a top view of a surface to be corrected during a complete revolution (rotation through 360°).The component 1 rotates around the center point M at a circumferential speed vcircumference11, defined by the processing radius 14 (r1). Pulses of laser radiation are coupled onto the surface at the processing radius r1 with the corresponding process parameters. The following pulse and the preceding pulse are spaced apart by a distance d. U (12). This distance d U between a subsequent pulse and a previous pulse is an essential parameter in the execution of the process, since this distance significantly limits the heat-induced process in terms of its controllability and precision. The distance d UIn the present example, this is defined by the focus diameter of the laser radiation and is set to at least ½ * focus diameter (defined according to 1 / e²), preferably at least 1 * focus diameter. The surface shown schematically / exemplarily in Figure 4 is the machined surface after the second revolution of the surface or component and follows the processing after the first revolution in Figure 3. It should be noted that the shape correction is carried out with spatially and temporally separated pulses. There is no direct superposition of the pulses on the surfaces to be corrected within one revolution. The superposition of the pulses or the material areas removed by the pulses only occurs in a subsequent revolution of the component.The surface of the component shown in Figure 4 with the regions 22 of the component removed by the individual pulses P2 from the second cycle U2 has a spacing dU between the individual pulses P2, through which the regions 22 removed during the second cycle U2 overlap the regions 21 removed by the individual pulses P1 from the first cycle U1, thus completing the surface correction along the machining radius r1. The correction process then continues at the machining radius r2 (15). In this schematically illustrated example, the correction of the surfaces on one radius is completed in two cycles. The number of cycles can be variably expanded to improve the controllability and precision of the heat-induced process. The method allows for multiple repetitions, whereby each individual pulse can be set, omitted, or varied in its parameters based on the excess material to be removed.For the definition of the distance d. U A schematic representation of the temperature field distribution between two pulses within one revolution on any machining radius r is shown in Figure 5. Based on simulations with validated process parameter combinations, the pulse spacing d U with ½ * focus diameter (defined according to 1 / e²), preferably at least 1 * focus diameter. Figure 5 schematically shows the temperature distribution in the form of temperature fields after coupling the laser radiation into the surface of the component over time t. The distance d Ubetween a subsequent and a previous pulse is defined as ½ * focus diameter (defined by 1 / e²), preferably at least 1 * focus diameter. The ablated regions 21 of the individual pulses are spatially and temporally offset and are smaller than the beam diameter. Immediately after the coupling of a pulse at time t = 0 s, the surface of the component heats up and reaches a temperature in region 21 over time t, which leads to the ablation of the glass material. Due to the material ablation from the glass surface in the order of a few nanometers, the coupled heat is distributed in the glass and forms a temperature field at a time t1 (31), which follows t = 0 s. Depending on the selected process parameters, in particular the repetition rate of the modulated laser radiation f rep , at time t2 a subsequent pulse is sent at a distance d Ucoupled into the glass surface with the preceding pulse. The temperature field 31 expands during the continuous time until time t2(32). At the same time, a new temperature field of the subsequent pulse forms after time t2(33). The temperature field of the second pulse grows after time t2(33) to the temperature field of the second pulse after time t3(34). In a very advantageous embodiment, the active laser medium is permanently excited and is in a state of thermal equilibrium. Only through rapid control (e.g., using an acousto-optical modulator; AOM) are pulses with a defined amplitude and pulse duration coupled out and transferred to the workpiece. The fluctuation of the laser power, calculated as a standard deviation, should be < 0.5%, preferably even < 0.2%. Typical laser powers used are in the range from 1 W to 100 W, with the preferred range being greater than 80 W for high repetition rates of 100 kHz.Further process parameters and their typical values ​​are: ^The pulse spacing dU depends on the repetition rate and the rotational speed 11. The pulses only need to be applied to the surface at locations where material is to be removed. ^The number of passes depends primarily on the surface quality to be corrected. Processing with at least two passes is preferred. ^The pulse duration is set between 1 µs < tp < 100 µs. ^Repetition rate is set between 0.1 kHz < frep < 200 kHz. Instead of constantly selecting process parameters for the respective component surface, individual process parameters can also be adjusted during the process. For example, the pulse duration can be changed during the process, and the ablation depth can be increased or decreased locally. In addition to changing the pulse duration, the ablation depth can also be changed via the average laser power per pulse.Another example is adjusting the number of passes. The surface is measured after a certain number of passes, and the target shape is corrected again based on the existing actual shape. This can be done in several iterative steps. In addition to the problems already described, the process makes it possible to solve another problem. In contrast to long-wave surface structures, surface structures with short spatial wavelengths (λ < 100 µm) are referred to as roughness and can be reduced to well below 1 nm by (pitch) polishing before or after the shape correction. Previously economical shape corrections for optics were limited to spatial wavelengths up to λ > 3000 µm. In total, there remains a gap in the spatial wavelength range of approximately 100 µm < λ < 3000 µm between polishing and shape correction.Surface defects in this spatial wavelength range are called mid-spatial frequency errors (MSFE) and pose major challenges to the optics industry, as they can have a severely negative impact on the optical performance of precision optics. However, optics manufacturers lack a manufacturing process for specifically eliminating MSFE. This gap can be closed by laser-based shape correction according to the method proposed here. This allows large and complex lens geometries, such as aspheres and freeform optics, to be manufactured energy-efficiently and made cost-effectively available to the mass market. Reference symbols: 1 Optical component 2 Rotation on a submerged arc lathe 3 Laser optics 4 Modulated orPulsed laser radiation 5 Actual shape 6 Target shape 7 Excess material 8 Feed directions 11 Circumferential speed Vcircumference 12 Distance du between the following pulse and the previous pulse 13 Radius of the optical element Roptic from the center point M 14 Machining radius r1 from the center point M 15 Machining radius r2 from the center point M with r1. r2 21 Ablated area of ​​a single pulse P1 during the first cycle U122 Ablated area of ​​a single pulse P2 during the second cycle U231 Temperature field of pulse 1 after a time t1; TField1(P1, t1)32 Temperature field of pulse 1 after a time t2; TField2(P1, t2)33 Temperature field of pulse 2 after a time t2; TField1(P2, t2)34 Temperature field of pulse 2 after a time t3; TField2(P2, t3)

Claims

Patent claims 1. Method for the shape correction of an optical component (1) with pulsed laser radiation, in which the component (1) is measured to obtain an actual geometry (5) of the component (1), and excess material (7) is determined by comparison with a predetermined target geometry (6) and is at least partially removed by processing with at least one pulsed laser beam (4) in order to at least approximate the actual geometry (5) to the target geometry (6), characterized in that the processing is carried out with pulse durations of the laser beam (4) of > 1 s and the component (1) is rotated about a rotational axis running through the component (1) during processing with the laser beam (4), wherein a distance of the laser beam (4) from the rotational axis is changed at least temporarily, and a rotational speed, a beam diameter of the laser beam (4) on the component (1), and a temporal pulse interval of the laser beam (4) are selected such thatthat material regions of the component (1) removed by successive pulses of the laser beam (4) do not overlap.

2. Method according to claim 1, characterized in that the machining is carried out with an ultra-precision lathe having a repeatability of < 200 nm, preferably < 50 nm.

3. Method according to claim 1 or 2, characterized in that the laser beam (4) is focused on the component (1) and a focus of the laser beam (4) on the component (1) is suitably adjusted during machining using an adjusting device.

4. Method according to one of claims 1 to 3, characterized in that the laser beam (4) is guided during machining such that machining takes place on circular or spiral paths on the component (1).

5. Method according to claim 4, characterized in that each circular or spiral path is swept over several times by the laser beam (4) for machining.

6. Method according to one of claims 1 to 5,characterized in that the rotational speed, the beam diameter of the laser beam (4) on the component (1) and the current pulse spacing of the laser beam (4) are selected such that successive pulses of the laser beam impinging on the component (1) have a center-to-center spacing on the component (1) which is greater than half 1 / e, 2 -Beam diameter of the laser beam (4) on the component (1) is preferably greater than the whole 1 / e 2 -Beam diameter.

7. Method according to one of claims 1 to 6, characterized in that parameters of the laser beam (4) are selected such that the material area of ​​the component (1) removed by a pulse of the laser beam (4) has a smaller diameter than half 1 / e 2-Beam diameter of the laser beam (4) on the component (1).

8. Method according to one of claims 1 to 7, characterized in that the processing of further outlying regions of the component (1) is carried out by adapting the rotational speed to the processing radius at a constant path speed and the processing of further inwardly lying regions is carried out by adapting the temporal pulse spacing to the processing radius at a constant rotational speed.

9. Method according to one of claims 1 to 8, characterized in that the pulsed laser beam (4) is generated by modulating a continuous laser beam with an acousto-optical modulator, wherein the temporal pulse spacing and / or pulse duration and / or pulse amplitude are varied for the processing via a control of the acousto-optical modulator.10.Method according to one of claims 1 to 9, characterized in that parameters of the laser beam (4) are selected such that both material is removed and underlying material is heated to a temperature above the softening temperature and smoothed under the influence of surface tension, thus increasing the roughness of the component (1), measured in Sa, over an area of ​​100 x 100 µm² by a maximum of 5 nm.

11. Method according to one of claims 1 to 10, characterized in that a pulse frequency of the laser beam (4) is selected in the range of 1 - 100 kHz, preferably in the range 10 - 100 kHz.

12. Method according to one of claims 1 to 11, characterized in that the pulse duration of the pulses of the laser beam (4) is selected in the range between 1 and 50 s.

13. Method according to one of claims 1 to 12, characterized in that after processing with the laser beam (4), the component (1) is tempered.14.Method according to one of claims 1 to 13, characterized in that the component (1) is subjected to mechanical polishing after processing with the laser beam (4) in order to further reduce roughness for spatial wavelengths^0 < 100 µm.15.Device for carrying out the method according to one of claims 1 to 14, which comprises an ultra-precision lathe, a laser arrangement for generating a pulsed laser beam (4) with pulse durations of > 1 s, a measuring device for measuring an actual shape (5) of a component (1) clamped in the ultra-precision lathe, and a control device, wherein the laser arrangement is arranged such that the component (1) clamped in the ultra-precision lathe can be machined with the pulsed laser beam (4), and has adjusting devices for varying a focus position of the laser beam (4) in the beam direction and for displacing the laser beam (4) in the radial direction to the rotation axis of the ultra-precision lathe, and wherein the control device is designed to control the ultra-precision lathe, the adjusting devices, and the laser arrangement for carrying out the proposed method.16.Device according to claim 15, characterized in that the laser arrangement comprises a laser beam source for generating continuous laser radiation and an acousto-optical modulator for generating the pulsed laser beam (4) from the continuous laser radiation.

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