A high-magnification objective lens for laser cutting

Abstract

The present invention discloses a high-magnification objective lens for laser cutting. The optical system of this lens sequentially includes a first lens G1 with a positive optical power and a meniscus structure, a second lens G2 with a negative optical power and a meniscus structure, a third lens G3 with a positive optical power and a biconvex structure, and a fourth lens G4 with a positive optical power and a meniscus structure along the light beam propagation direction. The focal length f of this high-magnification objective lens is 3 - 6 mm, the wavelength is 1064 nm, and the magnification is 40X - 60X. The structure of this high-magnification objective lens has a low cost and can achieve high magnification and micron-level laser precision machining.

Description

Technical Field

[0001] The present invention relates to the technical field of laser processing, and specifically to a high-magnification objective lens for laser cutting. The general focusing objective lens is generally 10 times to 20 times, and the high magnification in this application refers to 40 - 100 times. Background Art

[0002] The focusing objective lens is an essential optical module in laser cutting products. It can achieve cutting accuracy at the micron level. By optimizing the cutting process, the appearance of debris and chipping during product cutting can be avoided.

[0003] Currently, the magnification (M) of the focusing objective lenses for various laser applications is generally 10X and 20X (the magnification (M) of the objective lens is the ratio of the focal length (L) of the sleeve lens to the effective focal length (F) of the objective lens. The effective focal length is sometimes abbreviated as EFL: M = L / EFL, and the value of the focal length (L) of the sleeve lens is 200 mm). Due to the relatively large focusing spot, there is significant surface damage to the cutting of some ultra-thin products, resulting in relatively large micro-cracks or thermal effects, which affect the cutting quality. Moreover, in the existing focusing technologies, there are few reports on high-magnification focusing objective lenses specifically for ultra-thin products. In view of the above, it is necessary to design a high-magnification (40 - 100X) objective lens for laser cutting, which can be applied to cut ultra-thin (about 10 um - 30 um) products, with a micron-level diameter of the focused beam spot, such as less than 5 microns, reducing the focused spot, thereby improving the cutting quality and solving the problems in existing laser processing applications. Summary of the Invention

[0004] To solve the problems in the prior art, the present invention provides a high-magnification objective lens for laser cutting. The optical system of this lens sequentially includes a first lens G1 with positive optical power and a meniscus structure, a second lens G2 with negative optical power and a meniscus structure, a third lens G3 with positive optical power and a biconvex structure, and a fourth lens G4 with positive optical power and a meniscus structure in the light beam propagation direction. The focal length f of this high-magnification objective lens is 3 - 6 mm, the wavelength is 1064 nm, and the magnification is 40X - 60X. The structure of this high-magnification objective lens has a low cost and can achieve high magnification and micron-level laser precision machining.

[0005] A high-magnification objective lens for laser cutting includes a first lens G1 with positive optical power and a meniscus structure, a second lens G2 with negative optical power and a meniscus structure, a third lens G3 with positive optical power and a biconvex structure, and a fourth lens G4 with positive optical power and a meniscus structure, which are sequentially arranged in the incident direction of the light beam.

[0006] As a further improvement of the present invention, the image plane of the objective lens is arranged at the rear end of the fourth lens G4 along the propagation direction of the light beam. The air gap d2 between the first lens G1 and the second lens G2 is 0.66±10% mm, the air gap d4 between the second lens G2 and the third lens G3 is 1.03±10% mm, the air gap d6 between the third lens G3 and the fourth lens G4 is 0.1±10% mm, and the air gap d8 between the image plane and the fourth lens G4 is 3.1±10% mm.

[0007] As a further improvement of the present invention, the image plane of the objective lens is arranged at the rear end of the fourth lens G4 along the propagation direction of the light beam. The air gap d2 between the first lens G1 and the second lens G2 is 0.66±5% mm, the air gap d4 between the second lens G2 and the third lens G3 is 1.03±5% mm, the air gap d6 between the third lens G3 and the fourth lens G4 is 0.1±5% mm, and the air gap d8 between the image plane and the fourth lens G4 is 3.1±5% mm.

[0008] As a further improvement of the present invention, the radii of curvature of the front and rear sides of the first lens G1 are R1=-8.521±5% mm and R2=-2.815±5% mm respectively. The central thickness d1 of the first lens G1 is 1.5±5% mm. The focal length of the first lens G1 is f1, and it satisfies the following relationship with the total focal length f of the focusing objective lens: 1.55<f1 / f<2.75.

[0009] As a further improvement of the present invention, the radii of curvature of the front and rear sides of the second lens G2 are R3=-2.253±5% mm and R4=-6.762±5% mm respectively. The central thickness d3 of the second lens G2 is 1.4±5% mm. The focal length of the second lens G2 is f2, and it satisfies the following relationship with the total focal length f of the focusing objective lens: -2.85<f2 / f<-1.95.

[0010] As a further improvement of the present invention, the radii of curvature of the front and rear sides of the third lens G3 are R5=5.52±5% mm and R6=-20.064±5% mm respectively. The central thickness d5 of the third lens G3 is 1.15±5% mm. The focal length of the third lens G3 is f3, and it satisfies the following relationship with the total focal length f of the focusing objective lens: 2.15<f3 / f<3.25.

[0011] As a further improvement of the present invention, the radii of curvature of the front and rear sides of the fourth lens G4 are R7 = 2.817 ± 5% mm and R8 = 41.812 ± 5% mm respectively, the central thickness d7 of the fourth lens G4 is 1.22 ± 5% mm, and the focal length of the fourth lens G4 is f4, where the following relationship is satisfied with the total focal length f of the focusing objective: 0.75 < f4 / f < 1.75.

[0012] As a further improvement of the present invention, the optical materials of the first lens G1, the second lens G2, the third lens G3 and the fourth lens G4 are the same. The refractive index of the optical material is Nd, and the Abbe number is Vd, which satisfy the relational expressions 1.4 < Nd < 1.55 and 65 < Vd < 75.

[0013] As a further improvement of the present invention, the optical materials of the first lens G1, the second lens G2, the third lens G3 and the fourth lens G4 are the same. The refractive index of the optical material is Nd, and the Abbe number is Vd, which satisfy the relational expressions 1.45 < Nd < 1.50 and 68 < Vd < 72.

[0014] The beneficial effects of the present invention are as follows:

[0015] The present invention can reduce the focused spot, thereby improving the cutting quality, solve the problems of existing laser processing applications, and achieve a high magnification ratio and a spot size reaching the diffraction limit. The focal length of the lens of the present invention is 4 mm, the wavelength is 1064 nm, and the magnification ratio is 50X. The size of the dot punched by the 10X objective on the glass is 6 μm, and the diameter of the dot punched by the 50X objective on the glass is less than 2 μm. For some ultra-thin products, such as thin glass with a thickness of only 10 μm - 20 μm, using a 10X objective to cut the thin glass will cause damage with a diameter of 6 - 7 μm, and the chipping on the single-side glass edge is greater than 3 μm, having characteristics such as large chipping and low bending resistance. While for the 50X objective, it only causes damage with a diameter of 2 μm to the ultra-thin glass, and the chipping on the single-side glass edge is less than 1 μm, greatly improving the bending resistance of the ultra-thin glass and having good cutting quality at the same time. Description of the Drawings

[0016] Figure 1 It is a schematic geometric optical structure diagram of the high-magnification objective for laser cutting of the present invention;

[0017] Figure 2 It is a spot diagram of the high-magnification objective for laser cutting of the present invention; (referring to the parameters of the lens performance)

[0018] Figure 3 It is a schematic diagram of the wavefront function of the high-magnification objective for laser cutting of the present invention (referring to the parameters of the lens performance). Detailed Embodiments

[0019] The present invention will be further described below in conjunction with the accompanying drawings.

[0020] As Figure 1 shown, the high-magnification objective lens for laser cutting of the present invention includes four separated lenses arranged on the same optical path. The four lenses are located in the incident direction of the light beam and sequentially include a first lens G1 with a positive optical power and a meniscus structure, a second lens G2 with a negative optical power and a meniscus structure, a third lens G3 with a positive optical power and a biconvex structure, and a fourth lens G4 with a positive optical power and a meniscus structure. The first lens G1, the second lens G2, the third lens G3, and the fourth lens G4 form a lens sequence of "positive-negative-positive-positive" to achieve a high magnification rate and a spot size reaching the diffraction limit.

[0021] In one embodiment, the image plane is arranged at the rear end of the fourth lens G4 along the propagation direction of the light beam. The air gap d2 between the first lens G1 and the second lens G2 is 0.66 mm, the air gap d4 between the second lens G2 and the third lens G3 is 1.03 mm, the air gap d6 between the third lens G3 and the fourth lens G4 is 0.1 mm, and the air gap d8 between the image plane and the fourth lens G4 is 3.1 mm.

[0022] In one embodiment, the curvature radii of the front and rear sides of the first lens G1 are R1 = -8.521 mm and R2 = -2.815 mm respectively, and the central thickness d1 of the first lens G1 is 1.5 mm.

[0023] In one embodiment, the curvature radii of the front and rear sides of the second lens G2 are R3 = -2.253 mm and R4 = -6.762 mm respectively, and the central thickness d3 of the second lens G2 is 1.4 mm.

[0024] In one embodiment, the curvature radii of the front and rear sides of the third lens G3 are R5 = 5.52 mm and R6 = -20.064 mm respectively, and the central thickness d5 of the third lens G3 is 1.15 mm.

[0025] In one embodiment, the curvature radii of the front and rear sides of the fourth lens G4 are R7 = 2.817 mm and R8 = 41.812 mm respectively, and the central thickness d7 of the fourth lens G4 is 1.22 mm.

[0026] In this solution, the optical materials of the first lens G1, the second lens G2, the third lens G3, and the fourth lens G4 are the same. The refractive index of the optical material is Nd, and the Abbe number is Vd, which satisfy the relational expression 1.4 < Nd < 1.55 and 65 < Vd < 75.

[0027] For each lens provided by the present invention, that is, the curvature radius R, thickness T, material refractive index Nd, and Abbe number Vd of each lens in the lens assembly are shown in the following table:

[0028] Lens number Radius of front surface Radius of rear surface Thickness Refractive index of material Abbe number First lens -8.521 -2.815 1.5 1.46 67.82 Second lens -2.253 -6.762 1.4 1.46 67.82 Third lens 5.520 -20.064 1.15 1.46 67.82 Fourth lens 2.817 41.812 1.22 1.46 67.82

[0029] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0030] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions or substitutions can be made, and all should be regarded as belonging to the protection scope of the present invention.

Claims

1. A high magnification objective lens for laser cutting, characterized in that: It includes a first lens G1 with a positive focal power and a meniscus structure, a second lens G2 with a negative focal power and a meniscus structure, a third lens G3 with a positive focal power and a biconvex structure, and a fourth lens G4 with a positive focal power and a meniscus structure, which are sequentially arranged in the incident direction of the light beam; among the above high-magnification objective lenses, the optical elements with focal power are only the above four lenses; the radii of curvature on the front and rear sides of the first lens G1 are R1 = -8.521 ± 5% mm and R2 = -2.815 ± 5% mm respectively, the central thickness d1 of the first lens G1 is 1.5 ± 5% mm, the focal length of the first lens G1 is f1, and the following relationship is satisfied with the total focal length f of the focusing objective lens: 1.55 < f1 / f < 2.

75.

2. The high magnification objective lens for laser cutting according to claim 1, wherein: The image plane of the objective lens is arranged at the rear end of the fourth lens G4 along the propagation direction of the light beam. The air gap d2 between the first lens G1 and the second lens G2 is 0.66 ± 10% mm, the air gap d4 between the second lens G2 and the third lens G3 is 1.03 ± 10% mm, the air gap d6 between the third lens G3 and the fourth lens G4 is 0.1 ± 10% mm, and the air gap d8 between the image plane and the fourth lens G4 is 3.1 ± 10% mm.

3. The high-magnification objective lens for laser cutting according to claim 2, characterized in that: The image plane of the objective lens is arranged at the rear end of the fourth lens G4 along the propagation direction of the light beam. The air gap d2 between the first lens G1 and the second lens G2 is 0.66 ± 5% mm, the air gap d4 between the second lens G2 and the third lens G3 is 1.03 ± 5% mm, the air gap d6 between the third lens G3 and the fourth lens G4 is 0.1 ± 5% mm, and the air gap d8 between the image plane and the fourth lens G4 is 3.1 ± 5% mm.

4. A high magnification objective lens for laser cutting according to any one of claims 1 to 3, characterized in that: The radii of curvature on the front and rear sides of the second lens G2 are R3 = -2.253 ± 5% mm and R4 = -6.762 ± 5% mm respectively, the central thickness d3 of the second lens G2 is 1.4 ± 5% mm, the focal length of the second lens G2 is f2, and the following relationship is satisfied with the total focal length f of the focusing objective lens: -2.85 < f2 / f < -1.

95.

5. A high-magnification objective lens for laser cutting according to any one of claims 1 to 3, characterized in that: The radii of curvature on the front and rear sides of the third lens G3 are R5 = 5.52 ± 5% mm and R6 = -20.064 ± 5% mm respectively, the central thickness d5 of the third lens G3 is 1.15 ± 5% mm, the focal length of the third lens G3 is f3, and the following relationship is satisfied with the total focal length f of the focusing objective lens: 2.15 < f3 / f < 3.

25.

6. A high-magnification objective lens for laser cutting according to any one of claims 1 to 3, characterized in that: The radii of curvature on the front and rear sides of the fourth lens G4 are R7 = 2.817 ± 5% mm and R8 = 41.812 ± 5% mm respectively, the central thickness d7 of the fourth lens G4 is 1.22 ± 5% mm, the focal length of the fourth lens G4 is f4, and the following relationship is satisfied with the total focal length f of the focusing objective lens: 0.75 < f4 / f < 1.

75.

7. A high magnification objective lens for laser cutting according to any one of claims 1 to 3, characterized in that: The optical materials of the first lens G1, the second lens G2, the third lens G3, and the fourth lens G4 are all the same. The refractive index of the optical material is Nd, and the Abbe number is Vd, which satisfy the relational expressions 1.4 < Nd < 1.55 and 65 < Vd < 75.

8. A high-magnification objective lens for laser cutting according to any one of claims 7, characterized in that: The optical materials of the first lens G1, the second lens G2, the third lens G3, and the fourth lens G4 are all the same. The refractive index of the optical material is Nd, and the Abbe number is Vd, which satisfy the relational expressions 1.45 < Nd < 1.50 and 68 < Vd < 72.

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