A multi-band laser beam combining system and beam control method

Abstract

The present invention relates to a multi-band laser beam combining system and a beam control method, comprising a laser beam combining module and a synthetic beam monitoring module, wherein the laser beam combining module comprises a sub-beam laser, a control reflector, a beam combining mirror and a high-reflection mirror, wherein the sub-beam emitted by the sub-beam laser irradiates the control reflector, is reflected by the control reflector and reaches the beam combining mirror to be combined into a synthetic beam, passes through the beam combining mirror and reaches the high-reflection mirror, reflects the synthetic laser from one side of the high-reflection mirror, and outputs a test beam from the other side to enter the synthetic beam monitoring module. Compared with the prior art, the present invention has the advantages of realizing the synthesis of multiple beams, being suitable for lasers of various energies or wide bands; realizing the absolute position control of each beam, and then ensuring the synthesis accuracy through feedback adjustment; ensuring the pointing stability of the laser synthetic beam, and reducing the difficulty of the subsequent laser emission system.

Description

Technical Field

[0001] The invention relates to multi-band laser beam combining, and in particular to a multi-band laser beam combining system and a beam control method. Background Art

[0002] With the rapid development of laser technology, lasers are increasingly used in military, medical, communications and other fields. In recent years, many fields such as high-energy laser light sources, laser cladding, and advanced manufacturing have an urgent need for the application of high-brightness, multi-band laser systems. However, due to the combined influence of factors such as thermal damage, nonlinear effects, thermal lens effects, component structure, and heat dissipation conditions of a single laser, the wavelength and power of the output laser are limited. Laser beam combining technology is one of the effective methods to break through the output power of a single laser and ensure the beam quality, and to achieve wide wavelength.

[0003] Laser beam combining technology is divided into two categories. The first is coherent beam combining, which refers to combining multiple laser beams with the same wavelength, certain phase relationship and coherence into one outgoing laser beam. This technology has strict requirements on the phase, line width, frequency, etc. of the sub-beams, and controls the phase difference of each sub-beam to be constant, which makes the technology difficult, the system complex, and cannot be put into practical use. The second is incoherent beam combining, which is mainly based on mainstream spectral beam combining. It uses specific optical devices to combine multiple lasers of different wavelengths into one laser output. This technology does not have strict requirements on the parameters of the sub-beam lasers, so it has developed rapidly.

[0004] At present, researchers have proposed many laser beam combining system design methods based on the above basic principles of spectral beam combining. One type is without any beam adjustment or monitoring measures. This type of laser beam combining method cannot cope with the beam separation caused by the laser's own jitter, assembly error, vibration, ambient temperature change, etc., which greatly reduces the system's beam quality and efficiency and is not practical. For example, a laser beam combining system and a laser beam combining method disclosed in application publication number CN102289078A, in which the first laser beam is incident on the beam combining mirror at the Brewster angle, so that the two laser beams are combined into one beam, and the laser beam to the laser is linearly polarized light. This method not only has the above problems, but also cannot combine randomly polarized lasers, because the Brewster angle has polarization requirements for the reflected beam and the transmitted beam, and if the precise Brewster angle cannot be reached, the reflectivity and transmittance of the beam will be greatly reduced. Under high energy, most of the energy is absorbed, and the beam combiner (thin film polarizer) produces a very high temperature rise, resulting in serious separation of the synthetic light spot. In addition, the Brewster angle is generally the ratio of the refractive index of the two media, and its angle is very large. The lens coating is difficult and the absorption is large, so it is not suitable as a beam combiner. This beam combining method has a small number of synthesized beams, a complex system structure, a large system, and high requirements for sub-beam lasers, which leads to increased costs. One type is based on controlling the synthesized beam, monitoring the accuracy of the synthesized beam, and ensuring the synthesis accuracy of the system through adjustment, improving the beam quality and efficiency, and has a certain degree of practicality. However, the precision of the synthetic beam pointing cannot be controlled, and only the position precision of each sub-beam phase synthesis can be controlled. This places high demands on the subsequent beam expansion reflection system. The selected lens must take into account the random jitter of the light spot and the error of the light spot randomly irradiated to the lens caused by the environmental vibration, and the precise control of the direction of the combined light by the launch system to compensate for the error of the light spot jitter caused by the laser beam combining system, making the subsequent control system more complicated. For example, the papers "New Methods for Beam Monitoring and Adjustment of High-Energy Laser Launch System" and "Research on Direct Monitoring and Correction Methods for Multi-Band Laser Emission Direction" all use direct or indirect monitoring of the light spot of the synthetic beam to cooperate with active control to adjust the precision of the synthetic beam. The above method has the problem that when the overlapping multi-path beams enter at the same time, the light spots overlap together, making it difficult to determine the wavelength of the sub-beams, and the angle or position value of each sub-beam cannot be calculated by the algorithm. In order to distinguish the sub-beams of the synthetic light spot, it is necessary to add an electric switching optical gate or a target wheel filter to force the monitored wavelengths to enter the detector one after another and distinguish them, but this will reduce the monitoring accuracy and increase the complexity and stability of the system. Application publication number CN114006269A discloses a high-power semiconductor laser direct output system and a polarization beam combining structure thereof, but the number of beams that can be combined by the prior art is limited.

[0005] In summary, how to combine multiple laser beams and determine the angle value of each sub-beam is a technical problem that needs to be solved. Summary of the invention

[0006] The purpose of the present invention is to provide a multi-band laser beam combining system and a beam control method in order to overcome the defects of the prior art that a plurality of lasers cannot be combined or the angle value of each laser sub-beam cannot be known.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] According to one aspect of the present invention, a multi-band laser beam combining system is provided, comprising a laser beam combining module and a synthetic beam monitoring module, wherein the laser beam combining module comprises at least two sub-beam lasers, at least two control reflectors, a beam combining mirror and a high-reflection mirror, wherein the sub-beams emitted by the sub-beam lasers are irradiated onto the control reflectors, reflected by the control reflectors and reaching the beam combining mirror to be combined into a synthetic beam, then reaching the high-reflection mirror through the beam combining mirror, reflecting the synthetic laser from one side of the high-reflection mirror, and outputting a test beam from the other side to enter the synthetic beam monitoring module; the control reflector adjusts the angle of beam reflection, and the synthetic beam monitoring module monitors the position of the sub-beams.

[0009] As a preferred technical solution, there are at least four control reflectors, and each sub-beam emitted by the sub-beam laser passes through two control reflectors to adjust the beam position and beam angle respectively; the surface of the control reflector is coated with a high-reflection film, and the wavelength range corresponding to the high-reflection film includes the wavelength of the light beam reflected by the surface thereof.

[0010] As a preferred technical solution, the surface of the high-reflection mirror is coated with a wide-band reflective film, and the wavelength range corresponding to the wide-band reflective film includes the wavelengths of the sub-beams emitted by all the sub-beam lasers.

[0011] As a preferred technical solution, the synthetic laser has at least 99.95% of the energy of the synthetic light beam.

[0012] As a preferred technical solution, the surface of the beam combining mirror is coated with a beam combining film, and the angle tolerance range of the beam combining film coating is ±0.15°.

[0013] As a preferred technical solution, the system also includes a double-sided high-reflection mirror, the sub-beam lasers are no less than three, the surface of the double-sided high-reflection mirror is coated with a high-reflection film, and both sides simultaneously reflect the sub-beam lasers or control the light beams incident on the reflector.

[0014] As a preferred technical solution, the wavelength range corresponding to the high-reflective film includes the wavelength of the light beam reflected by the surface on which it is located, and the coating angle tolerance range is ±3°.

[0015] As a preferred technical solution, the installation angles of the control reflector, the beam synthesis mirror, the high-reflection mirror and the double-sided high-reflection mirror are consistent.

[0016] As a preferred technical solution, the system further comprises a collimating lens arranged at the laser output end of the sub-beam laser.

[0017] According to another aspect of the present invention, a beam control method using a multi-band laser beam combining system is provided, and a controller is also used, which specifically includes the following steps:

[0018] Step S1, the sub-beam laser emits a sub-beam to irradiate the control reflector;

[0019] Step S2, controlling the reflector to reflect the light beam to the beam synthesizer;

[0020] Step S3, the beam combiner combines at least two light beams into a composite light beam;

[0021] Step S4, the synthesized light beam reaches the high-reflection mirror, one side of the high-reflection mirror reflects the synthesized laser, and the other side outputs the test light beam into the synthesized light beam monitoring module;

[0022] Step S5, the composite beam monitoring module monitors the absolute position of each sub-beam in real time through the test beam and feeds back to the controller, and the controller adjusts the absolute position of the control reflector.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1) The present invention realizes the synthesis of multiple beams by arranging the positions of the beamlet lasers, the control reflector, the beam combiner and the high reflector, and has no special requirements for the beamlet lasers and the beam combiner, and is suitable for the synthesis of lasers of various energies or wide bands;

[0025] 2) The present invention realizes absolute position control of each light beam by controlling the pitch and movement of the reflector, and then adjusts the feedback of the synthetic beam monitoring module to ensure the synthesis accuracy;

[0026] 3) The angle tolerance range of the beam combining film coating on the surface of the beam combining mirror of the present invention is ±0.15°, and the angle tolerance range of the high reflection film coating on the surface of the double-sided high reflection mirror is ±3°, and the coating tolerance requirement is low;

[0027] 4) On the one hand, the present invention ensures the beam combining accuracy and improves the beam quality and efficiency of the laser beam combining system; on the other hand, it ensures the pointing stability of the laser synthesized beam and reduces the difficulty of the subsequent laser emission system. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the overall structure of a multi-band laser beam combining system of the present invention;

[0029] Figure 2 This is a schematic diagram of the structure of other parts of the present invention except the synthetic light beam monitoring module;

[0030] Figure 3 This is a schematic diagram of the structure of the light beam monitoring module of the present invention;

[0031] Figure 4 Schematic diagram of the beam direction of the first sub-beam laser 1-1 of the present invention;

[0032] Figure 5 Schematic diagram of the beam direction of the second sub-beam laser 1-2 of the present invention;

[0033] Figure 6 Schematic diagram of the beam direction of the third sub-beam laser 1-3 of the present invention;

[0034] Figure 7 This is a schematic diagram of controlling the angle of the reflector according to the present invention;

[0035] Figure 8 This is a functional schematic diagram of the beam combiner of the present invention;

[0036] Fig. 9 This is a schematic diagram of controlling the position and angle of a reflector simultaneously according to the present invention;

[0037] Fig.10 This is a schematic diagram of the function of controlling the position of the reflector according to the present invention;

[0038] Figure 1 As shown in the bid number:

[0039] 1. Laser beam combining module, 7. Synthetic beam monitoring module;

[0040] Figure 2 As shown in the bid number:

[0041] 11. first sub-beam laser, 12. second sub-beam laser, 13. third sub-beam laser, 21. first collimating lens, 22. second collimating lens, 23. third collimating lens, 3. double-sided high-reflection mirror, 41. first control reflector, 42. second control reflector, 43. third control reflector, 5. beam combining mirror, 61. first high-reflection mirror, 62. second high-reflection mirror;

[0042] Figure 3 As shown in the bid number:

[0043] 71. absorber, 72. high reflector, 73. attenuation plate, 74. focusing lens, 75. detector;

[0044] Fig. 9 As shown in the bid number:

[0045] 44. A first position-controlled reflector, 45. A second position-controlled reflector, 46. A third position-controlled reflector, 51. A first light beam synthesizing mirror, 52. A second light beam synthesizing mirror. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0047] Example 1

[0048] like Figure 1 As shown, the present invention provides a multi-band laser beam combining system, the system includes a laser beam combining module 1 (such as Figure 2 As shown) and the synthetic beam monitoring module 7 (as Figure 3 As shown). The present invention does not rely on the inherent design of the lens to achieve laser beam combining, but uses a double-sided high-reflection mirror 3, a control reflector, a beam combining mirror 5 and a high-reflection mirror to configure and surface-coat according to the actual requirements of the combined laser beam, which can achieve the synthesis of lasers of different bands, lasers of different angles and multiple laser beams. The laser beam combining module 1 includes a sub-beam laser, a collimating lens, a double-sided high-reflection mirror 3, a control reflector, a beam combining mirror 5 and a high-reflection mirror. The system has the absolute precision control and adjustment of the synthesized light beam. In theory, it can synthesize the light beams emitted by infinite sub-beam lasers into a laser output. The laser beam combining part combines each sub-beam laser into a laser beam, and most of the energy is reflected and emitted through the high-reflection mirror. A point of the synthesized light beam is transmitted as a test beam and incident on the synthesized light beam monitoring module 7. The synthesized light beam monitoring module 7 can monitor the state of light beam synthesis in real time, and feedback to the control reflector of the laser beam combining part, control the reflector to rotate in pitch, adjust and feedback the light beam, and ensure the pointing accuracy of the synthesized light beam.

[0049] like Figure 2 As shown, the present invention takes the synthesis of three light beams as an example, the sub-beam laser includes a first sub-beam laser 11, a second sub-beam laser 12 and a third sub-beam laser 13; the collimating lens includes a first collimating lens 21, a second collimating lens 22 and a third collimating lens 23; the control reflector includes a first control reflector 41, a second control reflector 42 and a third control reflector 43.

[0050] like Figure 3 As shown, the composite light beam monitoring module 7 includes an absorber 71, a high reflector 72, an attenuation plate 73, a focusing lens 74 and a detector 75, and has a real-time monitoring function for the positions of the three sub-beams of the composite light beam.

[0051] like Figure 4As shown, the first sub-beam laser 11 emits the first sub-beam, which is collimated by the first collimating lens 21 to become a parallel beam or compress the divergence angle of the sub-beam laser to make a small light spot emerge, and is reflected by the first control reflector 41 to the double-sided high-reflection mirror 3, and then reflected to the first high-reflection mirror 61, and then reflected to the beam synthesizer 5 to emit laser.

[0052] like Figure 5 As shown, the second sub-beam laser 12 emits a second sub-beam, which is collimated by the second collimating lens 22 to become a parallel beam or compress the divergence angle of the sub-beam laser to make a small light spot emerge, and is reflected by the second control reflector 42 to the double-sided high-reflection mirror 3, and then reflected to the first high-reflection mirror 61, and then reflected to the beam synthesizer 5 to emit laser.

[0053] like Figure 6 As shown, the third sub-beam laser 13 emits a third sub-beam, which is collimated by the third collimating lens 23 to become a parallel beam or compress the divergence angle of the sub-beam laser to make it emit a small light spot, which is reflected by the double-sided high-reflection mirror 3 to the third control reflector 43, and then reflected to the beam synthesizer 5 to emit laser.

[0054] The first sub-beam is combined with the second sub-beam through the double-sided high-reflection mirror 3, and then combined with the third sub-beam through the beam combining mirror 5. The absolute positions of the three sub-beam angles can be adjusted and controlled by the corresponding control reflectors to ensure the synthesis accuracy.

[0055] The synthesized light beam passes through the second high-reflection mirror 62, and 99.95% of the light beam energy is reflected and output. The surface of the second high-reflection mirror 62 is coated with a reflective film. The reflective film absorbs very little and basically does not produce a thermal lens effect. It mainly reflects most of the energy and is suitable for attenuation of high-energy lasers. The film coated on the surface of the high-reflection mirror is a wide-band reflective film. The wavelength range corresponding to the wide-band reflective film includes the wavelengths of the light beams emitted by all sub-beam lasers. The laser with a little energy is transmitted into the synthesized light beam monitoring module 7. The synthesized light beam enters the high-reflection mirror 72, and the energy is further attenuated. The film is removed according to the energy that the detector 75 can withstand to ensure the safety of the detector 75. The transmitted energy enters the attenuation plate 73 and continues to attenuate. Finally, the lasers of different wavelengths are focused on the corresponding positions of the detector 75 through the focusing lens 74, which is the theoretical absolute position. The light beams of different sub-beam lasers are subsequently controlled at the corresponding positions by adjusting the control reflector.

[0056] Among them, the installation angles of the lenses of the double-sided high-reflection mirror 3, the control reflector, the beam synthesis mirror 5 and the high-reflection mirror are consistent, and the angles of the lens are parallel. The incident angle of the laser incident on the lens (the angle between the laser and the normal of the lens) is generally between 10° and 45°, and no special angle of incidence is required. It is usually designed to be incident at a small angle. On the one hand, the system is small in size, simple and reliable, and easy to install. On the other hand, the lens coating efficiency is high, which can ensure tolerance and efficiency. The surface of the double-sided high-reflection mirror 3 is coated with a high-reflection film, and both sides simultaneously reflect the sub-beam laser or the light beam incident by the control reflector. The coating angle tolerance of the double-sided high-reflection mirror 3 needs to be large, generally giving a tolerance of 6° (i.e. ±3°). The high reflection efficiency within the tolerance range of 6° is 99.9% or above. The main function is to accommodate the angle deviation of the first sub-beam and the second sub-beam, and ensure that the two laser beams are well synthesized at a small angle.

[0057] The sub-beam laser emits the laser beam to be synthesized; the collimating lens converts the sub-beam laser into parallel light for output. If the laser has its own collimation or the divergence angle is very small, it is not necessary; the double-sided high-reflection mirror is a high-reflection mirror 72 with different film systems coated on both sides. The wavelength range corresponding to the high-reflection film includes the wavelength of the light beam reflected by the surface on which it is located, ensuring high reflection of sub-beams of different wavelengths, replacing the beam synthesizing mirror 5, reducing the complexity of the system, and the high-reflection mirror has basically no absorption and no thermal effect. In this example system, one side is coated with a high-reflection film corresponding to the wavelengths of the first incident laser and the second incident laser, and the other side is coated with a high-reflection film corresponding to the wavelength of the third incident laser; the control mirror adjusts the angle of each corresponding sub-beam. The adjustment schematic diagram is shown in Figure 7 As shown, it is ensured that the sub-beam laser can be incident on the corresponding position. The reflector is generally a fast reflector or a piezoelectric adjustment mirror. By controlling the rotation and pitch of the reflector, the absolute position of the light beam can be dynamically adjusted in real time to ensure that each sub-beam is accurately emitted at the required position. The reflector is controlled to be coated with a high-reflection film on both sides. The wavelength range corresponding to the high-reflection film includes the wavelength of the light beam reflected by the surface. The main function of the high-reflection film on the front side is to efficiently reflect the incident laser. The main function of the high-reflection film on the back side is to reflect the high-energy laser (when the synthetic laser is a high-energy laser) again to prevent the transmitted energy from damaging the control device of the reflector.

[0058] like Figure 8 As shown, the beam combiner 5 mainly utilizes the wavelength selection characteristics to combine the transmitted and reflected laser beams of different wavelengths into one laser beam for emission, mainly combining the transmitted laser beam of the third sub-beam laser 13 with the reflected laser beams of the first sub-beam laser 11 and the second sub-beam laser 12 into one laser beam, and has no requirements for the polarization of the laser beam. Figure 6As shown. The surface of the first high-reflection mirror 61 is coated with a wide-band reflective film, and the wavelength range corresponding to the wide-band reflective film includes the wavelength of the sub-beams emitted by the first sub-beam laser 11 and the second sub-beam laser 12, ensuring that the incident laser is efficiently reflected. The surface of the beam combining mirror is coated with a beam combining film, which can achieve both transmission and reflection. The coating angle tolerance range of the beam combining film is ±0.15°, which is lower than the coating angle tolerance range requirements of other existing beam combining systems or methods. Existing beam combining systems generally have specific requirements for key components. For example, polarization beam combining requires a 45° beam combining mirror, or requires incident angles such as the Brewster angle, which imposes relatively large synthesis restrictions. The beam combining mirror of the present invention has no special requirements for its own angle setting and the incident beam angle, and can be set according to actual system requirements.

[0059] Example 2

[0060] like Fig. 9 As shown, the present invention provides a multi-band laser beam combining system, the system includes a laser beam combining module 1 (such as Figure 2 As shown) and the synthetic beam monitoring module 7 (as Figure 3 As shown). The laser beam combining module 1 includes a sub-beam laser, a collimating lens, a control reflector, a position control reflector and a beam combining mirror 5. The position and angle of the present invention can be precisely controlled by adding multiple position control reflectors. This form is aimed at short-distance synthesis requirements or requirements for both beam position and angle. The overall device has a simple structure and is easy to install and control.

[0061] The present invention still takes the synthesis of three light beams as an example, the sub-beam laser includes a first sub-beam laser 11, a second sub-beam laser 12 and a third sub-beam laser 13; the collimating lens includes a first collimating lens 21, a second collimating lens 22 and a third collimating lens 23; the control reflector includes a first control reflector 41, a second control reflector 42 and a third control reflector 43; the position control reflector includes a first position control reflector 44, a second position control reflector 45 and a third position control reflector 46; the beam synthesizer includes a first beam synthesizer 51 and a second beam synthesizer 52.

[0062] The present invention controls the beam position and angle of the corresponding sub-beam laser by adding a position control reflector to cooperate with the control reflector (angle). The position control reflector mainly changes the position of the incident angle of the light beam to the control reflector by changing the position. The control reflector has the same function as that in the above-mentioned embodiment 1. The beam synthesizer 5 has a beam synthesis function, which synthesizes the first sub-beam laser 11 and the second sub-beam laser 12 into a laser output, and has the function of controlling the angle of the sub-beam laser.

[0063] like Fig.10 As shown, the position control mirror controls the position of the sub-beam by adjusting the translation.

[0064] Example 3

[0065] The present invention also provides a beam control method using a multi-band laser beam combining system, still taking the synthesis of three beams as an example, the steps are as follows:

[0066] The first sub-beam laser 11 emits a first sub-beam, which is collimated by the first collimating lens 21 to become a parallel beam or compress the divergence angle of the sub-beam laser to emit a small light spot, which is reflected by the first control reflector 41 to the double-sided high-reflection mirror 3, then reflected to the first high-reflection mirror 61, and then reflected to the beam synthesizer 5 to emit laser; the second sub-beam laser 12 emits a second sub-beam, which is collimated by the second collimating lens 22 to become a parallel beam or compress the divergence angle of the sub-beam laser to emit a small light spot, which is reflected by the second control reflector 42 to the double-sided high-reflection mirror 3, then reflected to the first high-reflection mirror 61, and then reflected to the beam synthesizer 5 to emit laser; the third sub-beam laser 13 emits a third sub-beam, which is collimated by the third collimating lens 23 to become a parallel beam or compress the divergence angle of the sub-beam laser to emit a small light spot, which is reflected by the double-sided high-reflection mirror 3 to the third control reflector 43, and then reflected to the beam synthesizer 5 to emit laser.

[0067] The first sub-beam is combined with the second sub-beam by the double-sided high-reflection mirror 3, and then combined with the third sub-beam by the beam combining mirror 5. The combined beam passes through the second high-reflection mirror 62, and 99.95% of the beam energy is reflected and output.

[0068] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A multi-band laser beam combining system, characterized in that: It comprises a laser beam combining module (1), a combined beam monitoring module (7) and a double-sided high-reflection mirror (3); the laser beam combining module (1) comprises at least three sub-beam lasers, at least three control reflectors, a beam combining mirror (5) and a high-reflection mirror; the surface of the double-sided high-reflection mirror (3) is plated with a high-reflection film; A part of the sub-beams emitted by at least three of the sub-beam lasers is irradiated onto the control reflector, and after being reflected by the control reflector, reaches one side of the double-sided high-reflection mirror (3), and the other part is directly irradiated onto the other side of the double-sided high-reflection mirror (3); the two sides of the double-sided high-reflection mirror (3) simultaneously reflect the sub-beam lasers or the light beams incident on the control reflector to the light beam synthesis mirror (5) to synthesize them into a synthesized light beam, and the synthesized light beam passes through the light beam synthesis mirror (5) to reach the high-reflection mirror, and reflects the synthesized laser from one side of the high-reflection mirror, and outputs a test light beam from the other side to enter the synthesized light beam monitoring module (7); the control reflector adjusts the angle of light beam reflection, and the synthesized light beam monitoring module (7) monitors the position of the sub-beams; the light beam synthesis mirror (5) utilizes the wavelength selection characteristic to synthesize the laser beams transmitted and reflected by the sub-beams of different wavelengths into a laser beam for output; The synthetic light beam monitoring module (7) comprises an absorber (71), a high reflector (72), an attenuation plate (73), a focusing lens (74) and a detector (75).

2. A multi-band laser beam combining system according to claim 1, characterized in that: There are at least four control reflectors, and each sub-beam emitted by the sub-beam laser passes through two control reflectors to adjust the beam position and beam angle respectively; the surface of the control reflector is coated with a high-reflection film, and the wavelength range corresponding to the high-reflection film includes the wavelength of the light beam reflected by the surface.

3. The multi-band laser beam combining system according to claim 1, characterized in that: The surface of the high-reflection mirror is coated with a wide-band reflective film, and the wavelength range corresponding to the wide-band reflective film includes the wavelengths of the sub-beams emitted by all the sub-beam lasers.

4. The multi-band laser beam combining system according to claim 1, characterized in that: The synthetic laser has at least 99.95% of the energy of the synthetic beam.

5. The multi-band laser beam combining system according to claim 1, characterized in that: The surface of the beam combining mirror (5) is coated with a beam combining film, and the angle tolerance range of the beam combining film coating is ±0.15°.

6. The multi-band laser beam combining system according to claim 1, characterized in that: The wavelength range corresponding to the high-reflection film includes the wavelength of the light beam reflected by the surface on which it is located, and the coating angle tolerance range is ±3°.

7. The multi-band laser beam combining system according to claim 1, characterized in that: The installation angles of the control reflector, the light beam synthesis mirror (5), the high reflection mirror and the double-sided high reflection mirror (3) are consistent.

8. The multi-band laser beam combining system according to claim 1, characterized in that: The system also includes a collimating lens, which is arranged at the laser output end of the sub-beam laser.

9. A beam control method using the multi-band laser beam combining system according to any one of claims 1 to 8, characterized in that: A controller is also used, which specifically includes the following steps: Step S1, the sub-beam laser emits a sub-beam to irradiate the control reflector; Step S2, controlling the reflector to reflect the light beam to reach the beam combining mirror (5); Step S3, the beam combiner (5) combines at least two light beams into a combined light beam; Step S4, the synthesized light beam reaches the high-reflection mirror, one side of the high-reflection mirror reflects the synthesized laser, and the other side outputs the test light beam to enter the synthesized light beam monitoring module (7); Step S5, the composite beam monitoring module (7) monitors the absolute position of each sub-beam in real time through the test beam and feeds back to the controller, and the controller adjusts the absolute position of the control reflector.

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