Telecentric achromatic lens structure and laser lens thereof

Abstract

The invention belongs to the field of laser, and discloses a telecentric achromatic lens structure and a laser lens thereof. The telecentric achromatic lens structure comprises a plurality of lenses located on the same optical axis, the lenses sequentially comprise the first lens, the second lens, the third lens, the fourth lens and the fifth lens in the light propagation direction, the first lens is a plano-concave lens, the concave surface of the first lens faces the light propagation direction, and the concave surface of the second lens faces the light propagation direction. The second lens is a meniscus lens, the concave surface of the second lens faces the light propagation direction, the third lens is a biconvex lens, the fourth lens is a biconcave lens, and the fifth lens is a biconvex lens. According to the telecentric achromatic lens structure, different lenses are matched with one another, different refractive indexes and dispersion characteristics offset chromatic aberration, it is ensured that different laser beams can be more accurately focused on a focal plane, effective correction of chromatic aberration is achieved, the structure is simple, and repeated correction is not needed.

Description

Technical Field

[0001] The invention relates to the field of laser technology, and in particular to a telecentric achromatic lens structure and a laser lens thereof. Background Art

[0002] With the continuous development of laser technology, different working environments have different requirements for laser wavelengths. Due to the inherent material dispersion of the lens system, chromatic aberration will inevitably occur when the laser pulse passes through the lens. Chromatic aberration refers to the phenomenon that light of different wavelengths focuses on different positions due to the difference in refractive index when passing through a lens or reflector, resulting in blurred imaging or color separation. As an efficient precision welding technology, laser welding requires high assembly accuracy of weldments, and the position of the laser beam on the workpiece cannot be significantly offset, otherwise it is easy to cause welding defects. Because the spot size is small and the weld is narrow after the laser is focused, it cannot be accurately positioned on the operating surface. Among them, the significant offset of the laser beam position is caused by chromatic aberration.

[0003] The common method is to use a lens with a special curvature to eliminate chromatic aberration. However, chromatic aberration is caused by the different refractive indices of light of different wavelengths in the lens material. This difference increases with the increase of wavelength. The ability to correct aberration is limited. For laser beams of different wavelengths, the focal plane position of the focusing lens needs to be repeatedly calibrated. The steps are cumbersome and easy to cause measurement errors. In summary, it is difficult to achieve achromatic aberration of lenses in the prior art. Summary of the invention

[0004] The main purpose of the present invention is to provide a telecentric achromatic lens structure and a laser lens thereof, aiming to solve the problem of focal position difference caused by different refractive indices of laser beams of different wavelengths.

[0005] To achieve the above-mentioned purpose, the present invention provides a telecentric achromatic lens structure, comprising a plurality of lenses on the same optical axis, wherein the lenses sequentially comprise a first lens, a second lens, a third lens, a fourth lens and a fifth lens along the direction of light propagation, wherein the first lens is a plano-concave lens, the concave surface of the first lens faces the direction of light propagation, the second lens is a meniscus lens, the concave surface of the second lens faces the direction of light propagation, the third lens is a biconvex lens, the fourth lens is a biconcave lens, and the fifth lens is a biconvex lens.

[0006] In one embodiment, along the light propagation direction, the first lens has a first curved surface and a second curved surface, the curvature of the first curved surface is -35.50 mm, and the curvature of the second curved surface is 0 mm, forming the plano-concave lens.

[0007] In one embodiment, along the light propagation direction, the second lens has a third curved surface and a fourth curved surface, the curvature of the third curved surface is -196.09 mm, and the curvature of the fourth curved surface is -52.72 mm, forming the meniscus lens.

[0008] In one embodiment, along the light propagation direction, the third lens has a fifth curved surface and a sixth curved surface, the curvature of the fifth curved surface is 196.09 mm, and the curvature of the sixth curved surface is -81.47 mm.

[0009] In one embodiment, along the light propagation direction, the fourth lens has a seventh curved surface and an eighth curved surface, the curvature of the seventh curved surface is -81.47 mm, and the curvature of the eighth curved surface is 81.47 mm.

[0010] In one embodiment, along the light propagation direction, the fifth lens has a ninth curved surface and a tenth curved surface, the curvature of the ninth curved surface is 81.47 mm, and the curvature of the tenth curved surface is -196.09 mm.

[0011] In one embodiment, the plurality of lenses include HLAF3B lenses and ZF6 lenses.

[0012] In one embodiment, an air gap is formed between two adjacent lenses.

[0013] The present invention also provides a laser lens, characterized in that it comprises:

[0014] a housing; and

[0015] A telecentric achromatic lens structure, wherein the telecentric achromatic lens structure is the telecentric achromatic lens structure according to any one of claims 1 to 8.

[0016] In one embodiment, the laser lens further includes a water cooling structure for cooling the housing.

[0017] The present invention provides a telecentric achromatic lens structure, comprising a plurality of lenses on the same optical axis, wherein the achromatic structure is formed by combining a plano-concave lens, a meniscus lens, a biconvex lens and a biconcave lens in a composite lens combination manner, and by using different lenses to match each other and offsetting chromatic aberrations through different refractive indices and dispersion characteristics, at least two main wavelengths of light (usually red light and blue light) are focused at the same focal length to reduce chromatic aberration, ensuring that different laser beams can be focused more accurately on a focal plane, achieving effective correction of chromatic aberration, and ensuring the accuracy of laser welding positioning, and having a simple structure without the need for repeated calibration. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1is a structural schematic diagram of a telecentric achromatic lens structure provided by an embodiment of the present invention;

[0019] Figure 2 It is the diffusion pattern of the optical lens;

[0020] Figure 3 is the modulation transfer function (MTF) curve of the optical lens;

[0021] Figure 4 It is a schematic diagram of the structure of a laser lens provided by an embodiment of the present invention.

[0022] Description of Figure Numbers:

[0023] 1000, 100, telecentric achromatic lens structure; 1, lens; 11, first lens 12, second lens; 13, third lens; 14, fourth lens; 15, fifth lens; 2, housing; 3, water cooling structure.

[0024] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0025] 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 only 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 are within the scope of protection of the present invention.

[0026] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0027] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0028] With the continuous development of laser technology, different working environments have different requirements for laser wavelengths. Due to the inherent material dispersion of the lens system, chromatic aberration will inevitably occur when the laser pulse passes through the lens. Chromatic aberration refers to the phenomenon that light of different wavelengths focuses on different positions due to the difference in refractive index when passing through a lens or reflector, resulting in blurred imaging or color separation. As an efficient precision welding technology, laser welding requires high assembly accuracy of weldments, and the position of the laser beam on the workpiece cannot be significantly offset, otherwise it is easy to cause welding defects. Because the spot size is small and the weld is narrow after the laser is focused, it cannot be accurately positioned on the operating surface. Among them, the significant offset of the laser beam position is caused by chromatic aberration.

[0029] The common method is to use a lens with a special curvature to eliminate chromatic aberration. However, chromatic aberration is caused by the different refractive indices of light of different wavelengths in the lens material. This difference increases with the increase of wavelength. The ability to correct aberration is limited. For laser beams of different wavelengths, the focal plane position of the focusing lens needs to be repeatedly calibrated. The steps are cumbersome and easy to cause measurement errors. In summary, it is difficult to achieve achromatic aberration of lenses in the prior art.

[0030] See also Figure 1 The present invention provides a telecentric achromatic lens structure 100, comprising a plurality of lenses 1 on the same optical axis, wherein the lenses 1 sequentially comprise a first lens 11, a second lens 12, a third lens 13, a fourth lens 14 and a fifth lens 15 along the light propagation direction, wherein the first lens 11 is a plano-concave lens, the concave surface of the first lens 11 faces the light propagation direction, the second lens 12 is a meniscus lens, the concave surface of the second lens 12 faces the light propagation direction, the third lens 13 is a biconvex lens, the fourth lens 14 is a biconcave lens, and the fifth lens 15 is a biconvex lens.

[0031] The present invention provides a telecentric achromatic lens structure 100, comprising a plurality of lenses 1 on the same optical axis, wherein the achromatic structure is formed by combining a plano-concave lens, a meniscus lens, a biconvex lens and a biconcave lens in a composite lens combination manner, and by using different lenses 1 to match each other, chromatic aberration is offset by different refractive indices and dispersion characteristics, so that at least two main wavelengths of light (usually red light and blue light) are focused at the same focal length to reduce chromatic aberration, ensuring that different laser beams can be focused more accurately on a focal plane, achieving effective correction of chromatic aberration, and ensuring the accuracy of laser welding positioning, and having a simple structure without the need for repeated calibration.

[0032] It should be noted that, in the present invention, there are multiple ways to set the lens structural parameters of the first lens 11, the second lens 12, the third lens 13, the fourth lens 14 and the fifth lens 15, which vary according to different actual working objects.

[0033] In one embodiment, the first lens 11 has a first curved surface and a second curved surface, the curvature of the first curved surface is -35.50 mm, and the curvature of the second curved surface is 0 mm, forming the plano-concave lens.

[0034] In addition, the second lens 12 has a third curved surface and a fourth curved surface, the curvature of the third curved surface is -196.09 mm, and the curvature of the fourth curved surface is -52.72 mm, forming the meniscus lens.

[0035] In one embodiment, the third lens 13 has a fifth curved surface and a sixth curved surface, the curvature of the fifth curved surface is 196.09 mm, and the curvature of the sixth curved surface is -81.47 mm.

[0036] In one embodiment, the fourth lens 14 has a seventh curved surface and an eighth curved surface, the curvature of the seventh curved surface is -81.47 mm, and the curvature of the eighth curved surface is 81.47 mm.

[0037] In one embodiment, the fifth lens 15 has a ninth curved surface and a tenth curved surface, the curvature of the ninth curved surface is 81.47 mm, and the curvature of the tenth curved surface is -196.09 mm.

[0038] Among them, in a specific embodiment provided by the present invention, the curvature of the first curved surface is -35.50mm, the curvature of the second curved surface is 0, the curvature of the third curved surface is -196.09mm, the curvature of the fourth curved surface is -52.72mm, the curvature of the fifth curved surface is 196.09mm, the curvature of the sixth curved surface is -81.47mm, the curvature of the seventh curved surface is -81.47mm, the curvature of the eighth curved surface is 81.47mm, the curvature of the ninth curved surface is 81.47mm, and the curvature of the tenth curved surface is -196.09mm. Through the coordination between lenses with different curvatures, using different dispersion characteristics and refractive indices, the telecentric achromatic lens structure 100 formed by the combination can achieve the function of achromatism.

[0039] See also Figure 2 , wherein, in this embodiment, the telecentric achromatic lens structure sequentially arranges the first lens 11, the second lens 12, the third lens 13, the fourth lens 14 and the fifth lens 15 in the direction of light propagation, RMS is a measure of wavefront error, which quantifies the deviation between the wavefront and the ideal wavefront. The smaller the RMS value, the smaller the wavefront error, and the better the performance of the optical system is generally.

[0040] In addition, in this embodiment, the interval of the first curved surface is 3.11mm, the interval of the second curved surface is 2.13, the interval of the third curved surface is 16.00mm, the interval of the fourth curved surface is 4.24, the interval of the fifth curved surface is 17.50mm, the interval of the sixth curved surface is 2.72mm, the interval of the seventh curved surface is 4mm, the interval of the eighth curved surface is 0mm, the interval of the ninth curved surface is 17.50mm, and the interval of the tenth curved surface is 130.57mm.

[0041] In addition, the plurality of lenses may be combined using lenses made of different materials, and the lenses are made of materials with different refractive indices and dispersion characteristics, so that the chromatic aberrations between the lenses can be offset.

[0042] Specifically, in this embodiment, the plurality of lenses include HLAF3B lenses and ZF6 lenses. The plurality of lenses include lenses made of two different materials, so that the characteristics of the lenses themselves have certain differences, and further achromatism is achieved by arranging and combining lenses of different materials.

[0043] In this embodiment, the refractive index of the first lens 11 is 1.4875, and the dispersion is 70.4405.

[0044] The refractive index of the second lens 12 is 1.7440, and the dispersion is 44.9024.

[0045] The refractive index of the third lens 13 is 1.7440, and the dispersion is 44.9024.

[0046] The refractive index of the fourth lens 14 is 1.7552, and the dispersion is 27.5462.

[0047] The refractive index of the fifth lens 15 is 1.7440, and the dispersion is 44.9024.

[0048] The materials of the first lens 11, the second lens 12, the third lens 13, the fourth lens 14 and the fifth lens 15 can be specifically configured and selected as required, as long as they can meet the requirements of refractive index and dispersion.

[0049] It should be noted that materials HLAF3B and ZF6 are common materials in the lens field. Among them, HLAF3B lenses usually have a higher refractive index and a moderate Abbe number, which can balance the focus position differences caused by different refractive indices of light beams of different wavelengths. ZF6 lenses usually have a high refractive index, a low Abbe number and good transmittance, and are often used in combination with other types of lenses (such as HLAF3B lenses) to balance and optimize the chromatic aberration caused by different refractive indices of different wavelengths.

[0050] Furthermore, an air gap is formed between two adjacent lenses 1, thereby eliminating defocus dispersion while ensuring the focal length of the lens.

[0051] It should be noted that, in this embodiment, the air gap between two adjacent lenses 1 is 4 mm.

[0052] It should also be noted that, in this embodiment, each lens 1 is movably arranged along the direction of the same optical axis to facilitate adjustment of the air gap between two adjacent lenses 1. Combining multiple lenses 1 overcomes the imaging defects of a single lens, improves the optical quality of the objective lens, and the distance between each lens 1 can be appropriately adjusted to reduce phase difference.

[0053] Based on the above telecentric achromatic lens structure 100, Figure 3 The modulation transfer function (MTF) curve of the optical lens is shown in Figure 1. The MTF within the cutoff frequency range is close to the diffraction limit, which meets the high-precision requirements of laser processing. The design results meet the requirements.

[0054] See also Figure 4Based on the above-mentioned telecentric achromatic lens structure 100, the present invention also provides a laser lens 1000, including the above-mentioned telecentric achromatic lens structure 100, and therefore, has all the technical features of the above-mentioned telecentric achromatic lens structure 100, that is, has the technical effects brought by all the above-mentioned technical features, which will not be repeated here one by one.

[0055] The laser lens 1000 also includes a housing 2, wherein the plurality of lenses 1 are disposed in the housing. The laser lens 1000 provided by the present invention is disposed on a laser, and the laser emitted by the laser passes through the first lens 11, the second lens 12, the third lens 13, the fourth lens 14 and the fifth lens 15 in sequence. Through the different types and materials of the lenses, the chromatic aberration of the light during the propagation process is eliminated, so that light of different wavelengths can be focused on the same position without causing deviations between light of different wavelengths due to reasons such as refractive index. The chromatic aberration can be effectively eliminated by means of a lens group, and at the same time, there is no need for repeated calibration, which is more accurate and convenient to use.

[0056] Furthermore, the laser lens further includes a water cooling structure 3 for cooling the housing 2. In this embodiment, the housing 2 is cooled by the water cooling structure 3 to prevent the laser lens from being damaged due to excessive heating during operation.

[0057] It should be noted that the water cooling structure 3 has multiple implementation modes. In the present embodiment, the water cooling structure includes a water inlet pipe, a water outlet pipe, and a water cooling channel formed in the shell 2. The water inlet pipe and the water outlet pipe are connected to the water cooling channel for circulating cooling water in the water cooling channel, which facilitates the cooling of the shell 2. The structure is simple and reliable.

[0058] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A telecentric achromatic lens structure, characterized in that: The invention comprises a plurality of lenses on the same optical axis, wherein the lenses sequentially comprise a first lens, a second lens, a third lens, a fourth lens and a fifth lens along the light propagation direction, wherein the first lens is a plano-concave lens, the concave surface of the first lens faces the light propagation direction, the second lens is a meniscus lens, the concave surface of the second lens faces the light propagation direction, the third lens is a biconvex lens, the fourth lens is a biconcave lens, and the fifth lens is a biconvex lens; An air gap is formed between two adjacent lenses.

2. The telecentric achromatic lens structure according to claim 1, characterized in that: Along the light propagation direction, the first lens has a first curved surface and a second curved surface, the curvature of the first curved surface is -35.50 mm, and the curvature of the second curved surface is 0, forming the plano-concave lens.

3. The telecentric achromatic lens structure according to claim 1, characterized in that: Along the light propagation direction, the second lens has a third curved surface and a fourth curved surface, the curvature of the third curved surface is -196.09 mm, and the curvature of the fourth curved surface is -52.72 mm, forming the meniscus lens.

4. The telecentric achromatic lens structure according to claim 1, characterized in that: Along the light propagation direction, the third lens has a fifth curved surface and a sixth curved surface, the curvature of the fifth curved surface is 196.09 mm, and the curvature of the sixth curved surface is -81.47 mm.

5. The telecentric achromatic lens structure according to claim 1, characterized in that: Along the light propagation direction, the fourth lens has a seventh curved surface and an eighth curved surface, the curvature of the seventh curved surface is -81.47 mm, and the curvature of the eighth curved surface is 81.47 mm.

6. The telecentric achromatic lens structure according to claim 1, characterized in that: Along the light propagation direction, the fifth lens has a ninth curved surface and a tenth curved surface, the curvature of the ninth curved surface is 81.47 mm, and the curvature of the tenth curved surface is -196.09 mm.

7. The telecentric achromatic lens structure according to claim 1, characterized in that: The plurality of lenses include HLAF3B lenses and ZF6 lenses.

8. A laser lens, characterized in that: include: case; as well as, A telecentric achromatic lens structure, wherein the telecentric achromatic lens structure is the telecentric achromatic lens structure according to any one of claims 1 to 8, wherein a plurality of the lenses are arranged in the housing.

9. The laser lens according to claim 8, characterized in that: The laser lens also includes a water cooling structure for cooling the shell.

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