An optical system of a field lens with short focal length and large working range

Abstract

The present invention discloses an optical system of a field lens with a short focal length and a large working range, comprising a first optical group, a second optical group and a third optical group arranged in sequence along the incident direction of light; along the incident direction of light, the first optical group comprises a first lens and a second lens, the second optical group comprises a third lens, and the third optical group comprises a fourth lens and a fifth lens; the first lens, the second lens, the third lens and the fifth lens are all positive lenses, and the fourth lens is a negative lens. The optical system of the field lens with a short focal length and a large working range of the present invention utilizes the principle of optical angle magnification to achieve a short focal length and a large working range, is suitable for laser processing such as large-scale cutting and marking, has higher processing efficiency, and can realize the processing of materials such as metals, PCB boards, and fabrics.

Description

Technical Field

[0001] The invention relates to an optical system of a field lens with a short focal length and a large working range, belonging to the technical field of laser processing. Background Art

[0002] As laser processing technology plays an increasingly important role in industrial production and processing, ordinary F-θ field lenses can only achieve a scanning area that is positively correlated with the focal length and angle due to the limitations of focal length and optical angle. If a large scanning range is required, it is necessary to increase the focal length. The consequence of increasing the focal length is that the size of the focused light spot increases linearly, which cannot achieve the required processing performance. The optical angle cannot be increased freely due to the influence of other mechanical components, which also restricts the processing efficiency. Therefore, an F-θ field lens with a short focal length and a large working range is needed to break through this limitation. Summary of the invention

[0003] The present invention provides an optical system of a field lens with a short focal length and a large working range. The optical system utilizes the principle of optical magnification to directly magnify the optical angle when the focal length is constant and the mechanical angle is satisfied, thereby achieving a short focal length and a large working range without increasing the size of the light spot, thereby satisfying laser processing that has requirements for the light spot and hopes to work on a large area.

[0004] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0005] An optical system of a short focal length and large working range field lens comprises a first optical group, a second optical group and a third optical group arranged in sequence along the incident direction of light; along the incident direction of light, the first optical group comprises a first lens and a second lens, the second optical group comprises a third lens, and the third optical group comprises a fourth lens and a fifth lens; the first lens, the second lens, the third lens and the fifth lens are all positive lenses, and the fourth lens is a negative lens.

[0006] In order to achieve the enlargement of the optical angle, it is necessary to design the focal lengths of the first light group and the second light group to be fixed so that their ratio is approximately equal to f1 / f2=θ2 / θ1, where f1 is the focal length of the first light group, f2 is the focal length of the second light group, θ1 is the incident angle of the front light of the first light group, and θ2 is the incident angle of the rear light of the second light group. Preferably, θ1 is 28° and θ2 is 56°.

[0007] In order to meet the requirements of short focal length and large working range and improve the focusing effect, the focal length of the first light group is f1 = 220 mm, the focal length of the second light group is f2 = 110 mm, and the focal length of the third light group is f3 = 150 mm.

[0008] The lens materials used in the present invention are all domestic common optical glass, and different materials can be selected according to different lasers and usage scenarios. Preferably, the present application uses crown and flint glasses, and the glass materials have good stability. In order to achieve a better achromatic effect, preferably, the material used for the first lens is crown glass, the materials used for the second lens, the third lens and the fifth lens are all heavy flint glass, and the material used for the fourth lens is light crown glass.

[0009] In order to improve the stability of the system and further ensure the focusing effect, the center thickness of the first lens is 4±0.05mm, the center thickness of the second lens is 4.6±0.05mm, the center thickness of the third lens is 6.2±0.05mm, the center thickness of the fourth lens is 3.1±0.05mm, and the center thickness of the fifth lens is 4.8±0.05mm.

[0010] In order to improve cutting efficiency, the center interval between the first light group and the second light group is 236±0.03mm, and the center interval between the second light group and the third light group is 94±0.03mm; the center interval between the first lens and the second lens is 3.1±0.01mm, and the center interval between the fourth lens and the fifth lens is 1.3±0.01mm.

[0011] Along the incident direction of light, the two sides of the first lens are the first object side surface and the first image side surface, the two sides of the second lens are the second object side surface and the second image side surface, the two sides of the third lens are the third object side surface and the third image side surface, the two sides of the fourth lens are the fourth object side surface and the fourth image side surface, and the two sides of the fifth lens are the fifth object side surface and the fifth image side surface; in order to further improve the focusing effect, the curvature radius of the first object side surface is 90.6±0.03mm, and the curvature radius of the first image side surface is -106.3±0.03mm; the second object side surface The radius of curvature of the side surface is -123.3±0.03mm, and the radius of curvature of the second image side surface is -86.3±0.03mm; the radius of curvature of the third object side surface is 63.2±0.03mm, and the radius of curvature of the third image side surface is -60.8±0.03mm; the radius of curvature of the fourth object side surface is -73.6±0.03mm, and the radius of curvature of the fourth image side surface is -130±0.03mm; the radius of curvature of the fifth object side surface is -630mm, and the radius of curvature of the fifth image side surface is -210±0.03mm.

[0012] The optical system of the short focal length and large working range field lens can be applied to different lasers, such as CO2 laser, YAG laser and ultraviolet 355nm laser.

[0013] The technologies not mentioned in the present invention are all referred to the prior art.

[0014] The optical system of the short-focal-length and large-working-range field lens of the present invention utilizes the principle of optical angle magnification to achieve a short-focal-length and large-working-range, is suitable for laser processing such as large-scale cutting and marking, has higher processing efficiency, and can realize the processing of materials such as metals, PCB boards, and cloth. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a light path diagram of the short focal length and large working range field lens optical system of the present invention;

[0016] Figure 2 The short focal length and large working range field lens optical system of the present invention realizes a spot diagram of y=70mm at a focal length of 150mm, and the geometrical light spots are all smaller than the Airy spots;

[0017] Figure 3 The field curvature and distortion diagram of the short focal length and large working range field lens optical system of the present invention;

[0018] Figure 4 It is a focusing spot diagram of the short focal length and large working range field lens optical system of the present invention;

[0019] Figure 5 It is a Letselby diagram of the short focal length and large working range field lens optical system of the present invention;

[0020] In the figure, L1 is the first lens, L2 is the second lens, L3 is the third lens, L4 is the fourth lens, and L5 is the fifth lens. DETAILED DESCRIPTION

[0021] 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.

[0022] Example 1

[0023] like Figure 1As shown, a short focal length and large working range field lens comprises a first optical group, a second optical group and a third optical group arranged in sequence along the incident direction of light, the focal length f1 of the first optical group is 220 mm, the focal length f2 of the second optical group is 110 mm, the focal length f3 of the third optical group is 150 mm, the incident angle θ1 of the light before the first optical group is 28°, and the incident angle θ2 of the light after the second optical group is 56°; along the incident direction of light, the first optical group comprises a first lens L1 and a second lens L2, the second optical group comprises a third lens L3, and the third optical group comprises a Four lenses L4 and a fifth lens L5; the first lens L1, the second lens L2, the third lens L3 and the fifth lens L5 are all positive lenses, the fourth lens L4 is a negative lens, the center interval between the first lens L1 and the second lens L2 is 3.1 mm, the center interval between the second lens L2 and the third lens L3 is 236 mm, the center interval between the third lens L3 and the fourth lens L4 is 94 mm, and the center interval between the fourth lens L4 and the fifth lens L5 is 1.3 mm. The parameters of each lens are shown in Table 1.

[0024] Table 1 Parameters of each lens

[0025]

[0026]

[0027] In the above table, the two sides of the first lens are the first object-side surface S1 and the first image-side surface S2, the two sides of the second lens are the second object-side surface S3 and the second image-side surface S4, the two sides of the third lens are the third object-side surface S5 and the third image-side surface S6, the two sides of the fourth lens are the fourth object-side surface S7 and the fourth image-side surface S8, and the two sides of the fifth lens are the fifth object-side surface S9 and the fifth image-side surface S10.

[0028] The laser uses a fiber laser with a wavelength of 1064nm and an incident spot diameter of 10mm. Figure 2 It can be seen that the focused spot at each point under different scanning formats is smaller than the diffraction limit, and the scanning effect and focusing effect are very good. Figure 3 It can be seen that the field curvature of the optical system is less than 0.4mm, the distortion is less than 0.3%, the image quality is good, the image is clear, and the precision is high; Figure 4 It can be seen that the focused spot size of the optical system is 29um-31.4um in the full-frame area, and the uniformity is good. Figure 5 It can be seen that within the defocus range of ±0.1 mm, the energy in the first diffraction ring of the light spot reaches more than 90%.

Claims

1. An optical system of a field lens with a short focal length and a large working range, characterized in that: It consists of a first light group, a second light group and a third light group which are arranged in sequence along the incident direction of the light; Along the incident direction of light, the first optical group consists of the first lens and the second lens, the second optical group consists of the third lens, and the third optical group consists of the fourth lens and the fifth lens; the first lens, the second lens, the third lens and the fifth lens are all positive lenses, and the fourth lens is a negative lens; Along the incident direction of light, the two sides of the first lens are the first object-side surface and the first image-side surface, the two sides of the second lens are the second object-side surface and the second image-side surface, the two sides of the third lens are the third object-side surface and the third image-side surface, the two sides of the fourth lens are the fourth object-side surface and the fourth image-side surface, and the two sides of the fifth lens are the fifth object-side surface and the fifth image-side surface; The radius of curvature of the first object side surface is 90.6±0.03mm, and the radius of curvature of the first image side surface is -106.3±0.03mm; the radius of curvature of the second object side surface is -123.3±0.03mm, and the radius of curvature of the second image side surface is -86.3±0.03mm; the radius of curvature of the third object side surface is 63.2±0.03mm, and the radius of curvature of the third image side surface is -60.8±0.03mm; the radius of curvature of the fourth object side surface is -73.6±0.03mm, and the radius of curvature of the fourth image side surface is -130±0.03mm; the radius of curvature of the fifth object side surface is -630mm, and the radius of curvature of the fifth image side surface is -210±0.03mm.

2. The optical system of the short focal length and large working range field lens according to claim 1, characterized in that: f1 / f2=θ2 / θ1, where f1 is the focal length of the first light group, f2 is the focal length of the second light group, θ1 is the incident angle of the front light of the first light group, and θ2 is the incident angle of the rear light of the second light group.

3. The optical system of the short focal length and large working range field lens according to claim 2, characterized in that: θ1 is 28° and θ2 is 56°.

4. The optical system of the short focal length and large working range field lens according to any one of claims 1 to 3, characterized in that: The focal length of the first light group is f1=220mm, the focal length of the second light group is f2=110mm, and the focal length of the third light group is f3=150mm.

5. The optical system of the short focal length and large working range field lens according to any one of claims 1 to 3, characterized in that: The material used for the first lens is crown glass, the materials used for the second lens, the third lens and the fifth lens are all heavy flint glass, and the material used for the fourth lens is light crown glass.

6. The optical system of the short focal length and large working range field lens according to any one of claims 1 to 3, characterized in that: The center thickness of the first lens is 4±0.05 mm, the center thickness of the second lens is 4.6±0.05 mm, the center thickness of the third lens is 6.2±0.05 mm, the center thickness of the fourth lens is 3.1±0.05 mm, and the center thickness of the fifth lens is 4.8±0.05 mm.

7. The optical system of a short focal length and large working range field lens according to any one of claims 1 to 3, characterized in that: The center interval between the first light group and the second light group is 236±0.03mm, and the center interval between the second light group and the third light group is 94±0.03mm; the center interval between the first lens and the second lens is 3.1±0.01mm, and the center interval between the fourth lens and the fifth lens is 1.3±0.01mm.

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