An optical lens, a camera module and a scanner

Abstract

This application relates to the field of camera technology, providing an optical lens, a camera module, and a scanner. The optical lens includes eight lenses arranged from the object side to the image side, including a first lens group and a second lens group. An aperture stop is provided between the first lens group and the second lens group. The first lens group has positive optical power, and the second lens group has positive optical power. The total image height H of the optical lens is equal to the maximum aperture CA of the optical lens. max Satisfying the relation: 1.5 ≤ CA max / H≤2.2. This optical lens achieves a balance between a large target area, high resolution, and miniaturization.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of camera, and particularly to an optical lens, a camera module and a scanner. BACKGROUND

[0002] Machine vision detection technology is widely applied to various fields of production and manufacturing industry. With the popularization of 3D imaging technology, an optical lens is usually arranged in a 3D scanner to realize 3D detection of a product. Especially for a handheld 3D scanner, not only higher measurement accuracy is required, but also the device needs to be miniaturized so as to be flexible and efficient in accurately mapping the measured object.

[0003] The optical lens with a fixed focal length in the related art, such as an optical lens with a focal length of 6 mm, has the problems of a small target surface, insufficient resolution and difficulty in miniaturization. SUMMARY

[0004] Embodiments of the present application provide an optical lens, a camera module and a scanner which can achieve the purposes of large target surface, high resolution and miniaturization.

[0005] To achieve the above-mentioned purposes, embodiments of the present application adopt the following technical solutions:

[0006] In a first aspect, an optical lens is provided, which includes eight lenses arranged from an object side to an image side in a first lens group and a second lens group, and an aperture stop is arranged between the first lens group and the second lens group; the first lens group has positive refractive power, and the second lens group has positive refractive power; a full image height H of the optical lens and a maximum clear aperture CA of the optical lens satisfy the relationship: 1.5≤CA max / H≤2.2. max

[0007] By reasonably allocating the refractive power and the number of lenses of the first lens group and the second lens group, the focal length of the optical lens is reduced on the basis of meeting the requirements, which is conducive to reducing the aberration of the optical lens; the first lens group and the second lens group located on both sides of the aperture stop both have refractive power, and by reasonably selecting the full image height H and the maximum clear aperture CA max of the optical lens, the change angle of light rays before and after the aperture stop is reduced, which not only improves the resolution of the optical lens and realizes the requirement of large target surface, but also reduces the aperture of the optical lens, thereby being conducive to miniaturization design, so that the optical lens achieves the purposes of large target surface, high resolution and miniaturization.

[0008] In some embodiments, the total optical length TTL of the optical lens satisfies the relationship: 46mm≤TTL≤55mm.

[0009] ​In some embodiments, the optical lens satisfies a relationship: |DIS near - DIS near |≤0.02% at the closest working distance WD far - DIS far |≤0.02% at the farthest working distance WD near - DIS far |≤0.02% at the closest working distance WD

[0010] In some embodiments, the first lens group comprises at least two lenses with negative refractive power and two lenses with positive refractive power; and in the first lens group, the refractive index nd and the Abbe number vd of the lens with negative refractive power satisfy nd≥1.75 and vd≤48.0.

[0011] In some embodiments, in the first lens group, the lens located at the first position is a first lens, and the lens located at the second position is a second lens, from the object side to the image side; the first lens has negative refractive power, and the second lens has negative refractive power; and the first lens is a meniscus structure.

[0012] In some embodiments, the focal length f1 of the first lens satisfies a relationship: f1≤-20.

[0013] In some embodiments, the focal length f2 of the second lens satisfies a relationship: f2≤-13.

[0014] In some embodiments, the second lens group comprises at least two lenses with positive refractive power and one lens with negative refractive power; and in the second lens group, the lens located at the last position is a biconvex structure and has positive refractive power, from the object side to the image side.

[0015] In some embodiments, the second lens group comprises a cemented lens, which is composed of two lenses.

[0016] In a second aspect, the embodiments of the present application provide a camera module, comprising a photosensitive element and the optical lens in the first aspect, and the photosensitive element is arranged on the image side of the optical lens.

[0017] The camera module in the embodiments of the present application has the same structure and technical effects as the optical lens in the first aspect, and will not be described here.

[0018] In a third aspect, the embodiments of the present application provide a scanner, comprising the camera module in the second aspect.

[0019] The camera module in the embodiments of the present application has the same structure and technical effects as the optical lens in the second aspect, and thus will not be described again. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 A structural schematic diagram of the optical lens provided for Embodiment One of the present application;

[0021] Figure 2 An MTFvs field diagram of the optical lens provided for Embodiment One of the present application;

[0022] Figure 3 An MTF diagram of the optical lens provided for Embodiment One of the present application;

[0023] Figure 4 A sagittal chromatic aberration diagram of the optical lens provided for Embodiment One of the present application;

[0024] Figure 5 A relative luminance diagram of the optical lens provided for Embodiment One of the present application;

[0025] Figure 6 A structural schematic diagram of the optical lens provided for Embodiment Two of the present application;

[0026] Figure 7 An MTFvs field diagram of the optical lens provided for Embodiment Two of the present application;

[0027] Figure 8 An MTF diagram of the optical lens provided for Embodiment Two of the present application;

[0028] Figure 9 A sagittal chromatic aberration diagram of the optical lens provided for Embodiment Two of the present application;

[0029] Figure 10 A relative luminance diagram of the optical lens provided for Embodiment Two of the present application;

[0030] Figure 11 A structural schematic diagram of the optical lens provided for Embodiment Three of the present application;

[0031] Figure 12 An MTFvs field diagram of the optical lens provided for Embodiment Three of the present application;

[0032] Figure 13 An MTF diagram of the optical lens provided for Embodiment Three of the present application;

[0033] Figure 14 A sagittal chromatic aberration diagram of the optical lens provided for Embodiment Three of the present application;

[0034] Figure 15 A relative luminance diagram of the optical lens provided for Embodiment Three of the present application.

[0035] In the drawings, reference numerals:

[0036] First lens group G1; second lens group G2; first lens L1; second lens L2; third lens L3; fourth lens L4; fifth lens L5; sixth lens L6; seventh lens L7; eighth lens L8; stop STOP; protective lens CG. DETAILED DESCRIPTION

[0037] For the convenience of understanding, the English abbreviations and related technical terms involved in the embodiments of the present application are explained and described below.

[0038] Focal power, equal to the difference between the convergence degree of the image side beam and the convergence degree of the object side beam, which represents the ability of the optical lens to deflect light.

[0039] Lens or lens group with positive focal power, the lens or lens group has a positive focal length, which has the effect of converging light.

[0040] Lens or lens group with negative focal power, the lens or lens group has a negative focal length, which has the effect of diverging light.

[0041] Focal length, also known as focal length, is a measure of the convergence or divergence of light in an optical lens, which refers to the vertical distance from the optical center of the lens or lens group to the focal plane when an infinite distant object forms a clear image through the lens or lens group. For a fixed focus lens, the position of the optical center is fixed; for a long focus lens, the change of the optical center of the lens leads to the change of the focal length of the lens.

[0042] Effective focal length (EFL) of the lens, which refers to the distance from the center of the lens to the focal point.

[0043] Synthetic focal length is the combination of the focal lengths of each lens in the lens group.

[0044] Object side, with the lens as the boundary, the side where the object is located is the object side, and the surface of the lens close to the object side is called the object side.

[0045] Image side, with the lens as the boundary, the side where the image of the object is located is the image side, and the surface of the lens close to the image side is called the image side.

[0046] Aperture diaphragm, which is a device used to control the amount of light that enters the body through the lens and reaches the light-sensitive surface, which is usually in the lens.

[0047] The imaging plane is located on the image side of all lenses in an optical lens, and is the surface on which light rays pass through each lens in the optical lens in sequence to form an image.

[0048] The optical axis is a vertical axis that passes through the center of a lens. The lens optical axis is the axis that passes through the centers of each lens in the lens.

[0049] The focal point is the point where parallel light rays converge after being refracted by a lens or lens group.

[0050] The Abbe number, also known as the dispersion coefficient, is the ratio of the difference in refractive index of an optical material at different wavelengths, representing the degree of dispersion of the material.

[0051] Aberrations: Optical lenses have the properties of an ideal optical system at the optical axis, where near-axis rays emitted from a point on an object intersect the image plane at a point (i.e., the optical axis image point). However, in reality, rays passing through different apertures of the lens rarely intersect perfectly at a single point, but rather deviate from the position of the near-axis image point. These differences are collectively referred to as aberrations.

[0052] Distortion, also known as image distortion, refers to the degree of distortion in the image formed by an optical lens relative to the object itself. Distortion is caused by the spherical aberration of the aperture. The height of the intersection point between the principal ray and the Gaussian image plane after passing through the optical lens in different fields of view is not equal to the ideal image height; the difference between the two is the distortion.

[0053] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0054] In the embodiments of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "multiple" means two or more.

[0055] like Figure 1 As shown, in some embodiments, the camera module includes an optical lens and a photosensitive element (…). Figure 1 (IMA), the image sensor is located on the image side of the optical lens.

[0056] The working principle of a camera module is as follows: the light reflected from the subject passes through the optical lens to generate an optical image, which is then projected onto the photosensitive surface of the photosensitive element. The photosensitive element converts the optical image into an electrical signal, i.e., an analog image signal, and transmits it to the processor.

[0057] A photosensitive element (also known as an image sensor) is a semiconductor chip containing hundreds of thousands to millions of photodiodes on its surface. When illuminated by light, these photodiodes generate electrical charges. Photosensitive elements can be charge-coupled devices (CCDs) or complementary metal-oxide-semiconductor (CMOS) devices. CCDs are made of a highly sensitive semiconductor material that converts light into electrical charges. A charge-coupled device consists of many photosensitive units, typically measured in megapixels. When light illuminates the surface of the photosensitive element, each photosensitive unit reflects a charge onto the component. The signals generated by all the photosensitive units are added together to form a complete image.

[0058] The aforementioned photosensitive element is also equipped with a protective lens CG, which can protect the photosensitive element.

[0059] Optical lenses primarily utilize the refraction principle of lenses to create images. Light from a scene passes through the optical lens, forming a clear image on the focal plane, which is then recorded by a photosensitive element located on the focal plane. These optical lenses can be, but are not limited to, industrial lenses.

[0060] like Figure 1 As shown, this application provides an optical lens comprising eight lenses arranged from the object side to the image side, including a first lens group G1 and a second lens group G2. An aperture stop is provided between the first lens group G1 and the second lens group G2. The first lens group G1 has positive optical power, and the second lens group G2 also has positive optical power. The total image height H of the optical lens is equal to the maximum aperture CA of the optical lens. max Satisfying the relation: 1.5 ≤ CA max / H≤2.2.

[0061] In the design of optical lenses, the number of lenses is eight, which is determined based on a focal length of 6mm. When the focal length of the optical lens changes, the number of lenses in the optical lens can also change according to the optical performance. The aforementioned optical lenses can be, but are not limited to, fixed-focus lenses with a focal length of 6mm.

[0062] Maximum aperture CA of optical lens max This is the maximum value of the aperture (CA) of the optical lens.

[0063] By rationally allocating the optical power and the number of lenses in the first lens group G1 and the second lens group G2, the focal length of the optical lens is made to meet the requirements while reducing the aberrations of the optical lens, thereby improving resolution and image quality. The first lens group G1 and the second lens group G2, located on both sides of the aperture stop, both have optical power, which reduces the change angle of light rays before and after the aperture stop. This not only helps to reduce tolerance sensitivity, thereby improving the imaging quality and large target area of ​​the optical lens, but also helps to reduce the aperture of the optical lens.

[0064] At the same time, if the maximum aperture of the optical lens CA max When the ratio of the optical lens's maximum aperture CA to the holographic height H is too large, it will reduce the maximum aperture CA of the optical lens. max An excessively large aperture is detrimental to miniaturizing the optical lens; if the maximum aperture CA of the optical lens is too large... max If the ratio of the optical lens's holographic height H to its maximum aperture CA is too small, the maximum aperture CA of the optical lens will be reduced. max However, this would result in an excessively large holographic height (H), leading to an excessively large overall aperture for the camera module, which is not conducive to miniaturization design.

[0065] By appropriately selecting the holographic height H and the maximum aperture CA of the optical lens max This not only improves the resolution of the optical lens and meets the requirements for a large target surface, but also reduces the aperture of the optical lens, which is conducive to miniaturization design, enabling the optical lens to achieve the goal of balancing a large target surface, high resolution and miniaturization.

[0066] In the design of optical lenses, in addition to controlling the aperture, it is also necessary to control the total optical length. By rationally designing the total optical length (TTL), when the focal length of the optical lens is 6mm, and the TTL satisfies the relationship 46mm≤TTL≤55mm, the total optical length can meet the requirements for miniaturization, for example, it can be applied in 3D mapping instruments.

[0067] In addition, during the optical performance design process of optical lenses, distortion consistency across different object distances is also an important indicator for improving image quality. When the optical lens is at its closest working distance (WD)... near The corresponding optical distortion DIS near With the furthest working distance WD far The corresponding optical distortion DIS far When the absolute value of the difference is too large, the distortion consistency of the optical lens is poor, which is not conducive to improving the resolution and imaging quality of the optical lens.

[0068] Keep the optical lens at its closest working distance WDnear The corresponding optical distortion DIS near With the furthest working distance WD far The corresponding optical distortion DIS far The absolute values ​​of the difference satisfy the following relationship: |DIS near - DIS far When |≤ 0.02%, the optical lens can not only meet the optical detection accuracy requirements when applied to a 3D scanner, but also, when the 3D scanner is being debugged, distortion only needs to be corrected at the optimal working distance. No further correction is required in subsequent use, resulting in high measurement accuracy.

[0069] In some embodiments, the first lens group G1 includes at least two lenses with negative optical power and two lenses with positive optical power; in the first lens group G1, the refractive index nd and Abbe number vd of the lenses with negative optical power satisfy nd≥1.75 and vd≤48.0. This design allows as much light as possible to enter the optical lens, thereby improving the resolution of the optical lens.

[0070] For example, such as Figure 1 As shown, the first lens group G1 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5 arranged from the object side to the image side. The first lens L1 has negative optical power and is a meniscus structure. The second lens L2 also has negative optical power. The first lens L1 and the second lens L2 are made of heavy flint (H-ZF) or heavy lanthanum flint (H-ZLaF) materials, such that the refractive index nd and the Abbe number vd of the first lens L1 and the second lens L2 satisfy nd≥1.75 and vd≤48.0.

[0071] In optical lens design, even without the presence of oblique beam vignetting, the relative illumination of the image plane will decrease according to the law of cos^4(ω') as the image half-field angle ω' increases. When oblique beam vignetting exists, if the ratio of the cross-sectional area of ​​the off-axis oblique beam to the cross-sectional area of ​​the on-axis point beam is Ka, then E' = KaE0'cos^4(ω').

[0072] Where E' represents the illuminance at an off-axis point, and E0' represents the illuminance at an on-axis image point. It can be concluded that the most direct way to increase relative illuminance is to increase Ka and decrease ω'.

[0073] Through the above design, especially the first lens group G1 which has negative optical power and a meniscus structure, the first lens group G1 can not only generate a large amount of aperture coma to improve the illuminance of off-axis image points, but also generate sufficient negative distortion (barrel distortion) to significantly reduce the image half-field angle ω' corresponding to the object half-field angle ω, thereby improving the uniformity of the image plane illuminance distribution.

[0074] Meanwhile, in the design process of the first lens group G1, the focal length f1 of the first lens L1 and the focal length f2 of the second lens L2 are also two important factors. On the basis of the first lens group G1 of the optical lens like the above structure, when the focal length f1 of the first lens satisfies the relationship: f1≤-20; and the focal length f2 of the second lens satisfies the relationship: f2≤-13, the relative luminance of the image plane of the optical lens is greatly improved, so that the target image can be clearly acquired and is not disturbed by the image background or the noise of the detector, thereby avoiding misjudgment.

[0075] Figure 1 A structure diagram of the optical lens of embodiment one is shown. The optical lens comprises a first lens group G1, a stop and a second lens group G2 arranged from the object side to the image side, the first lens group G1 has positive refractive power, and the second lens group G2 has positive refractive power; the first lens group G1 comprises a first lens L1, a second lens L2, a third lens L3, a fourth lens L4 and a fifth lens L5 arranged from the object side to the image side; the second lens group G2 comprises a sixth lens L6, a seventh lens L7 and an eighth lens L8 arranged from the object side to the image side, and the sixth lens L6 and the seventh lens L7 are cemented together to form a cemented lens.

[0076] Tables 1a to 1d respectively give the specific parameter values of each lens of the optical lens of an optional embodiment in the present application.

[0077]

[0078] It should be noted that in Table 1a, the "surface serial number" is the serial number of each surface arranged from the object side to the image side, the radius R value is the curvature radius of the object side surface or the image side surface of the lens corresponding to the surface number, that is, the curvature radius of the object side surface or the image side surface of the lens corresponding to each surface serial number at the optical axis, and "infinite" in the "curvature radius" parameter series of each lens means that the object side surface or the image side surface of the lens is a plane; the first value in the "thickness / interval" parameter series of each lens is the thickness of the lens on the optical axis, and the second value is the distance from the image side surface of the lens to the object side surface of the next lens on the optical axis; the value in the "thickness" parameter series of the stop STOP is the distance from the center of the stop STOP to the object side surface of the next lens on the optical axis.

[0079] The optical indicators of the optical lens in the present embodiment are as follows:

[0080] Total optical length: TTL = 53.8mm;

[0081] Optimal working distance: WD0 = 270mm;

[0082] F-number: Fno. = 5.6;

[0083] Focal length: f = 6mm;

[0084] Target surface: 1 / 1.8 inch;

[0085] Working waveband: visible light;

[0086] Relative illumination: RI≥82%;

[0087] Optical distortion: |DIS|<4.0%;

[0088] Optical distortion difference: in the working distance range of 150mm~450mm, |DIS near - DIS far |≤0.014%; in the working distance range of 200mm~400mm, |DISnear - DISfar |≤0.008%

[0089] The parameters of the optical lens in Example One satisfy the relationships shown in Table 1b.

[0090]

[0091] Note: The note of the relationships of the optical lens in each of the following examples is as follows:

[0092] f1 is the focal length of the first lens L1;

[0093] f2 is the focal length of the second lens L2;

[0094] H is the total image height of the optical lens;

[0095] TTL is the total optical length of the optical lens;

[0096] CA max is the maximum value of the Circula Aperture (CA) of the optical lens;

[0097] | DIS near - DIS far | is the absolute value of the difference between the optical distortion DIS near corresponding to the nearest working distance WD near of the optical lens and the optical distortion DIS far corresponding to the farthest working distance WD far of the optical lens.

[0098] The positive and negative cases of the optical power of each lens in the optical lens in Example One are shown in Table 1c.

[0099]

[0100] It should be noted that "+" and "-" in Table 1c represent the positive and negative cases of the optical power of each lens in the optical lens in Embodiment One. Among them, "+" represents that the lens has positive optical power; "-" represents that the lens has negative optical power.

[0101] The concave-convex cases of the object side or image side of each lens in the optical lens in Embodiment One at the optical axis are shown in Table 1d.

[0102]

[0103] It should be noted that "++", "+-", "-+", "∞+", "+∞", "--" in Table 1d represent the concave-convex cases of the object side or image side of each lens at the optical axis. Among them, "++" represents that the object side and the image side of the lens are both convex to the object side at the optical axis, also known as a meniscus structure; "+-" represents that the object side of the lens is convex to the object side at the optical axis, and the image side is convex to the object side at the optical axis, that is, a biconvex structure; "-+" represents that the object side of the lens is concave to the object side at the optical axis, and the image side is convex to the object side at the optical axis, that is, a biconcave structure; "∞+" represents that the object side of the lens is a plane at the optical axis, and the image side is convex to the object side; "+∞" represents that the object side of the lens is convex to the object side at the optical axis, and the image side is a plane; "--" represents that the object side and the image side of the lens are both concave to the object side at the optical axis. Of course, in addition to the above-mentioned concave-convex cases, each lens in the optical lens can also include any one or more of "∞-", "-∞", wherein "∞-" represents that the object side of the lens is a plane at the optical axis, and the image side is concave to the object side; "-∞" represents that the object side of the lens is concave to the object side at the optical axis, and the image side is a plane, which is not limited here.

[0104] In combination Figure 1 The structure diagram of the optical lens in Embodiment One, and the main parameters of the optical lens in Embodiment One given in Table 1a to Table 1d satisfy the relationship of Table 1b, and the concave-convex case at the optical axis in each lens. The simulation of the optical lens in Embodiment One is obtained by simulation Figures 2-5 .

[0105] Among them: Figure 2 The MTF vs field diagram of the optical lens provided in Embodiment One of the present application is also called MTH diagram. Figure 3The MTF curves corresponding to the meridional plane and sagittal plane of the optical lens provided in Embodiment One of the present application at six different positions at a frequency of 0-200 lp / mm are given, and the MTF curves under the condition of diffraction limit are given in a comparison chart. MTF is the abbreviation of Modulation Transfer Function, which is a function of modulation degree changing with spatial frequency and is called modulation degree transfer function. The MTH chart and the MTF chart are both chart reflecting the restoration of contrast (reduction) of the optical lens. The abscissa of the MTF chart is the distance from the center to the edge, and the ordinate of the MTF chart reflects the pros and cons of contrast, or the pros and cons of reduction. Only, the abscissa of the MTH chart is the normalized field angle, and the ordinate of the MTH chart is the same as that of the MTF chart. The higher the ordinate value of the MTH chart and the MTF chart, the better the reduction and the higher the resolution of the optical lens. From Figure 2 and Figure 3 It can be seen that the MTF value is greater than 0.1, and the light tends to the diffraction limit.

[0106] Figure 4 The optical lens provided in Embodiment One of the present application is given. From Figure 5 It can be seen that the aberration of the optical lens is small.

[0107] Figure 5 The relative illumination chart of the optical lens provided in Embodiment One of the present application is given. From Figure 5 It can be seen that the relative illumination of the optical lens is greater than 82%, which means that the brightness uniformity of the whole picture is high, there is no dark corner, and it meets the use requirement.

[0108] The above description of the MTF vs field chart, the axial chromatic aberration chart and the relative illumination chart is the same as that of other embodiments, and will not be repeated hereinafter.

[0109] Figure 6 The structure chart of the optical lens of Embodiment Two is shown. The main difference between the optical lens in Embodiment Two and the optical lens in the above-mentioned first embodiment is that the parameters of each lens and the conditions met are different, and the concave-convex situation of the object side or the image side of each lens at the optical axis.

[0110] Tables 2a to 2d respectively give the specific parameter values of each lens of the optical lens of an optional embodiment in Embodiment Two of the present application.

[0111]

[0112] The optical indexes of the optical lens in the present embodiment are as follows:

[0113] The total optical length: TTL = 53.8mm;

[0114] Optimal working distance: WD0 = 270mm;

[0115] F-number: Fno. = 5.6;

[0116] Focal length: f = 6mm;

[0117] Target surface: 1 / 1.8 inch;

[0118] Working waveband: 430nm~470nm;

[0119] Relative illumination: RI≥82%;

[0120] Optical distortion: |DIS|<4.2%;

[0121] Optical distortion difference value: in the range of working distance 150mm~450mm, |DIS near |≤0.018%; in the range of working distance 200mm~400mm, |DIS far |≤0.011%. near far

[0122] The parameters of the optical lens in Example Two satisfy the relationships shown in Table 2b.

[0123]

[0124] The refractive power of each lens in the optical lens in Example Two is shown in Table 2c.

[0125]

[0126] The concave-convex condition of the object side or image side surface of each lens in the optical lens in Example Two at the optical axis is shown in Table 2d.

[0127]

[0128] In combination Figure 6 The structure diagram of the optical lens in Example Two, and the main parameters of the optical lens in Example Two given in Table 2a to Table 2d satisfy the relationships in Table 2b, and the concave-convex condition of each lens at the optical axis. The simulation of the optical lens in Example Two is as follows Figures 7-10 .

[0129] From Figure 7 and Figure 8 It can be seen that the MTF value is greater than 0.1, and the light tends to be diffraction limited.

[0130] From Figure 9 It can be seen that the aberration of the optical lens is small. ​​

[0131] From Figure 10 It can be seen that the relative illumination of the optical lens is greater than 82%, indicating that the brightness uniformity of the whole picture is high, there is no dark corner, and the use requirement is met.

[0132] Figure 11 A structural diagram of the optical lens of embodiment three is shown. The main difference between the optical lens in embodiment three and the optical lens of the above-mentioned first embodiment is that the number of lenses in the first lens group G1 and the second lens group G2, the parameters of each lens and the conditions met, and the concave-convex condition of the object side or the image side of each lens at the optical axis are different.

[0133] As Figure 11 shown, the optical lens comprises a first lens group G1, a diaphragm and a second lens group G2 arranged from the object side to the image side, the first lens group G1 has positive focal power, and the second lens group G2 has positive focal power; the first lens group G1 comprises a first lens L1, a second lens L2, a third lens L3 and a fourth lens L4 arranged from the object side to the image side; the second lens group G2 comprises a fifth lens L5, a sixth lens L6, a seventh lens L7 and an eighth lens L8 arranged from the object side to the image side, and the sixth lens L6 and the seventh lens L7 are cemented together to form a lens.

[0134] Tables 3a to 3d respectively give the specific parameter values of each lens of the optical lens of one optional embodiment in embodiment three of the present application.

[0135]

[0136] The optical indexes of the optical lens in the present embodiment are as follows:

[0137] TTL = 53mm; optimal working distance: WD0 = 270mm;

[0138] F-number: Fno. = 5.6;

[0139] focal length: f = 6mm;

[0140] target surface: 1 / 1.8 inch;

[0141] working waveband: visible light;

[0142] relative illumination: RI ≥ 85%;

[0143] optical distortion: |DIS| < 4.2%;

[0144] absolute value of optical distortion difference: within the working distance range of 150mm-450mm, |DIS near - DIS far|≤0.018%; in the working distance range of 200mm~400mm, | DIS near - DIS far |≤0.011%.

[0145] The parameters of the optical lens in Embodiment Three satisfy the relationships shown in Table 3b.

[0146]

[0147] The positive and negative cases of the refractive power of each lens in the optical lens in Embodiment Three are shown in Table 3c.

[0148] Table 3c

[0149]

[0150] The concave-convex cases of the object side or image side at the optical axis in each lens in the optical lens in Embodiment Three are shown in Table 3d.

[0151]

[0152] In combination Figure 11 The structure diagram of the optical lens in Embodiment Three, and the main parameters of the optical lens in Embodiment Two given in Table 3a to Table 3d satisfy the relationships in Table 3b, and the concave-convex cases at the optical axis in each lens. The simulation of the optical lens in Embodiment Three is obtained by simulation simulation as Figures 12-15 .

[0153] From Figure 12 and Figure 13 It can be seen that the MTF value is greater than 0.1, and the light tends to the diffraction limit.

[0154] From Figure 14 It can be seen that the aberration of the optical lens is small.

[0155] From Figure 15 It can be seen that the relative luminance of the optical lens is greater than 85%, which means that the brightness uniformity of the whole picture is high, there is no dark corner, and the use requirement is met.

[0156] In summary, the optical lens with a focal length of 6mm in the application has an optical total length of about 53mm, realizing the miniaturization design of the optical lens; greatly improving the relative luminance RI of the image plane, which can reach RI≥80% when the 1 / 1.8inch is used, and the resolution is better than 6 million; the distortion consistency is good in the range of 150mm~450mm, which can meet the requirements of 3D scanning.

[0157] The application also provides a scanner comprising the camera module.

[0158] The scanner can be, but is not limited to, a 3D scanner.

[0159] The structure of the camera module is the same as that in any of the above embodiments and has the same effects, and is not specifically limited here.

[0160] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An optical lens characterized in that, The optical lens comprises eight lenses arranged from the object side to the image side, and a diaphragm is arranged between the first lens group and the second lens group; the first lens group has positive refractive power, and the second lens group has positive refractive power; The first lens group comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens arranged from the object side to the image side, and the second lens group comprises a sixth lens, a seventh lens and an eighth lens arranged from the object side to the image side; or the first lens group comprises a first lens, a second lens, a third lens and a fourth lens arranged from the object side to the image side, and the second lens group comprises a fifth lens, a sixth lens, a seventh lens and an eighth lens arranged from the object side to the image side; The first lens, the second lens and the sixth lens all have negative refractive power, and the fourth lens, the fifth lens, the seventh lens and the eighth lens all have positive refractive power. The total height H of the optical lens satisfies the relationship: 1.5 ≤ H / CA ≤ 2.

2. max The total height H of the optical lens satisfies the relationship: 1.5 ≤ H / CA ≤ 2.

2. max The total height H of the optical lens satisfies the relationship: 1.5 ≤ H / CA ≤ 2.

2. The optical lens is at its closest working distance WD near The corresponding optical distortion DIS near With the furthest working distance WD far The corresponding optical distortion DIS far The absolute values ​​of the difference satisfy the following relationship: |DIS near - DIS far |≤ 0.02%.

2. The optical lens according to claim 1, wherein an optical total length TTL of the optical lens satisfies a relationship: 46mm ≤ TTL ≤ 55mm.

3. The optical lens according to claim 1, wherein in the first lens group, the refractive index nd and the Abbe number vd of the lens with negative refractive power satisfy nd ≥ 1.75 and vd ≤ 48.

0.

4. The optical lens according to claim 3, wherein the first lens is a meniscus structure.

5. The optical lens according to claim 4, wherein the focal length f1 of the first lens satisfies a relationship: f1 ≤ -20mm, and the focal length f2 of the second lens satisfies a relationship: f2 ≤ -13mm.

6. The optical lens according to claim 3, wherein in the second lens group, the eighth lens located at the last position in the direction from the object side to the image side is a biconvex structure.

7. The optical lens according to claim 5, wherein the second lens group comprises a cemented lens composed of the sixth lens and the seventh lens.

8. An optical lens according to any one of claims 1 to 7.

9. A camera module comprising the optical lens according to any one of claims 1 to 7.

10. A camera module comprising the optical lens according to any one of claims 8. ​ ​ ​ 8. A camera module, comprising: ​ ​ ​ 9. A scanner characterized by, ​ ​

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