Optical device, optical system and sample

Abstract

Optical device (1) for processing a sample (2) by means of interfering laser beams (3), with a beam splitter (8) and an optical interference unit (11), wherein the beam splitter (8) is arranged such that a laser beam (7) incident on the optical device (1) can be split into at least two partial beams (9) in an interference axis (4) perpendicular to the optical axis, wherein the interference unit (11) is arranged such that the partial beams (9) can be deflected towards each other in such a way that the partial beams (9) interfere with each other in an interference region (14) so ​​that the sample (2) can be processed in the interference region (14), characterized in that the beam splitter (8) is associated with a rotation unit (19) which is rotatable about the optical axis.

Description

[0001] The invention relates to an optical device for processing a sample using interfering laser beams, an optical system comprising a laser and the optical device, and a sample.

[0002] Optical devices for processing a sample using interfering laser beams are known from the prior art (DE 10 2020 204 656 A1), comprising a beam splitter and an optical interference unit, wherein the beam splitter is arranged such that a laser beam incident on the optical device can be split into at least two partial beams in an interference axis perpendicular to the optical axis, wherein the interference unit is arranged such that the partial beams can be deflected towards each other in such a way that the partial beams interfere with each other in an interference region, so that the sample can be processed in the interference region.

[0003] The known devices have the disadvantage that the interference pattern and the interfering partial beams are always fixed in their rotational orientations relative to the sample. If an application requires the interference pattern to be rotated relative to the sample, this could previously only be achieved by rotating the sample relative to the interfering partial beams. However, this is complex and inaccurate, especially with comparatively large or heavy samples.

[0004] It is therefore the object of the invention to avoid the aforementioned disadvantages and in particular to increase the application range of the optical device and / or to produce more complex sample geometries.

[0005] The problem is solved with an optical device according to claim 1. The problem is also solved with an optical system according to claim 24 and with a sample according to claim 25.

[0006] The invention is based on the fundamental insight that the beam splitter causes the laser beam incident on the optical device to be divided along the interference axis. Since the beam splitter is rotatable around the optical axis as a component of the rotating unit, a simple yet precise rotation of the interference pattern is possible, thus expanding the range of applications for the optical device. For example, the optical device according to the invention can be used to generate complex periodic patterns on the sample, such as periodically distributed columns, which can be obtained by multiple irradiations of the sample surface with different orientations of the interference pattern relative to the sample.The rotating unit of the optical device according to the invention enables samples with complex three-dimensional topography to be processed interferometrically, i.e., by means of laser interference, to generate, for example, homogeneous periodic structures. The rotating unit ensures that the interference pattern always remains correctly oriented relative to the sample surface. In addition to the beam splitter, the rotating unit can also include other optical components. The beam splitter can be configured as a diffractive optical element, for example, as a grating, or as a prism. In a further embodiment of the invention, the beam splitter can be configured to split the laser beam only along the interference axis. In another embodiment of the invention, the beam splitter can be configured to split the laser beam along both the interference axis and the focusing axis.

[0007] Preferably, the optical device comprises an optical beam shaping unit arranged such that the laser beam, in particular its partial beams, can be focused in a focusing axis arranged perpendicular to both the interference axis and the optical axis. According to the invention, the interference plane is defined by the interference axis and the optical axis, and the focusing plane by the focusing axis and the optical axis. The beam shaping unit can, for example, include a spherical lens that focuses the partial beams in the focusing axis in order to influence the beam profile of the interfering partial beams in the interference region. In this form, the spherical lens can be both a component of the interference unit and a component of the beam shaping unit.According to the invention, the beam shaping unit can include a diverging lens to reduce the fluence of the emerging partial beams, which denotes their spatial energy density. This prevents damage to optical components and unwanted plasma generation in the air due to excessive fluence. The beam shaping unit can have multiple lenses, with each partial beam being assigned its own lens. The beam shaping unit can include at least one cylindrical lens, the axis of which can be aligned parallel to the interference axis or parallel to the focusing axis.

[0008] Preferably, the interference unit comprises at least two, and in particular exactly two, spherical converging lenses. The two converging lenses can be arranged at a distance from each other corresponding to the sum of their focal lengths. In particular, the two spherical converging lenses can form a 4f imaging system. The converging lens, and in particular all converging lenses, of the interference unit can each be designed as a plano-convex lens. At least two converging lenses of the interference unit can have identical focal lengths. In a further embodiment of the invention, the focal lengths of two lenses of the interference unit can differ from each other. A lens of the beam shaping unit can be arranged upstream of the lens of the interference unit facing the beam splitter or downstream of it.

[0009] Preferably, at least one converging lens of the interference unit is not rotatable relative to the beam splitter. In a further development of the invention, it can be provided that the converging lenses of the interference unit, and in particular the interference unit itself, are not rotatable relative to the beam splitter. A further development of the invention can provide that only the beam splitter is rotatable around the optical axis as a rotating unit, which is mechanically relatively easy to implement.

[0010] Preferably, the interference unit comprises a convex cylindrical lens and a spherical converging lens, wherein the cylindrical axis of the cylindrical lens is arranged perpendicular to the interference axis, and wherein, in particular, the cylindrical lens and the spherical converging lens are arranged at a distance from each other corresponding to the sum of the focal lengths of the spherical converging lens and the cylindrical lens along the interference axis. Due to the orientation of the cylindrical lens with its cylindrical axis perpendicular to the interference axis, the deflection of the partial rays incident on the cylindrical lens occurs only along the interference axis, while no significant deflection of the partial rays incident on the cylindrical lens occurs along the focusing axis, which is arranged perpendicular to both the interference axis and the optical axis.

[0011] Preferably, the cylindrical lens is arranged upstream of the spherical converging lens and is designed as a component of the rotating unit, so that the cylindrical lens can be rotated synchronously with the beam splitter. In a further development of the invention, the spherical converging lens can be provided that it is not a component of the rotating unit and therefore cannot be rotated relative to the beam splitter.

[0012] Preferably, the cylindrical lens is arranged downstream of the spherical converging lens, wherein the spherical converging lens and the cylindrical lens are designed as components of the rotating unit, so that the cylindrical lens and the spherical converging lens can each be rotated synchronously with the beam splitter. In a further development of the invention, it can be provided that all optical components between the beam splitter and the cylindrical lens are designed as components of the rotating unit, so that they can each be rotated synchronously with the beam splitter.

[0013] Alternatively, the cylindrical lens, but not the spherical converging lens, can be designed as a component of the rotation unit and be rotatable synchronously with the beam splitter.

[0014] Preferably, the lens of the interference unit facing away from the beam splitter is movable along the optical axis. This can be a cylindrical lens, the movement of which allows the shape of the partial beams in the interference region to be changed.

[0015] Preferably, the interference unit comprises two, in particular convex, cylindrical lenses whose cylinder axes are each arranged perpendicular to the interference axis, wherein it is particularly provided that the cylindrical lenses are arranged at a distance from each other that corresponds to the sum of the focal lengths of the cylindrical lenses along the interference axis. Alternatively or additionally, it can be provided that the cylindrical lenses are designed as components of the rotation unit, so that the cylindrical lenses can each be rotated synchronously with the beam splitter.

[0016] Preferably, the optical device comprises a lens unit with at least one diverging lens to keep the fluence of the partial beams, which corresponds to their spatial energy density according to the invention, comparatively low within the optical device. This prevents damage or plasma formation in the air. The diverging lens can be designed as a plano-convex lens and / or as a plano-concave and / or as a spherical lens. The lens unit can be designed as a component of the rotating unit and therefore be rotatable about the optical axis synchronously with the beam splitter. Particularly in combination with an interference unit with two spherical converging lenses, a structurally simple design results. In a further development of the invention, the diverging lens of the lens unit can be designed as a cylindrical lens, in particular as a plano-concave diverging lens.

[0017] Preferably, the at least one diverging lens of the lens unit is arranged upstream of the lens of the interference unit facing the beam splitter. Alternatively or additionally, the at least one diverging lens of the lens unit can be designed as a cylindrical lens, the axis of which can be arranged perpendicular or parallel to the interference axis. The lens unit can be arranged adjacent to, and in particular directly adjacent to, the lens of the interference unit facing the beam splitter.

[0018] Preferably, the lens unit comprises several diverging lenses, wherein it is particularly provided that each partial beam is assigned one, and in particular exactly one, diverging lens. The number of diverging lenses in the lens unit can correspond to the number of partial beams. This allows the unused lens surface to be reduced.

[0019] Preferably, the lens unit is designed as a component of the rotation unit, such that the lens unit can be rotated synchronously with the beam splitter. The lens of the interference unit facing the beam splitter cannot be rotated synchronously with the beam splitter.

[0020] Preferably, the lens unit is arranged downstream of the lens of the interference unit facing the beam splitter, wherein the lens of the interference unit facing the beam splitter and the lens unit are designed as components of the rotation unit, so that the lens of the interference unit facing the beam splitter and the lens unit can each be rotated synchronously with the beam splitter.

[0021] Preferably, at least one lens of the lens unit is designed as a spherical lens; in particular, all lenses of the lens unit are each designed as a spherical lens.

[0022] The laser of the optical system can be a solid-state, gas, or dye laser. The laser can have a fiber-shaped, disk-shaped, or rod-shaped active medium. The laser beam can be pulsed, particularly with pulse durations of 1 fs to 1 µs. The wavelength of the laser beam can be between 200 nm and 2 µm. In a further development of the invention, particularly when the laser is an excimer or CO2 laser, the wavelength can be between 100 nm and 10 µm. The power of the laser beam can be between 1 W and 100 kW.

[0023] The optical device according to the invention, in particular the optical system according to the invention, can be used to process a sample by ablation of the sample and / or by remelting the sample and / or by photochemical processing of the sample.

[0024] For the purposes of the invention, "probe" can refer to a physical body, in particular a workpiece, a component, a part of a component, a product or a surface.

[0025] In a further development of the invention, it can be provided that at least one optical component of the optical device, having an optical effect on the partial beams in the interference axis, and in particular exclusively in the interference axis, is designed as a component of the rotation unit, so that it can be rotated synchronously with the beam splitter. Furthermore, it can be provided that at least two optical components of the optical device, having an optical effect on the partial beams in the interference axis, and in particular exclusively in the interference axis, are designed as components of the rotation unit, so that they can be rotated synchronously with the beam splitter.In particular, all components of the optical device that have an optical effect on the partial beams in the interference axis, and especially exclusively in the interference axis, are designed as components of the rotation unit, so that they can be rotated synchronously with the beam splitter. In a further development of the invention, it can be provided that at least one lens of the beam shaping unit, which thus achieves an optical effect in the focusing axis, is designed as a component of the rotation unit.

[0026] The rotation of the rotating unit around the optical axis can be continuous or discrete, particularly via a user-defined angular increment, which can be, for example, 45° or 90°. The rotation of the rotating unit can be relative to the sample and / or the laser. In a further embodiment of the invention, the rotating unit can be freely rotatable at any angle, i.e., in particular, rotatable through 360°. The resolution of the rotation of the rotating unit can be in the arcsecond range.

[0027] The interference unit can comprise at least one lens, particularly for performing optical corrections, for example, to correct aberrations. Each lens can thus be configured as a lens system. The interference unit can also include optical magnification systems to keep the spatial energy density within the optical device sufficiently low, at least in certain areas, to prevent damage to the components of the optical devices or plasma generation in the air, since both effects are detrimental to sample processing. In a further embodiment of the invention, the interference unit can be configured such that the partial beams reaching the interference region have an angle of 0.05° to 85° relative to the optical axis, particularly between 60° and 70° or between 1° and 70°, preferably between 1° and 35°, and more preferably between 1° and 20°.

[0028] Preferably, the beam splitter of the optical device is designed such that the laser beam can be divided into at least three partial beams along the interference axis. In this case, the interference unit can comprise two spherical lenses, one spherical and one cylindrical lens, or two cylindrical lenses. Each partial beam can be assigned a cylindrical lens, the axis of which can be arranged perpendicular to or within the interference axis. The cylindrical lens can be arranged upstream or downstream of the first lens of the interference unit. In a further embodiment of the invention, the laser beam can be divided into four, five, or six partial beams along the interference axis.In a further development of the invention, the beam splitter of the optical device may be designed such that the laser beam can be divided into at least three partial beams along an axis that is different from the interference axis, in particular perpendicular to it. Preferably, the beam splitter of the optical device is designed such that the laser beam can be divided into at least four partial beams.

[0029] A further aspect of the invention relates to an optical device for processing a sample using interfering laser beams, comprising a beam splitter and an optical interference unit, wherein the beam splitter is arranged such that a laser beam incident on the optical device can be split into at least two partial beams in an interference axis perpendicular to the optical axis, wherein the interference unit is arranged such that the partial beams can be deflected relative to each other in such a way that the partial beams interfere with each other in an interference region, so that the sample can be processed in the interference region, wherein the interference unit has a first lens facing the beam splitter and a second lens facing away from the beam splitter, wherein the partial beams are collimated in at least one axis downstream of the first lens and upstream of the second lens, in particular immediately in front of the second lens.in which the second lens exerts an optical effect on the partial beams. This results in an optimized space requirement for the optical device according to the invention. By collimating the partial beams on the axis in which the second lens exerts an optical effect on the partial beams, the arrangement, in particular of the second lens of the optical device, is no longer necessarily determined by the divergence of the partial beams. Another aspect is that the power density of the partial beams in front of the second lens is constant due to its collimation.

[0030] The partial beams can be collimated in the entire region between the first lens and the second lens. For the purposes of the invention, a beam is collimated if it exhibits no or only negligible divergence along its direction of propagation. Thus, if a beam is collimated in one axis, it exhibits no or only negligible divergence along that axis in its direction of propagation. Therefore, if a beam is collimated in one axis, it also exhibits no divergence in the plane defined by that axis and the optical axis.

[0031] In a further development of the invention, it can be provided that the collimated partial beams are aligned parallel to the optical axis, which is also referred to as coaxial in the sense of the invention.

[0032] Preferably, the collimated partial beams are collimated in a focusing axis arranged perpendicular to the interference axis, in particular only in the focusing axis.

[0033] Preferably, the collimated partial beams are collimated in the interference axis, in particular only in the interference axis.

[0034] Preferably, the first lens is a cylindrical lens, wherein it is particularly provided that the cylinder axis of the first lens is aligned parallel to the interference axis. In a further development of the invention, it can be provided that the cylinder axis of the first lens is aligned perpendicular to the interference axis, and thus particularly parallel to the focusing axis.

[0035] Preferably, the first lens is a spherical lens, and a diverging lens is associated with the first lens, arranged either downstream or upstream of the first lens. This allows the diameter of the partial beams to be varied, particularly by adjusting the position of the diverging lens, and optimized for the specific application. If the diverging lens is modified to increase the diameter of the partial beams, smaller focal points with a correspondingly increased spatial power density can be obtained. The focal length of the first, particularly spherical, lens can be assigned to the focal length of the diverging lens and, in particular, selected in a predefined ratio to it to optimize the focusing of the partial beams.The ratio of the focal length of the first, in particular spherical, lens to the focal length of the diverging lens can correspond to the distance between the first, in particular spherical, lens and the diverging lens.

[0036] Preferably, each partial beam is assigned a diverging lens.

[0037] According to the invention, each lens can comprise a lens system with further auxiliary lenses to minimize imaging errors.

[0038] Preferably, the diverging lens is designed as a cylindrical lens whose cylinder axis is aligned parallel to the interference axis or perpendicular to the interference axis, and thus parallel to the focusing axis. The optical effect of the cylindrical lens can be selectively assigned to either the interference axis or the focusing axis.

[0039] Preferably, the diverging lens is designed as a spherical lens, which is arranged upstream or downstream of the first lens in order to achieve an optical effect in both the interference axis and the focusing axis.

[0040] For a similar reason, the second lens can be designed as a spherical lens.

[0041] Further advantages and features of the invention will become apparent from the claims and the following description, in which exemplary embodiments of the invention are explained in detail with reference to the drawings. These show: Fig. 1 an embodiment of the optical device according to the invention in the xz-plane, Fig. 2 the optical device according to Fig. 1 in the yz plane, Fig. 3 a schematic representation of the interference pattern of the optical device according to Fig. 1 in the xy-plane, Fig. 4 a further embodiment of the optical device according to the invention in the xz-plane, Fig. 5 the optical device according to Fig. 4 in the yz plane, Fig. 6 a schematic representation of the interference pattern of the optical device according to Fig. 4 in the xy-plane, Fig. 7 a further embodiment of the optical device according to the invention in the xz-plane, Fig. 8 the optical device according to Fig. 7 in the yz plane, Fig. 9 a schematic representation of the interference pattern of the optical device according to Fig. 7 in the xy-plane, Fig. 10 a further embodiment of the optical device according to the invention in the xz-plane, Fig. 11 the optical device according to Fig. 10 in the yz plane, Fig. 12 a schematic representation of the interference pattern of the optical device according to Fig. 10 in the xy-plane, Fig. 13 a further embodiment of the optical device according to the invention in the xz-plane, Fig. 14 the optical device according to Fig. 13 in the yz plane, Fig. 15 a schematic representation of the interference pattern of the optical device according to Fig. 13 in the xy-plane, Fig. 16 a further embodiment of the optical device according to the invention in the xz-plane, Fig. 17 the optical device according to Fig. 16 in the yz plane, Fig. 18 a schematic representation of the interference pattern of the optical device according to Fig. 16 in the xy-plane, Fig. 19 a further embodiment of the optical device according to the invention in the xz-plane, Fig. 20 the optical device according to Fig. 19 in the yz plane, Fig. 21 a schematic representation of the interference pattern of the optical device according to Fig. 19 in the xy-plane, Fig. 22 a further embodiment of the optical device according to the invention in the xz-plane, Fig. 23 the optical device according to Fig. 22 in the yz plane, Fig. 24 a schematic representation of the interference pattern of the optical device according to Fig. 22 in the xy-plane, Fig. 25 a further embodiment of the optical device according to the invention in the xz-plane, Fig. 26 the optical device according to Fig. 25 in the yz plane, Fig. 27 a schematic representation of the interference pattern of the optical device according to Fig. 25 in the xy-plane, Fig. 28 a further embodiment of the optical device according to the invention in the xz-plane, Fig. 29 the optical device according to Fig. 28 in the yz plane, Fig. 30 a schematic representation of the interference pattern of the optical device according to Fig. 28 in the xy-plane, Fig. 31 a further embodiment of the optical device according to the invention in the xz-plane, Fig. 32 the optical device according to Fig. 31 in the yz plane, Fig. 33 a schematic representation of the interference pattern of the optical device according to Fig. 33 in the xy-plane, Fig. 34 a further embodiment of the optical device according to the invention in the xz-plane, Fig. 35 the optical device according to Fig. 34 in the yz plane, Fig. 36 a schematic representation of the interference pattern of the optical device according to Fig. 34 in the xy-plane, Fig. 37 a further embodiment of the optical device according to the invention in the xz-plane, Fig. 38 the optical device according to Fig. 37 in the yz plane, Fig. 39 a schematic representation of the interference pattern of the optical device according to Fig. 37 in the xy-plane, Fig. 40 a further embodiment of the optical device according to the invention in the xz-plane, Fig. 41 the optical device according to Fig. 40 in the yz plane, Fig. 42 a schematic representation of the interference pattern of the optical device according to Fig. 40 in the xy-plane, Fig. 43 an optical system according to the invention in the xz-plane, Fig. 44 the optical system according to Fig. 43 in the yz plane, Fig. 45 a schematic representation of the interference pattern of the optical system according to Fig. 43 in the xy-plane, Fig. 46 a further embodiment of the optical device according to the invention with four partial beams in the xz-plane, Fig. 47 the optical device according to Fig. 46 in the yz plane, Fig. 48 a further embodiment of the optical device according to the invention with four partial beams in the xz-plane, Fig. 49 the optical device according to Fig. 48 in the yz plane, Fig. 50 a further embodiment of the optical device according to the invention with four partial beams in the xz-plane and Fig. 51 the optical device according to Fig. 50 in the yz plane.

[0042] Fig. Figure 1 shows an optical device 1 for processing a Fig. 1. Sample 2, shown in dashed lines, is focused by means of interfering laser beams 3 in the xz-plane, to which the interference axis 4 is arranged perpendicularly according to the invention. In this respect, the interference axis 4 corresponds to the y-axis in the present embodiment. The xz-plane contains the focusing axis 5, arranged perpendicular to the interference axis 4 according to the invention. Fig. Figure 2 shows the optical device 1 in the yz plane.

[0043] One from a in Fig. The collimated laser beam 7 emerging from laser 6 (not shown) strikes a beam splitter 8, which divides the laser beam 7 into two partial beams 9 and which may be configured as a grating. The division occurs only along the interference axis 4 and is therefore only visible in Fig. 2, but not in Fig. Figure 1 shows that the partial beams 9 still leave the beam splitter 8 collimated, but each exhibits a finite angle with respect to the optical axis. The partial beams 9 strike a first plano-convex, spherical converging lens 10 of an interference unit 11, which faces the beam splitter 8. This causes the partial beams 9 to be focused both in the Fig. 2 shown interference axis 4 as well as in the in Fig. The partial beams 9 are focused on the focusing axis 5 shown in Figure 1. Each partial beam passes through a beam waist 12 with a minimum diameter and then diverges to a second plano-convex, spherical converging lens 13, located away from the beam splitter, which serves as the second lens of the interference unit 11. The focal lengths of the converging lenses 10 and 13 of the interference unit 11 are identical, and the distance between them is equal to the sum of their focal lengths. Therefore, the converging lenses 10 and 13 form a 4f imaging system. After exiting the second converging lens 13, the partial beams 9 are collimated in the xz-plane, and their beam diameters correspond to their diameters before striking the first converging lens 10 of the interference unit 11.In the yz-plane, the partial beams 9 are each collimated, but exhibit a finite angle with respect to the optical axis, which corresponds to the inverse angle of the partial beams 9 before they strike the first converging lens 10 of the interference unit 11. As a result, the partial beams 9 interfere in an interference region 14 on the surface 15 of the sample 2. In the interference region 14, the... Fig. The interference pattern 16 shown in Figure 3 is formed in the xy-plane. This is an approximately circular region with linear structural elements 17 that are aligned parallel to the y-axis and thus parallel to the interference axis 4. The linear structural elements 17 are formed onto the surface 15 of the sample 2 by ablation when the interfering partial beams 9 have a sufficiently high fluence.

[0044] Due to the optical effect of the lenses 10, 13 of the interference unit 11 on the partial beams 9 also in the focusing axis 5, the two lenses 10, 13 can also be considered as components of an optical beam shaping unit 18 in the sense of the invention.

[0045] To rotate the interference pattern 16 relative to the surface 15 of the sample 2, the beam splitter 8 is rotatable about the optical axis and is designed as a component of a rotation unit 19, which in the exemplary embodiment of the Fig. 1 and Fig. 2 is each shown as a dashed rectangle. By rotating the beam splitter 8, the position of the interference axis 4 can be changed so that it no longer corresponds to the y-axis. Fig. 2 corresponds. The spherical converging lenses 10, 13 of the interference unit 11 are not rotatable around the optical axis, which can also be seen from the fact that they are not encompassed by the dashed rectangle of the rotation unit 19.

[0046] In the exemplary embodiment of the Fig. In figures 4 to 6, starting from the previous embodiment, the first lens 10 of the interference unit 11, facing the beam splitter 8, has been replaced by a cylindrical lens 10 whose cylindrical axis is aligned parallel to the x-axis and thus perpendicular to the interference axis 4. The cylindrical lens 10 therefore affects the beam path in the Fig. The xz-plane shown in Figure 4 has no effect; the collimated partial beams 9 are focused onto the interference region 14 by the second, spherical lens 13 of the interference unit 11. The second lens 13 of the interference unit 11 is thus a component of the beam shaping unit 18, while the first lens 10 of the interference unit 11 is not. In the Fig. The ray path shown in Figure 5 of the yz-plane essentially corresponds to the ray path of the Fig. 2, since the curvature of the cylindrical lens 10 in this plane corresponds to the curvature of the spherical first lens 10 of the interference unit 11. In contrast to the embodiment of the Fig. 1 to 3 is in the exemplary embodiment of the Fig. 4 to 6, the first cylindrical lens 10 of the interference unit 11 is designed as a component of the rotation unit 19 in addition to the beam splitter 8, as illustrated by the dashed rectangle. The cylindrical lens 10, as the first lens of the interference unit 11, is thus rotatable about the optical axis synchronously with the beam splitter 8. The in Fig. The interference pattern 16 shown in the interference region 14 is elliptical and exhibits linear structural elements 17 pointing along the x-axis. For the sake of clarity, the interference pattern 16 shown does not represent the absolute values ​​for the extents in the x- and y-axes, but primarily serves to illustrate the ratio of the extents in the x- and y-axes. In this respect, the interference pattern 16 is shown according to Fig. 6 in the x-axis is not necessarily larger than the interference pattern 16 according to Fig. 3; it simply has a smaller extent relative to the y-axis.

[0047] In the exemplary embodiment of the Fig. 7 to 9 are based on the exemplary embodiment of the Fig. 1 to 3 a cylindrical diverging lens 20 is provided as a component of a lens unit 21, which is additionally formed alongside the interference unit 11 and the beam shaping unit 18. The diverging lens 20 of the lens unit 21 is arranged upstream of the lens 10 of the lens unit 11 facing the beam splitter 8. The cylindrical axis of the diverging lens 20 is arranged parallel to the y-axis, so that the optical diverging effect on the partial beams 9 exiting after the beam splitter 8 takes place in the focusing axis 5 and in the xz-plane of the Fig. Figure 7 shows that the partial beams 9, which diverge after the diverging lens 20 of the lens unit 21, pass through the two spherical lenses 10, 13 of the interference unit 11 such that the partial beams 9 are collimated after the first lens 10 of the interference unit 11 and are focused after the second lens 13 of the interference unit 11 in the xz-plane in the direction of the interference region 14. The diverging lens 20 of the lens unit 21 serves to ensure that, compared to the previous embodiments, a larger area of ​​the lenses 10, 13 of the interference unit 11 can be used in the xz-plane. Furthermore, the diverging lens 20 reduces the fluence of the partial beams 9, i.e., their spatial energy density, particularly in the region of the interference unit 11. The cylindrical lens 20 has in the Fig. The yz-plane shown in Figure 8 has no effect on the partial beams 9 passing through it. The diverging lens 20 of the lens unit 21 is formed with the beam splitter 8 as a component of the rotation unit 19 and is therefore rotatable with it about the optical axis. The lenses 10, 13 of the interference unit 11, on the other hand, are not formed as components of the rotation unit 19. The interference pattern 16 according to Fig. 9 resembles the interference pattern 16 in its shape according to Fig. 6.

[0048] Starting from the previous embodiment, the lens unit 11 has, according to the Fig. 10 to 12 two cylindrical diverging lenses 20, 22, arranged at the same height along the optical axis. Each diverging lens 20, 22 is assigned to a partial beam 9, such that in Fig. 10 only the first diverging lens 20 is visible, since the second diverging lens 22 is perspectively obscured by it. In Fig. Figure 11 shows that the lengths of the diverging lenses 20, 22 of the lens unit 21 in the y-axis are each and also in sum smaller than the length of the single lens 20 of the lens unit 21. Fig. 8. The diverging lenses 20, 22 are designed as components of the rotating unit 19 and are therefore rotatable about the optical axis synchronously with the beam splitter 8. The interference pattern 16 according to Fig. 12 resembles the interference pattern 16 in its shape according to Fig. 9.

[0049] Starting from the previous embodiment, in the embodiment of the Fig. 13 to 15 the two cylindrical diverging lenses 20, 22 of the lens unit 21 are each rotated by 90° around their respective radial centers. In the focusing axis 5, which is in the xz-plane according to Fig. As shown in Figure 13, the diverging lenses 20 and 22 therefore have no optical effect on the partial rays 9. In this respect, the beam path is similar to that of Fig. 13 the beam path of the Fig. 1. In the Fig. In the yz-plane shown in Figure 14, the two diverging lenses 20, 22 of lens unit 20 each cause a divergence of the partial rays 9 passing through them, which are collimated after the first lens 10 of the interference unit 11 and refracted converging and focusing towards the interference region 14 after the second lens 13 of the interference unit 11. The Fig. The interference pattern 16 shown in the interference area 14 is larger in its extent than the elliptical interference pattern 16. Fig. 12 is rotated by 90° so that its major semi-axis now points in the x-direction. The interference pattern 16 still exhibits linear structural elements 17 aligned parallel to the x-axis.

[0050] The exemplary embodiment of the Fig. 16 to 18 is based on the exemplary embodiment of the Fig. 7 to 9, wherein, in contrast, the diverging lens 20 of the lens unit 21 is arranged downstream of the first lens 10 of the interference unit 11, in particular between the lenses 10, 13 of the interference unit 11. Due to the orientation of the cylindrical diverging lens 20, an optical effect on the partial beams 9 occurs in the Fig. 16 xz-plane shown, but not in the one in Fig. The yz-plane shown in Figure 17 takes place. In the focusing axis 5, the partial beams 9, which converge after passing through the first lens 10 of the interference unit 11, are collimated after passing through the diverging lens 20 and strike the second lens 13 of the interference unit 11, whereupon they are focused in the direction of the interference region 14. In addition to the diverging lens 20 of the lens unit 21, the first lens 10 of the interference unit 11, which faces the beam splitter 8, is also designed as a component of the rotation unit 19 and is thus rotatable about the optical axis synchronously with the beam splitter 8. The second lens 13 of the interference unit 11 is not rotatable about the optical axis synchronously with the beam splitter 8. The in Fig. The interference pattern 16 shown in Figure 18 has linear structural elements 17 aligned parallel to the x-axis and is therefore similar to the interference pattern 16 according to Figure 18. Fig. 12.

[0051] The exemplary embodiment of the Fig. 19 to 21 is based on the embodiment of the Fig. 10 to 12, wherein the two cylindrical diverging lenses 20, 22 are arranged downstream of the first lens 10 of the interference unit 11. In this respect, the diverging and, in combination with lens 10, collimating effect occurs in the Fig. The focusing axis 5 shown in Figure 19 is only reached after the partial beams 9 have passed through the first lens 10 of the interference unit 11. Due to the alignment of the cylindrical lenses 20, 22, the beam path in the yz-plane essentially corresponds to the beam path according to Figure 19. Fig. 11. The rotation unit 19 includes, in addition to the beam splitter 8 and the diverging lenses 20, 22, the first lens 10 of the interference unit 11, but not its second lens 13. This in Fig. The interference pattern shown in 21 corresponds in its form to the interference pattern 16 of the Fig. 18.

[0052] Compared to the exemplary embodiment of the Fig. 19 to 21 are in the exemplary embodiment of the Fig. In sections 22 to 24, the diverging lenses 20 and 22 of the lens unit 21 are each rotated by 90° around their radial center. The two diverging lenses 20 and 22, together with the first lens 10 of the interference unit 11, are designed as components of the rotation unit 19 and can therefore be rotated synchronously with the beam splitter 8 around the optical axis. The elliptical interference pattern 16 has linear structural elements 17 arranged parallel to the x-axis.

[0053] Starting from the previous embodiment, the diverging lenses 20, 22 of the lens unit 21 in the embodiment of Fig. Lenses 25 to 27 are each designed as spherical diverging lenses. This results in an optical effect in both the Fig. 25 shown xz-plane as well as in the in Fig. The yz-plane shown in 26 takes place. In the Fig. In the focusing axis 5 shown in Figure 25, the partial beams 9 are collimated after passing through the first lens 10 of the interference unit 11 and strike the second lens 13 of the interference unit 11 in this form, from where they are focused towards the interference area 14. In the Fig. In the interference axis 4 shown in Figure 26, the partial beams 9, which converge after passing through the first lens 10 of the interference unit 11, are collimated by the two diverging lenses 20, 22 of the lens unit 21 and, in this form, strike the second lens 13 of the interference unit 11, by which they are refracted, each converging, in the direction of the interference region 14, where they interfere with each other. Since all lenses 10, 13, 20, 22 of this embodiment are designed as spherical lenses, the Fig. The interference pattern shown in Figure 27 is circular and has linear structural elements 17 aligned parallel to the y-axis.

[0054] In the exemplary embodiment of the Fig. 28 to 30 were based on the exemplary embodiment of the Fig. 1 to 3, the second lens 13 of the interference unit 11, the one facing away from the beam splitter 8, is replaced by a cylindrical lens 13 whose cylinder axis is aligned parallel to the x-axis. In this respect, it could also be said that the lenses 10, 13 of the exemplary embodiment of Fig. 4 to 6 are interchanged. However, the first spherical lens 10 of the interference unit 11, facing the beam splitter, has a longer focal length than the spherical lens 10 of the interference unit 11 according to the Fig. 4 to 6, since the partial beams travel a longer distance to the interference region 14 in the Fig. The xz-plane shown in Figure 28, which includes the focusing axis 5, is focused. Simultaneously, the first lens 10 of the interference unit 11 works together with its second lens 13 to produce interference of the partial beams 9 in the interference region 14. Both lenses 10 and 13 of the interference unit 11 are designed as components of the rotation unit 19 and are therefore each rotatable synchronously with the beam splitter 8 about the optical axis. The Fig. The interference pattern 30 shown is elliptical and has linear structural elements 17 aligned parallel to the x-axis.

[0055] The second lens 13 of the interference unit 11 is axially movable and in the exemplary embodiment of the Fig. 31 to 33 starting from the exemplary embodiment of the Fig. 28 to 30, axially in the direction of the first lens 10 of the interference unit 11. The refractive power of the second lens 13 remains unchanged. Due to the negligible optical effect of the cylindrical lens 13 as the second lens of the interference unit 11, the beam path in the xz-plane differs. Fig. 31 not significantly from the beam path according to Fig. 28. In contrast, the axial movement of the second lens 13 changed the axial height of the interference region 14 in the Fig. The interference region 14 is therefore also shifted relative to the focusing of the partial beams in the xz-plane according to the figure shown in Figure 32. Fig. 31 is axially displaced in the direction of the beam splitter 8. The movement of the second lens 13 results in a variation of the sports shape from elliptical in the y-direction to circular, as can be seen from a comparison with the embodiment of the Fig. 30 with Fig. 33 results. That in Fig. The interference pattern 16 shown in 33 is circular and has structural elements 17 aligned parallel to the x-axis.

[0056] The exemplary embodiment of the Fig. 34 to 36 is essentially based on the embodiment of the Fig. 31 to 32, in particular the positions of lenses 10, 13 have been retained. However, in contrast, the focal length of lens 10 has been significantly reduced, so that the angle of the interfering partial beams 9 is also increased. This results in a reduction of the interference period and a reduction in the extent of the beam profile in the interference region 14 in the y-axis compared to the x-axis. This creates the Fig. 36 shown, elliptical interference patterns 16 with structural elements aligned parallel to the x-axis 17.

[0057] The Fig. Figures 37 to 39 show a further optical system 1 according to the invention, in which the interference unit 11 has two cylindrical lenses 10, 13 which are aligned parallel to each other, the cylinder axes each being parallel to the x-axis and thus perpendicular to the interference axis 4. Upstream of the second cylindrical lens 13, a further cylindrical lens 20 is arranged adjacent to it, the cylinder axis of which is aligned perpendicular to those of the cylindrical lenses 10, 13, and which is associated with the lens unit 21. The laser beam 7, and thus also the partial beams 9, are in the Fig. The xz-plane shown in Figure 37 is collimated and therefore exhibits no divergence. The cylindrical lenses 10 and 13 exert an optical effect on the partial rays 9 in the yz-plane according to... Fig. 38, which encompasses the interference axis 4. The collimated partial beams 9 exiting the beam splitter 8 are refracted parallel to the optical axis by the first lens 10 of the interference unit 11 and shaped to converge. The partial beams 9 pass through a beam waist 12 at approximately the midpoint between the two lenses 10, 13 of the interference unit 11, after which they pass through the second lens 13 of the interference unit 11 and are refracted from there to the interference region 14, whereby the partial beams 9 are again collimated and aligned at a finite angle to the optical axis. Only the lens 20 has an optical effect in the focusing plane, through which the partial beams 9 are refracted in the xz-plane according to Fig. 37 are focused to the interference area 14. Both lenses 10, 13 of the interference unit 11 and the lens 20 of the lens unit 21 are designed as components of the rotation unit 19 and are therefore rotatable synchronously with the beam splitter 9 around the optical axis. The in Fig. The interference pattern 16 shown in 39 is elliptical and has structural elements 17 aligned parallel to the x-axis.

[0058] The Fig. Figures 40 to 42 show a further embodiment of the optical device 1 according to the invention, whose interference unit 11 has two cylindrical lenses 10, 13 aligned parallel to each other, the cylinder axes of which are each arranged parallel to the x-axis. This results in the partial beams 9 being directed in the xz-plane according to Fig. 40 after the beam splitter 8 up to the interference region 14 parallel to the optical axis and collimated, while the in Fig. The beam path shown in section 41 in the yz-plane is essentially the beam path according to... Fig. 2 corresponds. Here too, both lenses 10, 13 of the interference unit 11 are designed as components of the rotation unit 19 and are therefore rotatable synchronously with the beam splitter 8 around the optical axis. The in Fig. The interference pattern 16 shown in Figure 42 has linear structural elements 17 that are aligned parallel to the x-axis.

[0059] The exemplary embodiment of the Fig. Figures 43 to 45 show an optical system 23 according to the invention with a laser 6 which directs a laser beam 7 in the direction of the optical device 1 according to the invention in the embodiment of Fig. 1 to 3 emitted. The laser beam 7 is split by the beam splitter 8 into two partial beams 9 in the manner already described, which are analogous to the embodiment of the Fig. Behavior 1 to 3.

[0060] The optical device 1 according to the invention, in particular the optical system 23 according to the invention, is used to process the sample 2 by means of interfering laser radiation 3, which corresponds to the partial beams 9, in particular ablatively.

[0061] In the Fig. 46 and Fig. Figure 47 shows an optical device 1, the construction of which is essentially the same as the optical device 1 according to the Fig. 1 to 3 corresponds, whereas in contrast the beam splitter 8 for splitting the incident laser beam 7 is now designed into four partial beams 9, namely into two partial beams 9 within the in Fig. 46 shown interference plane, which corresponds to the xz-plane, and in two partial beams within the in Fig. The focusing axis shown in Figure 47 corresponds to the yz-plane. The beam path of the individual partial beams 9 is essentially similar to that shown in the Fig. The embodiment shown in Figures 1 to 3 is described in detail below, so that reference is made to the relevant explanations to avoid repetition. The rotating unit 19 comprises only the beam splitter 8.

[0062] In the design of the optical device 1 according to the Fig. 48 and Fig. 49 is, based on the design according to the Fig. 46 and Fig. 47, upstream of the first lens 10, each partial beam 9 is assigned a plano-concave cylindrical lens 20 of the lens unit 21, the cylinder axis of which is perpendicular to the axis in Fig. The interference axis shown in Figure 48 is arranged as follows. The cylindrical lenses 20 cause the partial beams 9 to widen in front of the first lens 10 in the interference plane according to Figure 48. Fig. 48 and have in the focusing plane arranged perpendicular to the interference plane according to Fig. 49 no optical effect. Therefore, the design according to the Fig. 10 and Fig. 11 is attached. The rotation unit 19 comprises only the beam splitter 8 and the cylindrical lenses 20.

[0063] The Fig. 50 and Fig. Figure 51 shows a further embodiment of the optical device 1, which is attached to the optical device 1 according to the Fig. 48 and Fig. 49 is based on the previous embodiment, in contrast to which the plano-concave cylindrical lenses 20 of the lens unit 21, each assigned to a partial beam 9, are arranged downstream of the first lens 10. Starting from the previous embodiment, the cylindrical lenses 20 are each rotated by 90° about their radial center, so that the cylinder axes are normal to the one in Fig. 51 are aligned in the focal plane shown and are therefore in the Fig. The interference plane shown in section 50 is located there. Therefore, the design will be based on the following: Fig. 22 and Fig. 23 is attached. The rotation unit 19 comprises only the beam splitter 8, the first lens 10 and the cylindrical lenses 20. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2020 204 656 A1

[0002]

Claims

[1] Optical device (1) for processing a sample (2) using interfering laser beams (3), with a beam splitter (8) and an optical interference unit (11), wherein the beam splitter (8) is arranged such that a laser beam (7) incident on the optical device (1) can be split into at least two partial beams (9) in an interference axis (4) perpendicular to the optical axis, wherein the interference unit (11) is arranged such that the partial beams (9) can be deflected towards each other in such a way that the partial beams (9) interfere with each other in an interference region (14) so ​​that the sample (2) can be processed in the interference region (14), characterized by , that the beam splitter (8) is associated with a rotation unit (19) which is rotatable about the optical axis. [2] Optical device (1) according to claim 1, characterized byan optical beam shaping unit (18) arranged such that the laser beam (3), in particular its partial beams (9), can be focused in a focusing axis (5) arranged perpendicular to the interference axis (4) and perpendicular to the optical axis. [3] Optical device (1) according to any one of the preceding claims, characterized by , that the interference unit (11) has at least two spherical converging lenses (10, 13) which can be arranged at a distance from each other corresponding to the sum of the focal lengths of the converging lenses (10, 13). [4] Optical device (1) according to claim 3, characterized by , that the converging lenses (10, 13) of the interference unit (11), in particular the interference unit (11) itself, is not rotatable, especially relative to the beam splitter (8). [5] Optical device (1) according to any one of the preceding claims, characterized by, that the interference unit (11) comprises a convex cylindrical lens (10, 13) and a spherical converging lens (10, 13), wherein the cylinder axis of the cylindrical lens (10, 13) is arranged perpendicular to the interference axis (4), wherein in particular the cylindrical lens (10, 13) and the spherical converging lens (10, 13) are arranged at a distance from each other which corresponds to the sum of the focal lengths of the spherical converging lens (10, 13) and the cylindrical lens (10, 13) in the interference axis (4). [6] Optical device (1) according to claim 5, characterized by , that the cylindrical lens (10) is arranged upstream of the spherical converging lens (13) and is designed as a component of the rotation unit (19) so that the cylindrical lens (10) can be rotated synchronously with the beam splitter (8). [7] Optical device (1) according to claim 5, characterized by, that the cylindrical lens (13) is arranged downstream of the spherical converging lens (10), wherein the spherical converging lens (10) and the cylindrical lens (13) are designed as components of the rotation unit (19), so that the cylindrical lens (13) and the spherical converging lens (10) are each rotatable synchronously with the beam splitter (8). [8] Optical device (1) according to any one of the preceding claims, characterized by , that the lens (13) of the interference unit (11) facing away from the beam splitter (8) is movable along the optical axis. [9] Optical device (1) according to any one of the preceding claims, characterized by, that the interference unit (11) has two, in particular convex, cylindrical lenses (10, 13) whose cylinder axes are each arranged perpendicular to the interference axis (4), wherein it is particularly provided that the cylindrical lenses (10, 13) are arranged at a distance from each other which corresponds to the sum of the focal lengths of the cylindrical lenses (10, 13) in the interference axis (4), and / or wherein it is particularly provided that the cylindrical lenses (10, 13) are designed as components of the rotation unit (19) so that the cylindrical lenses (10, 13) are each rotatable synchronously with the beam splitter (8). [10] Optical device (1) according to any one of the preceding claims, characterized by a lens unit (21) with at least one diverging lens (20, 22). [11] Optical device (1) according to claim 10, characterized by, that the at least one diverging lens (20, 22) of the lens unit (21) is arranged upstream of the lens (10) of the interference unit (11) facing the beam splitter (8) and / or is designed as a cylindrical lens (20, 22) whose cylinder axis is arranged perpendicular or parallel to the interference axis (4). [12] Optical device (1) according to one of claims 10 or 11, characterized by , that the lens unit (21) has several diverging lenses (20, 22), wherein in particular it is provided that each partial beam (9) is assigned one, in particular exactly one, diverging lens (20, 22). [13] Optical device (1) according to any one of claims 10 to 12, characterized by , that the lens unit (21) is designed as a component of the rotation unit (19) so that the lens unit (21) can be rotated synchronously with the beam splitter (8). [14] Optical device (1) according to any one of claims 10 to 13, characterized by, that the lens unit (21) is arranged downstream of the lens (10) of the interference unit (11) facing the beam splitter (8), wherein the lens (10) of the interference unit (11) facing the beam splitter (8) and the lens unit (21) are designed as components of the rotation unit (19), so that the lens (10) of the interference unit (11) facing the beam splitter (8) and the lens unit (21) are each rotatable synchronously with the beam splitter (8). [15] Optical device (1) according to any one of claims 10 to 14, characterized by , that at least one lens (20, 22) of the lens unit (21) is designed as a spherical lens (20, 22), in particular all lenses (20, 22) of the lens unit (21) are each designed as a spherical lens. [16] Optical device (1) for processing a sample (2) using interfering laser beams (3), with a beam splitter (8) and an optical interference unit (11), wherein the beam splitter (8) is arranged such that a laser beam (7) incident on the optical device (1) can be split into at least two partial beams (9) in an interference axis (4) perpendicular to the optical axis, wherein the interference unit (11) is arranged such that the partial beams (9) can be deflected towards each other in such a way that the partial beams (9) interfere with each other in an interference region (14) so ​​that the sample (2) can be processed in the interference region (14), wherein the interference unit (11) has a first lens (10) facing the beam splitter (8) and a second lens (13) facing away from the beam splitter (8), wherein the partial rays (6) are collimated downstream of the first lens (10) and upstream of the second lens (13), in particular immediately in front of the second lens (13), in at least one axis in which the second lens (13) has an optical effect on the partial rays (6). [17] Optical device (1) according to any one of the preceding claims, characterized by , that the collimated partial beams (6) are collimated in a focusing axis (5) arranged perpendicular to the interference axis (4), in particular only in the focusing axis (5). [18] Optical device (1) according to any one of the preceding claims, characterized by , that the collimated partial beams (6) are collimated in the interference axis (4), in particular only collimated in the interference axis (4). [19] Optical device (1) according to any one of the preceding claims, characterized by , that the first lens (10) is a cylindrical lens, wherein in particular it is provided that the cylinder axis of the first lens (10) is aligned parallel to the interference axis (4). [20] Optical device (1) according to any one of the preceding claims, characterized by, that the first lens (10) is a spherical lens, wherein the first lens (10) is associated with a diverging lens (20) which is arranged downstream or upstream of the first lens (10). [21] Optical device (1) according to claim 20, characterized by , that each partial beam (6) is assigned a diverging lens (20). [22] Optical device (1) according to one of claims 20 or 21, characterized by , that the diverging lens (20) is designed as a cylindrical lens whose cylinder axis is aligned parallel to the interference axis (4) or perpendicular to the interference axis (4). [23] Optical device (1) according to any one of claims 20 to 22, characterized by , that the diverging lens (20) is designed as a spherical lens which is arranged upstream or downstream of the first lens (10). [24] Optical system (23) comprising a laser (6) and an optical device (1) according to any one of claims 1 to 23, wherein the laser (6) is configured to emit a laser beam (7) directed towards the optical device (1), in particular towards the beam splitter (8). [25] Sample (2) processed by an optical device (1) according to any one of claims 1 to 23, in particular by an optical system (23) according to claim 24.

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