Thin-disk laser system with homogenized optical pump source

Abstract

FIELD OF THE DISCLOSURE The present invention relates to a laser system. More particularly, the present invention relates to a diode pumped laser system. More particularly, the present invention relates to a laser diode pumped thin disk laser, where the laser head is connected to a laser diode pump source by a fiber cable.

Description

[Technical Field]

[0001] The present invention relates to a movable laser system. In particular, the present invention relates to a non-uniformly pumped thin disk laser system, preferably a stacked laser diode pumped thin disk laser system. In a preferred embodiment, the present invention relates to a laser diode pumped thin disk laser, in which a laser head including a thin amplifier disk is coupled to a laser diode pump source that delivers a non-uniform pump beam, and the system homogenizes the pump beam. [Background technology]

[0002] Thin-disk lasers are high-power, diode-pumped, solid-state lasers. The gain medium is a thin disk whose thickness is significantly smaller than its diameter. This geometry allows efficient cooling of the entire disk surface, providing a flat temperature profile across one-dimensional heat flow, leading to poor lensing and nonlinear effects such as self-phase modulation (SPM) or self-focusing (SF). Using only single or double passes typically leads to inefficient pump absorption due to the thin disk thickness. This problem is usually solved by using multi-pass pump arrays, which can be compact with well-designed optical setups, typically including parabolic mirrors and prismatic retroreflectors. Such arrays facilitate arranging multiple passes of pump light through the disk without placing excessive demands on pump beam quality.

[0003] The laser disk is separate from the diode pump source, and the pump light is delivered to the laser head by an optical fiber. The laser head contains the thin disk described above, which receives and absorbs the pump light. Figure 1 shows the basic configuration: a diode pump source 1 generates a pump beam and is connected to a pump chamber via an optical cable 2. The pump beam is directed to a collimating lens 3 and then to a parabolic mirror 4, which reflects the beam to a thin disk 5, which absorbs the pump beam. The thin disk 5 is connected to a heat sink 6. A reflector 7 is provided in the pump chamber to receive and reflect the pump beam back. At the end of the pump beam's final path, the laser beam 8 is nearly completely absorbed by the thin disk.

[0004] The optical fiber 2 has a circular cross section. However, after the first reflection from the parabolic mirror 4, the shape of the excitation spot on the thin disk is elliptical and degraded by aberrations introduced by the parabolic mirror 4. The actual elliptical excitation spot shape 10 after reflection from the parabolic mirror is shown in FIG. 2, along with the ideal circular shape 11 that would be obtained if a spherical focusing lens were used instead of the parabolic mirror 4. The scale shown in FIG. 2 is not limiting. This is a simple example of an embodiment that may be provided as shown in FIG. 3a. As the elliptical beam propagates through the excitation chamber, the degraded elliptical beams are superimposed after multiple reflections to form a quasi-circular excitation spot shape, as shown in FIG. 3b, and the cross section shows significant degradation and blurred edges of the excitation spot, as shown schematically in FIG. 3c.

[0005] Patent Document 1 discloses a laser system that delivers a uniform beam to a thin disk, and the pump source is a stacked laser diode that provides a non-uniform pump beam. The laser system according to the above solution can deliver a uniform beam to a thin disk, and the pump beam is amplified. However, this system includes multiple microlenses that are not easy to manufacture, and the microlenses also require additional alignment requirements. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] DE 108936 A1 Summary of the Invention [Problem to be solved by the invention]

[0007] In general, there is a technical need to provide a top-hat beam spot, preferably a circular spot of uniform intensity, delivered to a laser head containing a thin disk, so that the amplification of the excitation beam is efficient and uniform. Therefore, the present invention aims to provide a beam shaping system that corrects for non-uniform intensity and preferably provides a circular beam profile. At the same time, the present invention should solve the problem of light beam alignment, especially the alignment of optical elements such as lenses or prisms, in which case the precision required for all optical elements involved in the solution should be as low as possible. [Means for solving the problem]

[0008] The above technical problem is solved by the present invention as set forth in the independent claims attached hereto.

[0009] In a first aspect, the present invention relates to a laser system capable of forming an optical pump beam and homogenizing its intensity. The system provides the homogenized optical pump beam to a laser head, in particular to a thin disk that amplifies the pump beam. The pump light beam source is a non-uniform light beam, e.g., a beam with a rectangular or square profile, such as a pump beam from a stacked laser diode, and the system according to the invention is capable of delivering a homogenous beam spot to the thin disk, delivering a circular spot as the laser output. The system is defined by claim 1.

[0010] The system is a source that generates a light beam having a non-uniform light intensity, the non-uniform light beam may have a non-circular profile, such as, but not exclusively, a rectangular or square beam shape formed from a stacked laser diode; a beam splitting rotating prism configured to receive a non-uniform light beam, the beam splitting rotating prism having a first portion providing a longer light path and a second portion providing a shorter light path, the beam splitting rotating prism configured to split the non-uniform light beam into two portions, the first portion configured to propagate through the longer light path and the second portion configured to propagate through the shorter light path, and configured to rotate each portion in the same direction and by the same angle; a focusing means for receiving both beam portions from the beam splitting rotating prism and focusing them onto the homogenizing section, thereby providing a homogenized optical excitation beam; a laser head including a thin disk and receiving a homogenized light beam from a homogenizing portion, the homogenized light beam being directed toward the thin disk; Includes:

[0011] The combination of a beam-splitting rotating prism and an optical beam homogenizer provides a homogenized optical beam spot, which is transmitted onto a thin disk included in the laser head. By repeatedly rotating and overlapping multiple polygonal spots, a preferably nearly circular excitation spot shape can be obtained on the thin disk. In some embodiments, the beam-splitting rotating prism can reduce the aspect ratio of the optical beam to make it suitable as an excitation beam for a laser beam, in order to increase the coupling efficiency into the homogenizer. Furthermore, the present invention can be manufactured as a manually operable, movable system. Furthermore, the use of a single beam-splitting prism solves technical problems related to alignment and microlens precision. Furthermore, the use of a single beam-splitting rotating prism solves the beam alignment problems associated with solutions that require, for example, multiple prisms located at different positions on an optical bench.

[0012] The source generating a non-uniform light beam suitable for exciting the beam and sending it to the homogenizer can be a plurality of laser diodes housed in a diode stack, a plurality of diode stacks, a plurality of diode modules, or a plurality of additional laser beams. The light beam is non-uniform in intensity but can be spatially collimated between a source generating an optical excitation beam and a beam-splitting rotating prism receiving the light beam, in some embodiments with a vertical divergence angle of less than 1° and a horizontal divergence angle of less than 5°. In a preferred embodiment, the beam is non-uniform in intensity but can be spatially collimated between a source generating a non-uniform optical excitation beam, such as a plurality of laser diodes arranged in a circular, square, or rectangular configuration, and a focusing means receiving and focusing the rotated excitation beam onto a polygonal or elliptical homogenizer, in which the vertical divergence angle can be less than 1.8° and the horizontal divergence angle can be less than 3.6°. A preferred embodiment of the source generating a non-uniform light beam is defined by claim 2. The most preferred embodiment is a source that generates a non-uniform light beam, such as a laser diode, that comprises multiple elliptical or circular beams, which together, when arranged in the stack, form a rectangular or square envelope.

[0013] A beam-splitting rotating prism is a single prism with two sections. The first section provides a longer optical path. The second section provides a shorter optical path. Both sections are made of the same material, such as clear glass. When a non-uniform light beam is received by the front surface of the beam-splitting rotating prism, it is split into two sections. The first half propagates through the longer optical path. The second half propagates through the shorter optical path. Both sections are then reflected twice at 90 degrees, so that the first and second sections have opposite shapes and intensity distributions. At the back of the beam-splitting rotating prism, the beam remains non-uniform but is doubled, with each half changing direction and opposing each other.

[0014] In a preferred embodiment, the focusing means are two cylindrical lenses, the orientation of the second lens being orthogonal to the first lens, and the focal length being selected based on the size of the beam emerging from the beam splitting rotating prism to fall within the numerical aperture of the homogenizer.

[0015] The homogenizer is an optically transparent laser rod with a highly reflective coating on its surface that reflects the non-uniform optical excitation beam in a multiplicity of ways, resulting in a completely homogenized beam at the end of the laser rod. Such homogenizers are known in the art, for example, as described in U.S. Pat. No. 6,275,493, cited above as a prior art document. In a preferred embodiment, the homogenizer is polygonal, more preferably an octagonal homogenizer having an asymmetric geometric shape, with vertical and horizontal cross-sectional dimensions configured to compensate for the difference in magnification between the vertical and horizontal planes introduced by the aberrations of the parabolic mirror.

[0016] In a further preferred embodiment, the system further includes an anamorphic prism pair disposed between the multiple laser diode stacks, preferably multiple laser diode stacks with large rectangular output areas, and the beam splitting rotating prism, which can reduce the size of the non-uniform light beam and further convert the non-uniform light beam into a substantially square beam so that it fits on the beam splitting rotating prism.

[0017] In a further preferred embodiment, the system includes multiple sources of non-uniform light beams, at least two of which are more strongly pumped to produce laser beams of higher pump power emitted from the laser head.

[0018] In a further preferred embodiment, the system further includes a bar mirror array disposed between the plurality of laser diode stacks and the beam splitting rotating prism.

[0019] In a more preferred embodiment, the system further includes a polarizer disposed between the multiple laser diode stack and the beam-splitting rotating prism. In a more preferred embodiment, a half-wave plate is inserted before the laser diode stack. This arrangement combines the two polarized beams into a single, more intense beam.

[0020] In a further preferred embodiment, the system further includes a bar mirror array positioned between the multiple laser diode stacks and the beam-splitting rotating prism, which reflects beams emitted from the bars in one of the laser diode stacks toward the output of a second diode stack, thereby combining the beams into a single, more intense beam.

[0021] In a more preferred embodiment, the system further includes a laser diode stack module having a fast axis collimator and a slow axis collimator to provide a fast axis divergence angle of less than 0.5° and a slow axis divergence angle of less than 4°.

[0022] An alternative embodiment of the present invention is a laser system that homogenizes an optical pump beam from a non-uniform pump source and delivers the homogenized pump beam to a laser head that includes a thin disk active medium that amplifies the homogenized pump beam.

[0023] The system is a plurality of sources generating light beams having non-uniform light intensities; a beam splitting and collimating means, a first axis collimator for receiving non-uniform light beams from multiple sources; a beam twister that receives the light beam from the first axis collimator; and a means including a slow axis collimator for receiving the non-uniform light beam from the beam twister; focusing means for receiving the beam from the beam splitting and collimating means and focusing the beam onto the homogenizing section, thereby providing a homogenized optical excitation beam; and a laser head including the thin disk and receiving the homogenized light beam from the homogenizer, the homogenized light beam being directed toward the thin disk.

[0024] In another embodiment, the octagonal homogenizing section has octagonal front dimensions of 1.3 mm width, 1.6 mm height, and a 0.4 mm chamfer at 45 degrees for pump powers up to 1 kW average power.

[0025] In another embodiment, the octagonal equalizing portion has a length in the range of 80 to 100 mm.

[0026] In yet another embodiment, the octagonal equalizing portion has a length in the range of 100 to 120 mm.

[0027] In yet another embodiment, the octagonal equalizing portion has a length in the range of 120 to 150 mm.

[0028] The above embodiments may be used in all industrial fields, in particular, but not exclusively, in the fields of cutting, etching, annealing, welding, drilling, soldering, high temperature plasma generation, particle acceleration or as scientific instruments. [Brief explanation of the drawings]

[0029] [Figure 1] 1 is a schematic diagram showing a diode-pumped solid-state laser device including a thin disk located in a pump chamber according to the prior art. [Figure 2] FIG. 1 is a schematic diagram illustrating the difference between an optimal circular excitation spot from a lens-based system and an elliptical beam produced by reflection from a prior art parabolic mirror. [Figure 3a] 1 illustrates simulation results based on a prior art laser system, showing beam propagation from the end of a prior art pump fiber tip. [Figure 3b] 1 illustrates simulation results based on a prior art laser system, showing beam propagation through the first reflection from a parabolic mirror. [Figure 3c] 1 illustrates simulation results based on a conventional laser system, showing beam propagation to a point where all reflections from the parabolic mirror overlap. [Figure 3d] A cross section of the final excitation spot structure is shown. [Figure 4a] 10 illustrates simulation results based on a laser system according to the present invention, showing beam propagation from the end of a homogenizer according to the present invention. [Figure 4b] 10 illustrates simulation results based on a laser system according to the present invention, showing beam propagation through a first reflection from a parabolic mirror. [Figure 4c] 1 illustrates simulation results based on a laser system according to the present invention, showing beam propagation to a position where all reflections from the parabolic mirror overlap. [Figure 4d] A cross section of the final excitation spot structure is shown. [Figure 5] 1 is a schematic diagram illustrating an embodiment of the present invention. [Figure 6] FIG. 2 is a detailed view of a beam splitting prism according to one embodiment of the present invention. [Figure 7] 10 shows simulation results of the excitation beam cross-sectional intensity evolution in the homogenizer according to an embodiment of the present invention. [Figure 8] 1 shows a homogenizer according to the present invention, with the excitation beam directed into the excitation chamber, and also shows the end of the homogenizer and the beam profile on the thin disk. [Figure 9] 10 shows simulation results of the excitation beam profile on a thin disk after multiple reflections and propagation through a beam splitting rotating prism, a homogenizer, and an excitation chamber according to one embodiment of the present invention. [Figure 10a] 6 shows a cross section of the final excitation spot size simulated as output from the embodiment of FIG. 5. [Figure 10b] 6 shows a cross section of the final excitation spot size simulated as output from the embodiment of FIG. 5. [Figure 11]FIG. 10 is a schematic diagram illustrating an improved embodiment further including an anamorphic prism pair according to another embodiment of the present invention. [Figure 12] FIG. 12 is a schematic cross-sectional view of the second embodiment of FIG. 11, showing the optical path of the excitation beam. [Figure 13] 1 shows a bar mirror array according to a third embodiment of the present invention and a further improved embodiment aimed at a power scaling arrangement using two diode stacks to provide a 400 W laser beam. [Figure 14] FIG. 14 is a top view of the embodiment shown in FIG. 13 having two diode stacks, along with the propagation of the pump beam. [Figure 15] 15 shows a further embodiment aimed at a power scaling arrangement having a thin film polarizer, a half wave plate, and two diode stacks providing a 400 W laser beam according to the embodiment of FIG. 14. [Figure 16] FIG. 16 is a top view of the embodiment of FIG. [Figure 17] 10 shows an alternative embodiment for homogenizing the beam. [Figure 18] FIG. 18 is a detailed view of an alternative embodiment of FIG. 17, illustrating an embodiment according to the present invention including a laser diode with a fast axis collimator (FAC), a beam twister (BT), and a slow axis collimator (SAC). [Figure 19] The intensity beam distribution from four diode bars in a laser diode stack is shown along with the rectangular envelope of the beam. [Figure 20] FIG. 2 is a schematic diagram showing an octagonal homogenizer used in the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0030] The following description illustrates an exemplary embodiment of a system capable of providing a uniformly shaped light beam. This light beam can be used as a pump beam directed to a laser head that emits a laser beam, particularly a compact and robust laser head with direct laser diode pumping. The pump light beam can be emitted by multiple light sources, such as a laser diode stack, resulting in a light beam with a non-uniform light intensity. In the case of a laser diode stack, the final envelope can be rectangular or square, depending on the shape of the laser diode stack. Generally, it is desirable to deliver a uniform beam, e.g., a top-hat beam, to the laser head. A major advantage of the present invention is the portability of the laser system and the ease of installation of the system, without the need for further alignment of optical elements within the system.

[0031] In a first example, we propose direct pumping of a thin-disk laser head using a laser diode stack, which offers many advantages. First, robustness and reliability are greatly improved by eliminating the use of optical fibers, which are typically used to deliver pump light from fiber-coupled laser diodes to the thin-disk laser head. Such optical fibers require careful handling, especially during installation, and in the case of industrial thin-disk laser systems, part of the installation is performed at the customer's site, where the fiber exiting the laser system is connected to the laser housing with the fiber-coupled laser diode (both modules need to be disconnected for transportation and part of the installation). With this design, there is always a risk of breaking the tip of the high-power fiber during the connection.

[0032] Second, the cost of thin disk lasers can be significantly reduced by eliminating optical fibers and directly using inexpensive laser diode stacks instead of expensive and complex fiber-coupled laser diode modules.

[0033] Another important improvement is the simplification of maintenance of the beam pump source. Separating the diode and collimation optics may allow replacement of only a defective laser diode stack. In contrast, existing fiber-coupled laser diode modules typically require maintenance and repair of the entire module, and replacing the laser diode stack requires realignment of the fiber-coupled optics, making the overall repair process more complicated.

[0034] Furthermore, this solution offers further advantages since other pump wavelengths can be used for different gain materials simply by selecting the appropriate laser diode stack from a wide range of available pump wavelengths. Additionally, the elimination of optical fiber allows for further pump wavelengths to be considered, which is important for lasers in the 2 μm range, as this component is no longer a limiting factor.

[0035] In a standard fiber-pumped laser head, the pump beam from the fiber is circular (Figure 3a). After reflecting off the laser head's parabolic mirror, it is deformed by the parabolic mirror's aberrations, resulting in a spot on the thin disk with an elliptical cross section that is degraded and off-center (Figure 3b). As this elliptical beam propagates through the pump chamber, after multiple reflections, the elliptical degraded beams overlap, resulting in a quasi-circular pump spot shape (Figure 3c). As shown in the simulation results in Figure 3d, the cross section exhibits significant pump spot degradation and blurred edges. In the present invention, we correct the parabolic mirror aberrations so that the beam exiting the homogenizer is elliptical (Figure 4a) and becomes symmetric on the thin disk after reflecting off the parabolic mirror (Figure 4b). This beam propagates through the excitation chamber and after multiple reflections, the beams overlap, resulting in a circular excitation spot shape (Fig. 4c), and a cross section shows a significant improvement in excitation spot shape compared to the fiber-pumped solution (Fig. 4d).

[0036] FIG. 5 is a detailed diagram of an embodiment of the present invention. In particular, FIG. 5 shows a source 1 generating a non-uniform light beam 11. The non-uniform light beam 11 has a different intensity profile, such as that shown in FIG. 19. Such an intensity distribution can be provided by an arrangement of multiple diodes in a rectangular laser diode stack 1. FIG. 5 also shows a beam-splitting rotating prism 2 receiving the non-uniform light beam 11 from the source 1, specifically, the laser diode stack 1. The source 1 of the non-uniform beam 11 can include a laser diode stack with four bars (19 outputs per bar) delivering an average power of 200 W at a wavelength of 940 nm. The emitted beam is collimated by fast-axis and slow-axis collimators. The beam is then split in two, rotated 90 degrees, and focused by a pair of cylindrical lenses onto an octagonal homogenizing rod, as shown in FIG. 5. The beam-splitting rotating prism 2 splits the beam 11 into two parts, with the first part 201 propagating through a longer optical path and the second part 202 propagating through a shorter optical path. The prism 2 rotates each part in the same direction and by the same angle. However, due to the optical path difference, the beam 21 generated in the first part 201 is inverted relative to the second part 202 of the beam 21. Therefore, the beam 21 is doubled relative to the non-uniform beam 11. Figure 5 shows the focusing means 3, specifically, two cylindrical lenses 3 and 4. The orientation of the second lens 4 is orthogonal to the first lens 3, and its focal length is selected based on the size of the beam emerging from the beam-splitting rotating prism 2 to fit within the numerical aperture of the homogenizer. Figure 5 also shows the homogenizer 5, which may be the conventional homogenizer described in the prior art document. The light beam from the homogenizer 5 is fully homogenized and easily focused onto a thin-disk laser head for amplifying the pump beam. Focusing onto the laser head 7 may be provided by conventional focusing means 6 .

[0037] FIG. 6 is a detailed diagram of the beam-splitting rotating prism 2 that receives the non-uniform excitation light beam 11. FIG. 6 is a structural diagram of the beam-splitting rotating prism 2, specifically showing two sections 201 and 202 that provide short and long optical paths, indicated by lines. The beam-splitting rotating prism has two sections. The beam-splitting rotating prism is manufactured from a single piece of material, such as crystal or glass. The manufacturing method can involve manufacturing the sections separately and then joining them. The first section provides a longer optical path and thus corresponds to the slow axis. Compared to the first section of the beam-splitting rotating prism, the second section provides a shorter optical path. As can be seen from this diagram, the beam 21 further propagates through a pair of cylindrical lenses 3 and 4, which are the focusing means 3, and then the beam 41 propagates to the homogenizing section 5.

[0038] The circular, uniform pump spot structure obtained with the present invention is shown in the simulation results in Figure 7. This high-quality pump spot shape is important for the performance of high-power thin-disk lasers operating in the single-mode (TEM00) regime. In particular, Figure 7 shows the process of a beam that has been homogenized by multiple reflections through the beam homogenizer 5.

[0039] 8 shows that the excitation beam 51 emitted from the homogenizer 5 is received by a focusing means 6, and a focused homogenized excitation beam 61 is directed to a laser head 7. The laser head 7 may include a number of mirrors that direct the beam 61 onto a thin disk. The thin disk, the laser head 7, and the process of amplifying the excitation beam are known in the art.

[0040] FIG. 9 shows the simulation results of the amplified uniform beam obtained from the system according to the invention.

[0041] 10a and 10b are cross sections of the beam spot of FIG.

[0042] FIG. 11 shows a pair of anamorphic prisms 8 positioned between the beam splitting rotating prism 2 and the laser diode stack 1 .

[0043] FIG. 12 is a top view of the embodiment shown in FIG.

[0044] To increase the pump power of the present invention, there are three approaches that have been incorporated into further embodiments of the present invention. In certain embodiments, a laser diode stack with multiple diode bars may be used. As the emitting area of ​​the laser diode increases, an anamorphic prism pair 8 may be used to reduce the beam size to fit onto the beam splitting rotating prism, as shown in Figures 11 and 12.

[0045] Another way to increase power is beam combining of two (or more) laser diode stacks by bending the beam of the second (or more) diode stack in the same direction using a bar mirror array 11, as shown in Figures 13 and 14.

[0046] 15 and 16, it is also possible to combine multiple beams from two (or more) diode stacks using a thin film polarizer 12 and a half wave plate 91, and by changing the polarization, it is also possible to combine a beam from a second (or more) diode stack with a beam from a first diode stack. Non-uniform beams 102, 101 are combined.

[0047] By using the above-mentioned power increasing methods, pumping powers in the kW range can be obtained.

[0048] An alternative embodiment of the present invention is shown in Figures 17 and 18. A laser system for homogenizing an optical excitation beam from a non-uniform excitation source 1 and delivering the uniform excitation beam to a laser head 7 including a thin disk active medium that amplifies the homogenized excitation beam, the system including a plurality of sources 1 generating light beams of non-uniform optical intensity, beam splitting and collimating means 2' including a fast-axis collimator FAC that receives the non-uniform light beams 11 from the plurality of sources 1, a beam twister that receives the light beam from the fast-axis collimator FAC, and a slow-axis collimator SAC that receives the non-uniform light beam 11 from the beam twister, focusing means 301, 302 that receive the beam from the beam splitting and collimating means 2' and focus it onto a homogenizing section 5, thereby providing a homogenized optical excitation beam 51, and a laser head 7 including a thin disk that receives the homogenized light beam 51 from the homogenizing section 5, where the homogenized light beam 51 is directed towards the thin disk.

[0049] FIG. 20 shows a preferred embodiment of the equalizer with its size. [Explanation of symbols]

[0050] 1 Laser diode stack 2 beam splitting rotating prism 3. First Lens 4. Second Lens 5 Equalization section 6 Focusing means 7 Laser Head 8 Anamorphic Prism Pair 9 Bar Mirror Array 10 Second source of non-uniform beam - second diode stack 12 1 / 2 wave plate FAC First Axis Collimator BT Beam Twister SAC slow axis collimator

Claims

1. 1. A laser system for homogenizing an optical pump beam from a non-uniform pump source and delivering the homogenized pump beam to a laser head including a thin disk active medium that amplifies the homogenized pump beam, comprising: a source generating said optical excitation beam having a non-uniform light intensity; a beam splitting rotating prism configured to receive the non-uniform optical excitation beam, the beam splitting rotating prism having a first portion providing a longer optical path and a second portion providing a shorter optical path, the beam splitting rotating prism configured to split the non-uniform optical excitation beam into two portions, the first portion configured to propagate through the longer optical path and the second portion configured to propagate through the shorter optical path, and configured to rotate each portion in the same direction by the same angle; focusing means for receiving both portions of the beam from the beam splitting rotating prism and focusing them onto a homogenizing section, thereby providing a homogenized optical excitation beam; the laser head including a thin disk and receiving the homogenized optical excitation beam from the homogenizing unit, the homogenized optical excitation beam being directed toward the thin disk; A system including:

2. The system of claim 1 , wherein the source that generates the non-uniform optical excitation beam is a stack of multiple laser diodes.

3. The system of claim 1 , wherein the uniformizer is a polygonal uniformizer.

4. 2. The system of claim 1, wherein the focusing means is two cylindrical lenses, the orientation of the second of the lenses being orthogonal to the orientation of the first of the lenses, and the focal length selected based on the size of the beam exiting the beam splitting rotating prism to fall within the numerical aperture of the homogenizer.

5. an anamorphic prism pair disposed between the plurality of laser diode stacks and the beam splitting rotating prism; The system of claim 2 further comprising:

6. a bar mirror array disposed between the plurality of laser diode stacks and the beam splitting rotating prism; The system of claim 2 further comprising:

7. a polarizer disposed between the plurality of laser diode stacks and the beam splitting rotating prism; The system of claim 2 further comprising:

8. a half-wave plate disposed between the plurality of laser diode stacks and the polarizer; The system of claim 7 further comprising:

9. a further bar mirror array disposed between the plurality of laser diode stacks and the beam splitting rotating prism; The system of claim 7 further comprising:

10. 1. A laser system for homogenizing an optical pump beam from a non-uniform pump source and delivering the homogenized pump beam to a laser head including a thin disk active medium that amplifies the homogenized pump beam, comprising: a plurality of sources generating said optical excitation beams having non-uniform light intensity; a beam splitting and collimating means, a first axis collimator for receiving the non-uniform optical excitation beams from the plurality of sources; a beam twister that receives the optical excitation beam from the first axis collimator; and a slow axis collimator for receiving the non-uniform optical excitation beam from the beam twister; focusing means for receiving the beam from the beam splitting and collimating means and focusing the beam onto a homogenizing section, thereby providing a homogenized optical excitation beam; the laser head including a thin disk and receiving the homogenized optical excitation beam from the homogenizer, the homogenized optical excitation beam being directed toward the thin disk; A system including:

11. 2. The system of claim 1, wherein the source generating the non-uniform optical excitation beam is a stack of multiple laser diodes spatially arranged such that the non-uniform optical excitation beam is delivered to the beam-splitting rotating prism.

12. The system of claim 1 , wherein the source that generates the non-uniform optical excitation beam is a plurality of laser bars.

13. The system of claim 1 , wherein the source that generates the non-uniform optical excitation beam is a plurality of laser emitters.

14. 4. The system of claim 3, wherein the polygonal homogenizer is an octagonal homogenizer having an asymmetric geometric shape with vertical and horizontal cross-sectional dimensions configured to compensate for differences in magnification in the vertical and horizontal planes introduced by aberrations of a parabolic mirror.

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