Light beam adjusting device, laser system and light beam adjusting method

Abstract

The invention 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 which is configured to converge a first light beam to generate a second light beam; the cylindrical lens group is located on the emergent light path of the spherical lens, the action direction of the cylindrical lens group is one of the first direction and the second direction, and the cylindrical lens group is configured to adjust the second light beam to generate a third light beam; and the spatial filter is located on an emergent light path of the cylindrical lens group, and the spatial filter is configured to filter the third light beam to generate a fourth light beam.

Description

Technical Field

[0001] The present disclosure relates to the field of optical technology, and more specifically, to a beam adjustment device, a laser system, and a beam adjustment method. Background Art

[0002] With the rapid development of laser amplification technology, higher-power laser beams have been produced, which play an important role in many fields. However, due to the influence of thermal effects, in some laser systems, the cross-section of the output laser beam is not ideal, making such laser beams unsuitable for many scenarios. Therefore, there is a need to spatially shape the beam and optimize its quality. Summary of the invention

[0003] One of the purposes of the present disclosure is to provide a beam adjustment device, a laser system and a beam adjustment method, which use optical components such as a cylindrical lens group to adjust the beam waist parameters and divergence characteristics in one direction of the cross section of the laser beam as a reference to adjust the beam waist parameters and divergence characteristics in another direction, thereby achieving spatial shaping and quality optimization of the beam.

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

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

[0006] a cylindrical lens group, wherein the cylindrical lens group is located on the exit light path of the spherical lens and the action direction of the cylindrical lens group is one of the first direction and the second direction, and the cylindrical lens group is configured to adjust the second light beam to generate a third light beam, wherein a distance between a first axial position of a first beam waist in the first direction of the third light beam in the light beam propagation direction and a second axial position of a second beam waist in the second direction of the third light beam in the light beam propagation direction is less than or equal to a first preset length, and an absolute value of a difference between a first size of the first beam waist of the third light beam and a second size of the second beam waist of the third light beam is less than or equal to a second preset length; and

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

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

[0009] A beam quality analyzer is located on an output light path of the spatial filter, and the beam quality analyzer is configured to receive and measure at least a portion of the fourth light beam.

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

[0011] A light attenuation element is located between the spatial filter and the beam quality analyzer, and the light attenuation element is configured to attenuate the fourth light beam.

[0012] In some embodiments, the light attenuation element comprises:

[0013] A reflector is configured to reflect a portion of the fourth light beam to the optical mass analyzer.

[0014] In some embodiments, the cylindrical lens group is configured to adjust the second beam based on the size measurement of the at least a portion of the fourth beam by the beam quality analyzer so 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 size of the first beam waist of the third beam is equal to the second size of the second beam waist of the third beam.

[0015] In some embodiments, the spatial filter is configured to adjust filtering parameters according to a beam quality factor measurement of the at least a portion of the fourth light beam by the beam quality profiler to filter the third light beam.

[0016] In some embodiments, the cylindrical lens assembly comprises:

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

[0018] a second cylindrical lens, wherein the second cylindrical lens is disposed between the first cylindrical lens and the spatial filter, and an action direction of the second cylindrical lens is consistent with an action direction of the first cylindrical lens;

[0019] In which, the first distance between the cylindrical lens group and the spherical lens can be adjusted to change the position of the corresponding one of the first beam waist and the second beam waist of the third light 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 beam waist and the second beam waist of the third light beam.

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

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

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

[0023] a laser amplifier configured to generate a first light beam; and

[0024] As described above, the beam adjusting device is located on the output light path of the laser amplifier and is configured to adjust the first light beam.

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

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

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

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

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

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

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

[0032] A beam quality analyzer is provided on an output light path of the spatial filter, so that the beam quality analyzer receives and measures at least a portion of the fourth light beam.

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

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

[0035] In some embodiments, adjusting the spatial filter so that the third light beam passes through the spatial filter to generate the fourth light beam comprises:

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

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

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

[0040] Adjust the second spacing between the first column lens and the second column lens to change the size of the corresponding one of the first beam waist and the second beam waist of the third light beam, so that the absolute value of the difference between the first size of the first beam waist of the third light beam and the second size of the second beam waist of the third light beam is less than or equal to a second preset length.

[0041] In some embodiments, adjusting the spatial filter so that the third light beam passes through the spatial filter to generate the fourth light beam comprises:

[0042] The position of the spatial filter is adjusted so that the spatial filter is located at the positions of the first beam waist and the second beam waist after the overlap of the fourth light beam.

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

[0044] Other features and advantages of the present disclosure will become more apparent from the following detailed description of exemplary embodiments of the present disclosure with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The accompanying drawings, which constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0046] The present disclosure may be more clearly understood from the following detailed description with reference to the accompanying drawings, in which:

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

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

[0049] Figure 3 A schematic flow chart of a light 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 in common between different drawings to represent the same parts or parts with the same functions, and their repeated descriptions are omitted. In this specification, similar reference numerals and letters are used to represent similar items, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0051] For ease of understanding, the positions, sizes, and ranges of various structures shown in the drawings and the like sometimes do not represent actual positions, sizes, and ranges, etc. Therefore, the disclosed invention is not limited to the positions, sizes, and ranges, etc. disclosed in the drawings and the like. In addition, the drawings are not necessarily drawn to scale, and some features may be exaggerated to show details of specific components. DETAILED DESCRIPTION

[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 the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present disclosure unless otherwise specifically stated.

[0053] The following description of at least one exemplary embodiment is merely illustrative in nature and is not intended to limit the present disclosure and its application or use. It will be appreciated by those skilled in the art that they are merely exemplary, rather than exhaustive, ways in which the present disclosure may be implemented.

[0054] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0055] With the development of laser technology, some laser amplifiers have been able to output high-power laser beams. For example, some end-pumped slab amplifiers (Innoslab amplifiers) can be based on laser media such as Yb:YAG, Nd:YVO4, etc. In some cases, such amplifiers can output kilowatt-level laser beams. However, due to the optical structural characteristics of the laser amplifier itself, the cross-section of the laser beam it outputs may not be ideal, resulting in the application of such laser beams in many scenarios being limited. For example, in the Innoslab amplifier, due to the uniform linear pumping characteristics and the one-dimensional heat conduction in the crystal, the thermal gradient inside the slab crystal is also distributed in one dimension. Such a thermal gradient or temperature gradient will make the slab crystal equivalent to a cylindrical lens in the fast axis direction (perpendicular to the direction of the pump line), and there is almost no thermal effect in the slow axis direction (the direction of the pump line). The cylindrical thermal lens enables the light beam that passes through the amplifier multiple times to achieve self-reproduction in the fast axis direction, that is, the fast axis direction is equivalent to the existence of a stable resonant cavity, and energy extraction can be achieved through mode matching. The following two methods are usually used to make the injected light beam return through the gain medium in the Innoslab amplifier multiple times. In one method, a pair of confocal cylindrical mirrors can be used to form an unstable cavity in the slow axis direction and a stable cavity in the fast axis direction. In this way, the size of the light beam in the slow axis direction will be magnified once every time the light beam goes back and forth in the gain medium or crystal. In another method, only a pair of plane mirrors can be used as cavity mirrors of the amplifying cavity, and the divergence characteristics of the Gaussian beam itself can be used to make the injected light beam diverge freely in the slow axis direction. Regardless of which of the above methods is used to return the light beam, the cross-section of the light beam output by the Innoslab amplifier is elliptical rather than circular, and at the same time, the beam component in the fast axis direction will have a larger divergence angle than the beam component in the slow axis direction. Compared with the circular beam cross-section, the elliptical beam cross-section will cause the spot size obtained after focusing to be larger, thereby reducing the irradiance (power per unit area), so it is necessary to spatially shape and optimize the quality of the output beam, for example, to make the cross-section of the light beam output by the Innoslab amplifier as close to a circle as possible.

[0056] In some examples, a pair or two pairs of cylindrical telescopes can be used to spatially shape the output beam, where one or a pair of cylindrical lenses are used to achieve spatial shaping for two orthogonal directions on the beam cross section. However, the above two methods each have their disadvantages. Specifically, if only a pair of cylindrical lenses is used, that is, a cylindrical lens is placed in two orthogonal directions on the beam cross section, then it is necessary to accurately measure the spatial characteristics of the beam directly output by the amplifier. However, under high-power pumping conditions, such as Innoslab amplifiers, etc. will be limited by the focal length of the equivalent thermal lens of its gain medium, and thus require an extremely short cavity length (20 to 60 mm). In other words, the structure of the amplifier is extremely compact, which makes it very difficult to accurately measure the beam at the output of the amplifier. In addition, if two pairs of cylindrical lenses are used, that is, a pair of cylindrical lenses are placed in two orthogonal directions on the beam cross section, then it is obvious that the number of cylindrical lenses required is large, the accuracy of adjustment and calibration is high, and the operation is difficult.

[0057] In order to solve the above problems, the present disclosure proposes an optical adjustment device, which uses the beam waist parameters and divergence characteristics in one direction of the beam cross section as a reference to adjust the beam waist parameters and divergence characteristics in another direction, thereby achieving spatial shaping and quality optimization of the beam.

[0058] In an exemplary embodiment of the present disclosure, 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] Among them, the spherical lens 210 can be configured to converge the first light beam 910 to generate the second light beam 920. It can be understood that the spherical lens 210 can have curvature in all directions, so that the components in all directions of the light beam can be converged. Here, the first light beam 910 can be an output light beam from the laser amplifier 100. By using a spherical lens 210 with a suitable focal length, the first beam waist in the first direction of the second light beam 920 can be located at a first observable position, and the second beam waist in the second direction of the second light beam 920 can be located at a second observable position. In addition, the sizes of the first beam waist and the second beam waist can also be within a suitable range for subsequent adjustment. Here, the first direction and the second direction are both perpendicular to the propagation direction of the light beam, and the first direction and the second direction can be orthogonal to each other. The focal length range of the spherical lens 210 can be calculated according to the desired observable position range and the desired beam waist size range, and the spherical lens 210 with a suitable focal length can be selected accordingly. In this article, the technical solution of the present disclosure is described in detail by taking the first direction corresponding to the slow axis direction of the crystal in the laser amplifier 100 and the 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 light beam and the second direction is the fast axis direction of the light beam) as an example. However, it can be understood that in some other embodiments, the first direction and the second direction can also be other directions on the cross section perpendicular to the propagation direction of the light beam, as long as the first direction and the second direction are orthogonal to each other, and there is no limitation here.

[0060] like Figure 1 and Figure 2 As shown, the cylindrical lens group can be located on the output light path of the spherical lens 210 and the action direction of the cylindrical lens group can be one of the first direction and the second direction. That is to say, the cylindrical lens group can be configured to act only on the component of the second light beam in one of the first direction or the second direction, but not on the component in the other direction. In some embodiments, considering that the beam waist size of the light beam in the fast axis direction is usually smaller than the beam waist size in the slow axis direction, and the light 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. In this way, the action direction of the cylindrical lens group can be selected as the slow axis direction. As shown in FIG. Figure 2 As shown, the component of the light beam in the slow axis direction (such as Figure 2 The beam components in the fast axis direction (as shown by the dashed arrows in the middle) will converge or diverge under the action of the cylindrical lens group. Figure 2The beam parameters in the fast axis direction can be adjusted based on the beam parameters in the slow axis direction, and accordingly, the action direction of the column 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 light beam 920 to generate the third light beam 930. In order to obtain an ideal (e.g., circular) beam cross section, the cylindrical lens group can be adjusted so that the distance between the first axial position of the first waist in the first direction of the third light beam 930 in the beam propagation direction and the second axial position of the second waist in the second direction of the third light beam 930 in the beam propagation direction is less than or equal to the first preset length, and the absolute value of the difference between the first size of the first waist of the third light beam 930 and the second size of the second waist of the third light beam 930 is less than or equal to the second preset length. Here, the waist refers to the part of the light beam (e.g., Gaussian beam) with the smallest size on the cross section perpendicular to its propagation direction. In some embodiments, the adjustment of the cylindrical lens group can be divided into two parts: coarse adjustment and fine adjustment. First, the axial position (i.e., the position in the beam propagation direction) of the waist in two orthogonal directions of the third light beam 930 can be substantially overlapped by coarse adjustment of the cylindrical lens group, and the size of the waist in two orthogonal directions of the third light beam 930 is substantially consistent. Here, the first preset length and the second preset length can be set according to the adjustment accuracy requirements. When the first preset length and the second preset length are smaller, the cross section of the final generated light beam will be closer to an ideal circle. Further, in some embodiments, the cylindrical lens group can be fine-tuned with the aid of an optical mass analyzer, etc., so that the axial positions of the beam waists in two orthogonal directions of the third light beam 930 coincide, and the sizes of the beam waists in two orthogonal directions of the third light beam 930 are equal, as will be described in detail later.

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

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

[0064] On the other hand, the second spacing between the first cylindrical lens 221 and the second cylindrical lens 222 can be adjusted to change the size of the corresponding one of the first beam waist and the second beam waist of the third light beam 930. When the second spacing between the first cylindrical lens 221 and the second cylindrical lens 222 is changed, it 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 the slow axis direction, the size of the first beam waist in the slow axis direction of the third light beam 930 can be changed by adjusting the second spacing between the first cylindrical lens 221 and the second cylindrical lens 222, while the size of the second beam waist in the fast axis direction of the third light beam 930 remains unchanged or substantially unchanged. In this way, the size of the first beam waist in the slow axis direction of the third light beam 930 can be adjusted based on the size of the second beam waist in the fast axis direction of the third light beam 930, thereby achieving spatial shaping of the light 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 in the fast axis direction of the third light beam 930 can be changed by adjusting the second interval 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 may be located on the exit light path of the cylindrical lens group, and the spatial filter 230 may be configured to filter the third light beam 930 to generate a fourth light beam 940. The first divergence characteristic in the first direction of the fourth light beam 940 is consistent with the second divergence characteristic in the second direction of the fourth light beam 940. In this way, especially when the light beam (including any one of the first light beam 910, the second light beam 920, the third light beam 930 and the fourth light beam 940) is a Gaussian light beam, the fourth light beam 940 generated by the adjustment can always maintain a desired shape (for example, a circle) in a cross section perpendicular to the propagation direction of the light beam during the propagation process.

[0066] In some embodiments, the spatial filter 230 can be placed at a position where the first beam waist and the second beam waist of the adjusted third light beam 930 overlap each other or near the above position, and the spatial filter 230 is configured to filter stray light, thereby further optimizing the beam quality. Specifically, in the third light beam 930, there may be undesirable side lobes or stray light, etc. In the technical solution of the present disclosure, these undesirable side lobes or stray light, etc. can be filtered out by the spatial filter 230, or the high-frequency part of the light beam can be filtered out, and only the low-frequency part is retained to obtain a fourth light beam 940 with better quality. In some embodiments, the spatial filter 230 may include an aperture or grating with a through hole of a specific shape. Alternatively, in some embodiments, the spatial filter 230 may include a slit or hole with an adjustable light transmission size.

[0067] like Figure 1 As shown, the beam adjustment device according to the exemplary embodiment of the present disclosure may further include a beam quality analyzer 250, which may be located on the output light path of the spatial filter 230, and the beam quality analyzer 250 may be configured to receive and measure at least a portion of the fourth light beam to help achieve real-time and fine adjustment of the light beam and improve the 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 light beam can be observed by the beam quality analyzer 250, and then the first spacing and the second spacing 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 light beam 920 (for example, in real time) according to the size measurement of at least a portion of the fourth light beam 940 by the beam quality analyzer 250, so that the axial position of the beam waist of the third light beam 930 in two orthogonal directions (for example, the first axial position of the first beam waist and the second axial position of the second beam waist) coincide or substantially coincide, and the sizes of the beam waist of the third light beam 930 in two orthogonal directions (for example, the first size of the first beam waist and the second size of the second beam 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 Factor), according to the measurement result 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 according to the beam quality factor measurement of at least a portion of the fourth light beam 940 by the beam quality analyzer 250 to achieve filtering of the third light beam 930, so that the divergence characteristics of the components of the third light beam 930 in two orthogonal directions are the same or substantially the same.

[0070] In some embodiments, the beam quality analyzer 250 may be configured to directly receive and measure the fourth light 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 light beam directly output by the laser amplifier 100. Therefore, in order to protect the beam quality analyzer 250 and ensure measurement accuracy, the beam adjustment device may further include an optical attenuation element. The optical attenuation element may be located between the spatial filter 230 and the beam quality analyzer 250, and the optical attenuation element is configured to attenuate the fourth light beam 940.

[0071] In some embodiments, the light attenuation element may attenuate the fourth light beam 940 by absorbing a portion of the fourth light beam 940, for example, the light attenuation element may include a filter coated with a light absorbing substance. Figure 1 As shown, the light attenuation element may include a reflector 240, which may be configured to reflect a portion of the fourth light beam 940 to the optical quality analyzer 250, that is, to achieve attenuation by reflecting part of the fourth light beam 940. In some other embodiments, a filter and a reflector may be used in combination as a light attenuation element. By providing a light attenuation element, the intensity of the light beam input to the light beam quality analyzer 250 may be within a suitable range, thereby achieving a better detection effect and improving the reliability and safety of the device. It is understandable that, in some embodiments, the light beam quality analyzer 250 itself may also be integrated with a light attenuation element capable of adjusting the intensity of the light beam entering it, which is not limited here.

[0072] According to another aspect of the present disclosure, a laser system is also provided. Figure 1 As shown, in an 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 light beam 910, and the beam adjustment device may be located on the output light path of the laser amplifier 100 and configured to adjust the first light beam 910, thereby generating an output light beam having 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 an integral device. In other embodiments, the laser amplifier 100 and the beam adjustment device may also be separately provided and, if necessary, arranged in the manner described herein 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. The partially end-pumped slab amplifier can output a high-power Gaussian laser beam and has a wide range of applications in practice.

[0074] According to another aspect of the present disclosure, a beam adjustment method is also provided. The beam adjustment method can be implemented based on the beam adjustment device as described above, so as to generate a laser beam with an ideal (eg, circular) cross-sectional shape.

[0075] In an exemplary embodiment of the present disclosure, Figures 1 to 3 As shown, the beam adjustment method may include:

[0076] Step S310, providing a spherical lens 210, a cylindrical lens group and a spatial filter 230 arranged in sequence;

[0077] Step S320, adjusting the position of the spherical lens 210 so that the first light beam 910 passes through and is converged by the spherical lens 210 to generate a second light beam 920;

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

[0079] Step S340 , adjusting the spatial filter 230 , so that the third light beam 930 passes through the spatial filter 230 to generate a fourth light beam 940 .

[0080] Among them, the spherical lens 210 can have a first focal length, and combined with adjusting the position of the spherical lens 210, the first light beam 910 can pass through and be converged by the spherical lens 210 to generate a second light beam 920. Here, the first beam waist in the first direction of the second light beam 920 can be located at a first observable position, and the second beam waist in the second direction of the second light beam 920 is located at a second observable position. The relevant dimensions of the beam cross section can be conveniently observed or measured at the first observable position and the second observable position, and the dimensions themselves are suitable, so that at least one of the above optical components can be adjusted according to the results of the observation or measurement to achieve spatial shaping and quality optimization of the light beam. As described above, the first direction and the second direction are orthogonal to each other, and the first direction and the second direction are each perpendicular to the propagation direction of the light beam. In a specific example, the first direction can be a slow axis direction, and the second direction can be a fast axis direction.

[0081] Further, the action direction of the cylindrical lens group can be one of the first direction and the second direction, and the cylindrical lens group has a second adjustable focal length range. By adjusting the positions of the cylindrical lenses in the cylindrical lens group, the distance between the first axial position of the first beam waist in the first direction of the third light beam 930 in the beam propagation direction and the second axial position of the second beam waist in the second direction of the third light beam 930 in the beam propagation direction can be less than or equal to the first preset length, and the absolute value of the difference between the first size of the first beam waist of the third light beam 930 and the second size of the second beam waist of the third light beam 930 is less than or equal to the second preset length, that is, at least the coarse adjustment of the light 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 action 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 action direction of the second cylindrical lens 222 is consistent with the action direction of the first cylindrical lens 221. On this basis, adjusting the position of the cylindrical lens group so that the second light beam 920 passes through the cylindrical lens group to generate the third light beam 930 may include: adjusting the first spacing between the cylindrical lens group and the spherical lens 210 to change the position of the corresponding one of the first beam waist and the second beam waist of the third light beam 930, so that the distance between the first axial position of the first beam waist in the first direction of the third light beam 930 in the beam propagation direction and the second axial position of the second beam waist in the second direction of the third light beam 930 in the beam propagation direction is less than or equal to a first preset length; and adjusting the second spacing between the first cylindrical lens 221 and the second cylindrical lens 222 to change the size of the above corresponding one of the first beam waist and the second beam waist of the third light beam 930, so that the absolute value of the difference between the first size of the first beam waist of the third light beam 930 and the second size of the second beam waist of the third light 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 are installed on the same base, and the first distance is adjusted by adjusting the position of the base) so that the beam waist falls at the desired observable position; and then the second distance between the first cylindrical lens 221 and the second cylindrical lens 222 is adjusted to adjust the beam waist to the desired size.

[0083] Further, by adjusting the spatial filter 230, the first divergence characteristic in the first direction of the generated fourth light beam 940 can be made consistent with the second divergence characteristic in the second direction of the fourth light beam 940. In some embodiments, in order to simplify and optimize the filtering characteristics of the spatial filter 230, adjusting the spatial filter 230 so that the third light beam 930 passes through the spatial filter 230 to generate the fourth light 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 of the fourth light beam 940 after overlap.

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

[0085] In some embodiments, the beam adjustment method may further include: providing a beam quality analyzer 250 located on the output light path of the spatial filter 230, so that the beam quality analyzer 250 receives and measures at least a portion of the fourth light beam 940. In this way, parameters such as the position of the corresponding optical component can be adjusted according to the measurement result of the beam quality analyzer 250, thereby improving the adjustment accuracy.

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

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

[0088] In the technical solution disclosed in the present invention, the beam waist parameters and divergence characteristics in one direction of the beam cross section are used as a reference to adjust the beam waist parameters and divergence characteristics in another orthogonal direction, so that the spatial shaping and quality optimization of the beam can be conveniently achieved by using only a cylindrical lens group acting in one direction, thereby 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 at the outlet of the laser amplifier, which is inconvenient to measure, so that the position and size of the beam waist in two orthogonal directions in its cross section of the beam converted by the spherical lens can be accurately measured at an observable position. Furthermore, at least two cylindrical lenses can be used to form a cylindrical lens group with an adjustable focal length within a certain range, and the position of each cylindrical lens can be fine-tuned in real time in combination with the effect of shaping the beam measured by a beam quality analyzer, so that the size of the beam waist in two orthogonal directions in its cross section is precisely equal and located at the same axial position on the beam propagation path, so that the entire beam adjustment device has a certain degree of flexibility. According to the technical solution disclosed in the present invention, the spatial shaping and quality optimization of the light beam are performed, which is simple to operate, scientific and effective, and highly practical. The resulting light beam has good shaping effect and high quality, and can be applied to more application scenarios.

[0089] The words "left", "right", "front", "back", "top", "bottom", "up", "down", "high", "low", etc., in the specification and claims, if present, are used for descriptive purposes and are not necessarily used to describe an unchanging relative position. It should be understood that the words so used are interchangeable under appropriate circumstances, so that the embodiments of the present disclosure described herein, for example, can operate in other orientations than those shown or otherwise described herein. For example, when the device in the drawings is turned over, features previously described as "above" other features may now be described as "below" the other features. The device may also be oriented in other ways (rotated 90 degrees or in other orientations), and the relative spatial relationships will be interpreted accordingly.

[0090] In the specification and claims, when an element is referred to as being "on", "attached", "connected", "coupled", or "contacting" another element, the element may be directly on, directly attached, directly connected, directly coupled, or directly contacting another element, or one or more intermediate elements may be present. In contrast, when an element is referred to as being "directly" "on", "directly attached", "directly connected", "directly coupled", or "directly contacting" another element, there will be no intermediate elements. In the specification and claims, a feature being arranged "adjacent" to another feature may refer to a feature having a portion that overlaps with an adjacent feature or a portion that is located above or below an adjacent feature.

[0091] As used herein, the word "exemplary" means "serving as an example, instance, or illustration" rather than as a "model" to be exactly copied. Any implementation described as an example herein is not necessarily to be construed as preferred or advantageous over other implementations. Furthermore, the present disclosure is not to be limited by any expressed or implied theory given in the technical field, background, summary, or detailed description.

[0092] As used herein, the term "substantially" is intended to include any minor variations due to design or manufacturing imperfections, device or component tolerances, environmental influences, and / or other factors. The term "substantially" also allows for deviations from a perfect or ideal situation due to parasitic effects, noise, and other practical considerations that may exist in actual implementations.

[0093] In addition, the terms "first", "second" and the like may also be used herein for reference purposes only and are not intended to be limiting. For example, the terms "first", "second" and other such numerical terms referring to structures or elements do not imply a sequence or order unless the context clearly indicates otherwise.

[0094] It should also be understood that when the term “include / comprises” is used in this document, it indicates the presence of the specified features, integers, steps, operations, units and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, units and / or components and / or their combinations.

[0095] In this disclosure, the term "provide" is used in a broad sense to cover all ways of obtaining an object, and thus "providing an object" includes but is not limited to "purchasing", "preparing / manufacturing", "arranging / setting up", "installing / assembling", and / or "ordering" an object, etc.

[0096] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. The terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the present 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 appreciate that the boundaries between the above operations are merely illustrative. Multiple operations can be combined into a single operation, a single operation can be distributed in additional operations, and operations can be performed at least partially overlapping in time. Moreover, alternative embodiments may include multiple instances of a specific operation, and the order of operations may be changed in various other embodiments. However, other modifications, variations, and replacements are equally possible. Aspects and elements of all embodiments disclosed above may be combined in any manner and / or in combination with aspects or elements of other embodiments to provide multiple additional embodiments. Therefore, this specification and accompanying drawings should be considered illustrative, not restrictive.

[0098] Although some specific embodiments of the present disclosure have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present disclosure. The various embodiments disclosed herein may be combined in any manner without departing from the spirit and scope of the present disclosure. It should also be understood by those skilled in the art that various modifications may be made to the embodiments without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the appended claims.

Claims

1. A light beam adjustment device, characterized in that: The light beam adjustment device comprises: a spherical lens configured to converge the first light beam to generate a second light beam, wherein a first beam waist of the second light beam in a first direction is located at a first observable position, a second beam waist of the second light beam in a second direction is located at a second observable position, and the first direction and the second direction are orthogonal to each other; a cylindrical lens group, wherein the cylindrical lens group is located on the exit light path of the spherical lens and the action direction of the cylindrical lens group is one of the first direction and the second direction, and the cylindrical lens group is configured to adjust the second light beam to generate a third light beam, wherein a distance between a first axial position of a first beam waist in the first direction of the third light beam in the light beam propagation direction and a second axial position of a second beam waist in the second direction of the third light beam in the light beam propagation direction is less than or equal to a first preset length, and an absolute value of a difference between a first size of the first beam waist of the third light beam and a second size of the second beam waist of the third light beam is less than or equal to a second preset length; and A spatial filter is located on the exit light path of the cylindrical lens group, and the spatial filter is configured to filter the third light beam to generate a fourth light beam, wherein a first divergence characteristic of the fourth light beam in a first direction is consistent with a second divergence characteristic of the fourth light beam in a second direction.

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

3. The light beam adjustment device according to claim 2, characterized in that: The light beam adjustment device also includes: A light attenuation element is located between the spatial filter and the beam quality analyzer, and the light attenuation element is configured to attenuate the fourth light beam.

4. The light beam adjustment device according to claim 3, characterized in that: The light attenuation element comprises: A reflector is configured to reflect a portion of the fourth light beam to the optical mass analyzer.

5. The light beam adjustment device according to claim 2, characterized in that: The cylindrical lens group is configured to adjust the second beam according to the size measurement of the at least a portion of the fourth beam by the beam quality analyzer, so 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 size of the first beam waist of the third beam is equal to the second size of the second beam waist of the third beam.

6. The light beam adjustment device according to claim 2, characterized in that: The spatial filter is configured to adjust filtering parameters according to a beam quality factor measurement of the at least a portion of the fourth light beam by the beam quality profiler to filter the third light beam.

7. The light beam adjustment device according to claim 1, characterized in that: The cylindrical lens group comprises: a first cylindrical lens, wherein the first cylindrical lens is disposed between the spherical lens and the spatial filter, and an action direction of the first cylindrical lens is the one of the first direction and the second direction; and a second cylindrical lens, wherein the second cylindrical lens is disposed between the first cylindrical lens and the spatial filter, and an action direction of the second cylindrical lens is consistent with an action direction of the first cylindrical lens; In which, the first distance between the cylindrical lens group and the spherical lens can be adjusted to change the position of the corresponding one of the first beam waist and the second beam waist of the third light 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 beam waist and the second beam waist of the third light beam.

8. The light beam adjustment device according to claim 1, characterized in that: The action direction of the cylindrical lens group is a first direction, and the first direction is a slow axis direction; and / or The first light beam comprises a Gaussian light beam.

9. A laser system, characterized in that: The laser system comprises: a laser amplifier configured to generate a first optical beam, the laser amplifier comprising a partially end-pumped slab amplifier; and According to any one of claims 1 to 8, the beam adjusting device is located on an output light path of the laser amplifier and is configured to adjust the first beam.

10. A light beam adjustment method, characterized in that: The light beam adjustment method comprises: Providing a spherical lens, a cylindrical lens group and a spatial filter arranged in sequence, wherein the spherical lens has a first focal length, and the cylindrical lens group has a second adjustable focal length range; Adjusting the position of the spherical lens so that the first light beam passes through and is converged by the spherical lens to generate a second light beam, wherein a first beam waist in a first direction of the second light beam is located at a first observable position, a second beam waist in a second direction of the second light beam is located at a second observable position, and the first direction and the second direction are orthogonal to each other; Adjusting the position of the cylindrical lens group so that the second light beam passes through the cylindrical lens group to generate a third light beam, wherein the action direction of the cylindrical lens group is one of the first direction and the second direction, the distance between the first axial position of the first beam waist in the first direction of the third light beam in the beam propagation direction and the second axial position of the second beam waist in the second direction of the third light 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 size of the first beam waist of the third light beam and the second size of the second beam waist of the third light beam is less than or equal to a second preset length; and The spatial filter is adjusted so that the third light beam passes through the spatial filter to generate a fourth light beam, wherein a first divergence characteristic of the fourth light beam in a first direction is consistent with a second divergence characteristic of the fourth light beam in a second direction.

11. The light beam adjustment method according to claim 10, characterized in that: The light beam adjustment method further comprises: A beam quality analyzer is provided on an output light path of the spatial filter, so that the beam quality analyzer receives and measures at least a portion of the fourth light beam.

12. The light beam adjustment method according to claim 11, characterized in that: Adjusting the position of the cylindrical lens group so that the second light beam passes through the cylindrical lens group to generate a third light beam comprises: According to the size measurement of the at least a portion of the fourth light beam by the beam quality analyzer, the cylindrical lens group is adjusted so that the first axial position of the first beam waist of the third light beam coincides with the second axial position of the second beam waist of the third light beam, and the first size of the first beam waist of the third light beam is equal to the second size of the second beam waist of the third light beam.

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

14. The light beam adjustment method according to claim 10, characterized in that: The cylindrical lens group includes a first cylindrical lens and a second cylindrical lens, the first cylindrical lens is arranged between the spherical lens and the spatial filter, the action direction of the first cylindrical lens is the one of the first direction and the second direction, the second cylindrical lens is arranged between the first cylindrical lens and the spatial filter, and the action direction of the second cylindrical lens is consistent with the action direction of the first cylindrical lens; Adjusting the position of the cylindrical lens group so that the second light beam passes through the cylindrical lens group to generate a third light beam comprises: adjusting a first distance between the cylindrical lens group and the spherical lens to change a position of a corresponding one of a first beam waist and a second beam waist of the third light beam, so that a distance between a first axial position of a first beam waist in a first direction of the third light beam in a beam propagation direction and a second axial position of a second beam waist in a second direction of the third light beam in a beam propagation direction is less than or equal to a first preset length; as well as Adjust the second spacing between the first column lens and the second column lens to change the size of the corresponding one of the first beam waist and the second beam waist of the third light beam, so that the absolute value of the difference between the first size of the first beam waist of the third light beam and the second size of the second beam waist of the third light beam is less than or equal to a second preset length.

15. The light beam adjustment method according to claim 10, characterized in that: Adjusting the spatial filter so that the third light beam passes through the spatial filter to generate a fourth light beam comprises: The position of the spatial filter is adjusted so that the spatial filter is located at the positions of the first beam waist and the second beam waist after the overlap of the fourth light beam.

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