Precision machining scanning lens for femtosecond laser

Abstract

The invention discloses a precision machining scanning lens for a femtosecond laser. The precision machining scanning lens comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens which are sequentially arranged in the incident direction. Wherein the first lens is a concave-convex lens with a negative refractive index, the second lens is a concave-convex lens with a positive refractive index, the third lens is a convex-concave lens with a positive refractive index, the fourth lens is a concave-convex lens with a negative refractive index, the fifth lens is a biconvex lens with a positive refractive index, and the sixth lens is a biconcave lens with a negative refractive index. The seventh lens is a biconvex lens with a positive refractive index, and the eighth lens is a convex-concave lens with a negative refractive index. The precision machining lens used for the femtosecond laser can be matched with a D14 galvanometer, the focusing light spot is smaller than 3 microns, the machining efficiency is greatly improved, the focusing light spot is a round spot and cannot be ovalized, the heat affected area is small, and high-precision machining is achieved; the device can be used for processing various materials such as metal, glass and diamonds.

Description

Technical Field

[0001] The invention relates to a precision-processed scanning lens for a femtosecond laser, and belongs to the technical field of laser scanning. Background Art

[0002] Laser scanning lenses are used in various laser processing equipment, which can process various materials such as metals, plastics, glass, etc. In order to improve the efficiency of laser processing, new femtosecond lasers have emerged, so the corresponding laser processing lenses must also improve their performance.

[0003] In order to achieve a focused spot of less than 5um, conventional scanning lenses generally use a larger incident spot of the galvanometer, such as D20 and D30 galvanometers. However, as the caliber of the galvanometer increases, the deflection speed of the galvanometer will slow down, thus affecting the processing efficiency. For this reason, this application proposes a precision processing scanning lens for femtosecond lasers, which can match the D14 galvanometer to achieve a focused spot of less than 3um and greatly improve the processing efficiency. Summary of the invention

[0004] The present invention provides a precision processing lens for a femtosecond laser, which can match a D14 galvanometer mirror, realize a focused light spot smaller than 3um, greatly improve the processing efficiency, and can be used to process various metals, glass, diamonds and other materials.

[0005] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0006] A precision-processed scanning lens for a femtosecond laser comprises lens one, lens two, lens three, lens four, lens five, lens six, lens seven and lens eight which are sequentially arranged along an incident direction; wherein lens one is a concave-convex lens with a negative refractive power, lens two is a concave-convex lens with a positive refractive power, lens three is a convex-concave lens with a positive refractive power, lens four is a concave-convex lens with a negative refractive power, lens five is a biconvex lens with a positive refractive power, lens six is ​​a biconcave lens with a negative refractive power, lens seven is a biconvex lens with a positive refractive power, and lens eight is a convex-concave lens with a negative refractive power.

[0007] This application is used for the precision processing scanning lens of femtosecond laser, which can match the D14 galvanometer to achieve a focused spot of less than 3um, greatly improving the processing efficiency. It can be used to process various metals, glass, diamonds and other materials, especially suitable for processing high-precision products. D14 refers to the maximum light diameter of the galvanometer is 14mm, and the rest are similar expressions and have similar meanings.

[0008] Along the incident direction, the two sides of lens one are the first incident surface and the first exit surface, respectively; the two sides of lens two are the second incident surface and the second exit surface, respectively; the two sides of lens three are the third incident surface and the third exit surface, respectively; the two sides of lens four are the fourth incident surface and the fourth exit surface, respectively; the two sides of lens five are the fifth incident surface and the fifth exit surface, respectively; the two sides of lens six are the sixth incident surface and the sixth exit surface, respectively; the two sides of lens seven are the seventh incident surface and the seventh exit surface, respectively; and the two sides of lens eight are the eighth incident surface and the eighth exit surface, respectively.

[0009] In order to improve imaging quality and reduce the number of lenses, the first incident surface, the second incident surface, the third incident surface, the fourth incident surface, the seventh incident surface and the eighth incident surface are all aspherical surfaces; the first incident surface, the second incident surface, the third incident surface, the fourth incident surface, the fifth incident surface, the sixth incident surface, the sixth exit surface, the seventh incident surface and the eighth incident surface are all spherical surfaces.

[0010] The above lenses 1, 2, 3, 4, 7 and 8 all have one spherical surface and the other aspherical surface. However, both the surfaces of lens 5 and lens 6 are spherical.

[0011] In order to further ensure the focusing and scanning effects, the radius of curvature of the first incident surface is -44.64±0.005mm, and the radius of curvature of the first exit surface is -120.8018±0.005mm; the radius of curvature of the second incident surface is -228.4407±0.005mm, and the radius of curvature of the second exit surface is -42.407±0.005mm; the radius of curvature of the third incident surface is 108.3224±0.005mm, and the radius of curvature of the third exit surface is 1098.39±0.005mm; the radius of curvature of the fourth incident surface is -28.55±0.005mm, and the radius of curvature of the fourth exit surface is -228.4407±0.005mm. The radius of curvature of the fifth incident surface is 74.85±0.005mm, and the radius of curvature of the fifth exit surface is -57.41±0.005mm; the radius of curvature of the sixth incident surface is -57.41±0.005mm, and the radius of curvature of the sixth exit surface is 180±0.005mm; the radius of curvature of the seventh incident surface is 40.581±0.005mm, and the radius of curvature of the seventh exit surface is -81.8±0.005mm; the radius of curvature of the eighth incident surface is 84.72±0.005mm, and the radius of curvature of the eighth exit surface is 26.56±0.005mm.

[0012] In order to take into account the stability and use effect of the lens, the center thickness of lens one is 8.7±0.2mm, the center thickness of lens two is 16.8±0.2mm, the center thickness of lens three is 10.9±0.2mm, the center thickness of lens four is 16.4±0.2mm, the center thickness of lens five is 13.1±0.2mm, the center thickness of lens six is ​​3±0.2mm, the center thickness of lens seven is 16.1±0.2mm, and the center thickness of lens eight is 21.3±0.2mm.

[0013] The lens five and the lens six are glued together to form a glued lens, that is, the fifth exit surface and the sixth incident surface are glued together to form one surface.

[0014] In order to better ensure the focusing effect, the center distance between lens one and lens two is 25.271±0.005mm, the center distance between lens two and lens three is 262.705±0.005mm, the center distance between lens three and lens four is 76.926±0.005mm, the center distance between lens four and lens five is 0.974±0.005mm, the center distance between lens five and lens six is ​​0mm, the center distance between lens six and lens seven is 0.535±0.005mm, and the center distance between lens seven and lens eight is 0.5±0.005mm.

[0015] In order to improve the imaging quality, the material used for lens one is H-ZLAF51, the material used for lens two is H-ZLAF55D, the material used for lens three is H-ZLAF69A, the material used for lens four is H-ZLAF50E, the material used for lens five is H-ZLAF68C, the material used for lens six is ​​H-ZF88, the material used for lens seven is H-LAF2, and the material used for lens eight is H-ZF13.

[0016] The outer diameter of the above-mentioned lens one is 35-40mm, the outer diameter of the lens two is 58±0.02mm, the outer diameter of the lens three is 44±0.02mm, the outer diameter of the lens four is 40-50mm, the outer diameter of the lens five is 50±0.02mm, the outer diameter of the lens six is ​​50±0.02mm, the outer diameter of the lens seven is 50±0.02mm, and the outer diameter of the lens eight is 28-50mm.

[0017] The above scanning lens is suitable for 1030nm femtosecond laser.

[0018] The incident light diameter of the above scanning lens is 12.5mm, which can be used with the D14 galvanometer for scanning processing, and the focused spot is less than 3um.

[0019] The existing laser cutting lens cannot be used for laser scanning. The laser cutting lens has only one focusing point, while the present application generates a focusing point of a certain format.

[0020] Due to the group delay dispersion characteristics of femtosecond lasers, the spot of the existing lens used on the femtosecond laser is elliptical. The present application designs the lens optical system to make the lens produce a circular spot on the femtosecond laser.

[0021] The technologies not mentioned in the present invention are all referred to the prior art.

[0022] The invention is used for the precision processing lens of the femtosecond laser, which can match the galvanometer of D14 to achieve a focused light spot smaller than 3um, greatly improving the processing efficiency. The focused light spot is a circular spot and will not be elliptical, and the heat-affected area is small, thus achieving highly precise processing. The invention can be used to process various materials such as metals, glass, and diamonds. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the structure of a scanning lens for precision machining of a femtosecond laser according to the present invention;

[0024] Figure 2 This is a point diagram of the precision machining scanning lens for a femtosecond laser according to the present invention;

[0025] Figure 3 This is a field curvature distortion diagram of the precision machining scanning lens for femtosecond lasers of the present invention;

[0026] Figure 4 This is a quality analysis diagram of the scanning lens beam used for precision machining of femtosecond lasers in the present invention; DETAILED DESCRIPTION

[0027] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0028] like Figure 1 As shown, a precision machining lens for a femtosecond laser comprises eight lenses, namely, lens one 1, lens two 2, lens three 3, lens four 4, lens five 5, lens six 6, lens seven 7 and lens eight 8, which are sequentially arranged along the incident direction; wherein, lens one 1 is a concave-convex lens with a negative refractive power, lens two 2 is a concave-convex lens with a positive refractive power, lens three 3 is a convex-concave lens with a positive refractive power, lens four 4 is a concave-convex lens with a negative refractive power, lens five 5 is a biconvex lens with a positive refractive power, lens six 6 is a biconcave lens with a negative refractive power, lens seven 7 is a biconvex lens with a positive refractive power, and lens eight 8 is a convex-concave lens with a negative refractive power.

[0029] Along the incident direction, the two sides of lens one are the first incident surface S1 and the first exit surface S2, respectively; the two sides of lens two are the second incident surface S3 and the second exit surface S4, respectively; the two sides of lens three are the third incident surface S5 and the third exit surface S6, respectively; the two sides of lens four are the fourth incident surface S7 and the fourth exit surface S8, respectively; the two sides of lens five are the fifth incident surface S9 and the fifth exit surface S10, respectively; the two sides of lens six are the sixth incident surface S10 and the sixth exit surface S11, respectively; the two sides of lens seven are the seventh incident surface S12 and the seventh exit surface S13, respectively; the two sides of lens eight are the eighth incident surface S14 and the eighth exit surface S15; lens five and lens six are glued together to form a glued lens, that is, the fifth exit surface S10 and the sixth incident surface S10 are regarded as one surface.

[0030] The first incident surface, the second incident surface, the third incident surface, the fourth incident surface, the seventh incident surface and the eighth incident surface are all aspherical surfaces; the first incident surface, the second incident surface, the third incident surface, the fourth incident surface, the fifth incident surface, the fifth exit surface, the sixth incident surface, the sixth exit surface, the seventh incident surface and the eighth incident surface are all spherical surfaces.

[0031] The operating parameters of the above precision machining lens for femtosecond lasers are:

[0032] Laser: 1030nm femtosecond laser;

[0033] Processing area: 3mm×3mm;

[0034] Focal length: -21.5mm.

[0035] The optical parameters of the above lenses are shown in Table 1.

[0036] Table 1 Optical parameters of each lens in the lens

[0037]

[0038]

[0039] In order to reduce the number of lens elements, the present invention uses multiple even-order aspheric surfaces, and the formula used for the even-order aspheric surface is: The meaning of each letter is as follows: z: loss of height of the surface;

[0040] c: curvature;

[0041] r: radius of curvature;

[0042] k: cone coefficient;

[0043] a 1 、a 2 、a 3 、a 4 、a 5is the coefficient of the even-order term; the specific data is shown in Table 2.

[0044] Table 2 Even-order aspheric coefficients

[0045]

[0046]

[0047] Table 3 Center spacing between lenses

[0048]

[0049] Using a 1030nm femtosecond laser, the incident light diameter is 12.5mm, and the D14 galvanometer is used for scanning processing. The focused spot is less than 3um, and the focused spot is a circular spot without deformation. Figure 2 This is the spot diagram of the precision machining scanning lens for the femtosecond laser. From 2, it can be seen that the focused light spot is within the diffraction limit and the light spot focusing effect is good. Figure 3 This is the field curvature distortion diagram of the scanning lens used for precision machining of the femtosecond laser. From 3, it can be seen that the field curvature and distortion of the light spot of the entire format are very small, which meets the requirements of precision machining. Figure 4 The effect diagram of the above-mentioned precision machining scanning lens for femtosecond laser on beam quality analysis shows that the focusing circularity can reach more than 95%. It can be seen that the optical performance of the above-mentioned precision machining scanning lens for femtosecond laser meets various indicators of laser processing.

Claims

1. A precision machining scanning lens for a femtosecond laser, characterized in that: It comprises lens 1, lens 2, lens 3, lens 4, lens 5, lens 6, lens 7 and lens 8 which are sequentially arranged along the incident direction; wherein lens 1 is a meniscus lens with negative refractive power, lens 2 is a meniscus lens with positive refractive power, lens 3 is a convex-concave lens with positive refractive power, lens 4 is a meniscus lens with negative refractive power, lens 5 is a biconvex lens with positive refractive power, lens 6 is a biconcave lens with negative refractive power, lens 7 is a biconvex lens with positive refractive power, and lens 8 is a convex-concave lens with negative refractive power.

2. The precision machining scanning lens for femtosecond laser according to claim 1, characterized in that: Along the incident direction, two surfaces of lens one are the first incident surface and the first exit surface, two surfaces of lens two are the second incident surface and the second exit surface, two surfaces of lens three are the third incident surface and the third exit surface, two surfaces of lens four are the fourth incident surface and the fourth exit surface, two surfaces of lens five are the fifth incident surface and the fifth exit surface, two surfaces of lens six are the sixth incident surface and the sixth exit surface, two surfaces of lens seven are the seventh incident surface and the seventh exit surface, and two surfaces of lens eight are the eighth incident surface and the eighth exit surface; The first incident surface, the second incident surface, the third incident surface, the fourth incident surface, the seventh incident surface and the eighth incident surface are all aspherical surfaces; the first incident surface, the second incident surface, the third incident surface, the fourth incident surface, the fifth incident surface, the fifth exit surface, the sixth incident surface, the sixth exit surface, the seventh incident surface and the eighth incident surface are all spherical surfaces.

3. The precision machining scanning lens for femtosecond laser according to claim 2, characterized in that: The radius of curvature of the first incident surface is -44.64±0.005mm, and the radius of curvature of the first exit surface is -120.8018±0.005mm; the radius of curvature of the second incident surface is -228.4407±0.005mm, and the radius of curvature of the second exit surface is -42.407±0.005mm; the radius of curvature of the third incident surface is 108.3224±0.005mm, and the radius of curvature of the third exit surface is 1098.39±0.005mm; the radius of curvature of the fourth incident surface is -28.55±0.005mm, and the radius of curvature of the fourth exit surface is -49.66 ±0.005mm; the radius of curvature of the fifth incident surface is 74.85±0.005mm, and the radius of curvature of the fifth exit surface is -57.41±0.005mm; the radius of curvature of the sixth incident surface is -57.41±0.005mm, and the radius of curvature of the sixth exit surface is 180±0.005mm; the radius of curvature of the seventh incident surface is 40.581±0.005mm, and the radius of curvature of the seventh exit surface is -81.8±0.005mm; the radius of curvature of the eighth incident surface is 84.72±0.005mm, and the radius of curvature of the eighth exit surface is 26.56±0.005mm.

4. The precision machining scanning lens for femtosecond laser according to any one of claims 1 to 3, characterized in that: The center thickness of lens one is 8.7±0.2mm, the center thickness of lens two is 16.8±0.2mm, the center thickness of lens three is 10.9±0.2mm, the center thickness of lens four is 16.4±0.2mm, the center thickness of lens five is 13.1±0.2mm, the center thickness of lens six is ​​3±0.2mm, the center thickness of lens seven is 16.1±0.2mm, and the center thickness of lens eight is 21.3±0.2mm.

5. The precision machining scanning lens for femtosecond laser according to any one of claims 1 to 3, characterized in that: Lens five and lens six are cemented together to form a cemented lens.

6. The precision machining scanning lens for femtosecond laser according to any one of claims 1 to 3, characterized in that: The center distance between lens one and lens two is 25.271±0.005mm, the center distance between lens two and lens three is 262.705±0.005mm, the center distance between lens three and lens four is 76.926±0.005mm, the center distance between lens four and lens five is 0.974±0.005mm, the center distance between lens five and lens six is ​​0mm, the center distance between lens six and lens seven is 0.535±0.005mm, and the center distance between lens seven and lens eight is 0.5±0.005mm.

7. The precision machining scanning lens for femtosecond laser according to any one of claims 1 to 3, characterized in that: The material used for lens one is H-ZLAF51, the material used for lens two is H-ZLAF55D, the material used for lens three is H-ZLAF69A, the material used for lens four is H-ZLAF50E, the material used for lens five is H-ZLAF68C, the material used for lens six is ​​H-ZF88, the material used for lens seven is H-LAF2, and the material used for lens eight is H-ZF13.

8. The precision machining scanning lens for femtosecond laser according to any one of claims 1 to 3, characterized in that: The outer diameter of lens one is 35-40 mm, the outer diameter of lens two is 58±0.02 mm, the outer diameter of lens three is 44±0.02 mm, the outer diameter of lens four is 40-50 mm, the outer diameter of lens five is 50±0.02 mm, the outer diameter of lens six is ​​50±0.02 mm, the outer diameter of lens seven is 50±0.02 mm, and the outer diameter of lens eight is 28-50 mm.

9. The precision machining scanning lens for femtosecond laser according to any one of claims 1 to 3, characterized in that: Suitable for 1030nm femtosecond lasers.

10. The precision machining scanning lens for femtosecond laser according to any one of claims 1 to 3, characterized in that: The incident light diameter is 12.5mm, and the D14 galvanometer is used for scanning processing. The focused spot is less than 3um; the focused spot is a circular spot.

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