Beam conditioning device, laser system and method of beam conditioning

Abstract

The present disclosure relates to a light beam adjusting device, a laser system and a light beam adjusting method. The light beam adjusting device comprises: a spherical lens configured to converge a first light beam to generate a second light beam; a cylindrical lens group located on an outgoing light path of the spherical lens and having an acting direction being one of a first direction and a second direction, the cylindrical lens group being configured to adjust the second light beam to generate a third light beam; and a spatial filter located on an outgoing light path of the cylindrical lens group and configured to filter the third light beam to generate a fourth light beam.

Description

Technical Field

[0001] This disclosure relates to the field of optical technology, and more specifically, to a beam conditioning device, a laser system, and a beam conditioning method. Background Technology

[0002] With the rapid development of laser amplification technology, higher-power laser beams have been generated, playing an important role in many fields. However, due to factors such as thermal effects, the cross-section of the output laser beam in some laser systems is not ideal, making such beams unsuitable for many scenarios. Therefore, there is a need for spatial shaping and quality optimization of the laser beam. Summary of the Invention

[0003] One of the objectives of this disclosure is to provide a beam adjustment device, laser system, and beam adjustment method that, through optical components such as cylindrical lens groups, adjusts the beam waist parameters and divergence characteristics in another direction based on the beam waist parameters and divergence characteristics in one direction of the laser beam's cross-section, thereby achieving spatial shaping and quality optimization of the beam.

[0004] According to a first aspect of this disclosure, a beam adjustment device is provided, the beam adjustment device comprising:

[0005] A spherical lens configured to converge a first beam to produce a second beam, wherein a first beam waist in a first direction of the second beam is located at a first observable position, a second beam waist in a second direction of the second beam is located at a second observable position, and the first and second directions are orthogonal to each other.

[0006] A cylindrical lens group, located in the exit light path of the spherical lens, with the acting direction of the cylindrical lens group being one of a first direction and a second direction, is configured to adjust the second beam to generate a third beam. The distance between the first axial position of the first beam waist in the first direction of the third beam in the beam propagation direction and the second axial position of the second beam waist in the second direction of the third beam in the beam propagation direction is less than or equal to a first preset length, and the absolute value of the difference between the first dimension of the first beam waist and the second dimension of the second beam waist of the third beam is less than or equal to a second preset length.

[0007] A spatial filter is located in the outgoing light path of the cylindrical lens group and is configured to filter the third beam to generate a fourth beam, wherein a first divergence characteristic in a first direction of the fourth beam is consistent with a second divergence characteristic in a second direction of the fourth beam.

[0008] In some embodiments, the beam adjustment device further includes:

[0009] A beam quality analyzer is located in the outgoing optical path of the spatial filter and is configured to receive and measure at least a portion of the fourth beam.

[0010] In some embodiments, the beam adjustment device further includes:

[0011] An optical attenuator is located between the spatial filter and the beam quality analyzer, and the optical attenuator is configured to attenuate the fourth beam.

[0012] In some embodiments, the optical attenuator includes:

[0013] A reflector configured to reflect a portion of the fourth beam onto the optical quality analyzer.

[0014] In some embodiments, the cylindrical lens group is configured to adjust the second beam according to the size measurement of at least a portion of the fourth beam by the beam quality analyzer, such that the first axial position of the first beam waist of the third beam coincides with the second axial position of the second beam waist of the third beam, and the first dimension of the first beam waist of the third beam is equal to the second dimension of the second beam waist of the third beam.

[0015] In some embodiments, the spatial filter is configured to adjust filtering parameters based on beam quality factor measurements of at least a portion of the fourth beam by the beam quality analyzer to filter the third beam.

[0016] In some embodiments, the cylindrical lens group includes:

[0017] A first cylindrical lens is disposed between the spherical lens and the spatial filter, and the direction of action of the first cylindrical lens is one of the first and second directions; and

[0018] The second cylindrical lens is disposed between the first cylindrical lens and the spatial filter, and the direction of action of the second cylindrical lens is the same as that of the first cylindrical lens;

[0019] The first distance between the cylindrical lens group and the spherical lens can be adjusted to change the position of a corresponding one of the first and second beam waists of the third beam, and the second distance between the first cylindrical lens and the second cylindrical lens can be adjusted to change the size of the corresponding one of the first and second beam waists of the third beam.

[0020] In some embodiments, the direction of action of the cylindrical lens group is a first direction, and the first direction is the slow axis direction.

[0021] In some embodiments, the first beam comprises a Gaussian beam.

[0022] According to a second aspect of this disclosure, a laser system is provided, the laser system comprising:

[0023] A laser amplifier, the laser amplifier being configured to generate a first beam; and

[0024] The beam adjustment device described above is located in the output optical path of the laser amplifier and is configured to adjust the first beam.

[0025] In some embodiments, the laser amplifier includes a partially end-face pumped slab amplifier.

[0026] According to a third aspect of this disclosure, a beam adjustment method is provided, the beam adjustment method comprising:

[0027] A spherical lens, a cylindrical lens group, and a spatial filter are provided in sequence, wherein the spherical lens has a first focal length and the cylindrical lens group has a second adjustable focal length range;

[0028] The position of the spherical lens is adjusted so that the first beam passes through and is converged by the spherical lens to generate a second beam, wherein the first beam waist of the second beam in the first direction is located at a first observable position, the second beam waist in the second direction of the second beam is located at a second observable position, and the first direction and the second direction are orthogonal to each other;

[0029] The position of the cylindrical lens group is adjusted so that the second beam passes through the cylindrical lens group to generate a third beam, wherein the direction of action of the cylindrical lens group is one of the first and second directions, the distance between the first axial position of the first beam waist in the first direction of the third beam in the beam propagation direction and the second axial position of the second beam waist in the second direction of the third beam in the beam propagation direction is less than or equal to a first preset length, and the absolute value of the difference between the first dimension of the first beam waist and the second dimension of the second beam waist of the third beam is less than or equal to a second preset length; and

[0030] The spatial filter is adjusted so that the third beam passes through the spatial filter to generate a fourth beam, wherein the first divergence characteristic of the fourth beam in a first direction is consistent with the second divergence characteristic of the fourth beam in a second direction.

[0031] In some embodiments, the beam adjustment method further includes:

[0032] A beam quality analyzer is provided on the outgoing optical path of the spatial filter, such that the beam quality analyzer receives and measures at least a portion of the fourth beam.

[0033] In some embodiments, adjusting the position of the cylindrical lens group such that the second beam passes through the cylindrical lens group to generate a third beam includes:

[0034] Based on the size measurement of at least a portion of the fourth beam by the beam quality analyzer, the cylindrical lens group is adjusted such that the first axial position of the first beam waist of the third beam coincides with the second axial position of the second beam waist of the third beam, and the first dimension of the first beam waist of the third beam is equal to the second dimension of the second beam waist of the third beam.

[0035] In some embodiments, adjusting the spatial filter such that the third beam passes through the spatial filter to generate a fourth beam includes:

[0036] Based on the beam quality factor measurement of at least a portion of the fourth beam by the beam quality analyzer, the filtering parameters of the spatial filter are adjusted so that the first divergence characteristic of the fourth beam in the first direction is consistent with the second divergence characteristic of the fourth beam in the second direction.

[0037] In some embodiments, the cylindrical lens group includes a first cylindrical lens and a second cylindrical lens. The first cylindrical lens is disposed between the spherical lens and the spatial filter, and the direction of action of the first cylindrical lens is one of the first direction and the second direction. The second cylindrical lens is disposed between the first cylindrical lens and the spatial filter, and the direction of action of the second cylindrical lens is consistent with the direction of action of the first cylindrical lens.

[0038] Adjusting the position of the cylindrical lens group so that the second beam passes through the cylindrical lens group to generate the third beam includes:

[0039] Adjusting the first distance between the cylindrical lens group and the spherical lens to change the position of one of the corresponding first and second beam waists of the third beam, such that the distance between the first axial position of the first beam waist in the first direction of the third beam in the beam propagation direction and the second axial position of the second beam waist in the second direction of the third beam in the beam propagation direction is less than or equal to a first preset length; and

[0040] The second distance between the first cylindrical lens and the second cylindrical lens is adjusted to change the size of one of the corresponding first and second beam waists of the third beam, such that the absolute value of the difference between the first size of the first beam waist and the second size of the second beam waist of the third beam is less than or equal to a second preset length.

[0041] In some embodiments, adjusting the spatial filter such that the third beam passes through the spatial filter to generate a fourth beam includes:

[0042] Adjust the position of the spatial filter so that it is located at the first and second beam waists after the fourth beam overlaps.

[0043] In some embodiments, the direction of action of the cylindrical lens group is a first direction, and the first direction is the slow axis direction.

[0044] Other features and advantages of this disclosure will become clearer from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0045] The accompanying drawings, which form part of this specification, illustrate embodiments of this disclosure and, together with the specification, serve to explain the principles of this disclosure.

[0046] This disclosure will become clearer with reference to the accompanying drawings and the following detailed description, wherein:

[0047] Figure 1 A schematic diagram of the structure of a laser system according to an exemplary embodiment of the present disclosure is shown;

[0048] Figure 2 A schematic diagram of the optical path in a beam adjustment device according to an exemplary embodiment of the present disclosure is shown;

[0049] Figure 3 A schematic flowchart of a beam adjustment method according to an exemplary embodiment of the present disclosure is shown.

[0050] Note that in the embodiments described below, the same reference numerals are sometimes used across different figures to denote the same parts or parts having the same function, and repeated descriptions are omitted. In this specification, similar reference numerals and letters are used to denote similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0051] For ease of understanding, the positions, dimensions, and extents of the structures shown in the accompanying drawings and other materials may not represent actual positions, dimensions, and extents. Therefore, the disclosed invention is not limited to the positions, dimensions, and extents disclosed in the accompanying drawings and other materials. Furthermore, the drawings are not necessarily drawn to scale, and some features may be enlarged to show details of specific components. Detailed Implementation

[0052] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present disclosure.

[0053] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this disclosure or its application or use. Those skilled in the art will understand that they merely illustrate exemplary ways that can be used to implement this disclosure, and are not exhaustive.

[0054] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0055] With the development of laser technology, some laser amplifiers are now capable of outputting high-power laser beams. For example, some end-pumped slab amplifiers (Innoslab amplifiers) can be based on laser media such as Yb:YAG and Nd:YVO4, and in some cases, such amplifiers can output kilowatt-level laser beams. However, due to the inherent optical structure characteristics of the laser amplifier itself, the cross-section of the output laser beam may not be ideal, limiting the application of such laser beams in many scenarios. For instance, in Innoslab amplifiers, due to the uniform linear pump characteristics and the one-dimensional thermal conduction within the crystal, the thermal gradient inside the slab crystal is also one-dimensionally distributed. This thermal gradient or temperature gradient makes the slab crystal equivalent to a cylindrical lens in the fast axis direction (perpendicular to the pump line), while having almost no thermal effect in the slow axis direction (the direction of the pump line). The cylindrical thermal lens enables the beam passing through the amplifier multiple times to achieve self-reproduction in the fast axis direction, that is, equivalent to the existence of a stable resonant cavity in the fast axis direction, allowing energy extraction through mode matching. Two methods are typically used to refract the injected beam multiple times through the gain medium in an Innoslab amplifier. One method uses a pair of confocal cylindrical mirrors to create an unstable cavity along the slow axis and a stable cavity along the fast axis. This magnifies the beam's size along the slow axis with each round trip through the gain medium or crystal. Another method uses only a pair of plane mirrors as the cavity mirrors and leverages the divergence properties of the Gaussian beam to allow the injected beam to diverge freely along the slow axis. Regardless of the method used, the cross-section of the beam output from the Innoslab amplifier is elliptical rather than circular, and the beam component along the fast axis has a larger divergence angle than the component along the slow axis. Compared to a circular beam cross-section, an elliptical beam cross-section results in a larger focused spot size, leading to reduced irradiance (power per unit area). Therefore, spatial shaping and quality optimization of the output beam are necessary, for example, to make the cross-section of the beam output from the Innoslab amplifier as close to circular as possible.

[0056] In some examples, one or two pairs of cylindrical telescopes can be used to spatially shape the output beam. Here, one or a pair of cylindrical lenses are used for spatial shaping in each of the two orthogonal directions on the beam cross-section. However, both methods have their drawbacks. Specifically, if only one pair of cylindrical lenses is used, i.e., one cylindrical lens is placed in each of the two orthogonal directions on the beam cross-section, then precise measurement of the spatial characteristics of the beam directly output by the amplifier is required. However, under high-power pumping conditions, such as Innoslab amplifiers, the focal length of the equivalent thermal lens of its gain medium is limited, thus requiring an extremely short cavity length (20–60 mm). In other words, the amplifier structure is extremely compact, which makes it very difficult to accurately measure the beam at the amplifier's output. On the other hand, if two pairs of cylindrical lenses are used, i.e., one pair of cylindrical lenses is placed in each of the two orthogonal directions on the beam cross-section, then obviously a large number of cylindrical lenses are required, the adjustment and calibration accuracy requirements are high, and the operation is more difficult.

[0057] To address the aforementioned issues, this disclosure proposes an optical adjustment device that uses the beam waist parameter and divergence characteristics in one direction of the beam cross-section as a reference to adjust the beam waist parameter and divergence characteristics in another direction, thereby achieving spatial shaping and quality optimization of the beam.

[0058] In one exemplary embodiment of this disclosure, such as Figure 1 and Figure 2 As shown, the beam adjustment device may include a spherical lens 210, a cylindrical lens group and a spatial filter 230 arranged in sequence.

[0059] The spherical lens 210 can be configured to converge the first beam 910 to generate the second beam 920. It is understood that the spherical lens 210 can have curvature in all directions, thereby enabling the convergence of components of the beam in all directions. Here, the first beam 910 can be the output beam from the laser amplifier 100. By employing a spherical lens 210 with a suitable focal length, the first beam waist of the second beam 920 in the first direction can be located at a first observable position, and the second beam waist of the second beam 920 in the second direction can be located at a second observable position. Furthermore, the dimensions of the first and second beam waists can each be within a suitable range for subsequent adjustment. Here, both the first and second directions are perpendicular to the beam propagation direction, and the first and second directions can be orthogonal to each other. The focal length range of the spherical lens 210 can be calculated based on the desired observable position range and the desired beam waist size range, and a spherical lens 210 with a suitable focal length can be selected accordingly. In this document, the technical solution of this disclosure will be described in detail with the example of a first direction corresponding to the slow axis direction of the crystal in the laser amplifier 100 and a second direction corresponding to the fast axis direction of the crystal in the laser amplifier 100 (or, the first direction is the slow axis direction of the beam and the second direction is the fast axis direction of the beam). However, it is understood that in some other embodiments, the first direction and the second direction may also be other directions on a cross section perpendicular to the beam propagation direction, as long as the first direction and the second direction are orthogonal to each other, and no limitation is made here.

[0060] like Figure 1 and Figure 2 As shown, the cylindrical lens group can be located in the output light path of the spherical lens 210, and the direction of action of the cylindrical lens group can be one of the first and second directions. That is, the cylindrical lens group can be configured to act only on the component of the second beam in one of the first or second directions, and not on the component in the other direction. In some embodiments, considering that the beam waist size in the fast axis direction is generally smaller than the beam waist size in the slow axis direction, and that the beam diverges faster in the fast axis direction than in the slow axis direction, the beam parameters in the slow axis direction can be adjusted based on the beam parameters in the fast axis direction. Thus, the direction of action of the cylindrical lens group can be selected as the slow axis direction. Figure 2 As shown, the component of the beam in the slow axis direction (e.g.) Figure 2 The light beam (as indicated by the dashed arrow) will converge or diverge under the action of the cylindrical lens group, while the component of the light beam in the fast axis direction (such as...) Figure 2(As indicated by the solid arrow) will not be affected by the cylindrical lens group and will continue to travel in its original propagation mode. It is understood that in some other embodiments, the beam parameters in the fast axis direction can be adjusted based on the beam parameters in the slow axis direction, and correspondingly, the direction of action of the cylindrical lens group can be selected as the fast axis direction.

[0061] exist Figure 2 In the exemplary embodiment shown, the cylindrical lens group can be configured to adjust the second beam 920 to generate a third beam 930. To obtain an ideal (e.g., circular) beam cross-section, the cylindrical lens group is adjusted such that the distance between the first axial position of the first waist of the third beam 930 in the first direction along the beam propagation direction and the second axial position of the second waist of the third beam 930 in the second direction along the beam propagation direction is less than or equal to a first preset length, and the absolute value of the difference between the first dimension of the first waist of the third beam 930 and the second dimension of the second waist of the third beam 930 is less than or equal to a second preset length. Here, the waist refers to the portion of the beam (e.g., a Gaussian beam) having the smallest dimension in its cross-section perpendicular to its propagation direction. In some embodiments, the adjustment of the cylindrical lens group can be divided into coarse adjustment and fine adjustment. First, the cylindrical lens group can be coarsely adjusted so that the axial positions (i.e., positions in the beam propagation direction) of the waists in the two orthogonal directions of the third beam 930 substantially coincide, and the dimensions of the waists in the two orthogonal directions of the third beam 930 are substantially the same. Here, the first preset length and the second preset length can be set according to the adjustment accuracy requirements. The smaller the first and second preset lengths, the closer the cross-section of the final beam will be to the ideal circle. Furthermore, in some embodiments, the cylindrical lens group can be finely adjusted using an optical quality analyzer or the like, so that the axial positions of the beam waists in the two orthogonal directions of the third beam 930 coincide, and the dimensions of the beam waists in the two orthogonal directions of the third beam 930 are equal, as will be described in detail later.

[0062] like Figure 1 and Figure 2As shown, in a specific example of this disclosure, the cylindrical lens group may include a first cylindrical lens 221 and a second cylindrical lens 222. The first cylindrical lens 221 may be disposed between the spherical lens 210 and the spatial filter 230, and the direction of action of the first cylindrical lens 221 may be one of a first direction and a second direction. The second cylindrical lens 222 may be disposed between the first cylindrical lens 221 and the spatial filter 230, and the direction of action of the second cylindrical lens 222 is consistent with the direction of action of the first cylindrical lens 221. In some embodiments, the directions of action of the first cylindrical lens 221 and the second cylindrical lens 222 may both be the first direction or the slow-axis direction, that is, the first cylindrical lens 221 or the second cylindrical lens 222 has curvature only in the slow-axis direction, so as to achieve convergence or divergence of the component of the light beam in the slow-axis direction. Alternatively, in other embodiments, the directions of action of the first cylindrical lens 221 and the second cylindrical lens 222 may both be the second direction or the fast-axis direction, that is, the first cylindrical lens 221 or the second cylindrical lens 222 has curvature only in the fast-axis direction, so as to achieve convergence or divergence of the component of the light beam in the fast-axis direction. Since the cylindrical lens group operates only in one of the first and second directions, the components in the corresponding operating direction can be adjusted based on the parameters of the beam in the other direction, thereby easily and accurately achieving spatial shaping and quality optimization of the beam. In some embodiments, a first cylindrical lens 221 and a second cylindrical lens 222 with appropriate focal lengths can be selected according to, for example, relevant formulas for lens transformation of Gaussian beams, so that the cross-sectional shape of the third beam 930, as described below, can be adjusted to the desired shape.

[0063] In some embodiments, the first distance between the cylindrical lens group and the spherical lens 210 can be adjusted to change the position of a corresponding one of the first and second beam waists of the third beam 930. For example, when the first cylindrical lens 221 and the second cylindrical lens 222 are in the slow-axis direction, the axial position of the first beam waist in the slow-axis direction of the third beam 930 can be changed by adjusting the first distance between the cylindrical lens group and the spherical lens 210, while keeping the axial position of the second beam waist in the fast-axis direction of the third beam 930 unchanged or substantially unchanged. In this way, the axial position of the first beam waist of the third beam 930 can be adjusted based on the axial position of the second beam waist in the fast-axis direction of the third beam 930 to achieve spatial shaping of the beam. Similarly, when the first cylindrical lens 221 and the second cylindrical lens 222 are in the fast-axis direction, the position of the second beam waist in the fast-axis direction of the third beam can be changed by adjusting the first distance between the cylindrical lens group and the spherical lens 210.

[0064] On the other hand, the second distance between the first cylindrical lens 221 and the second cylindrical lens 222 can be adjusted to change the size of one of the corresponding first and second beam waists of the third beam 930. Changing the second distance between the first cylindrical lens 221 and the second cylindrical lens 222 is equivalent to changing the focal length of the entire cylindrical lens group. For example, when the action direction of the first cylindrical lens 221 and the second cylindrical lens 222 is in the slow axis direction, the size of the first beam waist of the third beam 930 in the slow axis direction can be changed by adjusting the second distance between the first cylindrical lens 221 and the second cylindrical lens 222, while keeping the size of the second beam waist of the third beam 930 unchanged or substantially unchanged in the fast axis direction. In this way, the size of the first beam waist of the third beam 930 in the slow axis direction can be adjusted based on the size of the second beam waist in the fast axis direction, thereby achieving spatial shaping of the beam. Similarly, when the action direction of the first cylindrical lens 221 and the second cylindrical lens 222 is the fast axis direction, the size of the second beam waist of the third beam 930 in the fast axis direction can be changed by adjusting the second distance between the first cylindrical lens 221 and the second cylindrical lens 222.

[0065] like Figure 1 and Figure 2 As shown, the spatial filter 230 can be located in the exit light path of the cylindrical lens group, and the spatial filter 230 can be configured to filter the third beam 930 to generate the fourth beam 940. The first divergence characteristic of the fourth beam 940 in a first direction is consistent with the second divergence characteristic of the fourth beam 940 in a second direction. Thus, especially when the beams (including any one of the first beam 910, second beam 920, third beam 930, and fourth beam 940) are Gaussian beams, the adjusted fourth beam 940 can maintain a desired shape (e.g., circular) in a cross-section perpendicular to the beam propagation direction during propagation.

[0066] In some embodiments, the spatial filter 230 may be placed at or near the location where the first and second beam waists of the adjusted third beam 930 coincide, and the spatial filter 230 is configured to filter stray light, thereby further optimizing the beam quality. Specifically, the third beam 930 may contain unwanted sidelobes or stray light. In the technical solutions of this disclosure, these unwanted sidelobes or stray light can be filtered out by the spatial filter 230, or in other words, the high-frequency components of the beam can be filtered out, retaining only the low-frequency components, to obtain a fourth beam 940 with better quality. In some embodiments, the spatial filter 230 may include an aperture or grating with a specific shaped aperture. Alternatively, in some embodiments, the spatial filter 230 may include a slit or aperture with an adjustable light transmission size.

[0067] like Figure 1 As shown, the beam conditioning apparatus according to an exemplary embodiment of the present disclosure may further include a beam quality analyzer 250, which may be located in the outgoing optical path of the spatial filter 230, and may be configured to receive and measure at least a portion of the fourth beam to help achieve real-time and fine-tuning of the beam and improve beam quality. In some embodiments, the beam quality analyzer 250 may include a CCD or CMOS imaging component.

[0068] In some embodiments, the spatial characteristics of the beam can be observed by the beam quality analyzer 250, and the first and second spacings associated with at least the cylindrical lens group can be adjusted based on the observation results. In other words, the cylindrical lens group can be configured to adjust the second beam 920 according to the size measurement of at least a portion of the fourth beam 940 by the beam quality analyzer 250 (e.g., real-time adjustment) such that the axial positions of the waists of the third beam 930 in two orthogonal directions (e.g., the first axial position of the first waist and the second axial position of the second waist) coincide or substantially coincide, and the dimensions of the waists of the third beam 930 in the two orthogonal directions (e.g., the first dimension of the first waist and the second dimension of the second waist) are equal or substantially equal.

[0069] In addition, the beam quality analyzer 250 can also be used to measure the beam quality factor (M) of the beam in two orthogonal directions. 2 Based on the measurement results of the beam quality analyzer 250, the spatial filter 230 can be adjusted. In other words, the spatial filter 230 can be configured to adjust the filtering parameters based on the beam quality factor measurement of at least a portion of the fourth beam 940 by the beam quality analyzer 250, so as to filter the third beam 930 such that the divergence characteristics of the components of the third beam 930 in the two orthogonal directions are the same or substantially the same.

[0070] In some embodiments, the beam quality analyzer 250 can be configured to directly receive and measure the fourth beam 940. However, in some cases, the maximum light intensity that the beam quality analyzer 250 can receive or detect is lower than the light intensity of the beam directly output by the laser amplifier 100. Therefore, to protect the beam quality analyzer 250 and ensure measurement accuracy, the beam adjustment device may also include an optical attenuator. The optical attenuator may be located between the spatial filter 230 and the beam quality analyzer 250, and the optical attenuator is configured to attenuate the fourth beam 940.

[0071] In some embodiments, the optical attenuator can attenuate the fourth beam 940 by absorbing a portion of it; for example, it may include a filter coated with a light-absorbing material. In other embodiments, such as Figure 1 As shown, the optical attenuation element may include a reflector 240, which can be configured to reflect a portion of the fourth beam 940 to the optical quality analyzer 250, i.e., attenuation is achieved by reflecting a portion of the fourth beam 940. In some embodiments, filters and reflectors may also be used in combination as optical attenuation elements. By setting the optical attenuation element, the intensity of the beam input to the beam quality analyzer 250 can be kept within a suitable range, thereby achieving better detection results and improving the reliability and safety of the device. It is understood that in some embodiments, the beam quality analyzer 250 itself may also integrate an optical attenuation element capable of adjusting the intensity of the beam entering it, which is not limited here.

[0072] According to another aspect of this disclosure, a laser system is also proposed. For example... Figure 1 As shown, in one exemplary embodiment, the laser system may include a laser amplifier 100 and a beam adjustment device as described above. The laser amplifier 100 may be configured to generate a first beam 910, and the beam adjustment device may be located in the output optical path of the laser amplifier 100 and configured to adjust the first beam 910 to generate an output beam with an ideal cross-sectional shape to meet the needs of various application scenarios. In some embodiments, the laser amplifier 100 and the beam adjustment device may be integrated into a single unit. In other embodiments, the laser amplifier 100 and the beam adjustment device may also be separately configured and arranged as described herein, if necessary, to achieve spatial shaping and quality optimization of the laser beam.

[0073] In some embodiments, the laser amplifier 100 may include a partially end-pumped slab amplifier as described above, which can output a high-power Gaussian laser beam and has wide applications in practice.

[0074] According to another aspect of this disclosure, a beam adjustment method is also provided, which can be implemented based on the beam adjustment device described above, thereby generating a laser beam with an ideal (e.g., circular) cross-sectional shape.

[0075] In one exemplary embodiment of this disclosure, such as Figures 1 to 3 As shown, the beam adjustment method may include:

[0076] Step S310: A spherical lens 210, a cylindrical lens group, and a spatial filter 230 are provided in sequence.

[0077] Step S320: Adjust the position of the spherical lens 210 so that the first beam 910 passes through and is converged by the spherical lens 210 to generate the second beam 920.

[0078] Step S330: Adjust the position of the cylindrical lens group so that the second beam 920 passes through the cylindrical lens group to generate the third beam 930; and

[0079] In step S340, the spatial filter 230 is adjusted so that the third beam 930 passes through the spatial filter 230 to generate the fourth beam 940.

[0080] The spherical lens 210 can have a first focal length. By adjusting the position of the spherical lens 210, the first beam 910 can pass through and be converged by the spherical lens 210 to generate a second beam 920. Here, the first beam waist of the second beam 920 in a first direction can be located at a first observable position, and the second beam waist of the second beam 920 in a second direction can be located at a second observable position. At the first and second observable positions, the relevant dimensions of the beam cross-section can be conveniently observed or measured, and these dimensions are appropriate. This allows at least one of the aforementioned optical components to be adjusted based on the observation or measurement results to achieve spatial shaping and quality optimization of the beam. As mentioned above, the first and second directions are orthogonal to each other, and each of the first and second directions is perpendicular to the beam propagation direction. In a specific example, the first direction can be the slow axis direction, while the second direction can be the fast axis direction.

[0081] Furthermore, the working direction of the cylindrical lens group can be one of the first and second directions, and the cylindrical lens group has a second adjustable focal length range. By adjusting the position of each cylindrical lens in the cylindrical lens group, the distance between the first axial position of the first beam waist in the first direction of the third beam 930 in the beam propagation direction and the second axial position of the second beam waist in the second direction of the third beam 930 in the beam propagation direction can be less than or equal to a first preset length, and the absolute value of the difference between the first dimension of the first beam waist of the third beam 930 and the second dimension of the second beam waist of the third beam 930 is less than or equal to the second preset length, that is, at least coarse adjustment of the beam is achieved.

[0082] In some embodiments, the cylindrical lens group may include a first cylindrical lens 221 and a second cylindrical lens 222. The first cylindrical lens 221 may be disposed between the spherical lens 210 and the spatial filter 230. The working direction of the first cylindrical lens 221 is one of the first direction and the second direction. The second cylindrical lens 222 may be disposed between the first cylindrical lens 221 and the spatial filter 230, and the working direction of the second cylindrical lens 222 is consistent with the working direction of the first cylindrical lens 221. Based on this, adjusting the position of the cylindrical lens group so that the second beam 920 passes through the cylindrical lens group to generate the third beam 930 may include: adjusting the first distance between the cylindrical lens group and the spherical lens 210 to change the position of a corresponding one of the first and second beam waists of the third beam 930, such that the distance between the first axial position of the first beam waist in the first direction of the third beam 930 in the beam propagation direction and the second axial position of the second beam waist in the second direction of the third beam 930 in the beam propagation direction is less than or equal to a first preset length; and adjusting the second distance between the first cylindrical lens 221 and the second cylindrical lens 222 to change the size of the aforementioned corresponding one of the first and second beam waists of the third beam 930, such that the absolute value of the difference between the first size of the first beam waist of the third beam 930 and the second size of the second beam waist of the third beam 930 is less than or equal to a second preset length. In some embodiments, the second distance between the first cylindrical lens 221 and the second cylindrical lens 222 can be fixed first, and the first distance between the cylindrical lens group and the spherical lens 210 can be adjusted (for example, the first cylindrical lens 221 and the second cylindrical lens 222 can be mounted on the same base, and the first distance can be adjusted by adjusting the position of the base) so that the waist falls at the desired observable position; then the second distance between the first cylindrical lens 221 and the second cylindrical lens 222 can be adjusted to adjust the waist to the desired size.

[0083] Furthermore, by adjusting the spatial filter 230, the first divergence characteristic of the generated fourth beam 940 in the first direction can be made consistent with the second divergence characteristic of the fourth beam 940 in the second direction. In some embodiments, to simplify and optimize the filtering characteristics of the spatial filter 230, adjusting the spatial filter 230 so that the third beam 930 passes through the spatial filter 230 to generate the fourth beam 940 may include: adjusting the position of the spatial filter 230 so that the spatial filter 230 is located at the position of the first beam waist and the second beam waist after the fourth beam 940 overlaps.

[0084] Through the above adjustments, especially when the beam being adjusted is a Gaussian beam, when the axial position and size of the beam waist in the two orthogonal directions of the beam cross-section are the same or substantially the same, and the divergence characteristics in the two orthogonal directions of the beam cross-section are also the same or substantially the same, it can be ensured that the cross-sectional shape of the output beam at any axial position after the beam waist in its propagation direction can be circular or substantially circular, thereby improving the beam quality and expanding the application field of the beam.

[0085] In some embodiments, the beam adjustment method may further include providing a beam quality analyzer 250 located on the outgoing optical path of the spatial filter 230, such that the beam quality analyzer 250 receives and measures at least a portion of the fourth beam 940. This allows adjustment of parameters such as the position of corresponding optical components based on the measurement results from the beam quality analyzer 250, thereby improving the accuracy of the adjustment.

[0086] Specifically, in some embodiments, adjusting the position of the cylindrical lens group such that the second beam 920 passes through the cylindrical lens group to generate the third beam 930 may include: adjusting the cylindrical lens group such that, based on the size measurement of at least a portion of the fourth beam 940 by the beam quality analyzer 250, the first axial position of the first waist of the third beam 930 coincides with the second axial position of the second waist of the third beam 930, and the first dimension of the first waist of the third beam 930 is equal to the second dimension of the second waist of the third beam 930. In other words, fine-tuning of the beam can also be achieved by means of the optical quality analyzer 250.

[0087] Furthermore, in some embodiments, adjusting the spatial filter 230 such that the third beam 930 passes through the spatial filter 230 to generate the fourth beam 940 may include: adjusting the filtering parameters of the spatial filter 230 based on the beam quality factor measurement of at least a portion of the fourth beam by the beam quality analyzer 250, such that the first divergence characteristic of the fourth beam 940 in a first direction is consistent with the second divergence characteristic of the fourth beam 940 in a second direction.

[0088] In the technical solution disclosed herein, the beam waist parameters and divergence characteristics in one direction of the beam cross-section are used as a reference, and the beam waist parameters and divergence characteristics in another orthogonal direction are adjusted. Thus, by utilizing only a cylindrical lens group acting in one direction, spatial shaping and quality optimization of the beam can be conveniently achieved, improving the irradiance of the output beam. Specifically, a single spherical lens with a suitable focal length can be used to transform the first beam output from the laser amplifier outlet, which is inconvenient to measure. This allows for precise measurement of the position and size of the beam waist in the two orthogonal directions of the beam transformed by the spherical lens at an observable location. Furthermore, at least two cylindrical lenses can be used to form a cylindrical lens group with an adjustable focal length within a certain range. The beam shaping effect measured by a beam quality analyzer can be combined to finely adjust the position of each cylindrical lens in real time, ensuring that the beam waist dimensions in the two orthogonal directions of the beam cross-section are precisely equal and located at the same axial position along the beam propagation path. This gives the entire beam adjustment device a certain degree of flexibility. The spatial shaping and quality optimization of the beam according to the technical solution disclosed herein is simple to operate, scientific and effective, and highly practical. The resulting beam has good shaping effect and high quality, and can be applied to more application scenarios.

[0089] The terms “left,” “right,” “front,” “back,” “top,” “bottom,” “upper,” “lower,” “high,” “lower,” etc., used in the specification and claims, if present, are for descriptive purposes and not necessarily for describing unchanging relative positions. It should be understood that such terms are interchangeable where appropriate, enabling embodiments of this disclosure described herein to operate, for example, in orientations different from those shown or otherwise described herein. For example, when the device in the drawings is reversed, a feature previously described as “above” other features may now be described as “below” other features. The device may also be oriented in other ways (rotated 90 degrees or in other orientations), in which case the relative spatial relationships will be interpreted accordingly.

[0090] In the specification and claims, when an element is described as being "on top of," "attached to," "connected to," "coupled to," or "in contact with" another element, the element may be directly located on top of, directly attached to, directly connected to, directly coupled to, or directly in contact with the other element, or one or more intermediate elements may be present. Conversely, when an element is described as being "directly" located on top of, directly attached to, directly connected to, directly coupled to, or directly in contact with another element, no intermediate elements are present. In the specification and claims, when a feature is arranged "adjacent" to another feature, it may mean that a feature has a portion overlapping with the adjacent feature or a portion located above or below the adjacent feature.

[0091] As used herein, the term “exemplary” means “serving as an example, instance, or illustration” and not as a “model” to be precisely copied. Any implementation described herein by example is not necessarily to be construed as preferred or advantageous over other implementations. Moreover, this disclosure is not limited to any theory expressed or implied as given in the field of art, background art, summary of invention, or detailed description.

[0092] As used herein, the term "substantially" means any minor variation resulting from design or manufacturing defects, device or component tolerances, environmental influences, and / or other factors. The term "substantially" also allows for differences from the perfect or ideal situation due to parasitic effects, noise, and other practical considerations that may exist in the actual implementation.

[0093] Furthermore, terms such as “first,” “second,” etc., may be used in this document for reference purposes only and are not intended to be limiting. For example, unless the context clearly indicates otherwise, the words “first,” “second,” and other such numerical terms relating to structures or elements do not imply order or sequence.

[0094] It should also be understood that when the term “including / contains” is used herein, it indicates the presence of the indicated feature, whole, step, operation, unit and / or component, but does not preclude the presence or addition of one or more other features, wholes, steps, operations, units and / or components and / or combinations thereof.

[0095] In this disclosure, the term “provide” is used broadly to cover all ways of obtaining an object, and therefore “provide an object” includes, but is not limited to, “purchasing,” “preparing / manufacturing,” “arranging / setting up,” “installing / assembling,” and / or “ordering” an object.

[0096] As used herein, the term “and / or” includes any and all combinations of one or more of the listed items in association. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this disclosure. As used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise.

[0097] Those skilled in the art will recognize that the boundaries between the above operations are merely illustrative. Multiple operations may be combined into a single operation, a single operation may be distributed among additional operations, and operations may be performed with at least partial overlap in time. Moreover, alternative embodiments may include multiple instances of a particular operation, and the order of operations may be changed in various other embodiments. However, other modifications, variations, and substitutions are equally possible. Aspects and elements of all the embodiments disclosed above may be combined in any way and / or in combination with aspects or elements of other embodiments to provide multiple additional embodiments. Therefore, this specification and the accompanying drawings should be considered illustrative rather than restrictive.

[0098] While specific embodiments of this disclosure have been described in detail by way of example, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of this disclosure. The various embodiments disclosed herein can be combined in any way without departing from the spirit and scope of this disclosure. Those skilled in the art should also understand that various modifications can be made to the embodiments without departing from the scope and spirit of this disclosure. The scope of this disclosure is defined by the appended claims.

Claims

1. A beam adjustment device, characterized in that, The beam adjustment device includes: A spherical lens configured to converge a first beam to produce a second beam, wherein a first beam waist in a first direction of the second beam is located at a first observable position, a second beam waist in a second direction of the second beam is located at a second observable position, and the first and second directions are orthogonal to each other. A cylindrical lens group, located in the exit light path of the spherical lens, with the acting direction of the cylindrical lens group being one of a first direction and a second direction, is configured to adjust the second beam to generate a third beam. The distance between the first axial position of the first beam waist in the first direction of the third beam in the beam propagation direction and the second axial position of the second beam waist in the second direction of the third beam in the beam propagation direction is less than or equal to a first preset length, and the absolute value of the difference between the first dimension of the first beam waist and the second dimension of the second beam waist of the third beam is less than or equal to a second preset length. A spatial filter is located in the outgoing light path of the cylindrical lens group and is configured to filter the third beam to generate a fourth beam, wherein a first divergence characteristic in a first direction of the fourth beam is consistent with a second divergence characteristic in a second direction of the fourth beam. The cylindrical lens group is configured to adjust the second beam based on a size measurement of at least a portion of the fourth beam, such that the first axial position of the first beam waist of the third beam coincides with the second axial position of the second beam waist of the third beam, and the first dimension of the first beam waist of the third beam is equal to the second dimension of the second beam waist of the third beam.

2. The beam adjustment device according to claim 1, characterized in that, The beam adjustment device further includes: A beam quality analyzer is located in the outgoing optical path of the spatial filter and is configured to receive and measure at least a portion of the fourth beam.

3. The beam adjustment device according to claim 2, characterized in that, The beam adjustment device further includes: An optical attenuator is located between the spatial filter and the beam quality analyzer, and the optical attenuator is configured to attenuate the fourth beam.

4. The beam adjustment device according to claim 3, characterized in that, The optical attenuator includes: A reflector configured to reflect a portion of the fourth beam to the beam quality analyzer.

5. The beam adjustment device according to claim 2, characterized in that, The spatial filter is configured to adjust filtering parameters based on beam quality factor measurements of at least a portion of the fourth beam by the beam quality analyzer to filter the third beam.

6. The beam adjustment device according to claim 1, characterized in that, The cylindrical lens group includes: A first cylindrical lens is disposed between the spherical lens and the spatial filter, and the direction of action of the first cylindrical lens is one of the first and second directions; and The second cylindrical lens is disposed between the first cylindrical lens and the spatial filter, and the direction of action of the second cylindrical lens is the same as that of the first cylindrical lens; The first distance between the cylindrical lens group and the spherical lens can be adjusted to change the position of a corresponding one of the first and second beam waists of the third beam, and the second distance between the first cylindrical lens and the second cylindrical lens can be adjusted to change the size of the corresponding one of the first and second beam waists of the third beam.

7. The beam adjustment device according to claim 1, characterized in that, The cylindrical lens group operates in a first direction, which is the slow axis direction; and / or The first beam includes a Gaussian beam.

8. A laser system, characterized in that, The laser system includes: A laser amplifier configured to generate a first beam, the laser amplifier including a partially end-face pumped slab amplifier; and According to any one of claims 1 to 7, the beam adjustment device is located in the output optical path of the laser amplifier and is configured to adjust the first beam.

9. A beam adjustment method, characterized in that, The beam adjustment method includes: A spherical lens, a cylindrical lens group, and a spatial filter are provided in sequence, wherein the spherical lens has a first focal length and the cylindrical lens group has a second adjustable focal length range; The position of the spherical lens is adjusted so that the first beam passes through and is converged by the spherical lens to generate a second beam, wherein the first beam waist of the second beam in the first direction is located at a first observable position, the second beam waist in the second direction of the second beam is located at a second observable position, and the first direction and the second direction are orthogonal to each other; The position of the cylindrical lens group is adjusted so that the second beam passes through the cylindrical lens group to generate a third beam, wherein the direction of action of the cylindrical lens group is one of the first and second directions, the distance between the first axial position of the first beam waist in the first direction of the third beam in the beam propagation direction and the second axial position of the second beam waist in the second direction of the third beam in the beam propagation direction is less than or equal to a first preset length, and the absolute value of the difference between the first dimension of the first beam waist and the second dimension of the second beam waist of the third beam is less than or equal to a second preset length; and The spatial filter is adjusted so that the third beam passes through the spatial filter to generate a fourth beam, wherein the first divergence characteristic of the fourth beam in a first direction is consistent with the second divergence characteristic of the fourth beam in a second direction. The adjustment of the position of the cylindrical lens group, so that the second beam passes through the cylindrical lens group to generate the third beam, includes: Based on the dimensional measurement of at least a portion of the fourth beam, the cylindrical lens group is adjusted such that the first axial position of the first beam waist of the third beam coincides with the second axial position of the second beam waist of the third beam, and the first dimension of the first beam waist of the third beam is equal to the second dimension of the second beam waist of the third beam.

10. The beam adjustment method according to claim 9, characterized in that, The beam adjustment method further includes: A beam quality analyzer is provided on the outgoing optical path of the spatial filter, such that the beam quality analyzer receives and measures at least a portion of the fourth beam.

11. The beam adjustment method according to claim 10, characterized in that, Adjusting the spatial filter so that the third beam passes through the spatial filter to generate the fourth beam includes: Based on the beam quality factor measurement of at least a portion of the fourth beam by the beam quality analyzer, the filtering parameters of the spatial filter are adjusted so that the first divergence characteristic of the fourth beam in the first direction is consistent with the second divergence characteristic of the fourth beam in the second direction.

12. The beam adjustment method according to claim 9, characterized in that, The cylindrical lens group includes a first cylindrical lens and a second cylindrical lens. The first cylindrical lens is disposed between the spherical lens and the spatial filter. The direction of action of the first cylindrical lens is one of the first direction and the second direction. The second cylindrical lens is disposed between the first cylindrical lens and the spatial filter, and the direction of action of the second cylindrical lens is the same as the direction of action of the first cylindrical lens. Adjusting the position of the cylindrical lens group so that the second beam passes through the cylindrical lens group to generate the third beam includes: Adjust the first distance between the cylindrical lens group and the spherical lens to change the position of one of the first beam waist and the second beam waist of the third beam, such that the distance between the first axial position of the first beam waist in the first direction of the third beam in the beam propagation direction and the second axial position of the second beam waist in the second direction of the third beam in the beam propagation direction is less than or equal to a first preset length. as well as The second distance between the first cylindrical lens and the second cylindrical lens is adjusted to change the size of one of the corresponding first and second beam waists of the third beam, such that the absolute value of the difference between the first size of the first beam waist and the second size of the second beam waist of the third beam is less than or equal to a second preset length.

13. The beam adjustment method according to claim 9, characterized in that, Adjusting the spatial filter so that the third beam passes through the spatial filter to generate the fourth beam includes: Adjust the position of the spatial filter so that it is located at the first and second beam waists after the fourth beam overlaps.

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