CN116449538A

CN116449538A - Optical lens and camera module

Info

Publication number: CN116449538A
Application number: CN202310714785.8A
Authority: CN
Inventors: 邝健; 叶波; 欧阳霞
Original assignee: Shenzhen Dongzheng Optical Technology Co Ltd
Current assignee: Shenzhen Dongzheng Optical Technology Co Ltd
Priority date: 2023-06-16
Filing date: 2023-06-16
Publication date: 2023-07-18
Anticipated expiration: 2043-06-16
Also published as: CN116449538B

Abstract

The embodiment of the application relates to the technical field of cameras and provides an optical lens and a camera module, wherein the optical lens comprises a first lens group, a diaphragm and a second lens group which are arranged from an object side to an image side, the first lens group and the second lens group all have positive focal power, and the combined focal length fs1 of the first lens group and the effective focal length f of the optical lens satisfy the following conditions: and 0.45-0.65 of fs 1/f. The optical lens can achieve the purposes of large target surface, large numerical aperture and high imaging quality.

Description

Optical lens and camera module

Technical Field

The application relates to the technical field of cameras, in particular to an optical lens and a camera module.

Background

Machine vision inspection techniques are widely used in various links of the manufacturing industry. In appearance defect detection links of various industries, machine vision detection technology plays an important role in the fields of circuit boards, semiconductor chips, display panels, food packaging and the like.

Along with the continuous improvement of the industrial intelligent level, the precision requirement on product defect detection is higher and higher. For this reason, it has become an important issue in the industry how to provide an optical lens with a large numerical aperture and a high imaging quality on the basis of a large target surface.

Disclosure of Invention

The embodiment of the application provides an optical lens and a camera module, which are used for providing an optical lens with a large target surface and high imaging quality.

In order to achieve the above purpose, the embodiments of the present application adopt the following technical solutions:

in a first aspect, an embodiment of the present application provides an optical lens, including: the optical lens comprises a first lens group, a diaphragm and a second lens group, wherein the first lens group, the diaphragm and the second lens group are arranged from an object side to an image side, the first lens group and the second lens group are provided with positive focal power, and the combined focal length fs1 of the first lens group and the effective focal length f of the optical lens meet the following conditions: 0.45 Not more than |fs1/f| not more than 0.65.

By adopting the technical scheme, light rays can pass through the diaphragm STO at a more gentle angle, the tolerance sensitivity is reduced, the front and back stability of the optical lens is improved, and the miniaturization of the whole optical lens is realized.

In some embodiments, the combined focal length fs2 of the second lens group and the effective focal length f of the optical lens satisfy: 3.0 Not more than |fs2/f| not more than 10.0.

By adopting the technical scheme, the second lens group can effectively bear the focal power distribution of the optical lens, which is beneficial to the aberration balance of the first lens group and the second lens group, and is beneficial to reducing the length of the optical lens, thereby realizing the miniaturization of the optical lens.

In some embodiments, the conjugate distance L of the total image height H of the optical lens and the optical lens satisfies: 0.10 H/L is more than or equal to 0.15.

By adopting the technical scheme, the optical lens is beneficial to achieving the purpose of taking the miniaturization design and the high imaging quality into consideration.

In some embodiments, the back focal length BFL of the optical lens and the total image height H of the optical lens satisfy: 5.0 BFL/H is more than or equal to 6.0.

By adopting the technical scheme, the optical lens is beneficial to achieving the purpose of improving the relative illumination of the system and achieving the miniaturization design.

In some embodiments, the second lens group includes at least four lenses, a first lens having negative power and a last lens having positive power along an object side to an image side of the at least four lenses; wherein at least two lenses in the middle are cemented together to form a cemented lens.

By adopting the technical scheme, the setting of the cemented lens suppresses chromatic aberration and spherical aberration of the second lens group, thereby reducing aberration of the optical lens as a whole and improving imaging quality.

In some embodiments, the second lens group includes five lenses, of which the first two lenses each have negative power and the last three lenses each have positive power along the object side to the image side; wherein the second lens and the third lens are cemented together to form a cemented lens.

By adopting the technical scheme, the arrangement of five lenses can form the combination of a plurality of cemented lenses, and is suitable for different optical lenses, thereby being beneficial to improving the imaging quality.

In some embodiments, the first lens group includes at least three cemented lenses, each formed by two adjacent lenses cemented together.

By adopting the technical scheme, the arrangement of at least three cemented lenses can well inhibit chromatic aberration and spherical aberration of the first lens group, thereby reducing aberration of the optical lens on the whole and improving imaging quality.

In some embodiments, the first lens group and the second lens group each comprise a plurality of lenses, and the first lens group and the second lens group each comprise a lens having an abbe number greater than 80.

By adopting the technical scheme, the chromatic aberration of the optical lens is reduced, and the imaging quality is improved.

In some embodiments, a beam splitting prism is disposed on a side of the first lens group away from the second lens group.

Through adopting above-mentioned technical scheme, conveniently set up the light source in the one side that beam splitter prism kept away from first lens group, provide coaxial light illumination for the optical lens, be favorable to promoting the illumination homogeneity of optical lens thing side.

In a second aspect, an embodiment of the present application provides a camera module, including a photosensitive element and the optical lens described in the first aspect, where the photosensitive element is disposed on an image side of the optical lens.

The technical effects obtained by the camera module in the embodiment of the present application are the same as those obtained by the optical lens in the first aspect, and are not described herein again.

Drawings

Fig. 1 is a schematic structural diagram of an optical lens according to a first embodiment of the present disclosure;

fig. 2 is a diagram of MTF (Modulation Transfer Function ) of an optical lens according to an embodiment of the present disclosure;

fig. 3 is a distortion chart of an optical lens according to a first embodiment of the present disclosure;

FIG. 4 is an axial aberration diagram of an optical lens according to an embodiment of the present disclosure;

fig. 5 is a chromatic aberration chart of magnification of an optical lens according to an embodiment of the present disclosure;

fig. 6 is a schematic structural diagram of an optical lens according to a second embodiment of the present disclosure;

fig. 7 is an MTF diagram of an optical lens provided in a second embodiment of the present application;

fig. 8 is a distortion chart of an optical lens according to a second embodiment of the present disclosure;

fig. 9 is an axial aberration diagram of an optical lens according to a second embodiment of the present disclosure;

fig. 10 is a chromatic aberration of magnification diagram of an optical lens according to a second embodiment of the present disclosure;

fig. 11 is a schematic structural diagram of an optical lens according to a third embodiment of the present disclosure;

fig. 12 is an MTF diagram of an optical lens provided in the third embodiment of the present application;

fig. 13 is a distortion chart of an optical lens according to a third embodiment of the present application;

fig. 14 is an axial aberration diagram of an optical lens according to a third embodiment of the present disclosure;

fig. 15 is a chromatic aberration of magnification diagram of an optical lens according to a third embodiment of the present application.

Wherein, each reference sign in the figure:

an optical lens 1; a beam-splitting prism 11; a first lens group S1; a second lens group S2; a first lens G1; a second lens G2; a third lens G3; a fourth lens G4; a fifth lens G5; a sixth lens G6; a seventh lens G7; an eighth lens G8; a ninth lens G9; a tenth lens G10; an eleventh lens G11; a twelfth lens G12; a thirteenth lens G13; a fourteenth lens G14; a fifteenth lens G15; a photosensitive element 2; stop STO.

Detailed Description

For convenience of understanding, the following description will explain and describe english abbreviations and related technical terms related to the embodiments of the present application.

A focal power (focal power), equal to the difference between the image Fang Guangshu convergence and the object beam convergence, characterizes the ability of the optical lens to deflect light.

A lens or group of lenses having positive optical power, the lens or group of lenses having a positive focal length, has the effect of converging light.

A lens or group of lenses having negative optical power, the lens or group of lenses having a negative focal length, has the effect of diverging light.

Focal length (focal length), also known as focal length, is a measure of the concentration or divergence of light in an optical lens, and refers to the perpendicular distance from the optical center of a lens or lens group to the focal plane when an infinitely distant scene is brought into clear images at the focal plane by the lens or lens group. From a practical point of view it is understood that the distance from the centre of the lens to the plane is at infinity. For a fixed focus lens, the position of the optical center is fixed; for a tele lens, a change in the optical center of the lens brings about a change in the focal length of the lens.

The effective focal length (effective focal length, EFL) of a lens refers to the distance from the center of the lens to the focal point.

The combined focal length is a combination of the focal lengths of the individual lenses in the lens group.

The object side surface is defined by a lens, the object side surface is defined by the side where the object is located, and the surface of the lens close to the object side is called the object side surface.

The image side surface is defined by a lens, the image side surface is defined by the side of the image of the object, and the surface of the lens close to the image side is called the image side surface.

An aperture stop (aperturedephlegm) is a device used to control the amount of light transmitted through a lens into a photosurface within the body, which is typically within the lens.

The optical total length (total track length, TTL) refers to the total length from the surface of the lens closest to the object side to the imaging plane.

The imaging surface is positioned at the image side of all the lenses in the optical lens, and the light rays sequentially pass through each lens in the optical lens to form an image carrier surface.

The optical axis is an axis passing perpendicularly through the center of the lens. The lens optical axis is an axis passing through the center of each lens of the lens. When light parallel to the optical axis enters the convex lens, the ideal convex lens is a point where all light is converged behind the lens, and the point where all light is converged is a focal point.

And a focus, which is a convergence point of the parallel light rays after being refracted by the lens or the lens group.

Abbe number (Abbe), the Abbe's coefficient, is the ratio of the difference in refractive index of an optical material at different wavelengths, and represents the magnitude of the material's dispersion.

Aberration: the optical lens has the property of an ideal optical system at the optical axis, and a light ray close to the axis, which is emitted by a point on an object, intersects with the image plane at a point (namely, an optical axis image point), but the light rays actually passing through different apertures of the lens are difficult to perfectly intersect at a point, and have a certain deviation from the position of the paraxial image point, and the differences are generally called aberration.

An axial aberration (longitudinal spherical aber), also known as longitudinal chromatic aberration or positional chromatic aberration or axial chromatic aberration, a bundle of rays parallel to the optical axis, after passing through the lens, converges at different positions back and forth, this aberration being known as positional chromatic aberration or axial chromatic aberration. This is because the lens images light of each wavelength at different positions, so that the image focal planes of light of different colors cannot coincide when the last imaging is performed, and the light of multiple colors is scattered to form dispersion.

Distortion (distortion), also known as distortion, is the degree of distortion of an image of an object by an optical lens relative to the object itself. The distortion is caused by the influence of the spherical aberration of the diaphragm, the height of the intersection point of the chief rays with different fields of view and the Gaussian image plane after passing through the optical lens is not equal to the ideal height, and the difference between the chief rays and the Gaussian image plane is the distortion. Therefore, the distortion only changes the imaging position of the off-axis object point on the ideal plane, so that the shape of the image is distorted, but the definition of the image is not affected.

Chromatic aberration of magnification, called magnification chromatic aberration or paraxial chromatic aberration, is the difference in paraxial magnification of the optical lens for different colors.

A plane formed by the principal ray (main beam) of the object point outside the optical axis and the optical axis is called a meridian plane.

A plane passing through a principal ray (main beam) of an object point outside the optical axis and perpendicular to the meridian plane is called a sagittal plane.

The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.

In the present embodiments, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present application, unless otherwise indicated, the meaning of "a plurality" is two or more.

As shown in fig. 1, in some embodiments, the camera module includes an optical lens and a photosensitive element 2, where the photosensitive element 2 is located on an image side of the optical lens.

The working principle of the camera module is as follows: the light reflected by the shot scenery generates an optical image through the optical lens and projects the optical image to the photosensitive surface of the photosensitive element 2, and the photosensitive element 2 converts the optical image into an electric signal, namely an analog image signal and transmits the electric signal to the processor.

The photosensitive element 2 (also referred to as an image sensor) is a semiconductor chip, and has a surface including several hundred thousand to several million photodiodes, which generate electric charges when irradiated with light. The photosensitive element 2 may be a charge coupled device (chargecoupled device, CCD) or a Complementary Metal Oxide Semiconductor (CMOS) device. CCDs are made of a high-sensitivity semiconductor material that converts light into electric charge. Charge-coupled devices are composed of a number of photosensitive units, typically in megapixels. When the surface of the photosensitive element 2 is irradiated by light, each photosensitive unit reflects charges on the component, and signals generated by all the photosensitive units are added together to form a complete picture.

The optical lens mainly uses the refraction principle of the lens to image, namely, the light of the scenery passes through the optical lens to form a clear image on the focal plane, and the image of the scenery is recorded by the photosensitive element 2 positioned on the focal plane. The optical lens may be, but is not limited to, an industrial lens.

As shown in fig. 1, fig. 1 is a structural diagram of an optical lens 1 in a camera module according to a first embodiment. The optical lens 1 includes a first lens group S1, a stop STO and a second lens group S2 arranged along an object side to an image side, wherein the first lens group S1 and the second lens group S2 have positive optical power, and a combined focal length fs1 of the first lens group S1 and an effective focal length f of the optical lens 1 satisfy: 0.45 Not more than |fs1/f| not more than 0.65.

The absolute value of the ratio of the combined focal length fs1 of the first lens group S1 to the effective focal length f of the optical lens 1 is an important parameter for designing the optical lens 1, if the absolute value of the ratio is smaller than 0.45, the combined focal length fs1 of the first lens group S1 is reduced, the spherical aberration of the first lens group S1 is increased, and the aberration balance between the first lens group S1 and the second lens group S2 is not facilitated; if the absolute value of the ratio is greater than 0.65, the combined focal length fs1 of the first lens group S1 is increased, thereby increasing the aperture of the object side of the optical lens 1, which is not beneficial to miniaturization of the optical lens 1.

By reasonably controlling the absolute value of the ratio of the combined focal length fs1 of the first lens group S1 to the effective focal length f of the optical lens 1, so that the above relation is satisfied, light rays can pass through the stop STO at a more gentle angle, the tolerance sensitivity is reduced, the front-rear stability of the optical lens 1 is improved, and the miniaturization of the whole optical lens 1 is realized.

In some embodiments, the combined focal length fs2 of the second lens group S2 and the effective focal length f of the optical lens 1 satisfy: 3.0 Not more than |fs2/f| not more than 10.0.

The absolute value of the ratio of the combined focal length fs2 of the second lens group S2 to the effective focal length f of the optical lens 1 is an important parameter for designing the optical lens 1, and if the absolute value of the ratio is smaller than 3.0, the combined focal length fs2 of the second lens group S2 is reduced, the light deflection angle borne by the second lens group S2 is increased, the sensitivity is increased, and the assembly and the processing are not facilitated. If the absolute value of the ratio is greater than 10.0, the resultant focal length fs2 of the second lens group S2 increases, which is disadvantageous for aberration balance between the first lens group S1 and the second lens group S2.

The absolute value of the ratio of the combined focal length fs2 of the second lens group S2 to the effective focal length f of the optical lens 1 satisfies the above range, so that the second lens group S2 can effectively bear the focal power distribution of the optical lens 1, which is further beneficial to balancing the focal powers of the first lens group S1 and the second lens group S2, reducing the length of the optical lens 1, and enabling the optical lens 1 to be miniaturized and easy to process.

In some embodiments, the conjugate distance L of the total image height H of the optical lens 1 and the optical lens 1 satisfies: 0.10 H/L is more than or equal to 0.15.

The ratio of the total image height H of the optical lens 1 to the conjugate distance L of the optical lens 1 is an important parameter for designing the optical lens 1, and if the ratio is smaller than 0.1, the conjugate length L of the optical lens 1 is increased, which is not beneficial to miniaturization of the optical lens 1; if the ratio is greater than 0.15, the conjugate length L of the optical lens 1 is smaller, but the design and assembly difficulty of the optical lens 1 is greatly improved, which is not beneficial to batch processing manufacturability.

The ratio of the total image height H of the optical lens 1 to the conjugate distance L of the optical lens 1 satisfies the above range, which is favorable for the optical lens 1 to achieve the purpose of considering both miniaturization design and high imaging quality.

In some embodiments, the back focal length BFL of the optical lens 1 and the total image height H of the optical lens 1 satisfy: 5.0 BFL/H is more than or equal to 6.0.

The ratio of the back focal length BFL of the optical lens 1 to the total image height H of the optical lens 1 is an important parameter for designing the optical lens 1, and if the ratio is smaller than 5.0, the back focal length BFL is reduced, so that the incidence angle of the image plane of the main light is increased, and the relative illuminance is reduced; if the ratio is greater than 6.0, the back focal length BFL increases, so that the conjugate length of the optical lens 1 increases, which is disadvantageous for miniaturization of the optical lens 1.

The ratio of the back focal length BFL of the optical lens 1 to the total image height H of the optical lens 1 satisfies the above range, which is beneficial to the optical lens 1 to achieve the purpose of improving the relative illuminance of the system and miniaturizing the design.

In some embodiments, the second lens group S2 comprises at least four lenses, of which at least two lenses are cemented together to form a cemented lens, the first lens having negative power and the last lens having positive power along the object side to the image side.

The arrangement of the cemented lens in the second lens group S2 can well suppress chromatic aberration and spherical aberration of the second lens group S2, thereby reducing aberration of the optical lens 1 as a whole and improving imaging quality.

In some embodiments, the second lens group S2 includes five lenses, of which the first two lenses each have negative power and the last three lenses each have positive power along the object side to the image side; wherein the second lens and the third lens are cemented together to form a cemented lens.

The arrangement of five lenses in the second lens group S2 can form a combination of a plurality of cemented lenses, and is suitable for different optical lenses 1, thereby being beneficial to improving imaging quality.

In some embodiments, the first lens group S1 includes at least three cemented lenses, each cemented lens being formed by two adjacent lenses cemented together.

The arrangement of at least three cemented lenses in the first lens group S1 not only can well inhibit chromatic aberration and spherical aberration of the first lens group S1, but also can reduce aberration of the optical lens 1 as a whole and improve imaging quality.

The first lens group S1 may be all cemented lenses, or may include at least three cemented lenses and a non-cemented lens, which is not particularly limited herein.

In some embodiments, the first lens group S1 and the second lens group S2 each include a plurality of lenses, and the first lens group S1 and the second lens group S2 each include a lens having an abbe number greater than 80. Wherein the lens with Abbe number greater than 80 is a lens with Abbe number greater than 80 at a wavelength of 0.587 um.

The arrangement of the low-dispersion lens can reduce chromatic aberration, ensure that light rays with various wavelengths are actually focused at the same point, generate images with strong light-dark contrast and almost no color distortion, and reduce distortion, spherical aberration and other aberration of the optical lens 1 by the first lens group S1 and the second lens group S2 which both comprise lenses with Abbe numbers larger than 80, so that imaging quality is improved.

As shown in fig. 1, in some embodiments, a side of the first lens group S1 away from the second lens group S2 is further provided with a beam splitter prism 11. By arranging the beam-splitting prism 11 on the side, far away from the second lens group S2, of the first lens group S1, the beam-splitting prism 11 is conveniently provided with a light source on the side, far away from the first lens group S1, of the beam-splitting prism, coaxial light illumination is provided for the optical lens 1, and the illumination uniformity of the object side of the optical lens 1 is facilitated to be improved.

Fig. 1 shows a structural diagram of an optical lens 1 of the first embodiment. The optical lens 1 includes an optical element, a first lens group S1, a stop STO, and a second lens group S2 arranged along an object side to an image side, the first lens group S1 including a first lens G1, a second lens G2, a third lens G3, a fourth lens G4, a fifth lens G5, a sixth lens G6, a seventh lens G7, an eighth lens G8, a ninth lens G9, a tenth lens G10; the second lens group S2 includes an eleventh lens G11, a twelfth lens G12, a thirteenth lens G13, a fourteenth lens G14, and a fifteenth lens G15.

In the first lens group S1, the first lens G1 and the second lens G2, the fifth lens G5 and the sixth lens G6, the seventh lens G7 and the eighth lens G8, the ninth lens G9 and the tenth lens G10 are combined and cemented together, respectively, so that the first lens group S1 conformally forms four cemented lenses; in the second lens group S2, the twelfth lens G12 and the thirteenth lens G13 are cemented together to form a cemented lens.

Tables 1a to 1d respectively show specific parameter values of each lens of the optical lens 1 in the first embodiment of the present application.

In table 1a, the "surface number" is the number of each surface sequentially arranged from the object side to the image side, the radius R value is the lens of the corresponding surface number, that is, the radius of curvature of the object side or the image side of the lens corresponding to each surface number at the optical axis, and the "infinite" in the "radius of curvature" parameter number series of the lens means that the object side or the image side of the lens is a plane; the first value of each lens in the parameter array of thickness/interval 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 values of the diaphragm STO in the thickness parameter series are the distances between the center of the diaphragm STO and the object side surface of the subsequent lens on the optical axis.

In the first embodiment, the conjugate distance l=700 mm, the object side numerical aperture na=0.26, the focal length f=114.42 mm, fs1=57.75 mm, fs2= 358.14mm, the back focal length bfl= 456.46mm, the optical magnification β= -5.0, and the hologram height h=84 mm.

In the first lens group S1 of the optical lens 1, abbe numbers of the second lens G2, the third lens G3 and the fourth lens G4 are 81.6, 90.2 and 90.2 respectively, and the second lens G2, the third lens G3 and the fourth lens G4 are low-dispersion lenses with abbe numbers (d light (yellow light): wavelength is under 0.587 um) higher than 80; in the second lens group S2, the Abbe number of the thirteenth lens G13 is 81.6, and the thirteenth lens G13 is a low-dispersion lens having an Abbe number (d light: wavelength at 0.587 um) higher than 80.

The parameters of the optical lens 1 in the first embodiment satisfy the relationship shown in table 1 b.

Note that: the following explanation of the annotation of the relationship of the optical lens 1 in each embodiment:

f is the effective focal length of the optical lens 1, and is equal to the EFL value of the optical lens 1;

fs1 is the combined focal length of the first lens group S1, i.e. the combined focal length of all lenses in the first lens group S1;

fs2 is the combined focal length of the second lens group S2, i.e. the combined focal length of all lenses in the second lens group S2;

h is the total image height, also referred to as target height;

l is the conjugate distance, namely the total optical length, which refers to the distance from the first surface to the image surface in the optical lens 1;

BFL is the back focal length, also known as the back focal length, and may also be denoted BFD, and is the distance from the last optical surface vertex of the optical lens 1 to the back focal point.

The positive and negative conditions of the optical power of each lens in the optical lens 1 in the first embodiment are shown in table 1 c.

In table 1c, "+" and "-" represent positive and negative powers of each lens in the optical lens 1 in the first embodiment. Wherein "+" represents that the lens has positive optical power; "-" means that the lens has negative optical power.

The concave-convex condition of the object side surface or the image side surface at the optical axis in each lens in the optical lens 1 of the first embodiment is shown in table 1 d.

It is to be noted that, in Table 1d, "≡", "fact+", "+", "- +", "++", "-", representing the relief of the object or image side surface at the optical axis in each lens. Wherein, the liquid crystal display device comprises a liquid crystal display device, the object side surface of the lens denoted by "++" is a plane at the optical axis, the image side surface protrudes towards the object side at the optical axis; object of lens represented by "+_ the side surface is a plane at the optical axis, the image side surface protrudes towards the image side at the optical axis; the "+ -" represents that the object side surface of the lens protrudes towards the object side at the optical axis, and the image side surface protrudes towards the image side at the optical axis, i.e. a biconvex structure; the "- +" indicates that the object side surface of the lens is convex toward the image side at the optical axis, and the image side surface is convex toward the object side region at the optical axis, i.e., the biconcave structure. Of course, each lens in the optical lens 1 may include, in addition to the above-described concave-convex case, may also include "+++", "-", "- +++", and any one or more of "+++", wherein "++" represents that the object side and the image side of the lens are both convex towards the object side at the optical axis; "-" represents that the object side and the image side of the lens are convex toward the image side; the object side surface of the lens represented by "- ≡" protrudes towards the image side at the optical axis, and the image side surface is a plane at the optical axis; represented by "+++" object side surface of lens protruding towards the object side at the optical axis, the image side surface is a plane at the optical axis, and is not particularly limited herein.

When the structure schematic diagram of the optical lens 1 in the first embodiment of fig. 1 and the main parameters of the optical lens 1 in the first embodiment of fig. 1 shown in tables 1a to 1d satisfy the relationship in table 1b, the MTH diagram, the distortion diagram, the axial aberration diagram, and the magnification chromatic aberration diagram simulation effect diagram shown in fig. 2 to 5 are obtained through simulation. Wherein:

fig. 2 shows an MTH diagram of the first embodiment. The MTH graph shows MTF (modulation transfer function) graphs of the field of view change of the optical lens 1 at 25lp/mm and 50lp/mm spatial frequencies, respectively, wherein the abscissa represents the normalized field of view height, the ordinate represents the MTF value, the solid line represents the meridian direction, and the broken line represents the sagittal direction.

Fig. 3 shows a distortion chart of the first embodiment. Wherein the distortion map represents the distortion percentage of the optical lens 1 with respect to the field of view, wherein the abscissa represents the distortion percentage and the ordinate represents the normalized field of view height.

Fig. 4 is an axial aberration diagram of the first embodiment. The axial aberration diagram represents axial aberration of the optical lens 1 along with aperture change, wherein three axial aberrations respectively correspond to the axial aberration at the wavelength of 0.486um, the wavelength of 0.587um and the wavelength of 0.656um, the abscissa represents axial aberration value, and the ordinate represents normalized aperture.

Fig. 5 shows a chromatic aberration of magnification chart of the first embodiment. The chromatic aberration of magnification diagram shows chromatic aberration of magnification of the optical lens 1 along with the change of the field of view, wherein three chromatic aberration of magnification under the corresponding wavelength of 0.486um, wavelength of 0.587um and wavelength of 0.656um respectively, the abscissa represents the chromatic aberration of magnification value, and the ordinate represents the normalized field of view height.

The MTH image, the distortion image, the axial aberration image, and the magnification chromatic aberration image are the same as those of the other embodiments, and will not be described in detail.

The full field MTF at each frequency in fig. 2 is substantially uniform with a center to edge difference of less than 0.1. At a frequency of 50lp/mm, the MTF values are all greater than 0.55, and the linear scanning camera with 16K5 mu pixels can be matched. The maximum distortion in fig. 3 is only 0.1%, which is located at the maximum field of view. In FIG. 4, the axial chromatic aberration is smaller than 0.2mm, and the shot object is not easy to generate chromatic dispersion. As is clear from fig. 5, the chromatic aberration of magnification is smaller than 1.6 μm, and the dispersion suppression performance of the optical lens 1 is prominent.

Fig. 6 shows a structural diagram of an optical lens 1 of the second embodiment. The optical lens 1 in the second embodiment is identical to the first lens group S1 and the second lens group S2 of the optical lens 1 of the first embodiment described above, except that the number of cemented lenses in the first lens group S1, and the parameters and the conditions satisfied by the respective lenses are different.

As shown in fig. 6, the optical lens 1 includes a beam splitting prism 11, a first lens group S1, a stop STO, and a second lens group S2 arranged along an object side to an image side, and the first lens group S1 includes a first lens G1, a second lens G2, a third lens G3, a fourth lens G4, a fifth lens G5, a sixth lens G6, a seventh lens G7, an eighth lens G8, a ninth lens G9, and a tenth lens G10.

Wherein the second lens G2 and the third lens G3, the fifth lens G5 and the sixth lens G6, the seventh lens G7 and the eighth lens G8, the ninth lens G9 and the tenth lens G10 are combined and cemented together, respectively, so that the first lens group S1 is formed into four cemented lenses.

The second lens group S2 includes an eleventh lens G11, a twelfth lens G12, a thirteenth lens G13, a fourteenth lens G14, a fifteenth lens G15, wherein the twelfth lens G12 and the thirteenth lens G13 are cemented together to form a cemented lens.

Tables 2a to 2d respectively show specific parameter values of each lens of the optical lens 1 in the second embodiment of the present application.

In the second embodiment, the conjugate distance l=700 mm, the object side numerical aperture na=0.26, the focal length f=111.99 mm, the back focal length bfl=448.28 mm, fs1=60.96 mm, fs2= 574.93mm, the optical magnification β= -5.0, and the hologram height h=84 mm.

In the first lens group S1 of the optical lens 1, abbe numbers of the third lens G3 and the fourth lens G4 are respectively 90.2 and 81.6, and the third lens G3 and the fourth lens G4 are low-dispersion lenses with Abbe numbers (d light: 0.587 um) higher than 80; in the second lens group S2, the Abbe number of the thirteenth lens G13 is 81.6, and the thirteenth lens G13 is a low-dispersion lens having an Abbe number (d light: 0.587 um) higher than 80.

The parameters of the optical lens 1 in the second embodiment satisfy the relationship shown in table 2 b.

The positive and negative conditions of the optical power of each lens in the optical lens 1 in the second embodiment are shown in table 2 c.

The concave-convex condition of the object side surface or the image side surface in each lens of the optical lens 1 in the second embodiment is shown in table 2 d.

When the structure schematic diagram of the optical lens 1 in the second embodiment of fig. 6 and the main parameters of the optical lens 1 in the second embodiment of fig. 2a to 2d satisfy the relationship in table 2b, the MTH diagram, the distortion diagram, the axial aberration diagram, and the magnification chromatic aberration diagram simulation effect diagram shown in fig. 7 to 10 are obtained through simulation.

As shown in fig. 7 to 10, fig. 7 shows an MTH diagram of the second embodiment, fig. 8 shows a distortion diagram of the second embodiment, fig. 9 shows an axial aberration diagram of the second embodiment, and fig. 10 shows a chromatic aberration of magnification diagram of the second embodiment. The full field MTF at each frequency in fig. 7 is substantially uniform with a center-to-edge difference of less than 0.1. At a frequency of 50lp/mm, the MTF values are all greater than 0.55, and the linear scanning camera with 16K5 mu pixels can be matched. The maximum distortion in fig. 8 is only 0.1%, which is located at the maximum field of view. In FIG. 9, the axial chromatic aberration is less than 0.35mm, and the shot object is not easy to generate chromatic dispersion. In FIG. 10, the chromatic aberration of magnification is less than 2. Mu.m, and the dispersion suppression is remarkable.

Fig. 11 shows a structural diagram of an optical lens 1 of the third embodiment. The optical lens 1 in the third embodiment is structurally different from the optical lens 1 in the first and second embodiments described above in that the number of lenses in the first lens group S1 is nine, which saves the number of lenses. In order to keep the same as the second lens group in the foregoing two embodiments, the second lens group S2 in the optical lens 1 in the third embodiment remains from the eleventh lens G11.

As shown in fig. 11, the optical lens 1 includes: the optical lens 1 includes a beam splitter prism 11, a first lens group S1, a stop STO, and a second lens group S2 arranged along an object side to an image side, the first lens group S1 including a first lens G1, a second lens G2, a third lens G3, a fourth lens G4, a fifth lens G5, a sixth lens G6, a seventh lens G7, an eighth lens G8, and a ninth lens G9; wherein the first lens G1 and the second lens G2, the fourth lens G4 and the fifth lens G5, the sixth lens G6 and the seventh lens G7, the eighth lens G8 and the ninth lens G9 are combined and cemented together, respectively, so that the first lens group S1 is formed into four cemented lenses; the second lens group S2 includes an eleventh lens G11, a twelfth lens G12, a thirteenth lens G13, a fourteenth lens G14, and a fifteenth lens G15, wherein the twelfth lens G12 and the thirteenth lens G13 are cemented together to form a cemented lens.

Table 3a to table 3d show specific parameter values of each lens of the optical lens 1 in the third embodiment.

In embodiment three, the optical system conjugate distance l=700 mm, the object side numerical aperture na=0.26, the focal length f= 109.33mm, the back focal length bfl=461.71 mm, fs1=61.50 mm, fs2= 928.10mm, the optical magnification β= -5.0, and the hologram height h=84 mm.

In the first lens group S1 of the optical lens 1, abbe numbers of the second lens G2 and the third lens G3 are 90.2 and 81.6, respectively, and the second lens G2 and the third lens G3 are low-dispersion lenses with abbe numbers (d light (yellow light): wavelength is 0.587 um) higher than 80; in the second lens group S2, the Abbe number of the twelfth lens G12 is 81.6, and the twelfth lens G12 is a lens having an Abbe number (d light: wavelength at 0.587 um) higher than 80.

The parameters of the optical lens 1 in the third embodiment satisfy the relationship shown in table 3 b.

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The positive and negative conditions of the optical power of each lens in the optical lens 1 in the third embodiment are shown in table 3 c.

The concave-convex condition of the object side surface or the image side surface at the optical axis in each lens in the optical lens 1 in the second embodiment is shown in table 3 d.

When the structure schematic diagram of the optical lens 1 in the third embodiment of fig. 11 and the main parameters of the optical lens 1 in the third embodiment of fig. 3a to 3d satisfy the relationship in table 3b, the MTH diagram, the distortion diagram, the axial aberration diagram, and the magnification chromatic aberration diagram simulation effect diagram shown in fig. 12 to 15 are obtained through simulation.

As shown in fig. 12 to 15, fig. 12 shows an MTH diagram of the third embodiment, fig. 13 shows a distortion diagram of the third embodiment, fig. 14 shows an axial aberration diagram of the third embodiment, and fig. 15 shows a magnification chromatic aberration diagram of the third embodiment. The full field MTF at each frequency in fig. 12 is substantially uniform with a center-to-edge difference of less than 0.1. At a frequency of 50lp/mm, the MTF values are all greater than 0.55, and the linear scanning camera with 16K5 mu pixels can be matched. The maximum distortion in fig. 13 is only 0.1%, which is located at the maximum field of view. In fig. 14, the axial chromatic aberration is less than 0.35mm, and the subject is not likely to generate chromatic dispersion. In FIG. 15, the chromatic aberration of magnification is smaller than 2.3. Mu.m, and the dispersion suppression is remarkable.

In summary, fig. 2, fig. 7, and fig. 12 are MTF diagrams corresponding to the optical lens 1 provided in the first to third embodiments of the present application respectively. The MTF curves are shown in the three examples to different extents proximate to the diffraction limit, indicating that the optical lens 1 has good imaging quality.

Fig. 3, 8 and 13 are distortion diagrams corresponding to the optical lens 1 according to the first to third embodiments of the present application. Where the horizontal axis is the percentage of distortion and the vertical axis is the height of the light on the image plane after scaling by the optical lens 1, and the FOV represents the field of view (field of view). The distortion base maximum distortion was around 0.1% in all three examples, essentially achieving "zero distortion".

Fig. 4, 9 and 14 are axial aberration diagrams corresponding to the optical lens 1 according to the first to third embodiments of the present application. Wherein, three axial aberration at the corresponding wavelength of 0.486um, 0.587um, 0.656um respectively, the abscissa represents axial aberration value, and the ordinate represents normalized aperture. The axial aberration is smaller than 0.35mm in all three embodiments, so that the shot object is not easy to generate dispersion.

Fig. 5, 10 and 15 are respectively magnification chromatic aberration diagrams corresponding to the optical lens 1 provided in the first to third embodiments of the present application. Wherein the horizontal axis (chromatic lateral aberration) represents the magnitude of chromatic aberration of magnification and the vertical axis (normalized image height) represents the normalized image height. The chromatic aberration of magnification in all three embodiments is about 2 μm. In such large target surface, small F-number systems, the chromatic aberration of magnification is very small and therefore can be referred to as "zero chromatic aberration".

In summary, the optical lens 1 of the present application achieves the purposes of increasing the numerical aperture, improving the resolution and thus improving the imaging quality on the basis of having a large target surface.

In the description of the present specification, a particular feature, structure, material, or characteristic may be combined in any suitable manner in one or more embodiments or examples.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and are not limiting thereof; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the corresponding technical solutions.

Claims

1. An optical lens is characterized by comprising a first lens group, a diaphragm and a second lens group which are arranged from an object side to an image side, wherein the first lens group and the second lens group are provided with positive focal power, and the combined focal length fs1 of the first lens group and the effective focal length f of the optical lens meet the following conditions: 0.45 Not more than |fs1/f| not more than 0.65.

2. The optical lens of claim 1, wherein,

the combined focal length fs2 of the second lens group and the effective focal length f of the optical lens satisfy: 3.0 Not more than |fs2/f| not more than 10.0.

3. The optical lens of claim 1, wherein,

the conjugate distance L between the total image height H of the optical lens and the optical lens is as follows: 0.10 H/L is more than or equal to 0.15.

4. The optical lens of claim 1, wherein,

the back focal length BFL of the optical lens and the total image height H of the optical lens satisfy: 5.0 BFL/H is more than or equal to 6.0.

5. The optical lens of claim 1, wherein,

the second lens group comprises at least four lenses, wherein the first lens has negative focal power along the object side to the image side and the last lens has positive focal power; wherein at least two lenses in the middle are cemented together to form a cemented lens.

6. The optical lens of claim 5, wherein,

the second lens group comprises five lenses, wherein the first two lenses have negative focal power and the last three lenses have positive focal power along the object side to the image side; wherein the second lens and the third lens are cemented together to form a cemented lens.

7. The optical lens according to any one of claims 1 to 6, wherein,

the first lens group includes at least three cemented lenses.

8. The optical lens according to any one of claims 1 to 6, wherein,

the first lens group and the second lens group each comprise a plurality of lenses, and the first lens group and the second lens group each comprise lenses with Abbe numbers greater than 80.

9. The optical lens according to any one of claims 1 to 6, wherein,

and a beam splitting prism is further arranged on one side, far away from the second lens group, of the first lens group.

10. A camera module comprising a photosensitive element and the optical lens of any one of claims 1 to 9, wherein the photosensitive element is disposed on an image side of the optical lens.