Optical lens

Abstract

The invention provides an optical lens, which comprises six lenses in total, and sequentially comprises a first lens with negative focal power, a second lens with negative focal power, a third lens with negative focal power, a fourth lens with negative focal power, a fifth lens with negative focal power and a sixth lens with negative focal power from an object plane to an imaging plane along a light transmission direction, the object side surface of the second lens is a convex surface; the object side surface of the third lens is a convex surface, and the image side surface of the third lens is a convex surface; the object side surface of the fourth lens is a concave surface, and the image side surface of the fourth lens is a concave surface; the fifth lens has positive focal power, and the image side surface of the fifth lens is a convex surface; the sixth lens has focal power, the object side surface of the sixth lens is a concave surface, and the image side surface of the sixth lens is a concave surface near the optical axis; the object plane, the main plane of the optical lens and the imaging plane intersect at a line. According to the optical lens provided by the invention, through reasonable matching of the focal power and the surface type of each lens, spherical aberration and trapezoidal distortion can be effectively corrected, and the imaging quality is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of imaging lenses, and in particular to an optical lens. Background Art

[0002] With the vigorous development of machine vision technology, the triangulation principle has been widely applied in the field of industrial inspection. It captures the laser line information projected by a laser on the surface of an object through an image sensor, thereby reconstructing the surface contour information of the object. During the image acquisition process, a lens is required to photograph an inclined target object. However, due to the limitation of the depth of field of traditional lenses, it is difficult to achieve clear imaging of the entire field of view of the inclined object surface, thus affecting the measurement accuracy of the oblique image lens in the field of industrial inspection. By using Scheimpflug's law and gradually tilting the lens, the extended planes of the object plane, the image plane, and the lens plane intersect at a straight line, enabling clear imaging of the entire object surface.

[0003] Existing lenses have problems such as large size, large distortion, and poor imaging quality, and cannot meet the imaging requirements. How to make the lens take into account miniaturization and high imaging quality has become a difficult problem to be solved urgently at present. Summary of the Invention

[0004] In view of the above problems, the purpose of the present invention is to provide an optical lens with excellent imaging quality.

[0005] The technical solution adopted by the present invention is as follows: An optical lens, comprising a total of six lenses, which in sequence from the object surface to the imaging surface along the light transmission direction include: A first lens with negative optical power, whose object side is concave near the optical axis and whose image side is convex near the optical axis; A second lens with positive optical power, whose object side is convex; A third lens with positive optical power, whose object side is convex and whose image side is convex; A fourth lens with negative optical power, whose object side is concave and whose image side is concave; A fifth lens with positive optical power, whose image side is convex; A sixth lens with optical power, whose object side is concave and whose image side is concave near the optical axis; The object surface, the principal plane of the optical lens, and the imaging surface intersect at a straight line; Wherein, the total optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 1 < TTL / f < 1.3.

[0006] More preferably, the maximum field of view FOV of the optical lens and the aperture value Fno of the optical lens satisfy: 11° < FOV / Fno < 13°; the true image height IHy in the Y direction corresponding to the maximum field of view of the optical lens and the true image height IHx in the X direction corresponding to the maximum field of view of the optical lens satisfy: 0.9 < IHy / IHx < 1.1.

[0007] More preferably, the back focal length BFL of the optical lens and the effective focal length f of the optical lens satisfy: 0.25 < BFL / f < 0.35; the back focal length BFL of the optical lens and the total optical length TTL of the optical lens satisfy: 0.23 < BFL / TTL < 0.28.

[0008] More preferably, the focal length f1 of the first lens and the effective focal length f of the optical lens satisfy: -4 < f1 / f < -3.2; the curvature radius R1 of the object side of the first lens and the effective focal length f of the optical lens satisfy: -1.6 < R1 / f < -1; the curvature radius R2 of the image side of the first lens and the effective focal length f of the optical lens satisfy: -4.2 < R2 / f < -1.9.

[0009] More preferably, the focal length f2 of the second lens and the effective focal length f of the optical lens satisfy: 0.9 < f2 / f < 1.6; the focal length f3 of the third lens and the effective focal length f of the optical lens satisfy: 0.75 < f3 / f < 0.9.

[0010] More preferably, the focal length f4 of the fourth lens and the effective focal length f of the optical lens satisfy: -1.85 < f4 / f < -1.35; the curvature radius R7 of the object side of the fourth lens and the effective focal length f of the optical lens satisfy: -7.2 < R7 / f < -6.9; the curvature radius R8 of the image side of the fourth lens and the effective focal length f of the optical lens satisfy: 0.95 < R8 / f < 1.1.

[0011] More preferably, the focal length f5 of the fifth lens and the effective focal length f of the optical lens satisfy: 1.9 < f5 / f < 105; the curvature radius R1 of the object side of the first lens, the curvature radius R2 of the image side of the first lens and the central thickness CT1 of the first lens on the optical axis satisfy: 0.39 < (R1 - CT1) / R2 < 0.57.

[0012] Further preferably, the focal length f6 of the sixth lens and the effective focal length f of the optical lens satisfy: -0.8 < f6 / f < 0.6; the object-side curvature radius R11 of the sixth lens and the effective focal length f of the optical lens satisfy: -0.45 < R11 / f < -0.34; the image-side curvature radius R12 of the sixth lens and the effective focal length f of the optical lens satisfy: 2.6 < R12 / f < 12.6.

[0013] Further preferably, the focal length f1 of the first lens and the combined focal length f23456 of the second, third, fourth, fifth, and sixth lenses satisfy: -6.5 < f1 / f23456 < -5.4; the focal length f1 of the first lens and the combined focal length f2345 of the second, third, fourth, and fifth lenses satisfy: -5.5 < f1 / f2345 < -4.6.

[0014] Further preferably, the object-side curvature radius R1 of the first lens and the image-side curvature radius R2 of the first lens satisfy: -0.45 < (R1 - R2) / (R1 + R2) < -0.3; the object-side curvature radius R11 of the sixth lens and the image-side curvature radius R12 of the sixth lens satisfy: -0.95 < (R11 + R12) / (R11 - R12) < -0.73.

[0015] Further preferably, the optical axis of the first lens is eccentric 301 mm in the Y direction and tilted -37° in the X direction relative to the center line of the object plane; the center line of the imaging plane is eccentric 0.04 mm to 0.32 mm in the X direction, eccentric 0.34 mm to 0.50 mm in the Y direction, and tilted 27.37° to 27.49° in the X direction relative to the optical axis of the sixth lens.

[0016] Compared with the prior art, the optical lens provided by the present invention, through the reasonable matching of the optical powers and surface types of each lens, is conducive to controlling the light trend and deflection angle entering the lens, reducing the tolerance sensitivity of the lens, and improving the yield; it can effectively correct spherical aberration and trapezoidal distortion, improve the realism of the lens to restore the scene, and is conducive to balancing the astigmatism of the optical system, and greatly improves the imaging quality. Description of the Drawings

[0017] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, where: Figure 1 It is a schematic structural diagram of the optical lens in Embodiment 1 of the present invention.

[0018] Figure 2Schematic diagram of the structure of each lens of the optical lens in Embodiment 1 of the present invention with respect to the object plane and the imaging plane.

[0019] Figure 3 X-direction - F-Theta distortion curve graph of the optical lens in Embodiment 1 of the present invention.

[0020] Figure 4 Y-direction - F-Theta distortion curve graph of the optical lens in Embodiment 1 of the present invention.

[0021] Figure 5 MTF curve graph of the optical lens in Embodiment 1 of the present invention.

[0022] Figure 6 Relative illumination curve graph of the optical lens in Embodiment 1 of the present invention.

[0023] Figure 7 Grid distortion map of the optical lens in Embodiment 1 of the present invention.

[0024] Figure 8 Schematic diagram of the structure of the optical lens in Embodiment 2 of the present invention.

[0025] Figure 9 X-direction - F-Theta distortion curve graph of the optical lens in Embodiment 2 of the present invention.

[0026] Figure 10 Y-direction - F-Theta distortion curve graph of the optical lens in Embodiment 2 of the present invention.

[0027] Figure 11 MTF curve graph of the optical lens in Embodiment 2 of the present invention.

[0028] Figure 12 Relative illumination curve graph of the optical lens in Embodiment 2 of the present invention.

[0029] Figure 13 Grid distortion map of the optical lens in Embodiment 2 of the present invention.

[0030] Figure 14 Schematic diagram of the structure of the optical lens in Embodiment 3 of the present invention.

[0031] Figure 15 X-direction - F-Theta distortion curve graph of the optical lens in Embodiment 3 of the present invention.

[0032] Figure 16 Y-direction - F-Theta distortion curve graph of the optical lens in Embodiment 3 of the present invention.

[0033] Figure 17 MTF curve graph of the optical lens in Embodiment 3 of the present invention.

[0034] Figure 18 This is the relative illuminance curve graph of the optical lens in Embodiment 3 of the present invention.

[0035] Figure 19 This is the grid distortion graph of the optical lens in Embodiment 3 of the present invention.

[0036] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. Specific Embodiments

[0037] To better understand the present application, more detailed descriptions of various aspects of the present application will be made with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of the embodiments of the present application and do not limit the scope of the present application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0038] It should be noted that in this specification, the expressions such as first, second, and third are only used to distinguish one feature from another feature and do not represent any limitation on the features. Therefore, without departing from the teachings of the present invention, the first lens discussed below may also be referred to as the second lens or the third lens.

[0039] In the drawings, for the sake of clarity, the thickness, dimensions, and shape of the lenses have been slightly exaggerated. Specifically, the spherical or aspherical shapes shown in the drawings are shown by way of example. That is, the spherical or aspherical shapes are not limited to the spherical or aspherical shapes shown in the drawings. The drawings are only examples and are not drawn to an exact scale.

[0040] In this document, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object being photographed is called the object side surface of the lens, and the surface of each lens closest to the imaging surface is called the image side surface of the lens.

[0041] It should also be understood that the terms "comprising", "comprises", "having", "including" and / or "includes", when used in this specification, denote the presence of the stated features, elements and / or components, but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof. Further, when an expression such as "at least one of..." appears after a list of listed features, it modifies the entire list of listed features rather than individual elements in the list. Further, when describing embodiments of the present application, the use of "may" means "one or more embodiments of the present application". Also, the term "exemplary" is intended to refer to an example or illustration.

[0042] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It should also be understood that terms (such as those defined in a common dictionary) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0043] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The present application will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0044] The optical lens provided by the embodiment of the present invention is a Scheimpflug lens, also known as an oblique shooting lens. Its principle is that the extension lines of the object plane, the main plane of the lens and the imaging plane intersect at a line, and the intersection line is unique, which can enable the entire inclined plane to achieve clear imaging. Through the Scheimpflug law, clear imaging can be achieved in the entire inclined field of view. It can be understood that among the lenses of the present invention, at least some of the optical axes of the lenses respectively form an angle with the object plane and the imaging plane, and at least some of the lenses are inclined with respect to the object plane and the imaging plane. The object plane of the optical lens of the present invention is arranged along the Y-axis direction.

[0045] The optical lens of the present invention has a total of six lenses, which are, in order from the object plane to the imaging plane along the light transmission direction, the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens.

[0046] Among them, the first lens may have a negative focal power. Its object side is concave near the optical axis, and its image side is convex near the optical axis. The second lens may have a positive focal power. Its object side is convex, and its image side may be concave or flat near the optical axis. The third lens may have a positive focal power. Its object side is convex, and its image side is convex. The fourth lens may have a negative focal power. Its object side is concave, and its image side is concave. The fifth lens may have a positive focal power. Its object side may be concave or convex, and its image side is convex. The sixth lens may have a focal power. Its object side is concave, and its image side is concave near the optical axis. The object plane, the principal plane of the optical lens, and the imaging plane intersect at a line.

[0047] In some embodiments, the optical lens may further include a diaphragm, and the diaphragm may be located between the first lens and the second lens. It can be understood that the diaphragm is used to limit the amount of incident light to change the brightness of the image.

[0048] In some embodiments, the optical lens may further include a filter, and the filter may be disposed between the sixth lens and the imaging plane. The filter is used to filter out interfering light to prevent the interfering light from reaching the imaging plane of the optical lens and affecting normal imaging.

[0049] In some embodiments, the total optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 1 < TTL / f < 1.3. Meeting the above range helps to achieve the overall miniaturization of the lens. More specifically, 1.07 < TTL / f < 1.28.

[0050] In some embodiments, the maximum field of view FOV of the optical lens and the f-number Fno of the optical lens satisfy: 11° < FOV / Fno < 13°. Meeting the above range provides a reasonable field of view and f-number, taking into account the design difficulty and the requirements of the field of view, and at the same time keeping the f-number within a reasonable range. More specifically, 11.69° < FOV / Fno < 12.02°.

[0051] In some embodiments, the true image height IHy in the Y direction corresponding to the maximum field of view of the optical lens and the true image height IHx in the X direction corresponding to the maximum field of view of the optical lens satisfy: 0.9 < IHy / IHx < 1.1. Meeting the above range, the image heights of the lens in the X and Y directions do not differ much, and the lens has a low grid distortion. More specifically, 0.95 < IHy / IHx < 1.08.

[0052] In some embodiments, the back focal length BFL of the optical lens and the effective focal length f of the optical lens satisfy: 0.25 < BFL / f < 0.35; the back focal length BFL of the optical lens and the overall optical length TTL of the optical lens satisfy: 0.23 < BFL / TTL < 0.28. Satisfying the above ranges and reasonably defining the proportion of the back focal length of the lens helps to maintain the miniaturization of the lens, have sufficient back focus, and reduce the lens assembly difficulty.

[0053] In some embodiments, the focal length f1 of the first lens and the effective focal length f of the optical lens satisfy: -4 < f1 / f < -3.2; the curvature radius R1 of the object side surface of the first lens and the effective focal length f of the optical lens satisfy: -1.6 < R1 / f < -1; the curvature radius R2 of the image side surface of the first lens and the effective focal length f of the optical lens satisfy: -4.2 < R2 / f < -1.9. Satisfying the above ranges and reasonably defining the proportion of the optical power of the first lens and the shapes of the object side surface and the image side surface can make the light enter the rear lens at a relatively gentle angle, which helps to improve the overall stability of the oblique shooting lens. More specifically, -4 < f1 / f < -3.25; -1.6 < R1 / f < -1.02; -4.13 < R2 / f < -1.95.

[0054] In some embodiments, the focal length f2 of the second lens and the effective focal length f of the optical lens satisfy: 0.9 < f2 / f < 1.6; the focal length f3 of the third lens and the effective focal length f of the optical lens satisfy: 0.75 < f3 / f < 0.9. Satisfying the above ranges and reasonably defining the proportion of the optical power of the second lens and the third lens helps to reduce aberration and reduce the sensitivity of the oblique shooting lens. More specifically, 0.95 < f2 / f < 1.53; 0.78 < f3 / f < 0.87.

[0055] In some embodiments, the focal length f4 of the fourth lens and the effective focal length f of the optical lens satisfy: -1.85 < f4 / f < -1.35; the curvature radius R7 of the object side surface of the fourth lens and the effective focal length f of the optical lens satisfy: -7.2 < R7 / f < -6.9; the curvature radius R8 of the image side surface of the fourth lens and the effective focal length f of the optical lens satisfy: 0.95 < R8 / f < 1.1. Satisfying the above ranges and reasonably defining the proportion of the optical power of the fourth lens and the shapes of the object side surface and the image side surface can effectively reduce distortion. More specifically, -1.81 < f4 / f < -1.39; -7.2 < R7 / f < -6.91; 0.98 < R8 / f < 1.08.

[0056] In some embodiments, the focal length f5 of the fifth lens and the effective focal length f of the optical lens satisfy: 1.9 < f5 / f < 105; the object-side curvature radius R1 of the first lens, the image-side curvature radius R2 of the first lens, and the central thickness CT1 of the first lens on the optical axis satisfy: 0.39 < (R1 - CT1) / R2 < 0.57. Satisfying the above ranges and reasonably limiting the proportion of the optical power of the fifth lens helps the light to travel smoothly, reduces the deflection angle of the marginal rays, and improves the imaging quality; reasonably limiting the central thickness of the first lens and the shapes of the object side and the image side helps to further reduce the incident light angle. More specifically, 1.93 < f5 / f < 104.4.

[0057] In some embodiments, the focal length f6 of the sixth lens and the effective focal length f of the optical lens satisfy: -0.8 < f6 / f < 0.6; the object-side curvature radius R11 of the sixth lens and the effective focal length f of the optical lens satisfy: -0.45 < R11 / f < -0.34; the image-side curvature radius R12 of the sixth lens and the effective focal length f of the optical lens satisfy: 2.6 < R12 / f < 12.6. Satisfying the above ranges and reasonably limiting the proportion of the optical power of the sixth lens and the shapes of the object side and the image side can effectively eliminate the grid distortion of the lens and improve the picture realism. More specifically, -0.79 < f6 / f < 0.6; -0.43 < R11 / f < -0.34; 2.62 < R12 / f < 12.53.

[0058] In some embodiments, the focal length f1 of the first lens and the combined focal length f23456 of the second, third, fourth, fifth, and sixth lenses satisfy: -6.5 < f1 / f23456 < -5.4; the focal length f1 of the first lens and the combined focal length f2345 of the second, third, fourth, and fifth lenses satisfy: -5.5 < f1 / f2345 < -4.6. Satisfying the above ranges and reasonably limiting the proportion of the optical power of the first lens and the rear lens group can effectively improve the imaging quality and structural stability of the lens. More specifically, -6.45 < f1 / f23456 < -5.49; -5.45 < f1 / f2345 < -4.69.

[0059] In some embodiments, the radius of curvature R1 of the object side surface of the first lens and the radius of curvature R2 of the image side surface of the first lens satisfy: -0.45 < (R1 - R2) / (R1 + R2) < -0.3; the radius of curvature R11 of the object side surface of the sixth lens and the radius of curvature R12 of the image side surface of the sixth lens satisfy: -0.95 < (R11 + R12) / (R11 - R12) < -0.73. Satisfying the above ranges and reasonably defining the shapes of the object side surface and the image side surface of the first lens helps to reduce the distortion generated by the first lens, reduce the difficulty of subsequent lenses for distortion correction, improve the imaging quality of the lens, and reasonably defining the shapes of the object side surface and the image side surface of the sixth lens helps to limit the deflection degree of the rear-end light rays while increasing the image height.

[0060] In some embodiments, the optical axis of the first lens is eccentric 301 mm in the Y direction and inclined -37° in the X direction relative to the center line of the object surface; the center line of the imaging surface is eccentric 0.04 mm to 0.32 mm in the X direction, eccentric 0.34 to 0.50 mm in the Y direction, and inclined 27.37° to 27.49° in the X direction relative to the optical axis of the sixth lens.

[0061] In some embodiments, the center line of the aperture is eccentric -0.05 mm to -0.04 mm in the Y direction and inclined 14.45° to 21.04° in the X direction relative to the optical axis of the first lens. And the center line of the aperture is collinear with the optical axes of the second lens and the third lens.

[0062] In some embodiments, the optical axis of the fourth lens is eccentric -0.21 mm to 0 in the Y direction and inclined -6.71° to 0 in the X direction relative to the optical axis of the third lens; the optical axis of the fifth lens is eccentric 0 to 0.21 mm in the Y direction and inclined 0 to 6.71° in the X direction relative to the optical axis of the fourth lens; the optical axis of the sixth lens is eccentric 0.19 mm to 0.49 mm in the Y direction and inclined -27.36° to -22.12° in the X direction relative to the optical axis of the fifth lens.

[0063] In some embodiments, the true image height IH corresponding to the maximum field of view angle of the optical lens, the effective focal length f of the optical lens, and the maximum field of view angle FOV of the optical lens satisfy: 0.7 < (IH / 2) / (f × Tan(FOV / 2)) < 0.84. Satisfying the above range makes the distortion within a reasonable range.

[0064] In some embodiments, the total optical length TTL of the optical lens and the sum ∑CT of the central thicknesses of the first lens to the sixth lens on the optical axis respectively satisfy: 0.35 < ∑CT / TTL < 0.41; the effective focal length f of the optical lens and the sum ∑CT of the central thicknesses of the first lens to the sixth lens on the optical axis respectively satisfy: 0.4 < ΣCT / f < 0.49. Meeting the above ranges helps to control the processability of the lens, reduce the production cost and the assembly difficulty.

[0065] In some embodiments, the optical lens satisfies the conditional expressions: 4.3 mm < f < 4.4 mm; 0.7 mm < EPD < 0.8 mm; 4.6 mm < TTL < 5.6 mm; 5.6 < Fno < 5.9; 39° < CRA < 43°; 1.1 mm < BFL < 1.6 mm; 65° < FOV < 70°; 4 mm < IHx < 5 mm; 3.8 mm < IHy < 5.4 mm. Wherein, f represents the effective focal length of the optical lens, EPD represents the entrance pupil diameter of the optical lens, TTL represents the total optical length of the optical lens, Fno represents the aperture value of the optical lens, CRA represents the chief ray angle of incidence of the optical lens, BFL represents the back focal length of the optical lens, FOV represents the maximum field of view angle of the optical lens, IHy represents the true image height in the Y direction corresponding to the maximum field of view angle of the optical lens, and IHx represents the true image height in the X direction corresponding to the maximum field of view angle of the optical lens. Meeting the above ranges, the optical lens has at least one or more advantages such as miniaturization, large field of view angle, large image height, etc. More specifically, 4.34 mm < f < 4.36 mm; 0.74 mm < EPD < 0.78 mm; 4.69 mm < TTL < 5.55 mm; 5.64 < Fno < 5.81; 39.61° < CRA < 42.71°; 1.11 mm < BFL < 1.51 mm; 67.82° < FOV < 67.86°; 4.11 mm < IHx < 4.85 mm; 3.95 mm < IHy < 5.22 mm.

[0066] In some embodiments, the lens material in the optical lens provided by the present invention can be glass or plastic. When the lens material is plastic, the production cost can be effectively reduced. Additionally, when the lens material is glass, the geometric chromatic aberration of the optical system can be effectively corrected due to the low dispersion characteristic of the glass itself. The optical lens provided by the present invention can adopt an all-plastic lens structure, which not only enables the lens to have excellent imaging performance, but also makes the structure of the lens relatively compact, and can better achieve the balance between the miniaturization of the lens and high image quality.

[0067] In some embodiments, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens may be spherical lenses or aspherical lenses. Compared with the spherical structure, the aspherical structure can effectively reduce the aberration of the optical system, thereby reducing the number of lenses and the size of the lenses, and better realizing the miniaturization of the lens. More specifically, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens of the present invention can all adopt aspherical lenses, which can effectively reduce the aberration of the optical lens, thereby reducing the number of lenses and the size of the lenses, and better realizing the miniaturization of the lens.

[0068] In various embodiments of the present invention, when the lens is an aspherical lens, the surface shapes of the aspherical surfaces of the optical lens satisfy the following equation: ; where z is the distance between the curved surface and the vertex of the curved surface in the optical axis direction, h is the distance from the optical axis to the curved surface, c is the curvature of the vertex of the curved surface, K is the conic coefficient, and B, C, D, E, F, G, H are the surface coefficients of the fourth order, sixth order, eighth order, tenth order, twelfth order, fourteenth order, and sixteenth order respectively.

[0069] The present invention will be further described in multiple embodiments below. In each embodiment, the thickness, radius of curvature, and material selection of each lens in the optical lens are somewhat different. For specific differences, please refer to the parameter tables of each embodiment. The following embodiments are only preferred embodiments of the present invention, but the embodiments of the present invention are not limited only by the following embodiments. Any changes, substitutions, combinations, or simplifications made without departing from the innovative points of the present invention should be regarded as equivalent replacement methods and are included in the protection scope of the present invention.

[0070] Embodiment 1 Please refer to Figure 1 , which shows a schematic structural diagram of the optical lens 100 provided in Embodiment 1 of the present invention. The optical lens sequentially includes, from the object side to the imaging surface along the light transmission direction: a first lens L1, a diaphragm ST, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a filter G1.

[0071] Among them, the first lens L1 has a negative optical power. Its object side surface S1 is concave near the optical axis, and its image side surface S2 is convex near the optical axis. The second lens L2 has a positive optical power. Its object side surface S3 is convex, and its image side surface S4 is flat near the optical axis. The third lens L3 has a positive optical power. Its object side surface S5 is convex, and its image side surface S6 is convex. The fourth lens L4 has a negative optical power. Its object side surface S7 is concave, and its image side surface S8 is concave. The fifth lens L5 has a positive focal power, its object side S9 is concave, and its image side S10 is convex; The sixth lens L6 has a negative focal power, its object side S11 is concave, and its image side S12 is concave near the optical axis; Both the object side S13 and the image side S14 of the filter G1 are flat; The imaging surface S15 is flat.

[0072] The first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, and the sixth lens L6 are all plastic aspherical lenses.

[0073] The optical lens of the present invention is a Scheimpflug lens, and the extension lines of its object plane, the principal plane of the lens, and the imaging plane intersect at a line. It can be understood that there are angles between the optical axes of the respective lenses and the object plane and the imaging plane, and the respective lenses are inclined with respect to the object plane and the imaging plane. The object plane of the optical lens of the present invention is set in the Y-axis direction. As Figure 2 shown, it is the positional relationship between the respective lenses and the object plane and the imaging plane in Embodiment 1.

[0074] The relevant parameters of the respective lenses in the optical lens 100 in Embodiment 1 are shown in Table 1-1.

[0075] Table 1-1 The aspherical surface parameters of the aspherical lenses of the optical lens 100 in Embodiment 1 are shown in Table 1-2.

[0076] Table 1-2 The eccentricity and tilt parameters of the respective lenses of the optical lens 100 in Embodiment 1 are shown in Table 1-3.

[0077] Table 1-3 As can be seen from Table 1-3, the optical axis of the first lens is eccentric 301 mm in the Y direction and inclined -37° in the X direction relative to the center line of the object surface; the center line of the aperture is eccentric -0.05 mm in the Y direction and inclined 21.04° in the X direction relative to the optical axis of the first lens; the center line of the aperture is collinear with the optical axes of the second lens, the third lens, the fourth lens, and the fifth lens; the optical axis of the sixth lens is eccentric 0.49 mm in the Y direction and inclined -27.36° in the X direction relative to the optical axis of the fifth lens; the center line of the filter is eccentric 0.04 mm in the X direction, eccentric 0.28 mm in the Y direction, and inclined 27.37° in the X direction relative to the optical axis of the sixth lens; the center line of the imaging surface is eccentric 0.21 mm in the Y direction relative to the center line of the filter. It can be understood that the center line of the imaging surface is eccentric 0.04 mm in the X direction, eccentric 0.49 mm in the Y direction, and inclined 27.37° in the X direction relative to the optical axis of the sixth lens.

[0078] In this embodiment, the X-direction F-Theta distortion curve graph, Y-direction F-Theta distortion curve graph, MTF curve graph, relative illumination curve graph, and grid distortion graph of the optical lens 100 are respectively as Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 shown.

[0079] Figure 3 shows the X-direction F-Theta distortion curve graph of Embodiment 1, which represents the F-Theta distortion of light rays at different image heights on the imaging surface in the X direction. The horizontal axis represents the distortion value (unit: %), and the vertical axis represents the half field of view angle (unit: °). As can be seen from the figure, the X-direction F-Theta distortion of the optical lens is controlled within 0 to 15%, indicating that the optical lens 100 can correct the distortion well.

[0080] Figure 4 shows the Y-direction F-Theta distortion curve graph of Embodiment 1, which represents the F-Theta distortion of light rays at different image heights on the imaging surface in the Y direction. The horizontal axis represents the distortion value (unit: %), and the vertical axis represents the half field of view angle (unit: °). As can be seen from the figure, the Y-direction F-Theta distortion of the optical lens is controlled within 0 to 16%, indicating that the optical lens 100 can correct the distortion well.

[0081] Figure 5The MTF (Modulation Transfer Function) curve of Embodiment 1 is shown, which represents the modulation of lens imaging at different spatial frequencies in each field of view. The horizontal axis represents the spatial frequency (unit: lp / mm), and the vertical axis represents the MTF value. It can be seen from the figure that the MTF value of this embodiment is above 0.28 within the entire field of view. In the range of 0 - 120 lp / mm, the MTF curve smoothly decreases uniformly from the center to the edge field of view, and it has good imaging quality and good detail resolution ability in both low-frequency and high-frequency cases.

[0082] Figure 6 The relative illumination curve of Embodiment 1 is shown, which represents the relative illumination values at different field angles on the imaging plane. The horizontal axis represents the semi-field angle (unit: °), and the vertical axis represents the relative illumination (unit: %). It can be seen from the figure that the relative illumination value of the optical lens is still greater than 65% at the maximum semi-field angle, indicating that the optical lens 100 has good relative illumination.

[0083] Figure 7 The grid distortion diagram of Embodiment 1 is shown. The abscissa is the image height in the X direction, and the ordinate is the image height in the Y direction. After the object plane is imaged on the image plane through this lens, the predicted values and the actual values of the checkerboard grid are relatively close at each position, indicating that the picture has no obvious distortion and can effectively eliminate trapezoidal distortion.

[0084] Embodiment 2 Please refer to Figure 8 , which shows the structural schematic diagram of the optical lens 200 provided in Embodiment 2 of the present invention. Compared with Embodiment 1, the main differences are: the sixth lens L6 has a positive optical power; the image side S4 of the second lens L2 is concave near the optical axis; the object side S9 of the fifth lens L5 is convex; the optical parameters such as the curvature radius and lens thickness of each lens surface are different.

[0085] The relevant parameters of each lens in the optical lens 200 in Embodiment 2 are shown in Table 2-1.

[0086] Table 2-1 The aspheric lens surface type parameters of the optical lens 200 in Embodiment 2 are shown in Table 2-2.

[0087] Table 2-2 The decentration and tilt parameters of each lens of the optical lens 200 in Embodiment 2 are shown in Table 2-3.

[0088] Table 2-3 As can be seen from Table 2-3, the optical axis of the first lens is eccentric 301 mm in the Y direction and tilted -37° in the X direction relative to the center line of the object plane; the center line of the aperture is eccentric -0.05 mm in the Y direction and tilted 14.45° in the X direction relative to the optical axis of the first lens; the center line of the aperture is collinear with the optical axes of the second lens and the third lens; the optical axis of the fourth lens is deflected -0.2 mm in the Y direction and tilted -6.71° in the X direction relative to the optical axis of the third lens; the optical axis of the fifth lens is deflected 0.2 mm in the Y direction and tilted 6.71° in the X direction relative to the optical axis of the fourth lens; the optical axis of the sixth lens is eccentric 0.19 mm in the Y direction and tilted -22.12° in the X direction relative to the optical axis of the fifth lens; the center line of the filter is eccentric 0.15 mm in the X direction, eccentric 0.29 mm in the Y direction, and tilted 27.49° in the X direction relative to the optical axis of the sixth lens; the center line of the imaging plane is eccentric 0.21 mm in the Y direction relative to the center line of the filter. It can be understood that the center line of the imaging plane is eccentric 0.15 mm in the X direction, eccentric 0.5 mm in the Y direction, and tilted 27.49° in the X direction relative to the optical axis of the sixth lens.

[0089] In this embodiment, the X-direction F-Theta distortion curve graph, Y-direction F-Theta distortion curve graph, MTF curve graph, relative illumination curve graph, and grid distortion graph of the optical lens 200 are respectively as Figure 9 , Figure 10 , Figure 11 , Figure 12 , Figure 13 shown.

[0090] From Figure 9 , it can be seen that the X-direction F-Theta distortion of the optical lens is controlled within 0 to 16%, indicating that the optical lens 200 can correct distortion well.

[0091] From Figure 10 , it can be seen that the Y-direction F-Theta distortion of the optical lens is controlled within 0 to 16%, indicating that the optical lens 200 can correct distortion well.

[0092] From Figure 11 , it can be seen that the MTF value of this embodiment is above 0.25 within the entire field of view. In the range of 0 to 120 lp / mm, the MTF curve smoothly decreases uniformly from the center to the edge of the field of view, and has good imaging quality and good detail resolution ability in both low-frequency and high-frequency cases.

[0093] From Figure 12 , it can be seen that the relative illumination value of the optical lens is still greater than 55% at the maximum half field of view angle, indicating that the optical lens 200 has good relative illumination.

[0094] From Figure 13 Figure 13

[0095] Embodiment 3 Please refer to Figure 14 which shows a schematic structural diagram of an optical lens 300 provided in Embodiment 3 of the present invention. Compared with Embodiment 1, the main differences are as follows: The sixth lens L6 has a positive optical power; the image side surface S4 of the second lens L2 is concave; the object side surface S9 of the fifth lens L5 is convex near the optical axis; and the optical parameters such as the curvature radius and lens thickness of each lens surface are different.

[0096] The relevant parameters of each lens in the optical lens 300 in Embodiment 3 are shown in Table 3-1.

[0097] Table 3-1 The aspherical lens surface type parameters of the optical lens 300 in Embodiment 3 are shown in Table 3-2.

[0098] Table 3-2 The decentration and tilt parameters of each lens of the optical lens 300 in Embodiment 3 are shown in Table 3-3.

[0099] Table 3-3 As can be seen from Table 3-3, the optical axis of the first lens is decentered by 301 mm in the Y direction and tilted by -37° in the X direction relative to the center line of the object surface; the center line of the aperture is decentered by -0.04 mm in the Y direction and tilted by 14.62° in the X direction relative to the optical axis of the first lens; the center line of the aperture is collinear with the optical axes of the second lens and the third lens; the optical axis of the fourth lens is deflected by -0.21 mm in the Y direction and tilted by -3.92° in the X direction relative to the optical axis of the third lens; the optical axis of the fifth lens is deflected by 0.21 mm in the Y direction and tilted by 3.92° in the X direction relative to the optical axis of the fourth lens; the optical axis of the sixth lens is decentered by 0.28 mm in the Y direction and tilted by -24.43 ° in the X direction relative to the optical axis of the fifth lens; the center line of the filter is decentered by 0.32 mm in the X direction, decentered by 0.16 mm in the Y direction, and tilted by 27.44° in the X direction relative to the optical axis of the sixth lens; the center line of the imaging surface is decentered by 0.18 mm in the Y direction relative to the center line of the filter. It can be understood that the center line of the imaging surface is decentered by 0.32 mm in the X direction, decentered by 0.34 mm in the Y direction, and tilted by 27.44° in the X direction relative to the optical axis of the sixth lens.

[0100] In this embodiment, the X-direction F-Theta distortion curve graph, Y-direction F-Theta distortion curve graph, MTF curve graph, relative illumination curve graph, and grid distortion graph of the optical lens 300 are respectively as shown in Figure 15 , Figure 16 , Figure 17 , Figure 18 , Figure 19 .

[0101] It can be seen from Figure 15 that the X-direction F-Theta distortion of the optical lens is controlled within 0-12%, indicating that the optical lens 300 can correct distortion well.

[0102] It can be seen from Figure 16 that the Y-direction F-Theta distortion of the optical lens is controlled within -2% to 15%, indicating that the optical lens 300 can correct distortion well.

[0103] It can be seen from Figure 17 that the MTF value of this embodiment is above 0.2 within the entire field of view. In the range of 0-120 lp / mm, the MTF curve smoothly decreases uniformly from the center to the edge of the field of view, and has good imaging quality and good detail resolution ability in both low-frequency and high-frequency cases.

[0104] It can be seen from Figure 18 that the relative illumination value of the optical lens is still greater than 68% at the maximum semi-field angle, indicating that the optical lens 300 has good relative illumination.

[0105] It can be seen from Figure 19 that after the object plane is imaged on the image plane through this lens, the predicted value and the actual value of the checkerboard grid are relatively close at each position, indicating that the picture has no obvious deformation and can effectively eliminate trapezoidal distortion.

[0106] Please refer to Table 4 for the optical characteristics corresponding to the above embodiments, including the effective focal length f of the optical lens, the total optical length TTL, the aperture value Fno, the true image height IHy in the Y direction corresponding to the maximum field of view angle, the true image height IHx in the X direction corresponding to the maximum field of view angle, the maximum field of view angle FOV, the chief ray angle of incidence CRA at the maximum image height, and the values corresponding to each conditional expression in each embodiment.

[0107] Table 4 In summary of the above embodiments, the optical lens provided by the present invention has at least the following advantages: The optical lens provided by the present invention, through the reasonable combination of the optical powers and surface shapes of the lenses, is beneficial to the light trend and deflection angle of the light entering the lens, reduces the tolerance sensitivity of the lens, and improves the yield rate; it can effectively correct spherical aberration and trapezoidal distortion, improve the realism of the scene restored by the lens, and is beneficial to balancing the astigmatism of the optical system, thereby greatly improving the imaging quality.

[0108] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0109] The above-described embodiments merely represent several implementation manners of the present invention, and their descriptions are relatively specific and detailed, but should not be construed as limiting the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims

1. An optical lens, comprising six lenses, characterized in that: It sequentially includes, along the light transmission direction, from the object surface to the imaging surface: A first lens with a negative optical power, whose object side is concave near the optical axis and whose image side is convex near the optical axis; A second lens with a positive optical power, whose object side is convex; A third lens with a positive optical power, whose object side is convex and whose image side is convex; A fourth lens with a negative optical power, whose object side is concave and whose image side is concave; A fifth lens with a positive optical power, whose image side is convex; A sixth lens with an optical power, whose object side is concave and whose image side is concave near the optical axis; The object surface, the principal plane of the optical lens, and the imaging surface intersect at a line; Wherein, the total optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 1 < TTL / f < 1.

3.

2. The optical lens according to claim 1, characterized in that: The maximum field of view FOV of the optical lens and the f-number Fno of the optical lens satisfy: 11° < FOV / Fno < 13°; the true image height IHy in the Y direction corresponding to the maximum field of view of the optical lens and the true image height IHx in the X direction corresponding to the maximum field of view of the optical lens satisfy: 0.9 < IHy / IHx < 1.

1.

3. The optical lens according to claim 1, characterized in that: The back focal length BFL of the optical lens and the effective focal length f of the optical lens satisfy: 0.25 < BFL / f < 0.35; the back focal length BFL of the optical lens and the total optical length TTL of the optical lens satisfy: 0.23 < BFL / TTL < 0.

28.

4. The optical lens according to claim 1, characterized in that: The focal length f1 of the first lens and the effective focal length f of the optical lens satisfy: -4 < f1 / f < -3.2; the curvature radius R1 of the object side of the first lens and the effective focal length f of the optical lens satisfy: -1.6 < R1 / f < -1; the curvature radius R2 of the image side of the first lens and the effective focal length f of the optical lens satisfy: -4.2 < R2 / f < -1.

9.

5. The optical lens according to claim 1, characterized in that: The focal length f2 of the second lens and the effective focal length f of the optical lens satisfy: 0.9 < f2 / f < 1.6; the focal length f3 of the third lens and the effective focal length f of the optical lens satisfy: 0.75 < f3 / f < 0.

9.

6. The optical lens according to claim 1, characterized in that: The focal length f4 of the fourth lens and the effective focal length f of the optical lens satisfy: -1.85 < f4 / f < -1.35; the curvature radius R7 of the object side of the fourth lens and the effective focal length f of the optical lens satisfy: -7.2 < R7 / f < -6.9; the curvature radius R8 of the image side of the fourth lens and the effective focal length f of the optical lens satisfy: 0.95 < R8 / f < 1.

1.

7. The optical lens according to claim 1, characterized in that: The focal length f5 of the fifth lens and the effective focal length f of the optical lens satisfy: 1.9 < f5 / f < 105; the curvature radius R1 of the object side of the first lens, the curvature radius R2 of the image side of the first lens, and the central thickness CT1 of the first lens on the optical axis satisfy: 0.39 < (R1 - CT1) / R2 < 0.

57.

8. The optical lens according to claim 1, characterized in that: The focal length f6 of the sixth lens and the effective focal length f of the optical lens satisfy: -0.8 < f6 / f < 0.6; the object-side curvature radius R11 of the sixth lens and the effective focal length f of the optical lens satisfy: -0.45 < R11 / f < -0.34; the image-side curvature radius R12 of the sixth lens and the effective focal length f of the optical lens satisfy: 2.6 < R12 / f < 12.

6.

9. The optical lens according to claim 1, characterized in that: The focal length f1 of the first lens and the combined focal length f23456 of the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens satisfy: -6.5 < f1 / f23456 < -5.4; the focal length f1 of the first lens and the combined focal length f2345 of the second lens, the third lens, the fourth lens, and the fifth lens satisfy: -5.5 < f1 / f2345 < -4.

6.

10. The optical lens according to claim 1, characterized in that: The object-side curvature radius R1 of the first lens and the image-side curvature radius R2 of the first lens satisfy: -0.45 < (R1 - R2) / (R1 + R2) < -0.3; the object-side curvature radius R11 of the sixth lens and the image-side curvature radius R12 of the sixth lens satisfy: -0.95 < (R11 + R12) / (R11 - R12) < -0.

73.

11. The optical lens according to claim 1, characterized in that: The optical axis of the first lens is eccentric 301 mm in the Y direction and tilted -37° in the X direction relative to the center line of the object plane; the center line of the imaging plane is eccentric 0.04 mm to 0.32 mm in the X direction, eccentric 0.34 mm to 0.50 mm in the Y direction, and tilted 27.37° to 27.49° in the X direction relative to the optical axis of the sixth lens.

Images