A high-definition FA lens

Abstract

This invention discloses a high-definition FA lens, comprising, from the object side to the image side, a first lens group, an aperture stop, and a second lens group arranged at intervals. The first lens group includes, along the optical axis, a first lens, a second lens, a third lens, a fourth lens, and a fifth lens, wherein the first lens is a biconvex positive lens, the second lens is a meniscus negative lens, the third lens is a biconcave negative lens, the fourth lens is a biconvex positive lens, and the fifth lens is a biconvex positive lens. The second lens group includes, along the optical axis, a sixth lens, a seventh lens, an eighth lens, and a ninth lens, wherein the ninth lens is a biconvex positive lens. Employing a two-set floating focusing structure, the optical power, shape, and materials of each optical lens are rationally matched and combined, achieving high-resolution images from infinity to a close object distance of 120mm even at the widest aperture, up to F2.4.

Description

Technical Field

[0001] This invention relates to the field of optical lens technology, and in particular to a high-definition FA lens. Background Technology

[0002] With the development of Industry 4.0 technology, the types of lenses used in industrial automation are also increasing. These lenses are playing an increasingly important role in automatic monitoring, automatic inspection, and machine vision. However, most of the currently popular FA lenses on the market have poor image quality and urgently need to be updated and iterated. Summary of the Invention

[0003] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a high-definition FA lens that effectively solves the problem of poor image quality.

[0004] According to an embodiment of the present invention, a high-definition FA lens includes, from the object side to the image side, the following: a first lens group, an aperture stop, and a second lens group, wherein the first lens group and the second lens group are floating focusing structures;

[0005] The first lens group includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens arranged sequentially along the optical axis. The first lens is a biconvex positive lens, the second lens is a meniscus negative lens, the third lens is a biconcave negative lens, the fourth lens is a biconvex positive lens, and the fifth lens is a biconvex positive lens.

[0006] The second lens group includes a sixth lens, a seventh lens, an eighth lens, and a ninth lens arranged sequentially along the optical axis. The sixth lens is a biconcave negative lens, the seventh lens is a biconvex positive lens, the eighth lens is a biconvex positive lens, and the ninth lens is a biconvex positive lens.

[0007] A high-definition FA lens according to an embodiment of the present invention has at least the following beneficial effects:

[0008] It adopts a two-set floating focusing structure, and rationally matches and combines the optical power, shape and material of each optical lens. It can still achieve high resolution images from infinity to 120mm close object distances even at the widest aperture, with a maximum aperture of F2.4.

[0009] According to some embodiments of the present invention, the third lens and the fourth lens are combined into an adhesive lens, and the combined focal length of the adhesive lens is negative.

[0010] According to some embodiments of the present invention, the sixth lens and the seventh lens are combined into an adhesive lens, and the combined focal length of the adhesive lens is negative.

[0011] According to some embodiments of the present invention, the focal length F1 of the first lens group and the focal length F of the high-definition FA lens satisfy the following relationship:

[0012] 1.8 ≤ F1 / F ≤ 3.5;

[0013] The focal length F2 of the second lens group and the focal length F of the high-definition FA lens satisfy the following relationship:

[0014] 1.1≤F2 / F≤3;

[0015] The focal length F of the large aperture lens and the total optical length L of the high-definition FA lens satisfy the following relationship:

[0016] 0.2≤F / L≤0.4.

[0017] According to some embodiments of the present invention, the refractive index of the first lens is ≥1.7 and the dispersion coefficient is ≥50.

[0018] According to some embodiments of the present invention, the difference in refractive index between the third lens and the fourth lens is ≥0.1, and the refractive index of the fifth lens is ≥1.8.

[0019] According to some embodiments of the present invention, the refractive index of the sixth lens is ≥1.7 and the dispersion coefficient is ≥25; the difference in refractive index between the sixth lens and the seventh lens is ≥0.2 and the difference in dispersion coefficient is ≥50.

[0020] According to some embodiments of the present invention, both the first lens group and the second lens group are made of glass lenses.

[0021] According to some embodiments of the present invention, a photosensitive chip is disposed on the image side, and a filter group and / or protective glass are disposed between the nine lenses and the photosensitive chip.

[0022] According to some embodiments of the present invention, the high-definition FA lens has a focal length of F = 12mm, an aperture value of FNO = 2.4, and the image sensor has a pixel size of 1.85um and a chip size of 1 / 1.7".

[0023] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0025] Figure 1 This is a schematic diagram of the optical system structure of Embodiment 1 of the present invention when the object distance is 500mm;

[0026] Figure 2This is the MTF plot of Embodiment 1 of the present invention at an object distance of 500 mm;

[0027] Figure 3 This is the vertical chromatic difference image of Embodiment 1 of the present invention at an object distance of 500mm.

[0028] Icon labels:

[0029] First lens group G1, aperture STO, second lens group G2, first lens L1, second lens L2, third lens L3, fourth lens L4, fifth lens L5, sixth lens L6, seventh lens L7, eighth lens L8, ninth lens L9. Detailed Implementation

[0030] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0031] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, etc., are based on the orientation or positional relationship shown in the drawings and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0032] In the description of this invention, "multiple" refers to two or more. The use of "first" and "second" is for distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features or their sequential relationship.

[0033] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0034] Reference Figure 1 As shown, a high-definition FA lens according to an embodiment of the present invention includes: a first lens group G1, an aperture stop STO, and a second lens group G2 arranged sequentially from the object side to the image side. The first lens group G1 and the second lens group G2 are floating focusing structures, and the imaging quality at different object distances is ensured by moving the first lens group G1 and the second lens group G2.

[0035] Specifically, the first lens group G1 includes, sequentially arranged along the optical axis, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5. The first lens L1 is a biconvex positive lens, the second lens L2 is a meniscus negative lens, the third lens L3 is a biconcave negative lens, the fourth lens L4 is a biconvex positive lens, and the fifth lens L5 is a biconvex positive lens. In the first lens group G1, the negative optical power surface is located at a lower light height, while the positive optical power surface is located at a higher light height, and they are separated by a relatively large distance. This arrangement is very beneficial for the correction of field curvature in the off-axis field of view.

[0036] The second lens group G2 includes a sixth lens L6, a seventh lens L7, an eighth lens L8, and a ninth lens L9 arranged sequentially along the optical axis. The sixth lens L6 is a biconcave negative lens, the seventh lens L7 is a biconvex positive lens, the eighth lens L8 is a biconvex positive lens, and the ninth lens L9 is a biconvex positive lens. At the end of the second lens group G2, one or two positive lenses are used to correct the remaining aberrations of the entire system.

[0037] It can be seen that this solution achieves high resolution requirements at different object distances by reasonably allocating lens power, appropriately matching materials, and using a simple floating focusing method.

[0038] In some embodiments of the present invention, the third lens L3 and the fourth lens L4 are combined as an adhesive lens, and the combined focal length of the adhesive lens is negative, which can effectively reduce the chromatic aberration of the front lens group.

[0039] Furthermore, since the first lens group G1 and the second lens group G2 are far apart before and after the aperture stop, the chromatic aberration accumulated by the light over a longer travel distance will become greater. Therefore, in some embodiments of the present invention, the sixth lens L6 and the seventh lens L7 are combined as a bonded lens, and the combined focal length of the bonded lens is negative, which can effectively correct the chromatic aberration of the rear lens group.

[0040] In some embodiments of the present invention, the focal length F1 of the first lens group G1 and the focal length F of the high-definition FA lens satisfy the following relationship:

[0041] 1.8 ≤ F1 / F ≤ 3.5;

[0042] The focal length F2 of the second lens group G2 and the focal length F of the high-definition FA lens satisfy the following relationship:

[0043] 1.1≤F2 / F≤3;

[0044] The focal length F of the large aperture lens and the total optical length L of the high-definition FA lens satisfy the following relationship:

[0045] 0.2≤F / L≤0.4.

[0046] It adopts a two-set floating focusing structure, and rationally matches and combines the optical power, shape and material of each optical lens. It can still achieve high resolution images from infinity to 120mm close object distances even at the widest aperture, with a maximum aperture of F2.4.

[0047] In some embodiments of the present invention, the refractive index of the first lens L1 is ≥1.7 and the dispersion coefficient is ≥50. By setting the first lens L1 of the first piece as a positive lens with high refractive index and high Abbe number, and combining it with the second lens L2 connected afterward, spherical aberration and chromatic aberration can be effectively reduced.

[0048] Because the light rays from the central field of view are strongly diverged by the second lens L2 with negative optical power, the ray height increases sharply, and spherical aberration also increases accordingly. In some embodiments of the present invention, the refractive index difference between the third lens L3 and the fourth lens L4 is ≥0.1, and the refractive index of the fifth lens L5 is ≥1.8. By using a bonded lens with a certain refractive index difference and a fifth lens L5 with a high refractive index, spherical aberration can be better corrected.

[0049] In some embodiments of the present invention, the refractive index of the sixth lens L6 is ≥1.7 and the dispersion coefficient is ≥25; the difference in refractive index between the sixth lens L6 and the seventh lens L7 is ≥0.2 and the difference in dispersion coefficient is ≥50. The bonded lens uses a combination of high refractive index and ultra-high dispersion materials, and the large difference in refractive index and Abbe number can better correct chromatic aberration.

[0050] In particular, in some embodiments of the present invention, the first lens group G1 and the second lens group G2 are both made of glass lenses. Compared with plastic materials, glass has a higher transmittance of visible light, resulting in less light energy loss and better image transparency. At the same time, glass is not easy to age and deform, and has a longer service life.

[0051] In some embodiments of the present invention, by minimizing or eliminating vignetting, as much peripheral field light as possible is allowed to pass through the lens to the chip surface, thereby enabling the lens to obtain higher relative illumination and ensuring the overall uniformity and transparency of the image surface brightness.

[0052] In some embodiments of the present invention, a photosensitive chip is provided on the image side, and a filter group and / or protective glass are provided between the nine-lens L9 and the photosensitive chip. The filter can attenuate a portion of long-wavelength and stray light, and prevent the photosensitive chip from being interfered with by infrared rays, thereby making the image quality clear and the colors bright; the protective glass can protect the chip from direct damage by external forces.

[0053] In some embodiments of the present invention, the high-definition FA lens has a focal length of F = 12mm, an aperture value of FNO = 2.4, and the image sensor has a pixel size of 1.85um and a chip size of 1 / 1.7”, which can achieve 12 million pixels.

[0054] The following specific embodiments illustrate the high-definition FA lens. The parameters of each embodiment that meets the above conditions are shown in Table 1 below: the units for radius R and thickness are millimeters.

[0055] Example 1 Example 2 F1 25.17 18.47 F2 19.42 25.00

[0056] Table 1

[0057] The specific parameters of Example 1 are shown in Table 2:

[0058] Surface number radius thickness Refractive index 1 74.17 3.98 1.73 2 -60.87 0.10 3 39.02 4.90 1.62 4 7.39 3.28 5 -8.31 1.41 1.76 6 12.96 4.55 1.64 7 -11.75 1.37 8 18.24 2.93 1.85 9 -54.65 D1 STO Infinity 1.49 11 -10.29 0.99 1.72 12 14.49 2.91 1.49 13 -9.67 0.10 14 61.21 2.01 1.70 15 -30.25 0.10 16 21.10 2.12 1.59 17 766.36 D2 Image - -

[0059] Table 2 shows the focusing data for different object distances in Example 1, as shown in Table 3 below:

[0060] Infinity 0.5M 0.12M D1 8.74 8.57 8.012 D2 13.35 13.57 14.48

[0061] Table 3

[0062] See Figure 1 As can be seen from Tables 1 to 3, this example ensures imaging quality at different object distances by moving the first lens group and the second lens group back and forth along the optical axis.

[0063] like Figure 2 As shown, this is the MTF graph of Example 1 at an object distance of 500mm, used to evaluate the lens's resolving power. The curve in the graph shows that the MTF of the entire field of view is greater than 0.25 at 200lp / mm, indicating excellent resolving power, which can be used in high-pixel chips. Furthermore, the on-axis and off-axis MTF curves within a 0.7 field of view show basically the same trend.

[0064] Figure 3 The image shown is a transverse chromatic aberration diagram for Example 1 at an object distance of 500 mm. Throughout the entire field of view, the chromatic aberration is controlled within the Airy disk range.

[0065] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A high-definition FA lens, characterized in that, It includes the following components arranged sequentially from the object side to the image side: a first lens group (G1), an aperture stop (STO), and a second lens group (G2), wherein the first lens group (G1) and the second lens group (G2) are floating focusing structures; The first lens group (G1) includes, in sequence along the optical axis, a first lens (L1), a second lens (L2), a third lens (L3), a fourth lens (L4), and a fifth lens (L5). The first lens (L1) is a biconvex positive lens, the second lens (L2) is a meniscus negative lens, the third lens (L3) is a biconcave negative lens, the fourth lens (L4) is a biconvex positive lens, and the fifth lens (L5) is a biconvex positive lens. The second lens group (G2) includes a sixth lens (L6), a seventh lens (L7), an eighth lens (L8), and a ninth lens (L9) arranged sequentially along the optical axis. The sixth lens (L6) is a biconcave negative lens, the seventh lens (L7) is a biconvex positive lens, the eighth lens (L8) is a biconvex positive lens, and the ninth lens (L9) is a biconvex positive lens. The optical elements with optical power in the above lens are only the nine lenses mentioned above.

2. The high-definition FA lens according to claim 1, characterized in that: The third lens (L3) and the fourth lens (L4) are combined to form an adhesive lens, and the combined focal length of the adhesive lens is negative.

3. A high-definition FA lens according to claim 1, characterized in that: The sixth lens (L6) and the seventh lens (L7) are combined to form an adhesive lens, and the combined focal length of the adhesive lens is negative.

4. A high-definition FA lens according to claim 1, characterized in that: The focal length F1 of the first lens group (G1) and the focal length F of the high-definition FA lens satisfy the following relationship: 1.8 ≤ F1 / F ≤ 3.5; The focal length F2 of the second lens group (G2) and the focal length F of the high-definition FA lens satisfy the following relationship: 1.1 ≤ F2 / F ≤ 3; The focal length F and the total optical length L of the high-definition FA lens satisfy the following relationship: 0.2 ≤ F / L ≤ 0.

4.

5. A high-definition FA lens according to claim 1 or 2, characterized in that: The first lens (L1) has a refractive index ≥1.7 and a dispersion coefficient ≥50.

6. A high-definition FA lens according to claim 2, characterized in that: The refractive index difference between the third lens (L3) and the fourth lens (L4) is ≥0.1, and the refractive index of the fifth lens (L5) is ≥1.

8.

7. A high-definition FA lens according to claim 3, characterized in that: The refractive index of the sixth lens (L6) is ≥1.7 and the dispersion coefficient is ≥25; the difference in refractive index between the sixth lens (L6) and the seventh lens (L7) is ≥0.2 and the difference in dispersion coefficient is ≥50.

8. A high-definition FA lens according to claim 1, characterized in that: Both the first lens group (G1) and the second lens group (G2) use glass lenses.

9. A high-definition FA lens according to claim 1, characterized in that: A photosensitive chip is provided on the image side, and a filter group and / or protective glass are provided between the nine-lens (L9) and the photosensitive chip.

10. A high-definition FA lens according to claim 9, characterized in that: The high-definition FA lens has a focal length of F=12mm and an aperture of Fn0=2.

4. The image sensor has a pixel size of 1.85um and a chip size of 1 / 1.7".

Images