CN116338908A

CN116338908A - Optical lens

Info

Publication number: CN116338908A
Application number: CN202310572773.6A
Authority: CN
Inventors: 谢先国; 章彬炜
Original assignee: Jiangxi Lianyi Optics Co Ltd
Current assignee: Jiangxi Lianyi Optics Co Ltd
Priority date: 2023-05-22
Filing date: 2023-05-22
Publication date: 2023-06-27
Anticipated expiration: 2043-05-22
Also published as: CN116338908B

Abstract

The invention discloses an optical lens, which sequentially comprises from an object side to an imaging surface along an optical axis: a first lens with positive focal power, the object side surface of which is a convex surface; a diaphragm; a second lens element with negative refractive power having a concave object-side surface and a concave image-side surface at a paraxial region; a third lens element with positive refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region; a fourth lens element with positive refractive power having a concave object-side surface and a convex image-side surface; a fifth lens element with positive refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region; wherein, at least one plastic lens and one glass lens are contained in the optical lens. The optical lens provided by the invention has the advantages of at least large aperture, miniaturization, low cost and night high-definition imaging by reasonably setting the focal power distribution, the diaphragm position, the lens thickness and the lens spacing.

Description

Optical lens

Technical Field

The invention relates to the technical field of imaging lenses, in particular to an optical lens.

Background

Along with the continuous development and application of the intelligent technology of the automobile, the application of the vehicle-mounted lens is more and more extensive, at present, the vehicle-mounted lens on the market mainly comprises an external lens, the internal lens is relatively low in occupation but is rapidly increased, for example, a DMS (Driver Monitor System, driver monitoring system) camera is mainly applied to the interior of the automobile, and the main functions of the camera comprise the functions of fatigue detection, face recognition and the like of a driver, so that the camera has extremely wide market prospect.

When detecting the driving behavior and the facial information of a driver by using a DMS camera, a proper light source needs to be selected; in order to reduce the influence of the ambient light on the imaging, the intensity of the active light source needs to be higher than that of the ambient light, but strong light may interfere with human eyes to reduce the comfort of users, so the active light source is preferably located in an invisible band, such as infrared light, ultraviolet light, and the like. Long-term irradiation of ultraviolet light easily causes permanent injury to human skin and eyes, and medium-far infrared band light imaging loses most information on the surface of an object and is not generally used for object imaging, so that near infrared band light becomes the best choice of DMS, namely a camera applied to the DMS needs to have good imaging capability in near infrared band light so as to ensure that the system is also applicable to complex illumination environments such as night, backlight, shade sunlight and the like.

Along with the miniaturization of photoelectric components, and because the DMS camera is mainly installed on the automobile instrument panel, the DMS system needs to be matched with an infrared optical imaging lens with small volume and low cost to meet the use requirement. However, most of the lenses in the market are composed of glass spherical lenses, so that the size is large and the cost is high, and the size can be reduced by adopting a plastic lens, but the plastic material has a larger thermal expansion coefficient, so that the focus offset problem caused by temperature change is easy to occur. And most of the lenses on the market have small aperture and blurred imaging at night, which is not beneficial to normal work in a dim environment in a vehicle.

Disclosure of Invention

Therefore, the present invention is directed to an optical lens having at least the advantages of large aperture, miniaturization, low cost, and night high definition imaging.

The invention provides an optical lens, which sequentially comprises from an object side to an imaging surface along an optical axis: a first lens with positive focal power, wherein the object side surface of the first lens is a convex surface; a diaphragm; a second lens with negative focal power, wherein the object side surface of the second lens is a concave surface, and the image side surface of the second lens is a concave surface at a paraxial region; a third lens element with positive refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region; a fourth lens element with positive refractive power, wherein the object-side surface of the fourth lens element is concave and the image-side surface of the fourth lens element is convex; a fifth lens element with positive refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region; wherein the optical lens at least comprises a plastic lens and a glass lens; the optical lens satisfies the following conditional expression: 40 ° < FOV/f# <60 °, FOV represents the maximum field angle of the optical lens, and f# represents the F-number of the optical lens.

Compared with the prior art, the optical lens provided by the invention adopts five glass-plastic mixed lenses, and the lens has a more compact structure and effectively reduces the manufacturing cost through reasonable collocation of the lens surfaces and the optical power; meanwhile, the lens has a large aperture characteristic, so that more luminous flux can enter the lens system, and the lens can be imaged clearly in a dim environment; the optical lens provided by the invention can clearly image in the near infrared region 800-1100 nm (especially 920-960nm) wave band, namely, the night imaging quality is effectively improved under the assistance of an infrared light source, and the imaging requirements of the infrared imaging characteristic and the high imaging quality in the DMS can be met.

Drawings

The foregoing and/or additional aspects and advantages of the invention will become apparent and may be readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:

fig. 1 is a schematic structural diagram of an optical lens according to a first embodiment of the present invention.

Fig. 2 is a graph showing a field curvature of an optical lens according to a first embodiment of the present invention.

Fig. 3 is a distortion graph of an optical lens according to a first embodiment of the present invention.

Fig. 4 is an axial chromatic aberration diagram of an optical lens in a first embodiment of the invention.

Fig. 5 is a schematic structural diagram of an optical lens according to a second embodiment of the present invention.

Fig. 6 is a field curvature chart of an optical lens according to a second embodiment of the present invention.

Fig. 7 is a distortion graph of an optical lens according to a second embodiment of the present invention.

Fig. 8 is an axial chromatic aberration diagram of an optical lens in a second embodiment of the invention.

Fig. 9 is a schematic structural diagram of an optical lens according to a third embodiment of the present invention.

Fig. 10 is a field curve diagram of an optical lens according to a third embodiment of the present invention.

Fig. 11 is a distortion graph of an optical lens according to a third embodiment of the present invention.

Fig. 12 is an axial chromatic aberration diagram of an optical lens in a third embodiment of the invention.

Fig. 13 is a schematic structural diagram of an optical lens according to a fourth embodiment of the present invention.

Fig. 14 is a field curve diagram of an optical lens according to a fourth embodiment of the present invention.

Fig. 15 is a distortion graph of an optical lens according to a fourth embodiment of the present invention.

Fig. 16 is an axial chromatic aberration diagram of an optical lens in a fourth embodiment of the invention.

Fig. 17 is a schematic structural diagram of an optical lens according to a fifth embodiment of the present invention.

Fig. 18 is a field curvature chart of an optical lens according to a fifth embodiment of the present invention.

Fig. 19 is a distortion graph of an optical lens according to a fifth embodiment of the present invention.

Fig. 20 is an axial chromatic aberration diagram of an optical lens in a fifth embodiment of the invention.

Detailed Description

In order that the objects, features and advantages of the invention will be readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Several embodiments of the invention are presented in the figures. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Like reference numerals refer to like elements throughout the specification.

In this context, near the optical axis means the area near the optical axis. If the lens surface is convex and the convex position is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the concave position is not defined, it means that the lens surface is concave at least in the paraxial region.

The invention provides an optical lens, which sequentially comprises from an object side to an imaging surface along an optical axis: the optical lens comprises a first lens, a diaphragm, a second lens, a third lens, a fourth lens, a fifth lens, an optical filter and protective glass.

The first lens has positive focal power, the object side surface of the first lens is a convex surface, and the image side surface of the first lens can be a concave surface or a convex surface; the first lens is in a shape similar to a meniscus, and is mainly used for collecting light rays and improving luminous flux.

The second lens has negative focal power, the object side surface is concave, and the image side surface is concave at a paraxial region.

The third lens element has positive refractive power, wherein an object-side surface thereof is convex at a paraxial region and an image-side surface thereof is concave at the paraxial region.

The fourth lens element has positive refractive power, wherein an object-side surface thereof is concave, and an image-side surface thereof is convex.

The fifth lens element has positive refractive power, wherein an object-side surface thereof is convex at a paraxial region and an image-side surface thereof is concave at the paraxial region; the fifth lens adopts an M-shaped aspheric lens, is mainly used for correcting aberration such as astigmatism, distortion and the like, and is also used for controlling the light emergent angle and improving the overall imaging quality.

The optical lens at least comprises a plastic lens and a glass lens, and through the design of the glass-plastic mixed lens, the total length of the lens can be effectively reduced, the production cost of the lens can be effectively reduced, and the thermal stability of a product is improved.

In some embodiments, the optical lens satisfies the following conditional expression: 40 ° < FOV/f# <60 °, FOV represents the maximum field angle of the optical lens, and f# represents the F-number of the optical lens. The method meets the conditions, is favorable for expanding the field angle of the optical lens and realizing the large aperture characteristic of the lens, is favorable for acquiring more scene information by the optical lens, meets the requirement of large-scale shooting, and is favorable for improving the problem of rapid reduction of the relative brightness of the edge field of view caused by the wide angle, thereby being favorable for acquiring more scene information.

In some embodiments, the optical lens satisfies the following conditional expression: 1.7< TTL/f <2.5, wherein TTL represents the total optical length of the optical lens and f represents the effective focal length of the optical lens. The length of the lens can be effectively limited by meeting the above conditions, and the miniaturization of the optical lens can be realized.

In some embodiments, the optical lens satisfies the following conditional expression: 1.3< f/IH <2.0, wherein IH represents an image height corresponding to a maximum half field angle of the optical lens, and f represents an effective focal length of the optical lens. The lens has a large field angle, can realize large image surface characteristics, can ensure to carry a chip with a large size, and realizes high-definition imaging of the system in a dim environment.

In some embodiments, the optical lens satisfies the following conditional expression: 1.3< f1/f <4, wherein f1 represents a focal length of the first lens and f represents an effective focal length of the optical lens. The first lens has proper positive focal power, so that more light rays can enter the rear optical system, the field angle of the lens is increased, and the overall imaging quality is improved.

In some embodiments, the optical lens satisfies the following conditional expression: -2< f2/f < -0.2, -6< R3/R4< -0.5, wherein f2 represents a focal length of the second lens, f represents an effective focal length of the optical lens, R3 represents a radius of curvature of an object side of the second lens, and R4 represents a radius of curvature of an image side of the second lens. The second lens has proper negative focal power and surface shape, so that the second negative lens is matched with other four positive lenses better, the effective correction of the integral aberration is realized, and the integral imaging quality is improved.

In some embodiments, the optical lens satisfies the following conditional expression: 0.2< f3/f <2.5,0.1< f3/f4<1, wherein f3 represents a focal length of the third lens, f4 represents a focal length of the fourth lens, and f represents an effective focal length of the optical lens. The lens system meets the conditions, is beneficial to reducing spherical aberration and coma aberration generated by the third lens and the fourth lens, and simultaneously effectively corrects aberration brought by the front lens and improves the overall imaging quality.

In some embodiments, the optical lens satisfies the following conditional expression: 0.03< f4/f5<0.15,3< f5/f <50, wherein f4 represents a focal length of the fourth lens, f5 represents a focal length of the fifth lens, and f represents an effective focal length of the optical lens. The optical power distribution of the fourth lens and the fifth lens is reasonably arranged, so that the converging of marginal view field light rays is facilitated, the converged light rays smoothly enter the rear-end optical system, the smooth transition of the light rays is further realized, the distortion correction difficulty is reduced, and the imaging quality of the optical lens is improved.

In some embodiments, the optical lens satisfies the following conditional expression: 1.3< f4/f <6, wherein f4 represents a focal length of the fourth lens and f represents an effective focal length of the optical lens. The fourth lens has proper positive focal power, is favorable for smooth transition of light trend and improves imaging quality of the optical lens.

In some embodiments, the optical lens satisfies the following conditional expression: 0.8< R1/f <2, wherein R1 represents a radius of curvature of an object side surface of the first lens, and f represents an effective focal length of the optical lens. The imaging system meets the requirements of high-definition imaging under dark conditions, and can reasonably control the clear aperture of the optical lens, increase the light quantity of the system, enable the optical lens to have the characteristic of a large aperture, reduce the aberration of an edge view field and simultaneously enhance the imaging effect under dark conditions.

In some embodiments, the optical lens satisfies the following conditional expression: 0.6< R7/R8<3, wherein R7 represents a radius of curvature of an object side surface of the fourth lens, and R8 represents a radius of curvature of an image side surface of the fourth lens. And the surface type of the fourth lens is reasonably arranged, so that the aberration of peripheral light rays can be adjusted, the distortion correction difficulty of the marginal view field can be reduced, and the imaging quality of the optical lens can be improved.

In some embodiments, the optical lens satisfies the following conditional expression: -1.2< R8/R9< -0.8, wherein R8 represents a radius of curvature of the image side of the fourth lens and R9 represents a radius of curvature of the object side of the fifth lens. And the surface shape of the fourth lens is reasonably arranged, so that the aberration of peripheral light rays can be adjusted, the distortion correction difficulty of the marginal view field can be reduced, and the imaging quality of the optical lens can be improved.

In some embodiments, the optical lens satisfies the following conditional expression: 1.25< CT4/CT5<3, wherein CT4 represents a center thickness of the fourth lens and CT5 represents a center thickness of the fifth lens. The light beam entering the fourth lens tends to be deflected slowly by meeting the conditions, the miniaturization of the head of the system can be maintained, the sensitivity of the system is reduced, the shape of the lens is controlled by adjusting the central thickness distribution of the fourth lens and the fifth lens, and the compactness of the system structure is facilitated.

In some embodiments, the optical lens satisfies the following conditional expression: 0.9< f/D1<1.5,0.3< (D5-D1)/f <1, wherein f represents an effective focal length of the optical lens, D1 represents a maximum effective diameter of the first lens, and D5 represents a maximum effective diameter of the fifth lens. The condition is satisfied, the large aperture characteristic of the lens is facilitated, the light passing quantity of the system is improved, meanwhile, the loss of light entering and exiting the system is reduced, and the response speed of the system can be improved while the system performs high-definition imaging in a low-light or even dim environment.

In some embodiments, the optical lens satisfies the following conditional expression: 0.4< f345/f <1, wherein f345 represents a combined focal length of the third lens, the fourth lens and the fifth lens, and f represents an effective focal length of the optical lens. The lens group formed by the third lens, the fourth lens and the fifth lens can bear certain positive focal power, so that the deflection efficiency of light rays is quickened, and the total length of the optical lens is favorably shortened.

In some embodiments, the optical lens satisfies the following conditional expression: -0.1< (sag1+sag2)/R2 <0.1, wherein R2 represents the radius of curvature of the image side of the first lens, SAG1 represents the edge sagittal height of the object side of the first lens, SAG2 represents the edge sagittal height of the image side of the first lens. The shape of the first lens can be reasonably controlled to bear corresponding positive focal power, so that the deflection efficiency of light rays is quickened, and the shortening of the total length of the optical lens is facilitated.

In some embodiments, the optical lens satisfies the following conditional expression: and 0.15< BFL/TTL <0.20, wherein BFL represents the optical back focus of the optical lens, and TTL represents the total optical length of the optical lens. The optical lens has larger optical back focus, thereby being beneficial to reducing interference between the lens and the imaging chip and further reducing the correction difficulty of CRA.

As an implementation mode, the optical lens can adopt glass spherical lens and plastic aspherical lens to match, also can adopt glass aspherical lens and plastic aspherical lens to match, in this application, guarantee high pixel formation of image in order to realize that the camera lens is miniaturized, first lens adopts glass spherical lens, and second lens, third lens, fourth lens and fifth lens all adopt plastic aspherical lens, can effectively reduce cost, revise the aberration, provide the optical performance product of higher price/performance ratio.

In various embodiments of the present invention, the aspherical profile of each lens satisfies the following equation:

；

where z is the distance sagittal height from the aspherical surface vertex when the aspherical surface is at a position of height h in the optical axis direction, c is the paraxial curvature of the surface, k is the quadric coefficient, A _2i The aspherical surface profile coefficient of the 2 i-th order.

The invention is further illustrated in the following examples. In various embodiments, the thickness, radius of curvature, and material selection portion of each lens in the optical lens may vary, and for specific differences, reference may be made to the parameter tables of the various embodiments. The following examples are merely preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the following examples, and any other changes, substitutions, combinations or simplifications that do not depart from the gist of the present invention are intended to be equivalent substitutes within the scope of the present invention.

First embodiment

Referring to fig. 1 for a schematic structural diagram of an optical lens 100 according to a first embodiment of the present invention, the optical lens 100 includes, in order from an object side to an imaging surface S15 along an optical axis: a first lens L1, a diaphragm ST, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a filter G1, and a cover glass G2.

The first lens element L1 has positive refractive power, wherein an object-side surface S1 of the first lens element is convex, and an image-side surface S2 of the first lens element is concave. The second lens element L2 has negative refractive power, wherein an object-side surface S3 of the second lens element is concave, and an image-side surface S4 of the second lens element is concave at a paraxial region; the third lens element L3 has positive refractive power, wherein an object-side surface S5 of the third lens element is convex at a paraxial region thereof, and an image-side surface S6 of the third lens element is concave at a paraxial region thereof; the fourth lens element L4 has positive refractive power, wherein an object-side surface S7 of the fourth lens element is concave, and an image-side surface S8 of the fourth lens element is convex; the fifth lens element L5 has positive refractive power, wherein an object-side surface S9 of the fifth lens element is convex at a paraxial region thereof, and an image-side surface S10 of the fifth lens element is concave at a paraxial region thereof; the object side surface of the optical filter G1 is S11, and the image side surface is S12; the object side surface of the cover glass G2 is S13, and the image side surface is S14.

The first lens L1 is a glass spherical lens, and the second lens L2, the third lens L3, the fourth lens L4 and the fifth lens L5 are plastic aspherical lenses.

The relevant parameters of each lens in the optical lens 100 provided in this embodiment are shown in table 1.

TABLE 1

The surface profile coefficients of the aspherical surfaces of the optical lens 100 in this embodiment are shown in table 2.

TABLE 2

Referring to fig. 2, 3 and 4, a field curvature curve, a distortion curve and an axial chromatic aberration curve of the optical lens 100 are shown.

The field curvature curve of fig. 2 shows the degree of curvature of the meridional image plane and the sagittal image plane, and in the figure, the horizontal axis shows the amount of shift (in mm) and the vertical axis shows the angle of view (in degrees). As can be seen from the figure, the curvature of field of the meridional image plane and the sagittal image plane are controlled within ±0.35 mm, which indicates that the curvature of field of the optical lens 100 is well corrected.

The distortion curves of fig. 3 represent distortion at different image heights on the imaging plane, with the horizontal axis representing the percent distortion and the vertical axis representing the angle of view (in degrees). As can be seen from the figure, the distortion at different image heights on the imaging plane is controlled to be within 5%, which means that the optical distortion of the optical lens 100 is well corrected.

The axial chromatic aberration curve of fig. 4 represents aberration on the optical axis at the imaging plane, in which the horizontal axis represents a sphere value (unit: mm) and the vertical axis represents a normalized pupil radius. As can be seen from the figure, the offset of the axial chromatic aberration is controlled within ±0.09mm, which indicates that the axial chromatic aberration of the optical lens 100 is well corrected.

Second embodiment

Referring to fig. 5, a schematic structural diagram of an optical lens 200 according to a second embodiment of the present invention is shown, and the optical lens 200 according to the present embodiment is substantially the same as the first embodiment, and the main differences are that: the image side surface S2 of the first lens is convex, and the curvature radius, aspherical coefficient, thickness, and the like of each lens surface are different.

The relevant parameters of each lens in the optical lens 200 provided in this embodiment are shown in table 3.

TABLE 3 Table 3

The surface profile coefficients of the aspherical surfaces of the optical lens 200 in this embodiment are shown in table 4.

TABLE 4 Table 4

Referring to fig. 6, 7 and 8, a field curvature curve, a distortion curve and an axial chromatic aberration curve of the optical lens 200 are shown.

The curvature of field curve of fig. 6 shows the degree of curvature of the meridional image plane and the sagittal image plane, and it can be seen from the figure that the curvature of field of the meridional image plane and the sagittal image plane is controlled within ±0.35 mm, which indicates that the curvature of field of the optical lens 200 is well corrected.

The distortion curves of fig. 7 show distortions at different image heights on the imaging plane, and it can be seen from the figure that the distortions at different image heights on the imaging plane are controlled within 5%, which indicates that the optical distortion of the optical lens 200 is well corrected.

The axial chromatic aberration curve of fig. 8 shows the aberration on the optical axis at the imaging plane, and it can be seen from the figure that the offset of the axial chromatic aberration is controlled within ±0.035mm, which indicates that the axial chromatic aberration of the optical lens 200 is well corrected.

Third embodiment

Referring to fig. 9, a schematic structural diagram of an optical lens 300 according to a third embodiment of the present invention is shown, and the optical lens 300 of the present embodiment is substantially the same as the first embodiment, and the main differences are that: the radius of curvature, aspherical coefficient, thickness, and the like of each lens surface are different.

The relevant parameters of each lens in the optical lens 300 in this embodiment are shown in table 5.

TABLE 5

The surface profile coefficients of the aspherical surfaces of the optical lens 300 in this embodiment are shown in table 6.

TABLE 6

Referring to fig. 10, 11 and 12, a field curvature curve, a distortion curve and an axial chromatic aberration curve of the optical lens 300 are shown.

The curvature of field curve of fig. 10 shows the degree of curvature of the meridional image plane and the sagittal image plane, and it can be seen from the figure that the curvature of field of the meridional image plane and the sagittal image plane is controlled within ±0.20 mm, which indicates that the curvature of field of the optical lens 300 is well corrected.

The distortion curves of fig. 11 show distortions at different image heights on the imaging plane, and it can be seen from the graph that distortions at different image heights on the imaging plane are controlled within 5.5%, which indicates that the optical distortion of the optical lens 300 is well corrected.

The axial chromatic aberration curve of fig. 12 shows the aberration on the optical axis at the imaging plane, and it can be seen from the figure that the offset of the axial chromatic aberration is controlled within ±0.09mm, which indicates that the axial chromatic aberration of the optical lens 300 is well corrected.

Fourth embodiment

Referring to fig. 13, a schematic structural diagram of an optical lens 400 according to a fourth embodiment of the present invention is shown, and the optical lens 400 according to the present embodiment is substantially the same as the first embodiment, and the main differences are that: the radius of curvature, aspherical coefficient, thickness, and the like of each lens surface are different.

The relevant parameters of each lens in the optical lens 400 in this embodiment are shown in table 7.

TABLE 7

The surface profile coefficients of the aspherical surfaces of the optical lens 400 in this embodiment are shown in table 8.

TABLE 8

Referring to fig. 14, 15 and 16, a field curvature curve, a distortion curve and an axial chromatic aberration curve of the optical lens 400 are shown.

The curvature of field curve of fig. 14 shows the degree of curvature of the meridional image plane and the sagittal image plane, and it can be seen from the figure that the curvature of field of the meridional image plane and the sagittal image plane is controlled within ±0.20 mm, which indicates that the curvature of field of the optical lens 400 is well corrected.

The distortion curves of fig. 15 show distortions at different image heights on the imaging plane, and it can be seen from the figures that the distortions at different image heights on the imaging plane are controlled within 4.5%, which indicates that the optical distortion of the optical lens 400 is well corrected.

The axial chromatic aberration curve of fig. 16 shows the aberration on the optical axis at the imaging plane, and it can be seen from the figure that the offset of the axial chromatic aberration is controlled within ±0.08mm, which indicates that the axial chromatic aberration of the optical lens 400 is well corrected.

Fifth embodiment

Referring to fig. 17, a schematic diagram of an optical lens 500 according to a fifth embodiment of the present invention is shown, and the optical lens 500 according to the present embodiment is substantially the same as the first embodiment, and the main differences are that: the radius of curvature, aspherical coefficient, thickness, and the like of each lens surface are different.

The relevant parameters of each lens in the optical lens 500 in this embodiment are shown in table 9.

TABLE 9

The surface profile coefficients of the aspherical surfaces of the optical lens 500 in this embodiment are shown in table 10.

Table 10

Referring to fig. 18, 19 and 20, a field curvature curve, a distortion curve and an axial chromatic aberration curve of the optical lens 500 are shown.

The curvature of field curve of fig. 18 shows the degree of curvature of the meridional image plane and the sagittal image plane, and it can be seen from the figure that the curvature of field of the meridional image plane and the sagittal image plane is controlled within ±0.20 mm, which indicates that the curvature of field of the optical lens 500 is well corrected.

The distortion curves of fig. 19 show distortions at different image heights on the imaging plane, and it can be seen from the figures that the distortions at different image heights on the imaging plane are controlled within 4.5%, which indicates that the optical distortion of the optical lens 500 is well corrected.

The axial chromatic aberration curve of fig. 20 shows the aberration on the optical axis at the imaging plane, and it can be seen from the figure that the offset of the axial chromatic aberration is controlled within ±0.05mm, which indicates that the axial chromatic aberration of the optical lens 500 is well corrected.

Table 11 is an optical characteristic corresponding to the above five embodiments, and mainly includes the effective focal length F, f#, the maximum field angle FOV and the half-image height IH, the total optical length TTL, and the numerical value corresponding to each of the above conditional expressions.

TABLE 11

Compared with the prior art, the glass-plastic mixed optical lens provided by the invention has at least the following advantages:

(1) Because the optical lens provided by the invention has better light transmittance and higher refractive index, the transmittance of light is enhanced by adopting 1 glass lens and 4 plastic lenses, the offset of the lens at different temperatures is optimized, the optical performance is better, and the optical lens can be matched with an imaging chip with larger size to realize ultra-high definition imaging.

(2) According to the optical lens provided by the invention, 5 glass-plastic mixed lenses are adopted, and through specific surface shape collocation and reasonable focal power distribution, the lens has a compact structure and low cost, and can realize equalization of miniaturization, large wide angle and high pixels, so that the lens is better suitable for the development trend of a DMS (digital camera) system.

(3) The optical lens provided by the invention has reasonable lens shape and diaphragm position arrangement, so that the lens has large aperture characteristic, light quantity can be controlled to enter the body in a larger range, the control range of the light quantity is also larger, and the lens is favorable for shooting in low-light or dim environments.

(4) The general lens design wavelength is 435 nm-650 nm (visible light) wave band, no infrared light is required, so that the infrared resolution is poor, the optical lens provided by the invention can clearly image in the near infrared region 800-1100 nm (especially 920-960 nm) wave band, namely, the night imaging quality is effectively improved under the assistance of an infrared light source, and the imaging requirements of the infrared imaging characteristic and the high imaging quality in the DMS can be met.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the 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 embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The foregoing examples illustrate only a few embodiments of the invention and are described in detail herein without thereby limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.

Claims

1. An optical lens comprising, in order from an object side to an imaging surface along an optical axis:

a first lens with positive focal power, wherein the object side surface of the first lens is a convex surface;

a diaphragm;

a second lens with negative focal power, wherein the object side surface of the second lens is a concave surface, and the image side surface of the second lens is a concave surface at a paraxial region;

a third lens element with positive refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region;

a fourth lens element with positive refractive power, wherein the object-side surface of the fourth lens element is concave and the image-side surface of the fourth lens element is convex;

a fifth lens element with positive refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region;

wherein the optical lens at least comprises a plastic lens and a glass lens;

the optical lens satisfies the following conditional expression: 40 ° < FOV/f# <60 °, FOV represents the maximum field angle of the optical lens, and f# represents the F-number of the optical lens.

2. The optical lens according to claim 1, wherein the optical lens satisfies a conditional expression: 1.7< TTL/f <2.5, wherein TTL represents the total optical length of the optical lens and f represents the effective focal length of the optical lens.

3. The optical lens according to claim 1, wherein the optical lens satisfies a conditional expression: 1.3< f/IH <2.0, wherein f represents the effective focal length of the optical lens, and IH represents the image height corresponding to the maximum half field angle of the optical lens.

4. The optical lens according to claim 1, wherein the optical lens satisfies a conditional expression: 1.3< f1/f <4, wherein f1 represents a focal length of the first lens and f represents an effective focal length of the optical lens.

5. The optical lens according to claim 1, wherein the optical lens satisfies a conditional expression: -2< f2/f < -0.2, -6< R3/R4< -0.5, wherein f2 represents a focal length of the second lens, f represents an effective focal length of the optical lens, R3 represents a radius of curvature of an object side of the second lens, and R4 represents a radius of curvature of an image side of the second lens.

6. The optical lens according to claim 1, wherein the optical lens satisfies a conditional expression: 0.1< f3/f4<1, wherein f3 represents a focal length of the third lens and f4 represents a focal length of the fourth lens.

7. The optical lens according to claim 1, wherein the optical lens satisfies a conditional expression: 0.03< f4/f5<1,3< f5/f <50, wherein f4 represents a focal length of the fourth lens, f5 represents a focal length of the fifth lens, and f represents an effective focal length of the optical lens.

8. The optical lens according to claim 1, wherein the optical lens satisfies a conditional expression: 0.8< R1/f <2, wherein R1 represents a radius of curvature of an object side surface of the first lens, and f represents an effective focal length of the optical lens.

9. The optical lens according to claim 1, wherein the optical lens satisfies a conditional expression: -1.2< R8/R9< -0.8, wherein R8 represents a radius of curvature of the image side of the fourth lens and R9 represents a radius of curvature of the object side of the fifth lens.

10. The optical lens according to claim 1, wherein the optical lens satisfies a conditional expression: 1.25< CT4/CT5<3, wherein CT4 represents a center thickness of the fourth lens and CT5 represents a center thickness of the fifth lens.

11. The optical lens according to claim 1, wherein the optical lens satisfies a conditional expression: 0.9< f/D1<1.5,0.3< (D5-D1)/f <1, wherein f represents an effective focal length of the optical lens, D1 represents a maximum effective diameter of the first lens, and D5 represents a maximum effective diameter of the fifth lens.