Laser zoom beam expander

Abstract

The utility model relates to the technical field of laser, in particular to a laser zoom beam expander which comprises a first lens, a second lens, a third lens and a fourth lens, in the laser zoom beam expander, the first lens, the second lens, the third lens and the fourth lens are sequentially arranged at intervals, the first lens is a negative lens, the second lens is a positive lens, and the fourth lens is a negative lens. The second lens is a positive lens, the third lens is a negative lens, and the fourth lens is a positive lens, so that the area of a laser spot converged on the negative lens by the positive lens in a light path is increased, the laser intensity is reduced, and the problems that the area of the light spot on the negative lens of a traditional laser beam expander is small, the laser intensity is large, and the negative lens is prone to being damaged are solved.

Description

Technical Field

[0001] This application relates to the field of laser technology, and particularly to a laser variable magnification beam expander. Background Art

[0002] In a laser processing system, the laser spot diameter emitted by a laser is generally small and the energy is high. A laser beam expander can change the laser beam diameter, divergence angle, and intensity distribution, and is one of the most widely used components in a laser processing system. For a Gaussian beam, the smaller the waist radius, the larger the divergence angle. When a Gaussian beam passes through an expanding system, the waist diameter of the output beam is larger than that of the input beam, and the output divergence angle is smaller than the input divergence angle.

[0003] Laser intensity is represented by the ratio of laser power to spot area. When the laser power is constant, increasing the spot area can reduce the laser intensity and reduce damage to optical devices. The variable magnification beam expander used in laser applications generally adopts a Galilean "positive-negative-positive" optical structure arrangement. Therefore, the beam formed by the positive lens of the laser beam will converge on the negative lens, resulting in a smaller laser spot area and a larger laser intensity on the negative lens, which is prone to damage in laser processing applications and affects the service life of the beam expander. Summary of the Utility Model

[0004] This application provides a laser variable magnification beam expander, aiming to solve the problem that the spot area on the negative lens of a traditional laser beam expander is small, the laser intensity is large, and it is easy to cause damage to the negative lens.

[0005] To solve the above technical problems, this application proposes a laser variable magnification beam expander, which includes: a first lens, a second lens, a third lens, and a fourth lens;

[0006] The first lens, the second lens, the third lens, and the fourth lens are arranged at intervals in sequence. The first lens is a negative lens, the second lens is a positive lens, the third lens is a negative lens, and the fourth lens is a positive lens.

[0007] Further, the first lens is a meniscus lens.

[0008] Further, the second lens is a biconvex lens.

[0009] Further, the third lens is a biconcave lens.

[0010] Further, the fourth lens is a meniscus lens.

[0011] Further, a first protective mirror is provided on the side of the first lens away from the second lens, and the first protective mirror is a flat plate structure.

[0012] Further, a second protective mirror is provided on a side of the fourth lens away from the third lens, and the second protective mirror has a flat structure.

[0013] Further, the radius of curvature of a side of the first lens close to the second protective mirror is R1 = -11.9 mm, the radius of curvature of a side of the first lens close to the first protective mirror is R2 = -20.2 mm, the central thickness of the first lens is d1 = 2 mm, the refractive index of the first lens is n1, and the Abbe number is v1, which satisfy the relational expression: 1.4 < n1 < 1.55, 65 < v1 < 75.

[0014] Further, the radius of curvature of a side of the second lens close to the second protective mirror is R3 = 64.4 mm, the radius of curvature of a side of the second lens close to the first protective mirror is R4 = -28.6 mm, the central thickness of the second lens is d3 = 3 mm, the refractive index of the second lens is n2, and the Abbe number is v2, which satisfy the relational expression: 1.4 < n2 < 1.55, 65 < v2 < 75.

[0015] Further, the distance between the first lens and the second lens on the optical axis is d2, and the value range of d2 is 23 mm ≤ d2 ≤ 59 mm. The distance between the second lens and the third lens on the optical axis is d4, and the range of d4 is 9 mm ≤ d4 ≤ 45 mm. The distance between the third lens and the fourth lens on the optical axis is d6, and the range of d6 is 34 mm ≤ d4 ≤ 56 mm, and the tolerance range of d2, d4, and d6 is 5%.

[0016] The beneficial effects of the present application are as follows: In the laser zoom expander provided in the present application, the first lens, the second lens, the third lens, and the fourth lens are arranged at intervals in sequence. The first lens is a negative lens, the second lens is a positive lens, the third lens is a negative lens, and the fourth lens is a positive lens. By adopting the lens arrangement order of negative, positive, negative, and positive, the spot area on the third lens is relatively large, the intensity of the laser is reduced, the third lens is effectively prevented from being damaged by the laser, and the service life of the laser expander is prolonged. Description of the Drawings

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts. Among them:

[0018] Figure 1 is a schematic diagram of a laser zoom expander according to an embodiment of the present invention;

[0019] Figure 2 is the spot diagram of the laser zoom beam expander according to an embodiment of the present utility model;

[0020] Figure 3 is the optical transfer function diagram of the laser zoom beam expander according to an embodiment of the present utility model.

[0021] Description of reference numerals: 100, first protective mirror; 200, first lens; 300, second lens; 400, third lens; 500, fourth lens; 600, second protective mirror. Detailed implementation manners

[0022] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0023] Those skilled in the art of the present technology can understand that, unless specifically stated otherwise, the singular forms "a", "an", "above-mentioned" and "the" used herein may also include the plural forms. It should be further understood that the term "including" used in the specification of the present application means the presence of features, integers, steps, operations, elements, modules, modules and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, modules, modules, components and / or their groups. It should be understood that when we say that an element is "connected" or "coupled" to another element, it can be directly connected or coupled to other elements, or there may also be intermediate elements. In addition, the "connection" or "coupling" used herein may include wireless connection or wireless coupling. The phrase "and / or" used herein includes all or any one of the listed items and all combinations of one or more related items.

[0024] Those skilled in the art of the present technology can understand that, unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as the general understanding of those of ordinary skill in the field to which the present application belongs. It should also be understood that terms such as those defined in a general dictionary should be understood to have a meaning consistent with the meaning in the context of the prior art, and will not be interpreted with an idealized or overly formal meaning unless specifically defined as here.

[0025] Such as Figure 1As shown in the figure, the present application provides a laser variable magnification beam expander, which includes a first lens 200, a second lens 300, a third lens 400, and a fourth lens 500. The first lens 200, the second lens 300, the third lens 400, and the fourth lens 500 are arranged at intervals in sequence. The first lens 200 is a negative lens, the second lens 300 is a positive lens, the third lens 400 is a negative lens, and the fourth lens 500 is a positive lens.

[0026] In a specific embodiment, a negative lens is a lens with a negative focal length, and a negative lens can diverge light rays. A positive lens is a lens with a positive focal length, and a positive lens can converge light rays. By alternately arranging negative lenses and positive lenses, the incident laser beam can be effectively modulated. When the laser beam first enters the first lens 200 with a negative focal length, the light beam will be diverged, and then passes through the second lens 300 with a positive focal length, and the light beam will be converged to a certain extent. Then, it passes through the third lens 400 with a negative focal length to further adjust the divergence degree of the light beam. Finally, it passes through the fourth lens 500 with a positive focal length to achieve the final beam expansion and variable magnification effect. This structural design can flexibly adjust the parameters of the light beam, achieve beam expansion functions of different multiples, and meet the requirements of various application scenarios. By adopting the lens arrangement order of negative, positive, negative, and positive, the spot area on the third lens is relatively large, reducing the intensity of the laser, effectively preventing the third lens from being damaged by the laser, and extending the service life of the laser beam expander.

[0027] As Figure 1 shown, the first lens 200 is a meniscus lens.

[0028] In a specific embodiment, the first lens 200 is a meniscus lens, whose shape is similar to a crescent moon. The side of the first lens 200 close to the second lens 300 is a convex surface, and the side of the first lens 200 far from the second lens 300 is a concave surface. Designing the first lens 200 as a meniscus lens is based on its special processing ability for light beams. When light of different wavelengths passes through the meniscus-shaped first lens 200, it can form an image at the same focal point, thereby effectively reducing chromatic aberration.

[0029] In summary, the first lens 200 adopting a meniscus structure has advantages in optical aberration correction, can effectively reduce spherical aberration, coma and other aberrations during the propagation of the light beam, improve the quality of the light beam, make the output laser beam clearer and more accurate, and is beneficial to improving the performance of the laser in high-precision application scenarios.

[0030] As Figure 1 shown, the second lens 300 is a biconvex lens.

[0031] In a specific embodiment, after the laser beam is diverged by the first lens 200, it enters the second lens 300 with a biconvex structure. The biconvex structure enables the second lens 300 to have a stronger converging ability for the beam, and can more effectively converge the diverged beam to a certain extent, adjusting the propagation direction and energy distribution of the beam. This biconvex structure helps to improve the beam concentration and energy utilization rate, provides more suitable beam conditions for subsequent lens processing, and further optimizes the beam expansion and magnification effects of the beam expander. At the same time, the second lens 300 with a biconvex structure has good performance in optical imaging and beam transmission, can better adapt to the characteristics of the laser beam, and ensures the stability and reliability of the entire optical system.

[0032] As Figure 1 shown, the third lens 400 is a biconcave structure lens.

[0033] In a specific embodiment, during the process of laser magnification and beam expansion, the third lens 400, as a negative lens and with a biconcave structure, plays a key role. When the beam is converged by the second lens 300 and then enters the third lens 400 with a biconcave structure, the biconcave structure enables the third lens 400 to further diverge and adjust the beam, cooperate with the diverging effect of the first lens 200, and more precisely control the propagation and divergence angle of the beam. This structure helps to achieve fine adjustment of the beam parameters during the entire beam expansion process, enabling the beam to enter the fourth lens 500 for final processing in a suitable state, thereby ensuring that the beam expander can achieve a stable and accurate magnification and beam expansion function. At the same time, the biconcave structure lens can also play a certain role in correcting aberration in the optical system, cooperate with other lenses, and improve the beam quality and imaging effect.

[0034] As Figure 1 shown, the fourth lens 500 is a meniscus structure lens.

[0035] In a specific embodiment, after the beam is sequentially processed by the first, second, and third lenses, the beam enters the fourth lens 500 with a meniscus structure. The meniscus structure of the fourth lens 500 can perform the final convergence and shaping of the beam, enabling it to meet the required beam expansion ratio and beam quality requirements. The special shape of the meniscus structure enables the fourth lens 500 to effectively control the aberration and divergence angle of the beam while converging the beam, ensuring that the output laser beam has good directivity and uniformity. Compared with lenses of other structures, the fourth lens 500 with a meniscus structure can better cooperate with the previous lenses to complete the entire process of laser magnification and beam expansion.

[0036] In summary, the fourth lens 500 with a meniscus structure can perform a final fine adjustment on the light beam processed by the previous lenses, enabling the output laser beam to have higher quality and stability. When light of different wavelengths passes through the fourth lens 500 with a meniscus structure, it can be imaged at the same focal point, thus effectively reducing chromatic aberration.

[0037] As Figure 1 shown, a first protective mirror 100 is provided on the side of the first lens 200 away from the second lens 300, and the first protective mirror 100 has a flat structure.

[0038] In a specific embodiment, the first protective mirror 100 has a flat structure and can play a certain role in filtering and homogenizing the light beam before the light beam enters the first lens 200. The first protective mirror 100 can block some possible contaminants such as dust and impurities from entering the optical system, thereby protecting the first lens 200 from damage and extending its service life. At the same time, the design of the flat structure has little influence on the propagation direction and energy distribution of the light beam, ensuring that the laser beam can smoothly enter the first lens 200 for subsequent processing. In addition, the first protective mirror 100 can also play a role in buffering and dispersing the laser energy to a certain extent, reducing the risk of damage to the first lens 200 caused by excessive laser energy, and improving the reliability and stability of the entire laser beam expander.

[0039] As Figure 1 shown, a second protective mirror 600 is provided on the side of the fourth lens 500 away from the third lens 400, and the second protective mirror 600 has a flat structure.

[0040] In a specific embodiment, the flat-structured second protective mirror 600 can perform secondary filtering and sorting on the light beam before the light beam leaves the laser beam expander. The second protective mirror 600 can prevent some tiny particles, debris and other impurities that may be generated inside the laser beam expander from being emitted together with the light beam, thereby protecting the external optical equipment or working environment from pollution. In addition, the design of the flat structure enables the second protective mirror 600 to better cooperate with the fourth lens 500, and will not have an obvious negative impact on the beam quality and beam expansion effect after the light beam is processed by the fourth lens 500, ensuring the stability and reliability of the output beam of the entire laser beam expander.

[0041] In one embodiment, the first lens 200 has a central thickness of d1 on the optical axis, a refractive index of n1, and an Abbe number of v1, which satisfy the relational expression: 1.4 < n1 < 1.55, 65 < v1 < 75. The second lens 300 has a central thickness of d3 on the optical axis, a refractive index of n2, and an Abbe number of v2, which satisfy the relational expression: 1.4 < n2 < 1.55, 65 < v2 < 75. The third lens 400 has a central thickness of d5 on the optical axis, a refractive index of n3, and an Abbe number of v3, which satisfy the relational expression: 1.4 < n3 < 1.55, 65 < v3 < 75. The fourth lens 500 has a central thickness of d7 on the optical axis, a refractive index of n4, and an Abbe number of v4, which satisfy the relational expression: 1.4 < n4 < 1.55, 65 < v4 < 75. The curvature radii of the surfaces of the first lens 200, the second lens 300, the third lens 400, and the fourth lens 500 that are close to the second protective mirror 600 are the first curvature radii, and the curvature radii of the surfaces of the above-mentioned lenses that are close to the first protective mirror 100 are the second curvature radii. In this embodiment, the distance between the first lens 200 and the second lens 300 on the optical axis is d2, the distance between the second lens 300 and the third lens 400 on the optical axis is d4, and the distance between the third lens 400 and the fourth lens 500 on the optical axis is d6. The specific data parameters of the laser variable magnification beam expander are shown in Table 1.

[0042] Table 1:

[0043]

[0044] By adjusting d2, d4, and d6, the laser variable magnification beam expander can produce different beam expansion ratios. Specifically, when d2 + d4 = 68 mm, moving the second lens 300 and the fourth lens 500 can produce different magnification ratios. The beam expansion ratios produced by the laser variable magnification beam expander corresponding to the relationships of d2, d4, and d6 are shown in Table 2 below, where Φ is from 4 mm to 6 mm, β is from 1 to 5, λ is 355 nm, Φ is the range of the incident beam diameter allowed by the laser variable magnification beam expander in this application, β is the beam expansion ratio, and λ is the wavelength of the input beam.

[0045] Table 2:

[0046]

[0047] The spot diagram of the laser variable magnification beam expander in this embodiment is as shown in Figure 2 . It can be clearly seen from the figure that the beam quality of the output beam of the laser variable magnification beam expander is within the diffraction limit. The optical transfer function diagram is as shown in Figure 3 . It can be clearly seen from the figure that the optical transfer functions of the output beams of the laser variable magnification beam expander have reached the diffraction limit.

[0048] The above are only the preferred embodiments of the present application, which do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present application.

Claims

1. A laser variable magnification beam expander, characterized in that, Including: A first lens, a second lens, a third lens, and a fourth lens; The first lens, the second lens, the third lens, and the fourth lens are arranged at intervals in sequence. The first lens is a negative lens, the second lens is a positive lens, the third lens is a negative lens, and the fourth lens is a positive lens.

2. The laser variable magnification beam expander according to claim 1, wherein, The first lens is a meniscus lens.

3. The laser variable magnification beam expander according to claim 1, wherein, The second lens is a biconvex lens.

4. The laser variable magnification beam expander according to claim 1, wherein The third lens is a biconcave lens.

5. The laser variable magnification beam expander according to claim 1, wherein, The fourth lens is a meniscus lens.

6. The laser variable magnification beam expander according to claim 1, wherein A first protective lens is provided on the side of the first lens away from the second lens, and the first protective lens is a flat structure.

7. The laser variable magnification beam expander according to claim 6, wherein, A second protective lens is provided on the side of the fourth lens away from the third lens, and the second protective lens is a flat structure.

8. The laser variable magnification beam expander according to claim 7, characterized in that The radius of curvature of the side of the first lens close to the second protective lens is R1 = -11.9 mm, the radius of curvature of the side of the first lens close to the first protective lens is R2 = -20.2 mm, the central thickness of the first lens is d1 = 2 mm, the refractive index of the first lens is n1, and the Abbe number is v1, which satisfies the relationship: 1.4 < n1 < 1.55, 65 < v1 < 75.

9. The laser variable magnification beam expander according to claim 7, characterized in that, The radius of curvature of the side of the second lens close to the second protective lens is R3 = 64.4 mm, the radius of curvature of the side of the second lens close to the first protective lens is R4 = -28.6 mm, the central thickness of the second lens is d3 = 3 mm, the refractive index of the second lens is n2, and the Abbe number is v2, which satisfies the relationship: 1.4 < n2 < 1.55, 65 < v2 < 75.

10. The laser variable magnification beam expander according to claim 1, characterized in that, The distance between the first lens and the second lens on the optical axis is d2, and the value range of d2 is 23 mm ≤ d2 ≤ 59 mm. The distance between the second lens and the third lens on the optical axis is d4, and the range of d4 is 9 mm ≤ d4 ≤ 45 mm. The distance between the third lens and the fourth lens on the optical axis is d6, and the range of d6 is 34 mm ≤ d4 ≤ 56 mm.

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