Optical lens

Abstract

The present invention provides an optical lens having a total of six lenses, which, along the direction of light transmission from the object plane to the imaging plane, include: a first lens having negative optical power, whose object side surface is concave at the near optical axis and whose image side surface is convex at the near optical axis; a second lens having positive optical power, whose object side surface is convex; a third lens having positive optical power, whose object side surface is convex and whose image side surface is convex; a fourth lens having negative optical power, whose object side surface is concave and whose image side surface is concave; a fifth lens having positive optical power, whose image side surface is convex; a sixth lens having optical power, whose object side surface is concave and whose image side surface is concave at the near optical axis; the object plane, the principal plane of the optical lens, and the imaging plane intersect on a straight line. The optical lens provided by the present invention, through the reasonable combination of the optical power and surface shape of each lens, can effectively correct spherical aberration and keystone distortion, thereby greatly improving imaging quality.

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 rapid development of machine vision technology, the principle of triangulation has been widely applied in industrial inspection. Image sensors capture the laser line projected onto an object's surface, thereby reconstructing the object's surface contour. During image acquisition, a lens is required to capture tilted objects. However, due to the limited depth of field, traditional lenses struggle to clearly image the entire tilted surface, thus affecting the measurement accuracy of oblique imaging lenses used in industrial inspection. However, by utilizing Scham's law, the lens is gradually tilted so that the extended planes of the object plane, the image plane, and the lens plane intersect in a straight line, resulting in a clear image of the entire object surface.

[0003] Existing lenses suffer from issues such as large size, high distortion, and poor image quality, making them unable to meet imaging needs. Striking a balance between miniaturization and high image quality has become a pressing challenge. Summary of the Invention

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

[0005] The technical solution adopted in the present invention is:

[0006] An optical lens, comprising six lenses, including the following elements in order from the object plane to the imaging plane along the direction of light transmission:

[0007] The first lens has a negative optical power, the object side surface of which is concave at the near optical axis, and the image side surface of which is convex at the near optical axis;

[0008] a second lens having positive optical power and a convex object-side surface;

[0009] a third lens element having positive optical power, whose object-side surface is convex and whose image-side surface is convex;

[0010] a fourth lens element having negative optical power, whose object-side surface and image-side surface are concave;

[0011] a fifth lens element having positive refractive power and a convex image-side surface;

[0012] a sixth lens element having optical power, wherein the object side surface thereof is concave and the image side surface thereof is concave near the optical axis;

[0013] The object plane, the principal plane of the optical lens, and the imaging plane intersect on a line;

[0014] Among them, 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.

[0015] Further 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.

[0016] Further 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.

[0017] Further 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 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.

[0018] Further 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.

[0019] Further 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 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.

[0020] Further 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 surface of the first lens, the curvature radius R2 of the image side surface 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.

[0021] 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.

[0022] Further preferably, 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.

[0023] 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.

[0024] 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.

[0025] Compared with the prior art, the optical lens provided by the present invention, through the reasonable combination of the optical powers and surface shapes of each lens, is beneficial to controlling the light trend and deflection angle entering the lens, reducing the tolerance sensitivity of the lens, and improving the yield rate; it can effectively correct spherical aberration and trapezoidal distortion, improve the realism of the lens to restore the scene, and is beneficial to balancing the astigmatism of the optical system, and greatly improves the imaging quality. Description of the Drawings

[0026] 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:

[0027] Figure 1 is a schematic structural diagram of the optical lens in Embodiment 1 of the present invention.

[0028] Figure 2Schematic diagram of the structure of each lens, object plane and imaging plane of the optical lens in Example 1 of the present invention.

[0029] Figure 3 Graph showing the X-direction F-Theta distortion of the optical lens in Example 1 of the present invention.

[0030] Figure 4 Graph showing the Y-direction F-Theta distortion of the optical lens in Example 1 of the present invention.

[0031] Figure 5 This is the MTF curve of the optical lens in Example 1 of the present invention.

[0032] Figure 6 This is a relative illumination curve diagram of the optical lens in Example 1 of the present invention.

[0033] Figure 7 This is a grid distortion diagram of the optical lens in Example 1 of the present invention.

[0034] Figure 8 Schematic diagram of the structure of the optical lens in Example 2 of the present invention.

[0035] Figure 9 This is a graph showing the X-direction F-Theta distortion of the optical lens in Example 2 of the present invention.

[0036] Figure 10 This is a Y-direction F-Theta distortion curve of the optical lens in Example 2 of the present invention.

[0037] Figure 11 This is an MTF curve diagram of the optical lens in Example 2 of the present invention.

[0038] Figure 12 This is a relative illumination curve diagram of the optical lens in Example 2 of the present invention.

[0039] Figure 13 This is a grid distortion diagram of the optical lens in Example 2 of the present invention.

[0040] Figure 14 Schematic diagram of the structure of the optical lens in Example 3 of the present invention.

[0041] Figure 15 Graph showing the X-direction F-Theta distortion of the optical lens in Example 3 of the present invention.

[0042] Figure 16 2 is a Y-direction F-Theta distortion curve of the optical lens in Example 3 of the present invention.

[0043] Figure 17 This is the MTF curve of the optical lens in Example 3 of the present invention.

[0044] Figure 18 This is a relative illumination curve diagram of the optical lens in Example 3 of the present invention.

[0045] Figure 19 This is a grid distortion diagram of the optical lens in Example 3 of the present invention.

[0046] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0047] For a better understanding of the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely descriptions of embodiments of the present application and are not intended to 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.

[0048] It should be noted that in this specification, the terms "first," "second," "third," etc., are used solely to distinguish one feature from another and do not limit the features. Thus, the first lens discussed below could also be referred to as the second lens or the third lens without departing from the teachings of the present invention.

[0049] In the drawings, the thickness, size, and shape of the lenses are slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical and aspherical surfaces shown in the drawings are provided by way of example. That is, the shapes of the spherical and aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustration only and are not drawn strictly to scale.

[0050] In this article, the paraxial region refers to the area near the optical axis. If a lens surface is convex and the location of the convex surface is undefined, it means that the lens surface is convex at least in the paraxial region. If a lens surface is concave and the location of the concave surface is undefined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the subject is called the object-side surface of the lens, and the surface of each lens closest to the imaging plane is called the image-side surface of the lens.

[0051] It should also be understood that the terms "comprises," "including," "having," "includes," and / or "comprising," when used in this specification, indicate 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. In addition, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features rather than modifying the individual elements in the list. In addition, when describing embodiments of the present application, "may" is used to mean "one or more embodiments of the present application." And, the term "exemplary" is intended to refer to an example or illustration.

[0052] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by those skilled in the art to which this application belongs. It should also be understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology and will not be interpreted in an idealized or overly formal sense unless expressly defined as such herein.

[0053] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0054] The optical lens provided in the embodiments of the present invention is a Sham lens, also known as an oblique lens. Its principle is that the extended lines of the object plane, the principal lens plane, and the imaging plane intersect in a single line, enabling clear imaging across the entire inclined plane. Sham's law enables clear imaging across the entire inclined field of view. It is understood that among the lenses of the present invention, at least some of the lenses have angles between their optical axes and the object plane and the imaging plane, respectively. At least some of the lenses are tilted relative 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.

[0055] The optical lens of the present invention has a total of six lenses, which are the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens in order from the object plane to the imaging plane along the light transmission direction.

[0056] Among them, the first lens may have a negative optical 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 optical 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 optical power. Its object side is convex, and its image side is convex. The fourth lens may have a negative optical power. Its object side is concave, and its image side is concave. The fifth lens may have a positive optical power. Its object side may be concave or convex, and its image side is convex. The sixth lens may have an optical power. Its object side is concave, and its image side is concave near the optical axis. The object plane, the main plane of the optical lens, and the imaging plane intersect at a line.

[0057] In some embodiments, the optical lens may further include an aperture, and the aperture may be located between the first lens and the second lens. It can be understood that the aperture is used to limit the amount of incident light to change the brightness of the image.

[0058] 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 and prevent the interfering light from reaching the imaging plane of the optical lens and affecting normal imaging.

[0059] 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.

[0060] 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°.

[0061] 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.

[0062] 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 total optical length TTL of the optical lens satisfy: 0.23 < BFL / TTL < 0.28. Satisfying the above ranges and reasonably limiting 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.

[0063] 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 object-side curvature radius R1 of the first lens and the effective focal length f of the optical lens satisfy: -1.6 < R1 / f < -1; the image-side curvature radius R2 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 limiting the proportion of the optical power of the first lens and the shapes of the object side and the image side 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.

[0064] 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 limiting 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.

[0065] 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 object-side curvature radius R7 of the fourth lens and the effective focal length f of the optical lens satisfy: -7.2 < R7 / f < -6.9; the image-side curvature radius R8 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 limiting the proportion of the optical power of the fourth lens and the shapes of the object side and the image side can effectively reduce distortion. More specifically, -1.81 < f4 / f < -1.39; -7.2 < R7 / f < -6.91; 0.98 < R8 / f < 1.08.

[0066] 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 curvature radius R1 of the object side surface of the first lens, the curvature radius R2 of the image side surface 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 rays to have a stable trend, reduces the deflection angle of the marginal light rays, and improves the imaging quality; reasonably limiting the central thickness of the first lens and the shapes of the object side surface and the image side surface helps to further reduce the incident light ray inclination angle. More specifically, 1.93 < f5 / f < 104.4.

[0067] 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 curvature radius R11 of the object side surface of the sixth lens and the effective focal length f of the optical lens satisfy: -0.45 < R11 / f < -0.34; the curvature radius R12 of the image side surface 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 surface and the image side surface 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.

[0068] 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.

[0069] In some embodiments, the object-side curvature radius R1 of the first lens and the image-side curvature radius R2 of the first lens satisfy the following conditions: -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 the following conditions: -0.95 < (R11+R12) / (R11-R12) < -0.73. Meeting the above ranges and reasonably defining the shapes of the object-side and image-side surfaces of the first lens help reduce distortion produced by the first lens, reduce the difficulty of distortion correction for subsequent lenses, and improve the imaging quality of the lens. Reasonably defining the shapes of the object-side and image-side surfaces of the sixth lens help limit the degree of deflection of rear-end light while increasing image height.

[0070] In some embodiments, the optical axis of the first lens is 301 mm off-centered in the Y direction relative to the centerline of the object plane and tilted by -37° in the X direction; the centerline of the imaging plane is 0.04 mm to 0.32 mm off-centered in the X direction, 0.34 mm to 0.50 mm off-centered in the Y direction, and tilted by 27.37° to 27.49° in the X direction relative to the optical axis of the sixth lens.

[0071] In some embodiments, the centerline of the aperture is offset by -0.05 mm to -0.04 mm relative to the optical axis of the first lens in the Y direction and tilted by 14.45° to 21.04° in the X direction. Furthermore, the centerline of the aperture is collinear with the optical axes of the second and third lenses.

[0072] In some embodiments, the optical axis of the fourth lens is decentered by -0.21 mm to 0° in the Y direction relative to the optical axis of the third lens, and is tilted by -6.71° to 0° in the X direction; the optical axis of the fifth lens is decentered by 0 to 0.21 mm in the Y direction relative to the optical axis of the fourth lens, and is tilted by 0 to 6.71° in the X direction; and the optical axis of the sixth lens is decentered by 0.19 mm to 0.49 mm in the Y direction relative to the optical axis of the fifth lens, and is tilted by -27.36° to -22.12° in the X direction.

[0073] In some embodiments, the true image height IH corresponding to the maximum field of view of the optical lens, the effective focal length f of the optical lens, and the maximum field of view FOV of the optical lens satisfy the following conditions: 0.7 < (IH / 2) / (f × Tan (FOV / 2)) < 0.84. Meeting these limits ensures that distortion is within a reasonable range.

[0074] 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 production costs and assembly difficulties.

[0075] 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 f-number 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 angle of the optical lens, IHy represents the true image height in the Y direction corresponding to the maximum field angle of the optical lens, and IHx represents the true image height in the X direction corresponding to the maximum field angle of the optical lens. Meeting the above ranges, the optical lens has at least one or more advantages such as miniaturization, large field 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.

[0076] 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. On the other hand, when the lens material is glass, due to the low dispersion characteristic of the glass itself, the geometric chromatic aberration of the optical system can be effectively corrected. 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 miniaturization and high image quality of the lens.

[0077] In some embodiments, the first lens, second lens, third lens, fourth lens, fifth lens, and sixth lens may be spherical lenses or aspherical lenses. Compared to spherical structures, aspherical structures can effectively reduce the aberrations of the optical system, thereby reducing the number and size of lenses, and better achieving lens miniaturization. More specifically, the first lens, second lens, third lens, fourth lens, fifth lens, and sixth lens of the present invention may all be aspherical lenses, which can effectively reduce the aberrations of the optical lens, thereby reducing the number and size of lenses, and better achieving lens miniaturization.

[0078] In various embodiments of the present invention, when the lens is an aspheric lens, the shapes of the aspheric surfaces of the optical lens satisfy the following equations:

[0079] ;

[0080] Where z is the distance between the surface and the vertex in the direction of the optical axis, h is the distance from the optical axis to the surface, c is the curvature of the surface vertex, K is the quadratic surface coefficient, and B, C, D, E, F, G, and H are the fourth-order, sixth-order, eighth-order, tenth-order, twelfth-order, fourteenth-order, and sixteenth-order surface coefficients, respectively.

[0081] The present invention is further illustrated below with reference to several embodiments. In each embodiment, the thickness, radius of curvature, and material selection of each lens in the optical lens vary; for details, please refer to the parameter tables of each embodiment. The following embodiments are merely preferred embodiments of the present invention, but the present invention is not limited thereto. Any other changes, substitutions, combinations, or simplifications that do not deviate from the novelties of the present invention shall be considered equivalent replacements and are included within the scope of protection of the present invention.

[0082] Example 1

[0083] See also Figure 1 , shown is a schematic structural diagram of the optical lens 100 provided in Example 1 of the present invention, which includes, in order from the object side to the imaging surface along the light transmission direction: a first lens L1, an aperture 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.

[0084] The first lens L1 has negative refractive power, its object-side surface S1 is concave near the optical axis, and its image-side surface S2 is convex near the optical axis;

[0085] The second lens L2 has positive refractive power, its object-side surface S3 is convex, and its image-side surface S4 is flat near the optical axis;

[0086] The third lens L3 has positive refractive power, its object-side surface S5 is convex, and its image-side surface S6 is convex;

[0087] The fourth lens L4 has negative refractive power, its object-side surface S7 is concave, and its image-side surface S8 is concave;

[0088] The fifth lens L5 has positive refractive power, its object-side surface S9 is concave, and its image-side surface S10 is convex;

[0089] The sixth lens L6 has negative refractive power, its object-side surface S11 is concave, and its image-side surface S12 is concave near the optical axis;

[0090] The object-side surface S13 and the image-side surface S14 of the filter G1 are both flat surfaces;

[0091] The imaging surface S15 is a plane.

[0092] 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.

[0093] The optical lens of the present invention is a Sham lens, and the extension lines of the object plane, the lens principal plane, and the imaging plane are aligned to form a straight line. It is understood that there is an angle between the optical axis of each lens and the object plane and the imaging plane, and each lens is tilted relative 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. Figure 2 The figure shows the positional relationship between each lens, the object plane and the imaging plane in this embodiment 1.

[0094] The relevant parameters of each lens in the optical lens 100 in Example 1 are shown in Table 1-1.

[0095] Table 1-1

[0096]

[0097] The surface parameters of the aspheric lens of the optical lens 100 in Example 1 are shown in Table 1-2.

[0098] Table 1-2

[0099]

[0100] The eccentricity and tilt parameters of each lens of the optical lens 100 in Example 1 are shown in Table 1-3.

[0101] Table 1-3

[0102]

[0103] As can be seen from Tables 1-3, the optical axis of the first lens is 301 mm off-centered in the Y direction relative to the centerline of the object plane and tilted at -37° in the X direction; the centerline of the aperture is -0.05 mm off-centered in the Y direction relative to the optical axis of the first lens and tilted at 21.04° in the X direction; the centerline of the aperture is collinear with the optical axes of the second, third, fourth, and fifth lenses; the optical axis of the sixth lens is 0.49 mm off-centered in the Y direction relative to the optical axis of the fifth lens and tilted at -27.36° in the X direction; the centerline of the filter is 0.04 mm off-centered in the X direction, 0.28 mm off-centered in the Y direction, and tilted at 27.37° in the X direction relative to the optical axis of the sixth lens; and the centerline of the imaging plane is 0.21 mm off-centered in the Y direction relative to the centerline of the filter. It can be understood that the centerline of the imaging plane is 0.04 mm off-centered in the X direction, 0.49 mm off-centered in the Y direction, and tilted at 27.37° in the X direction relative to the optical axis of the sixth lens.

[0104] In this embodiment, the X-direction-F-Theta distortion curve, the Y-direction-F-Theta distortion curve, the MTF curve, the relative illumination curve, and the grid distortion curve of the optical lens 100 are shown as follows: Figure 3 、 Figure 4 、 Figure 5 、 Figure 6 、 Figure 7 shown.

[0105] Figure 3 The X-direction F-Theta distortion curve for Example 1 is shown. It represents the F-Theta distortion of light at different image heights on the X-direction imaging plane. The horizontal axis represents the distortion value (unit: %), and the vertical axis represents the half field of view (unit: °). As can be seen from the graph, the X-direction F-Theta distortion of the optical lens is controlled within 0-15%, indicating that the optical lens 100 is capable of effectively correcting distortion.

[0106] Figure 4 The Y-direction F-Theta distortion curve for Example 1 is shown, representing the F-Theta distortion of light at different image heights on the Y-direction imaging plane. The horizontal axis represents the distortion value (unit: %), and the vertical axis represents the half field of view (unit: °). As can be seen from the figure, the Y-direction F-Theta distortion of the optical lens is controlled within 0-16%, indicating that the optical lens 100 is capable of effectively correcting distortion.

[0107] Figure 5The MTF (Modulation Transfer Function) curve for Example 1 is shown. It represents the degree of lens imaging modulation at different spatial frequencies across the field of view. The horizontal axis represents spatial frequency (lp / mm), and the vertical axis represents the MTF value. As can be seen from the graph, the MTF value of this example is consistently above 0.28 across the entire field of view. Within the range of 0 to 120 lp / mm, the MTF curve decreases evenly and smoothly from the center to the edge of the field of view, demonstrating excellent imaging quality and detail resolution at both low and high frequencies.

[0108] Figure 6 A relative illumination curve for Example 1 is shown, showing relative illumination values at different field angles on the imaging plane. The horizontal axis represents the half field angle (unit: degrees), and the vertical axis represents relative illumination (unit: %). As can be seen from the graph, at the maximum half field angle, the relative illumination value of the optical lens is still greater than 65%, indicating that the optical lens 100 has good relative illumination.

[0109] Figure 7 The grid distortion diagram of Example 1 is shown, with the horizontal axis representing the image height in the X direction and the vertical axis representing the image height in the Y direction. After the object plane is imaged onto the image plane through the lens, the predicted value of the checkerboard grid is relatively close to the actual value at each position, indicating that there is no obvious deformation of the image and that keystone distortion can be effectively eliminated.

[0110] Example 2

[0111] See also Figure 8 , shown is a schematic structural diagram of the optical lens 200 provided in Example 2 of the present invention. Compared with Example 1, this embodiment has the following main differences: the sixth lens L6 has positive focal power; the image-side surface S4 of the second lens L2 is concave at the near optical axis; the object-side surface S9 of the fifth lens L5 is convex; and the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0112] The relevant parameters of each lens in the optical lens 200 in Example 2 are shown in Table 2-1.

[0113] Table 2-1

[0114]

[0115] The surface parameters of the aspheric lens of the optical lens 200 in Example 2 are shown in Table 2-2.

[0116] Table 2-2

[0117]

[0118] The eccentricity and tilt parameters of each lens of the optical lens 200 in Example 2 are shown in Table 2-3.

[0119] Table 2-3

[0120]

[0121] As can be seen from Table 2-3, the optical axis of the first lens is 301 mm off-centered in the Y direction relative to the centerline of the object plane and tilted at -37° in the X direction; the centerline of the aperture is -0.05 mm off-centered in the Y direction relative to the optical axis of the first lens and tilted at 14.45° in the X direction; the centerline of the aperture is collinear with the optical axes of the second and third lenses; the optical axis of the fourth lens is -0.2 mm off-centered in the Y direction relative to the optical axis of the third lens and tilted at -6.71° in the X direction; the optical axis of the fifth lens is 0.2 mm off-centered in the Y direction relative to the optical axis of the fourth lens and tilted at 6.71° in the X direction; the optical axis of the sixth lens is 0.19 mm off-centered in the Y direction relative to the optical axis of the fifth lens and tilted at -22.12° in the X direction; the centerline of the filter is 0.15 mm off-centered in the X direction relative to the optical axis of the sixth lens, 0.29 mm off-centered in the Y direction, and tilted at 27.49° in the X direction; and the centerline of the imaging plane is 0.21 mm off-centered in the Y direction relative to the centerline of the filter. It can be understood that the center line of the imaging plane is eccentric with respect to the optical axis of the sixth lens in the X direction by 0.15 mm, eccentric with respect to the Y direction by 0.5 mm, and tilted by 27.49° in the X direction.

[0122] In this embodiment, the X-direction-F-Theta distortion curve, the Y-direction-F-Theta distortion curve, the MTF curve, the relative illumination curve, and the grid distortion curve of the optical lens 200 are shown as follows: Figure 9 、 Figure 10 、 Figure 11 、 Figure 12 、 Figure 13 shown.

[0123] from Figure 9 It can be seen from the figure that the F-Theta distortion of the optical lens in the X direction is controlled within 0~16%, indicating that the optical lens 200 can correct the distortion well.

[0124] from Figure 10 It can be seen from the figure that the F-Theta distortion of the optical lens in the Y direction is controlled within 0~16%, indicating that the optical lens 200 can correct the distortion well.

[0125] from Figure 11 As can be seen, the MTF value of this embodiment is above 0.25 throughout the entire field of view. In the range of 0 to 120 lp / mm, the MTF curve decreases evenly and smoothly from the center to the edge of the field of view, achieving good imaging quality and detail resolution in both low-frequency and high-frequency conditions.

[0126] from Figure 12It 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.

[0127] from Figure 13 It can be seen that after the object surface is imaged on the image plane through the lens, the predicted value of the chessboard grid is close to the actual value at each position, indicating that there is no obvious deformation of the image and the keystone distortion can be effectively eliminated.

[0128] Example 3

[0129] See also Figure 14 , shown is a schematic structural diagram of the optical lens 300 provided in Example 3 of the present invention. Compared with Example 1, this embodiment has the following main differences: the sixth lens L6 has positive focal 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 at the near optical axis; and the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0130] The relevant parameters of each lens in the optical lens 300 in Example 3 are shown in Table 3-1.

[0131] Table 3-1

[0132]

[0133] The surface parameters of the aspheric lens of the optical lens 300 in Example 3 are shown in Table 3-2.

[0134] Table 3-2

[0135]

[0136] The eccentricity and tilt parameters of each lens of the optical lens 300 in Example 3 are shown in Table 3-3.

[0137] Table 3-3

[0138]

[0139] As can be seen from Table 3-3, the optical axis of the first lens is 301 mm off-centered in the Y direction relative to the centerline of the object plane and tilted at -37° in the X direction; the centerline of the aperture is -0.04 mm off-centered in the Y direction relative to the optical axis of the first lens and tilted at 14.62° in the X direction; the centerline of the aperture is collinear with the optical axes of the second and third lenses; the optical axis of the fourth lens is -0.21 mm off-centered in the Y direction relative to the optical axis of the third lens and tilted at -3.92° in the X direction; the optical axis of the fifth lens is 0.21 mm off-centered in the Y direction relative to the optical axis of the fourth lens and tilted at 3.92° in the X direction; the optical axis of the sixth lens is 0.28 mm off-centered in the Y direction relative to the optical axis of the fifth lens and tilted at -24.43° in the X direction; the centerline of the filter is 0.32 mm off-centered in the X direction relative to the optical axis of the sixth lens, 0.16 mm off-centered in the Y direction, and tilted at 27.44° in the X direction; and the centerline of the imaging plane is 0.18 mm off-centered in the Y direction relative to the centerline of the filter. It can be understood that the center line of the imaging plane is eccentric with respect to the optical axis of the sixth lens in the X direction by 0.32 mm, eccentric with respect to the Y direction by 0.34 mm, and tilted by 27.44° in the X direction.

[0140] In this embodiment, the X-direction-F-Theta distortion curve, the Y-direction-F-Theta distortion curve, the MTF curve, the relative illumination curve, and the grid distortion curve of the optical lens 300 are shown as follows: Figure 15 、 Figure 16 、 Figure 17 、 Figure 18 、 Figure 19 shown.

[0141] from Figure 15 It can be seen from the figure that the F-Theta distortion of the optical lens in the X direction is controlled within 0~12%, indicating that the optical lens 300 can correct the distortion well.

[0142] from Figure 16 It can be seen that the F-Theta distortion of the optical lens in the Y direction is controlled within -2%~15%, indicating that the optical lens 300 can correct the distortion well.

[0143] from Figure 17 As can be seen, the MTF value of this embodiment is above 0.2 throughout the entire field of view. In the range of 0 to 120 lp / mm, the MTF curve decreases evenly and smoothly from the center to the edge of the field of view, achieving good imaging quality and detail resolution in both low-frequency and high-frequency conditions.

[0144] from Figure 18 It can be seen from the figure that the relative illumination value of the optical lens is still greater than 68% at the maximum half field of view angle, indicating that the optical lens 300 has good relative illumination.

[0145] from Figure 19 It can be seen that after the object surface is imaged on the image plane through the lens, the predicted value of the chessboard grid is close to the actual value at each position, indicating that there is no obvious deformation of the image and the keystone distortion can be effectively eliminated.

[0146] Please refer to Table 4, which shows 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 incidence angle CRA at the maximum image height, and the numerical value corresponding to each conditional expression in each embodiment.

[0147] Table 4

[0148]

[0149] In summary of the above embodiments, the optical lens provided by the present invention has at least the following advantages:

[0150] The optical lens provided by the present invention, through the reasonable combination of the optical power and surface shape of each lens, is beneficial to the trend and deflection angle of light entering the lens, reducing the tolerance sensitivity of the lens and improving the yield rate; it can effectively correct spherical aberration and keystone distortion, improving the realism of the lens in restoring the scene, and is beneficial to balancing the astigmatism of the optical system, thereby greatly improving the imaging quality.

[0151] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0152] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by 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 plane to the imaging plane: A first lens with a negative focal 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 focal power, whose object side is convex; A third lens with a positive focal power, whose object side is convex and whose image side is convex; A fourth lens with a negative focal power, whose object side is concave and whose image side is concave; A fifth lens with a positive focal power, whose image side is convex; A sixth lens with a focal power, whose object side is concave and whose 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; 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; the maximum field angle 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 angle of the optical lens and the true image height IHx in the X direction corresponding to the maximum field angle of the optical lens satisfy: 0.9 < IHy / IHx < 1.

1.

2. The optical lens according to claim 1, wherein: The true image height IH corresponding to the maximum field angle of the optical lens, the effective focal length f of the optical lens, and the maximum field angle FOV of the optical lens satisfy: 0.7 < (IH / 2) / (f×Tan(FOV / 2)) < 0.

84.

3. The optical lens according to claim 1, wherein: 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, wherein: 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 object side curvature radius R1 of the first lens and the effective focal length f of the optical lens satisfy: -1.6 < R1 / f < -1; the image side curvature radius R2 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, wherein: 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, wherein: 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 object side curvature radius R7 of the fourth lens and the effective focal length f of the optical lens satisfy: -7.2 < R7 / f < -6.9; the image side curvature radius R8 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, wherein: 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, wherein: 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 curvature radius R11 of the object side of the sixth lens and the effective focal length f of the optical lens satisfy: -0.45 < R11 / f < -0.34; the curvature radius R12 of the image side 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, wherein: 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.

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

73.

11. The optical lens according to claim 1, wherein: 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