CN114326055A

CN114326055A - Infrared field lens with large scanning angle

Info

Publication number: CN114326055A
Application number: CN202111648880.XA
Authority: CN
Inventors: 邹武兵; 郑淑娥; 吴飞龙
Original assignee: Shenzhen Inte Laser Technology Co ltd
Current assignee: Shenzhen Inte Laser Technology Co ltd
Priority date: 2021-12-30
Filing date: 2021-12-30
Publication date: 2022-04-12
Anticipated expiration: 2041-12-30
Also published as: CN114326055B

Abstract

The invention provides an infrared field lens with a large scanning angle, which comprises an entrance pupil surface, a first lens G1, a second lens G2, a third lens G3, a protective lens SG and an image surface which are arranged on the same light path in sequence, wherein the first lens G1 has negative focal power and a meniscus structure, the second lens G2 has positive focal power and a meniscus structure, the third lens G3 has positive focal power and a double convex structure, and the protective lens SG has a flat plate structure; the total focal length of the scan field lens is f, the focal lengths of the first lens G1, the second lens G2 and the third lens G3 are f1, f2 and f3 respectively, and the following relations are satisfied: -0.9< f1/f < -0.5, 0.7< f2/f <1.1, 0.8< f3/f < 1.5. When the focal length is 125mm, the maximum allowable value of the incident beam diameter is not less than 12mm, the scanning angle is not less than +/-28 degrees, the scanning range is more than 85mm x 85mm, the F-theta distortion is less than 0.15 percent, and the spot size reaches the diffraction limit.

Description

Infrared field lens with large scanning angle

Technical Field

The invention relates to the field of optics, in particular to an optical lens.

Background

The F-theta lens is widely applied to laser engraving and laser marking industries. The field lens can obtain high-quality flat field effect and minimum geometric distortion on the premise of ensuring that the light spot reaches the diffraction limit.

The field lens is an optical scanning focusing lens matched with the galvanometer, and forms a laser beam into a focusing light spot with uniform size in the whole marking plane. With the continuous development of laser processing, the field lens with the same focal length needs a larger scanning range to improve the processing speed, the scanning range is enlarged under the condition of ensuring that the focused light spot at the edge is not distorted, the processing operations such as drilling, cutting and marking on a workpiece in a larger range can be realized, and the processing efficiency is improved. Here, the application of a 1064nm field lens with a large scanning angle to infrared laser processing is more advantageous.

The large scan angle means: 2w is 56 °. w refers to the scan angle.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides an infrared field lens with a large scanning angle, which comprises an entrance pupil surface, a first lens G1, a second lens G2, a third lens G3, a protective lens SG and an image surface which are arranged on the same optical path in sequence, wherein the first lens G1 has negative focal power and a meniscus structure, the second lens G2 has positive focal power and a meniscus structure, the third lens G3 has positive focal power and a biconvex structure, and the protective lens SG has a flat plate structure; the total focal length of the scanning field lens is f, the focal lengths of the first lens G1, the second lens G2 and the third lens G3 are f1, f2 and f3 respectively, and the following relations are satisfied: -0.9< f1/f < -0.5, 0.7< f2/f <1.1, 0.8< f3/f < 1.5.

As a further improvement of the invention, -0.75< f1/f < -0.5, 0.8< f2/f <1.0, 0.9< f3/f < 1.4.

As a further improvement of the present invention, an air interval d0 between the entrance pupil surface and the first lens G1 is 30mm, an air interval d2 between the first lens G1 and the second lens G2 is 1.33mm, an air interval d4 between the second lens G2 and the third lens G3 is 0.1mm, an air interval d6 between the third lens G3 and the protective mirror SG is 3mm, and an air interval d8 between the image surface and the protective mirror SG is 144.8 mm.

As a further improvement of the present invention, the front and rear sides of the first lens G1 have radii of curvature of R1 ═ 31.31mm and R2 ═ 139.81mm, respectively, and the first lens G1 has a center thickness d1 of 4 mm; the refractive index of the first lens G1 is n1, the Abbe number is v1, and the relation is satisfied: 1.4< n1< 1.55; 65< v1< 75.

As a further improvement of the present invention, the front and rear sides of the second lens G2 have radii of curvature of R3-88.06 mm and R4-46.58 mm, respectively, the second lens G2 has a center thickness d3 of 12.08mm, the second lens G2 has a refractive index of n2 and an abbe number of v2, and satisfy the following relation: 1.75< n2< 1.85; 40< v2< 50.

As a further improvement of the present invention, the radii of curvature of the front and rear sides of the third lens G3 are R3 ═ 851.28mm and R4 ═ -122.86mm, respectively, the center thickness d5 of the third lens G3 is 7.43mm, the refractive index of the third lens G3 is n3, the abbe number is v3, and the relationship: 1.75< n3< 1.85; 40< v3< 50.

As a further improvement of the invention, the protective glass SG has a central thickness d7 of 3 mm.

The invention has the beneficial effects that:

the infrared field lens with large scanning angle of the invention comprises a first lens G1, a second lens G2, a third lens G3 and a protective lens SG which are arranged in the same optical path and are 3 separated lenses, wherein the lenses form a lens sequence of 'negative-positive', and the infrared field lens realizes large scanning angle and low distortion.

When the focal length is 125mm, the maximum allowable value of the incident beam diameter is not less than 12mm, the scanning angle is not less than +/-28 degrees, the scanning range is more than 85mm x 85mm, the F-theta distortion is less than 0.15 percent, and the spot size reaches the diffraction limit.

Drawings

FIG. 1 is a schematic diagram of the geometric optical structure of a large scan angle infrared field lens of the present invention;

FIG. 2 is a graph of field curvature and F-theta distortion for a large scan angle infrared field lens according to the present invention;

FIG. 3 is a schematic view of different field of view point arrays of the large scan angle IR field lens of the present invention;

FIG. 4 is a schematic diagram of the modulation transfer function of the large scan angle IR field lens of the present invention.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

Fig. 1 is a schematic diagram of an optical path, fig. 2 to 4: parameters representing the performance of the lens. In fig. 3, OBJ denotes an object plane and IMA denotes an image plane.

The large scanning angle infrared field lens comprises a first lens G1, a second lens G2, a third lens G3 and a protective lens SG which are arranged on the same optical path and are 3 separated lenses, wherein the lenses form a negative-positive lens sequence, large scanning angle and low distortion are realized, and the large scanning angle infrared field lens also comprises an entrance pupil surface and an image surface.

The first lens G1 has a negative power, meniscus configuration, the second lens G2 has a positive power, meniscus configuration, the third lens G3 has a positive power, biconvex configuration, and the protective glass SG has a flat plate configuration.

The entrance pupil surface is arranged at the front end of the first lens G1 along the light beam propagation direction, the image surface is arranged at the rear end of the protective mirror SG along the light beam propagation, the entrance pupil surface and the air interval d0 between the first lens G1 are 30mm, the air interval d2 between the first lens G1 and the second lens G2 is 1.33mm, the air interval d4 between the second lens G2 and the third lens G3 is 0.1mm, the air interval d6 between the third lens G3 and the protective mirror SG is 3mm, and the air interval d8 between the image surface and the protective mirror SG is 144.8 mm.

The front and rear sides of the first lens G1 have radii of curvature of-31.31 mm (R1) and-139.81 mm (R2), respectively, and the center thickness d1 of the first lens G1 is 4 mm. The refractive index of the first lens G1 is n1, the Abbe number is v1, and the relation is satisfied: 1.4< n1< 1.55; 65< v1< 75;

the front and rear sides of the second lens G2 have radii of curvature of-88.06 mm and-46.58 mm for R3 and R4, respectively, and the center thickness d3 of the second lens G2 is 12.08 mm. The refractive index of the second lens G2 is n2, the Abbe number is v2, and the relation is satisfied: 1.75< n2< 1.85; 40< v2< 50;

the curvature radii of the front side and the rear side of the third lens G3 are 851.28mm for R3 mm and 122.86mm for R4 mm, and the center thickness d5 of the third lens G3 is 7.43 mm. The refractive index of the third lens G3 is n3, the Abbe number is v3, and the third lens G3 satisfies the relation: 1.75< n3< 1.85; 40< v3< 50;

the protective glass SG has a central thickness d7 of 3 mm.

The total focal length of the scan field lens is f, and the focal lengths of the first lens G1, the second lens G2 and the third lens G3 are f1, f2 and f3 respectively, wherein the following relations are satisfied with the total focal length f of the scan field lens: -0.9< f1/f < -0.5, 0.7< f2/f <1.1, 0.8< f3/f < 1.5. Preferably-0.75 < f1/f < -0.5, 0.8< f2/f <1.0, 0.9< f3/f < 1.4.

In the present embodiment, the optical configuration parameters of the field lens composed of the first lens G1, the second lens G2, the third lens G3, and the protection mirror SG obtain f 1/f-0.68, f 2/f-0.88, and f 3/f-1.1, and the positional relationship of the arrangement of these parameters obtains the total focal length f of the field lens 125mm, the entrance pupil 12mm, and the scan field 2w 56 °.

The curved surface radius R, the thickness T, the material refractive index Nd and the Abelian coefficient Vd of each lens, namely each lens in the lens component, provided by the invention are shown in the following table:

in the description of the present application, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present application.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.

Claims

1. An infrared field lens with a large scanning angle is characterized in that: the optical lens comprises an entrance pupil surface, a first lens G1, a second lens G2, a third lens G3, a protective lens SG and an image surface which are arranged on the same optical path in sequence, wherein the first lens G1 has negative focal power and a meniscus structure, the second lens G2 has positive focal power and a meniscus structure, the third lens G3 has positive focal power and a double convex structure, and the protective lens SG has a flat plate structure; the total focal length of the scanning field lens is f, the focal lengths of the first lens G1, the second lens G2 and the third lens G3 are f1, f2 and f3 respectively, and the following relations are satisfied: -0.9< f1/f < -0.5, 0.7< f2/f <1.1, 0.8< f3/f < 1.5.

2. The large scan angle infrared field lens of claim 1, wherein: wherein: -0.75< f1/f < -0.5, 0.8< f2/f <1.0, 0.9< f3/f < 1.4.

3. The large scan angle infrared field lens of claim 1, wherein: an air interval d0 between the entrance pupil surface and the first lens G1 is 30mm, an air interval d2 between the first lens G1 and the second lens G2 is 1.33mm, an air interval d4 between the second lens G2 and the third lens G3 is 0.1mm, an air interval d6 between the third lens G3 and the protective mirror SG is 3mm, and an air interval d8 between the image surface and the protective mirror SG is 144.8 mm.

4. The large scan angle infrared field lens of claim 1, wherein: the front and back curvature radii of the first lens G1 are respectively-31.31 mm (R1) and-139.81 mm (R2), and the center thickness d1 of the first lens G1 is 4 mm; the refractive index of the first lens G1 is n1, the Abbe number is v1, and the relation is satisfied: 1.4< n1< 1.55; 65< v1< 75.

5. The large scan angle infrared field lens of claim 1, wherein: the curvature radii of the front side and the rear side of the second lens G2 are respectively-88.06 mm and-46.58 mm in terms of R3 and R4, the central thickness d3 of the second lens G2 is 12.08mm, the refractive index of the second lens G2 is n2, the Abbe number is v2, and the relation is satisfied: 1.75< n2< 1.85; 40< v2< 50.

6. The large scan angle infrared field lens of claim 1, wherein: the curvature radii of the front side and the rear side of the third lens G3 are R3-851.28 mm and R4-122.86 mm respectively, the center thickness d5 of the third lens G3 is 7.43mm, the refractive index of the third lens G3 is n3, the abbe number is v3, and the relationship is satisfied: 1.75< n3< 1.85; 40< v3< 50.

7. The large scan angle infrared field lens of claim 1, wherein: the protective glass SG has a central thickness d7 of 3 mm.