Optical arrangement

Abstract

The invention relates to an optical arrangement (10) for converting a laser beam (18) that emerges from an output (22) of a laser beam source (12) and propagates in a propagation direction (24) into a linear laser beam (18). A beam diameter of the linear laser beam (18) in an X-direction is greater than a beam diameter of the linear laser beam (18) in a Y-direction that is orthogonal to the X-direction. The optical arrangement (10) comprises an imaging optics unit (26) for imaging the output (22) in the Y-direction in an image plane (28) by means of the laser beam (18), and a beam shaping optics unit (32). The beam shaping optics unit (32) is configured to exchange a divergence of the laser beam (18) in the X-direction and a divergence of the laser beam (18) in the Y-direction or to exchange a beam diameter of the laser beam (18) in the X-direction and a beam diameter of the laser beam (18) in the Y-direction. The beam shaping optics unit (32) is disposed downstream of the imaging optics unit (26) in the propagation direction (24). An absolute value of a distance (40) between the image plane (28) and the beam shaping optics unit (32) is less than or equal to a Rayleigh length of the laser beam (18).

Description

[0001] Title: Optical arrangement

[0002] Description

[0003] The invention relates to an optical arrangement.

[0004] Optical arrangements are often used to shape a laser beam. For example, a beam profile of the laser beam can be shaped using an optical arrangement such that the laser beam is linear. A linear laser beam can be understood as a beam diameter of the laser beam in an X direction that is larger than a beam diameter of the laser beam in a Y direction orthogonal to the X direction. For example, in a linear laser beam, the beam diameter in the X direction can be at least 5 times, in particular 10 times, larger than the beam diameter in the Y direction. Preferably, in a linear laser beam, the beam diameter in the X direction can be 8 to 20 times or 8 to 200 times larger than the beam diameter in the Y direction.

[0005] One possible application of a linear laser beam is the optical pumping of a slab-shaped laser-active medium, i.e., a medium with, for example, a rectangular cross-section. DE 10 2014 004 891 A1 discloses an optical waveguide or a bundle of optical waveguides for transporting radiation from a pump radiation source to a beam-shaping unit. The beam-shaping unit transforms the radiation into a defined radiation field with a rectangular cross-section with a long edge and a short edge. The intensity distribution of the radiation field along the long edges is approximately homogeneous.

[0006] WO 2007 / 140969 A1 discloses a device for generating a line-shaped intensity distribution in a working plane by beam shaping of multi-mode laser radiation.

[0007] The object of the invention is to provide an optical arrangement which in particular enables a compact construction.

[0008] The invention solves this problem by providing an optical arrangement having the features of claim 1. Advantageous embodiments and further developments of the invention emerge from the dependent claims.

[0009] An optical arrangement according to the invention is configured for converting, in particular beam shaping, a laser beam emerging from an output of a laser beam source and propagating along a propagation direction into a linear, in particular line-shaped, laser beam. A beam diameter of the linear laser beam is larger in an X direction than a beam diameter of the linear laser beam in a Y direction orthogonal to the X direction. The optical arrangement has imaging optics and beam shaping optics. The imaging optics are configured to image the output in the Y direction using the laser beam in an image plane. The beam shaping optics are configured to interchange a divergence of the laser beam in the X direction and a divergence of the laser beam in the Y direction, or to interchange a beam diameter of the laser beam in the X direction and a beam diameter of the laser beam in the Y direction.The beam-shaping optics are arranged downstream of the imaging optics in the propagation direction. A distance between the image plane and the beam-shaping optics is less than or equal to a Rayleigh length of the laser beam, in particular the one impinging on the beam-shaping optics. Advantageously, by arranging the beam-shaping optics at a distance from the image plane that is less than or equal to the Rayleigh length, a small area of ​​a floor plan of the optical arrangement can be achieved, which is why the optical arrangement enables a particularly compact design.

[0010] The laser beam emerging from the output can be rotationally symmetrical.

[0011] The imaging optics and / or the beam shaping optics can each be configured to be passed through by the laser beam.

[0012] The imaging optics are positioned downstream of the output in the direction of propagation. No additional optical element can be positioned between the imaging optics and the output.

[0013] The imaging optics can be configured to image the output, in particular only in the Y direction, using the laser beam in the image plane. The absolute value of the beam diameter of the laser beam on the imaging optics in the Y direction can be greater than the absolute value of the beam diameter of the laser beam in the Y direction on the beam-shaping optics. The image plane can be oriented orthogonally to the propagation direction.

[0014] The beam shaping optics can have a stair mirror or be designed as a stair mirror.

[0015] The beam-shaping optics may comprise a mirror transformer or be designed as a mirror transformer.

[0016] The beam-shaping optics can comprise an inclined plate or be designed as an inclined plate. For example, the beam diameter of the laser beam in the X direction and the beam diameter of the laser beam in the Y direction can be interchanged by repeatedly reflecting the laser beam off the inclined plate.

[0017] The beam-shaping optics can be configured, in particular, to only interchange the divergence of the laser beam in the X direction and the divergence of the laser beam in the Y direction. Alternatively, the beam-shaping optics can be configured, in particular, to only interchange the beam diameter of the laser beam in the X direction and the beam diameter of the laser beam in the Y direction.

[0018] The beam-shaping optics can be configured to interchange the divergence of the laser beam in the X direction and the divergence of the laser beam in the Y direction, or to interchange the beam diameter of the laser beam in the X direction and the beam diameter of the laser beam in the Y direction, using a "director / redirector" principle. By interchanging the beam diameter of the laser beam in the X direction with the beam diameter of the laser beam in the Y direction, the beam size of the laser beam in the X direction and the beam size of the laser beam in the Y direction can be changed using the beam-shaping optics.

[0019] The diameter of the laser beam in the X direction after passing through the beam-shaping optics can be equal to the diameter of the laser beam in the X direction before passing through the beam-shaping optics. The diameter of the laser beam in the Y direction after passing through the beam-shaping optics can be equal to the diameter of the laser beam in the Y direction before passing through the beam-shaping optics. In other words, the beam-shaping optics can be configured to keep the diameter of the laser beam in the X direction and the diameter of the laser beam in the Y direction unchanged.

[0020] The divergence of the laser beam in the X direction after passing through the beam-shaping optics can be equal to the divergence of the laser beam in the Y direction before passing through the beam-shaping optics. The divergence of the laser beam in the Y direction after passing through the beam-shaping optics can be equal to the divergence of the laser beam in the X direction before passing through the beam-shaping optics.

[0021] The Rayleigh length of the laser beam incident on the beam-forming optics can be defined as: z R where ZR is the Rayleigh length, n is the refractive index of the

[0022] Beam-forming optics surrounding medium, where a radius of the laser beam in focus in the image plane in the Y direction, Ao the vacuum wavelength of the laser beam and M 2is the diffraction index of the laser beam. The medium surrounding the beam-shaping optics can be air, for example. The refractive index of the medium surrounding the beam-shaping optics can have a value in the range from 1 to 1.1. For example, the refractive index of the medium surrounding the beam-shaping optics can be 1.00029. A wavelength, in particular a vacuum wavelength, of the laser beam can have a value in a range from 800 nm (nanometers) to 1200 nm, in particular 850 nm to 980 nm or 880 nm to 890 nm. Preferably, the wavelength can be 885 nm. Additionally or alternatively, the wavelength of the laser beam can have a value in a range from 1000 to 1180 nm, in particular 1025 nm to 1035 nm.

[0023] The laser beam can be linear after passing through the beam shaping optics.

[0024] In a further development of the optical arrangement, the beam-shaping optics are arranged at least partially within the image plane of the imaging optics. This advantageously reduces imaging errors. Preferably, the image plane can extend through the beam-shaping optics.

[0025] In a further development of the optical arrangement, a beam entrance surface of the beam-shaping optics is arranged at least partially within the image plane. The laser beam can enter the beam-shaping optics through the beam entrance surface for the purpose of passing through the beam-shaping optics.

[0026] In a further development of the optical arrangement, the optical arrangement comprises collimating optics for collimating the laser beam in the X-direction. After passing through the collimating optics, in particular immediately after passing through them, the laser beam can exhibit a slight divergence in the X-direction. The collimating optics are arranged between the output of the laser beam source and the beam-shaping optics. For example, the collimating optics can be arranged between the imaging optics and the beam-shaping optics.

[0027] In a further development of the optical arrangement, the optical arrangement has a beam homogenization unit for homogenizing an intensity distribution of the laser beam in the X-direction. The beam homogenization unit is arranged downstream of the beam-shaping optics in the propagation direction. This allows a particularly homogeneous, linear laser beam to be achieved. The beam homogenization unit can be configured, in particular only, to homogenize the intensity distribution of the laser beam in the X-direction. The beam homogenization unit can have at least one lens array or be designed as a lens array. The lens array can be designed as a cylindrical lens array. The lens array can be a microlens array. The beam homogenization unit can be designed as an imaging or non-imaging beam homogenization unit.An imaging beam homogenization unit can be understood as comprising two lens arrays spaced apart by a distance equal to one of the focal lengths of the lens arrays. The beam homogenization unit can implement the principle of a honeycomb condenser.

[0028] In a further development of the optical arrangement, the optical arrangement comprises focusing optics for focusing the laser beam. The focusing optics are arranged downstream of the beam homogenization unit in the propagation direction. After passing through the focusing optics, the laser beam can form a focus in the X-direction and the Y-direction.

[0029] The laser beam can be linear in the focus downstream of the focusing optics. The beam diameter of the linear laser beam can have a value in a range from 10 mm (millimeters) to 1000 mm in the X-direction at the focus. For example, the beam diameter of the linear laser beam can be 40 mm or 100 mm in the X-direction at the focus. The beam diameter of the linear laser beam can have a value in a range from 0.05 mm to 5 mm in the Y-direction at the focus. For example, the beam diameter of the linear laser beam can be 0.1 mm or 0.3 mm in the Y-direction at the focus.

[0030] The focusing optics can comprise two separate cylindrical lenses. For example, one cylindrical lens can be configured to focus the laser beam in the X direction, and another cylindrical lens can be configured to focus the laser beam in the Y direction. A telescope can be arranged between the focusing optics and the beam homogenization unit to adjust the beam diameter of the laser beam in the X direction and / or in the Y direction.

[0031] In a further development of the optical arrangement, the output of the laser beam source is rotationally symmetrical, in particular circular. In a further development of the optical arrangement, the laser beam emerging from the output of the laser beam source has a diffraction index, in particular in the X-direction and / or in the Y-direction, of greater than or equal to 15. The diffraction index can be defined as M 2The magnitude of the diffraction index of the laser beam emerging from the output of the laser beam source in the X direction and the magnitude of the diffraction index of the laser beam emerging from the output of the laser beam source in the Y direction may be equal.

[0032] In a further development of the optical arrangement, the laser beam emerging from the output of the laser beam source has a circular, and in particular homogeneous, intensity profile. The imaging optics and the beam-shaping optics can be configured to convert the circular laser beam into a linear laser beam. The laser beam emerging from the output can have a top-hat-shaped intensity distribution.

[0033] In a further development of the optical arrangement, the imaging optics comprises a cylindrical lens or is designed as a cylindrical lens. The cylindrical lens of the imaging optics can be made of quartz glass. The cylindrical lens of the imaging optics can be a

[0034] anti-reflective coating for one wavelength of the laser beam.

[0035] Anti-reflective coating can be used to reduce the reflection level of the laser beam at interfaces of the cylindrical lens of the imaging optics.

[0036] In a further development of the optical arrangement, the beam-shaping optics comprises a cylindrical lens array or is designed as a cylindrical lens array. Each cylindrical lens of the cylindrical lens array is arranged at +45° or -45° with respect to the X-direction. The cylindrical lenses of the cylindrical lens array can be arranged adjacent to one another. The cylindrical lens array can be formed from quartz glass. The cylindrical lens array can have an anti-reflective coating for a wavelength of the laser beam. The anti-reflective coating can be suitable for reducing the reflectance of the laser beam at interfaces of the cylindrical lens array. The laser beam can impinge on the cylindrical lens array in such a way that the laser beam impinges on a plurality, for example at least 5, 8, 15, or 20, of cylindrical lenses of the cylindrical lens array.The cylindrical lens array can split the laser beam into individual beam segments, with each beam segment assigned to a cylindrical lens. Each cylindrical lens can redirect the beam segment assigned to it. By arranging the cylindrical lenses at +45° or -45°, the divergence of the laser beam in the X direction and the divergence of the laser beam in the Y direction can be reversed after passing through the beam-shaping optics.

[0037] In a further development of the optical arrangement, the collimating optics comprises a cylindrical lens or is designed as a cylindrical lens. The cylindrical lens of the collimating optics can be made of quartz glass. The cylindrical lens of the collimating optics can be a

[0038] anti-reflective coating for one wavelength of the laser beam.

[0039] Anti-reflective coating can be used to reduce the reflection of the laser beam at interfaces of the cylindrical lens of the collimation optics.

[0040] In a further development of the optical arrangement, the focusing optics has a spherical lens or is designed as a spherical lens. The spherical lens of the

[0041] Focusing optics can be made of quartz glass. The spherical lens of the

[0042] Focusing optics may have an anti-reflective coating for a wavelength of the laser beam. The anti-reflective coating may be suitable for reducing the reflection of the laser beam at the interfaces of the spherical lens of the focusing optics.

[0043] In a further development of the optical arrangement, a value of a diffraction index of the laser beam after passing through the beam shaping optics and / or the beam homogenization unit in the Y direction is less than or equal to ten, in particular eight.

[0044] In a further development of the optical arrangement, the optical arrangement comprises a slab-shaped laser-active medium. The slab-shaped laser-active medium is arranged downstream of the beam-shaping optics in the propagation direction. The laser beam passes through the slab-shaped laser-active medium for the purpose of optical pumping. This advantageously allows for the realization of a compact slab laser or slab amplifier. The slab-shaped laser-active medium can be embodied as a slab-shaped laser-active solid.

[0045] A slab-shaped medium can be understood to mean that the medium is plate-shaped. In other words, the medium can be cuboid-shaped, with a height of the medium being less than its width and length. Such a shape enables better cooling of the medium, in particular, heat dissipation of the heat generated by amplifying and / or generating a laser beam is improved. A laser-active medium can be understood to mean that the medium is configured to generate and / or amplify a laser beam, in particular by means of stimulated emission.

[0046] In a further development of the optical arrangement, the optical arrangement has the laser beam source with the output for providing the laser beam.

[0047] In a further development of the optical arrangement, the laser beam source comprises an optical fiber. The output of the laser beam source is formed by a region of an end face of the optical fiber. The optical fiber can be designed as an optical fiber cable. The optical fiber can be designed as a glass fiber. The laser beam source can have a laser diode for generating the laser beam. The laser beam generated by the laser diode can be coupled into the optical fiber at an end face opposite the end face forming the output. The optical fiber can be configured to transport the laser beam from the laser diode to the output.

[0048] In a further development of the optical arrangement, an amount of an aspect ratio of the transformation is greater than 5. The aspect ratio of the transformation can be determined, for example, by dividing a beam parameter product of the line-like laser beam after passing through the beam-shaping optics in the X direction by a beam parameter product of the line-like laser beam after passing through the beam-shaping optics in the Y direction.

[0049] Further advantages and advantageous embodiments of the invention can be gathered from the figures, their description, and the claims. All features disclosed in the figures, their description, and the claims can be essential to the invention both individually and in any combination. They show:

[0050] Fig. 1 is a schematic representation of an optical arrangement,

[0051] Fig. 2 is a schematic representation of an imaging optics and a beam-shaping optics of the optical arrangement of Fig. 1 in a YZ plane spanned by a Y-direction and a Z-direction, Fig. 3 is a schematic representation of the imaging optics and the beam-shaping optics of the optical arrangement of Fig. 1 in an XZ plane spanned by an X-direction and the Z-direction,

[0052] Fig. 4 is a schematic representation of the beam-forming optics of the optical arrangement of Fig. 1 in an XY plane spanned by the X-direction and the Y-direction,

[0053] Fig. 5 is a graph of a radiation density of a laser beam at an output of a laser beam source of the optical arrangement of Fig. 1,

[0054] Fig. 6 is a graph of a radiance in the angular space of the laser beam at the output of the laser beam source of the optical arrangement of Fig. 1,

[0055] Fig. 7 is a graph of a radiation density of the laser beam in a focus after a focusing optics of the optical arrangement of Fig. 1 ,

[0056] Fig. 8 is a graph of a radiance in the angular space of the laser beam in a focus after the focusing optics of the optical arrangement of Fig. 1 , and

[0057] Fig. 9 is a schematic view of another embodiment of an optical arrangement.

[0058] Fig. 1 shows an optical arrangement 10. The optical arrangement 10 has a laser beam source 12. The laser beam source 12 has a laser diode 14 and an optical fiber 16. The laser diode 14 is configured to generate a laser beam 18. The laser beam 18 generated by the laser diode 14 is coupled into the optical fiber 16. The optical fiber 16 is configured to guide the laser beam 18. In the illustrated embodiment, the optical fiber 16 has a numerical aperture of 0.18 and a core with a core diameter of 220 pm (micrometers).

[0059] The laser beam source 12 has an output 22. The output 22 is arranged in and / or on an end face 20 of the optical fiber 16. The output 22 is delimited in the end face 20 by the core of the optical fiber 16. The output 22 of the laser beam source 12 is circular. The laser beam 18 exits the output 22 after passing through the optical fiber 16. When the laser beam 18 exits the output 22, the laser beam 18 leaves the laser beam source 12. The laser beam 18 exiting the output 22 propagates along a propagation direction 24. The propagation direction 24 is oriented perpendicular to the end face 20. The propagation direction 24 of the laser beam 18 exiting the output 22 is oriented parallel to a Z direction.

[0060] Fig. 5 shows a graph of the radiance of the laser beam 18 at the output 22. The laser beam 18 exiting the output 22 has a circular intensity profile. A beam diameter of the laser beam 18 exiting the output 22 in an X direction orthogonal to the Z direction and a beam diameter of the laser beam 18 exiting the output 22 in a Y direction orthogonal to the X direction and the Z direction are equal. In particular, it can be seen in Fig. 5 that the laser beam 18 exiting the output 22 has a homogeneous intensity profile. In other words, the laser beam 18 exiting the output 22 has a top-hat-shaped intensity distribution.

[0061] Fig. 6 shows a graph of a radiance in the angular space of the laser beam 18 emerging from the output 22. In particular, it can be seen in Fig. 6 that the laser beam 18 is a divergent laser beam 18. In other words, a beam diameter of the laser beam 18 increases in the propagation direction 24 with increasing distance from the output 22.

[0062] Fig. 5 and 6 show that at the output 22 the spatial and angular space of the laser beam 18 are of equal size.

[0063] A wavelength of the laser beam 18 is 890 nm. A diffraction index M 2 of the laser beam 18 emerging from the output 22 has a magnitude greater than 15.

[0064] Fig. 1 shows that an imaging optic 26 of the optical arrangement 10 is arranged downstream of the output 22 in the propagation direction 24. The imaging optic 26 is configured to image the output 22 only in the Y direction using the laser beam 18 in an image plane 28. The image plane 28 is aligned orthogonally to the propagation direction 24. The imaging optic 26 is designed as a cylindrical lens made of quartz glass. The cylindrical lens of the imaging optic 26 has an anti-reflection coating for the wavelength of the laser beam 18 to reduce the degree of reflection at the interfaces of the cylindrical lens of the imaging optic 26.

[0065] The cylindrical lens of the imaging optics 26 has an optical plane. The optical plane of the cylindrical lens of the imaging optics 26 is a mirror plane of symmetry of the cylindrical lens of the imaging optics 26. The optical plane of the cylindrical lens of the imaging optics 26 is aligned parallel to the Z-direction and the X-direction. The laser beam 18, which passes through the cylindrical lens of the imaging optics 26, is refracted by the cylindrical lens of the imaging optics 26 toward the optical plane.

[0066] After passing through the cylindrical lens of the imaging optics 26, the diameter of the laser beam 18 decreases in the Y direction up to the image plane 28 and the diameter of the laser beam 18 increases in the X direction up to a collimation optics 30 of the optical arrangement 10.

[0067] The collimation optics 30 are configured to collimate the laser beam 18 in the X-direction. The collimation optics 30 are designed as a cylindrical lens made of quartz glass. The cylindrical lens of the collimation optics 30 has an anti-reflection coating for the wavelength of the laser beam 18 to reduce the degree of reflection at the interfaces of the cylindrical lens of the collimation optics 30.

[0068] The cylindrical lens of the collimating optics 30 has an optical plane. The optical plane of the cylindrical lens of the collimating optics 30 is a mirror plane of symmetry of the cylindrical lens of the collimating optics 30. The optical plane of the cylindrical lens of the collimating optics 30 is aligned parallel to the Z-direction and the Y-direction. The laser beam 18, which passes through the cylindrical lens of the collimating optics 30, is refracted by the cylindrical lens of the collimating optics 30 in the direction of the optical plane. The optical plane of the imaging optics 26 and the optical plane of the collimating optics 30 are aligned orthogonally to each other.

[0069] After passing through the cylindrical lens of the collimating optics 30, the laser beam 18 is collimated in the X direction. In other words, after passing through the cylindrical lens of the collimating optics 30, the laser beam 18 exhibits a slight divergence in the X direction. The collimating optics 30 are arranged downstream of the imaging optics 26 in the propagation direction 24. In other words, the imaging optics 26 are arranged between the output 22 and the collimating optics 30.

[0070] The optical arrangement 10 has a beam-shaping optic 32. The beam-shaping optic 32 is arranged downstream of the collimating optic 30 in the propagation direction 24. In other words, the collimating optic 30 is arranged between the beam-shaping optic 32 and the imaging optic 26.

[0071] The beam-shaping optics 32 are configured to interchange a divergence of the laser beam 18 in the X direction and a divergence of the laser beam 18 in the Y direction. In other words, the divergence of the laser beam 18 in the X direction after passing through the beam-shaping optics 32 is equal to the divergence of the laser beam 18 in the Y direction before passing through the beam-shaping optics 32, and the divergence of the laser beam 18 in the Y direction after passing through the beam-shaping optics 32 is equal to the divergence of the laser beam 18 in the X direction before passing through the beam-shaping optics 32.

[0072] The beam-shaping optics 32 do not change the diameter of the laser beam 18 in the X direction or the diameter of the laser beam 18 in the Y direction. In other words, the diameter of the laser beam 18 in the X direction after passing through the beam-shaping optics 32 is equal to the diameter of the laser beam 18 in the X direction before passing through the beam-shaping optics 32, and the diameter of the laser beam 18 in the Y direction after passing through the beam-shaping optics 32 is equal to the diameter of the laser beam 18 in the Y direction before passing through the beam-shaping optics 32.

[0073] In the illustrated embodiment of Figures 1 to 8, the beam-shaping optics 32 is designed as a cylindrical lens array. The beam-shaping optics 32 in the form of a cylindrical lens array is shown in Fig. 4. The cylindrical lens array of the beam-shaping optics 32 has a plurality of cylindrical lenses 34. Ten cylindrical lenses 34 of the cylindrical lens array are shown as an example in Fig. 4. In total, the cylindrical lens-excited beam-shaping optics 32 has twenty cylindrical lenses 34.

[0074] The cylindrical lenses 34 of the cylindrical lens array are arranged side by side. Each cylindrical lens 34 of the cylindrical lens array has an optical plane 36. The optical plane 36 of each cylindrical lens 34 of the cylindrical lens array is a mirror plane of symmetry of the cylindrical lens 34 of the cylindrical lens array. For reasons of clarity, only the optical plane 36 of the left cylindrical lens 34, as seen by a viewer in Fig. 4, is shown in Fig. 4.

[0075] Each cylindrical lens 34 of the cylindrical lens array is arranged at an angle of -45° relative to the X-direction. In other words, each optical plane 36 is arranged at an angle 38 of +45° relative to the X-direction. Such an arrangement of the cylindrical lenses 34 results in the interchange of the divergence of the laser beam 18 in the X-direction and the divergence of the laser beam 18 in the Y-direction. The laser beam 18 is shown in dashed lines in Fig. 4.

[0076] Each cylindrical lens 34 of the cylindrical lens array is made of quartz glass. Each cylindrical lens 34 of the cylindrical lens array has an anti-reflection coating for the wavelength of the laser beam 18 to reduce reflection at the interfaces of the cylindrical lenses 34.

[0077] The beam-forming optics 32 are arranged relative to the imaging optics 26 such that an amount of a distance 40 between the image plane 28 and the beam-forming optics 32 in the Z-direction is smaller than a Rayleigh length of the laser beam 18 impinging on the beam-forming optics 32. The Rayleigh length of the laser beam 18 impinging on the beam-forming optics 32

[0078] Laser beam 18 meets the condition: z R = n ^° , where ZR is the Rayleigh length, n is the refractive index of the medium surrounding the beam-forming optics 32, where a radius of the laser beam in the image plane in the Y direction, Ao is the vacuum wavelength of the laser beam 18 and M 2 is the diffraction index of the laser beam 18. The medium surrounding the beam-shaping optics 32 is air with a refractive index of 1.00029.

[0079] The beam shaping optics 32 are arranged such that the beam shaping optics 32 are arranged within the image plane 28 of the imaging optics 26, see Figs. 2 and 3. A beam entrance surface 42 of the beam shaping optics 32 is arranged within the image plane 28.

[0080] After passing through the beam-shaping optics 32, the laser beam 18 strikes a beam homogenization unit 44 of the optical arrangement 10. The beam homogenization unit 44 is arranged downstream of the beam-shaping optics 32 in the propagation direction 24. In other words, the beam-shaping optics 32 are arranged between the collimation optics 30 and the beam homogenization unit 44.

[0081] The beam homogenization unit 44 is configured to homogenize the intensity distribution of the laser beam 18 only in the X direction. After passing through the beam homogenization unit 44, the intensity distribution of the laser beam 18 is top-hat-shaped only in the X direction. The value of the diffraction index of the laser beam 18 in the Y direction after passing through the beam homogenization unit 44 is less than or equal to eight.

[0082] After passing through the beam homogenization unit 44, the laser beam 18 strikes a focusing optics 46 of the optical arrangement 10. The focusing optics 46 are arranged downstream of the beam homogenization unit 44 in the propagation direction 24. In other words, the beam homogenization unit 44 is arranged between the beam-shaping optics 32 and the focusing optics 46.

[0083] The focusing optics 46 are configured to focus the laser beam 18. The focusing optics 46 are designed as a spherical lens made of quartz glass. The spherical lens of the focusing optics 46 has an anti-reflection coating for the wavelength of the laser beam 18 to reduce the degree of reflection at the interfaces of the spherical lens of the focusing optics 46.

[0084] After passing through the focusing optics 46, the laser beam 18 forms a focus in a focusing plane 50 of the focusing optics 46. The focusing plane 50 is aligned orthogonal to the propagation direction 24. The focusing plane 50 is aligned parallel to the image plane 28.

[0085] Fig. 7 shows a graph of a radiance of the laser beam 18 in the focusing plane 50. The intensity profile of the laser beam 18 in the focusing plane 50 is linear. In the focusing plane 50, the beam diameter of the laser beam 18 in the X direction is larger than the beam diameter of the laser beam 18 in the Y direction. In the illustrated embodiment, the beam diameter of the laser beam 18 in the focusing plane 50 in the X direction is 50 mm, and the beam diameter of the laser beam 18 in the focusing plane 50 in the Y direction is 0.4 mm. Fig. 8 shows a graph of a radiance in the angular space of the laser beam 18 in the focusing plane 50. In particular, it can be seen in Fig. 8 that the laser beam 18 is a divergent laser beam 18. In other words, a beam diameter of the laser beam 18 increases in the propagation direction 24 with increasing distance from the focusing plane 50.

[0086] Fig. 7 and 8 show that in the focusing plane 50 the spatial and angular space of the laser beam 18 is smaller in the Y-direction than in the X-direction.

[0087] In particular, Figs. 5 to 8 show that the optical arrangement 10 is designed to convert the circular laser beam 18 emerging from the output 22 of the laser beam source 12 and propagating along the propagation direction 24 into a line-like laser beam 18.

[0088] The optical arrangement 10 has a slab-shaped laser-active medium 52. The slab-shaped laser-active medium 52 is arranged downstream of the focusing optics 46 in the propagation direction 24. In other words, the focusing optics 46 are arranged between the beam homogenization unit 44 and the slab-shaped laser-active medium 52.

[0089] The slab-shaped laser-active medium 52 is arranged such that the focusing plane 50 extends through the slab-shaped laser-active medium 52. The laser beam 18 passes through the slab-shaped laser-active medium 52 for the purpose of optical pumping.

[0090] Fig. 9 shows a further embodiment of the optical arrangement 10 of Figs. 1 to 8, wherein the same reference numerals are used for identical and functionally equivalent elements and in this respect reference can be made to the above explanations regarding the embodiment of Figs. 1 to 8, so that essentially only the existing differences are discussed.

[0091] In Fig. 9, the beam shaping optics 32 is designed as a microlens array.

Claims

Patent claims 1. An optical arrangement (10) for converting a laser beam (18) emerging from an output (22) of a laser beam source (12) and propagating along a propagation direction (24) into a linear laser beam (18), wherein a beam diameter of the linear laser beam (18) in an X-direction is greater than a beam diameter of the linear laser beam (18) in a Y-direction orthogonal to the X-direction, comprising: imaging optics (26) for imaging the output (22) in the Y-direction by means of the laser beam (18) in an image plane (28), and beam-shaping optics (32) configured to combine a divergence of the laser beam (18) in the X-direction and a divergence of the laser beam (18) in the Y-direction with one another or a beam diameter of the laser beam (18) in the X-direction and a beam diameter of the laser beam (18) to swap in the Y direction,wherein the beam-shaping optics (32) are arranged downstream of the imaging optics (26) in the propagation direction (24), wherein an amount of a distance (40) between the image plane (28) and the beam-shaping optics (32) is less than or equal to a Rayleigh length of the laser beam (18).

2. Optical arrangement (10) according to claim 1, wherein the beam-shaping optics (32) are arranged at least partially within the image plane (28).

3. Optical arrangement (10) according to one of the preceding claims, wherein a beam entry surface (42) of the beam shaping optics (32) is arranged at least partially within the image plane (28).

4. Optical arrangement (10) according to one of the preceding claims, wherein the optical arrangement (10) has a collimation optics (30) for collimating the laser beam (18) in the X-direction, wherein the collimation optics (30) are arranged between the output (22) of the laser beam source (12) and the beam shaping optics (32).

5. Optical arrangement (10) according to one of the preceding claims, wherein the optical arrangement (10) has a beam homogenization unit (44) for homogenizing an intensity distribution of the laser beam (18) in the X-direction, wherein the beam homogenization unit (44) is arranged downstream of the beam shaping optics (32) in the propagation direction (24).

6. Optical arrangement (10) according to one of the preceding claims, wherein the optical arrangement (10) has a focusing optics (46) for focusing the laser beam (18), wherein the focusing optics (46) is arranged downstream of the beam homogenization unit (44) in the propagation direction (24).

7. Optical arrangement (10) according to one of the preceding claims, wherein the output (22) of the laser beam source (12) is rotationally symmetrical, in particular circular.

8. Optical arrangement (10) according to one of the preceding claims, wherein the laser beam (18) emerging from the output (22) of the laser beam source (12) has a diffraction index of greater than or equal to 15.

9. Optical arrangement (10) according to one of the preceding claims, wherein the laser beam (18) emerging from the output (22) of the laser beam source (12) has a circular, and in particular homogeneous, intensity profile.

10. Optical arrangement (10) according to one of the preceding claims, wherein the imaging optics (26) comprises a cylindrical lens or is designed as a cylindrical lens.

11. Optical arrangement (10) according to one of the preceding claims, wherein the beam-shaping optics (32) comprises a cylindrical lens array or is designed as a cylindrical lens array, wherein each cylindrical lens (34) of the cylindrical lens array is arranged at +45° or -45° with respect to the X-direction.

12. Optical arrangement (10) according to one of claims 4 to 11, wherein the collimation optics (30) comprises a cylindrical lens or is designed as a cylindrical lens.

13. Optical arrangement (10) according to one of claims 6 to 12, wherein the focusing optics (46) comprises a spherical lens or is designed as a spherical lens.

14. Optical arrangement (10) according to one of the preceding claims, wherein a value of a diffraction index of the laser beam (18) after passing through the beam shaping optics (32) in the Y direction is less than or equal to ten.

15. Optical arrangement (10) according to one of the preceding claims, wherein the optical arrangement (10) comprises a slab-shaped laser-active medium (52), wherein the slab-shaped laser-active medium (52) is arranged downstream of the beam-shaping optics (32) in the propagation direction (24), wherein the laser beam (18) passes through the slab-shaped laser-active medium (52) for the purpose of optical pumping.

16. Optical arrangement (10) according to one of the preceding claims, wherein the optical arrangement (10) comprises the laser beam source (12) with the output (22) for providing the laser beam (18).

17. Optical arrangement (10) according to one of the preceding claims, wherein the laser beam source (12) comprises an optical fiber (16), the output (22) of the laser beam source (12) being formed by a region of an end face (20) of the optical fiber (16).

18. Optical arrangement (10) according to one of the preceding claims, wherein an aspect ratio of the conversion is greater than 5.

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