CN113970840B

CN113970840B - Optical lens

Info

Publication number: CN113970840B
Application number: CN202111609339.8A
Authority: CN
Inventors: 王俊晨; 陈伟建
Original assignee: Jiangxi Lianchuang Electronic Co Ltd
Current assignee: Jiangxi Lianchuang Electronic Co Ltd
Priority date: 2021-12-27
Filing date: 2021-12-27
Publication date: 2022-05-24
Anticipated expiration: 2041-12-27
Also published as: CN113970840A

Abstract

The invention discloses an optical lens, which comprises five lenses in total and sequentially comprises the following components from an image side to an object side along an optical axis: the image side surface of the first lens is a concave surface; a second lens having a positive refractive power, both the object-side surface and the image-side surface of the second lens being convex; a diaphragm; a third lens with positive focal power, wherein the object side surface of the third lens is a concave surface, and the image side surface of the third lens is a convex surface; a fourth lens with negative focal power, wherein the object side surface of the fourth lens is a convex surface, and the image side surface of the fourth lens is a concave surface; and the fourth lens and the fifth lens are mutually cemented to form the cemented lens. According to the optical lens, at least one beneficial effect of miniaturization, large aperture, good temperature performance, high relative illumination and the like can be realized.

Description

Optical lens

Technical Field

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

Background

At present, the application of the optical lens is more and more extensive, and the requirement of miniaturization of the lens is more and more prominent. In order to increase the amount of light entering, a large-aperture lens is generally required, however, in general, the smaller the FNO, the more blurred the imaging, and therefore, it is difficult to achieve a high resolution for a lens with a small FNO. In order to improve the image quality, the number of lenses generally needs to be increased, but the volume and weight of the lens are increased accordingly, which is not favorable for the miniaturization of the lens and causes the increase of the manufacturing cost. In addition, some lenses used in special applications are affected by harsh environments, and the image quality is deteriorated, so that the requirements for stable imaging of the lens in a large temperature difference range are high.

Disclosure of Invention

Accordingly, the present invention provides an optical lens for solving at least one technical defect of the conventional optical lens.

In order to achieve the purpose, the technical scheme of the invention is as follows:

the invention provides an optical lens, which comprises five lenses in total, and the optical lens sequentially comprises the following components from an object side to an imaging surface:

the image side surface of the first lens is a concave surface;

a second lens having a positive refractive power, both the object-side surface and the image-side surface of which are convex surfaces;

a diaphragm;

a third lens with positive focal power, wherein the object side surface of the third lens is a concave surface, and the image side surface of the third lens is a convex surface;

a fourth lens with negative focal power, wherein the object side surface of the fourth lens is a convex surface, and the image side surface of the fourth lens is a concave surface;

the fourth lens and the fifth lens are mutually cemented to form a cemented lens;

wherein a maximum field angle FOV of the optical lens satisfies: FOV is more than or equal to 80 degrees and less than or equal to 100 degrees; the aperture value FNO of the optical lens meets the following conditions: FNO is less than or equal to 1.1; the relative illumination RI corresponding to the maximum field angle of the optical lens meets the following requirements: RI > 85%.

In some embodiments, the total optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: TTL/f is more than 3.5 and less than 5.0.

In some embodiments, the maximum field angle FOV of the optical lens and the aperture value FNO of the optical lens satisfy: 70 < FOV/FNO < 100.

In some embodiments, the effective focal length f of the optical lens satisfies with the radius of curvature R3 of the object-side surface of the second lens and the radius of curvature R4 of the image-side surface of the second lens: f/(R3-R4) < 0.15 < 0.25.

In some embodiments, a radius of curvature R5 of the object-side surface of the third lens and a radius of curvature R6 of the image-side surface of the third lens satisfy: 4.5 < R5/R6 < 6.5.

In some embodiments, the effective focal length f of the optical lens and the focal length f3 of the third lens satisfy: f3/f is more than 2.0 and less than 3.0.

In some embodiments, the effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: 2.2 < f5/f < 3.5.

In some embodiments, the total optical length TTL of the optical lens and the separation distance T23 on the optical axis between the second lens and the third lens satisfy: 0.06 < T23/TTL < 0.12.

In some embodiments, the first lens to the fifth lens are all glass spherical lenses.

Compared with the prior art, the invention has the beneficial effects that: the optical lens adopts five lenses, and at least one of the beneficial effects of miniaturization, large aperture, good temperature performance, high relative illumination and the like of the optical lens is realized by optimally setting the shapes of the lenses and reasonably distributing the focal power of each lens.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

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

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

fig. 2 is a contrast chart of the optical lens system according to embodiment 1 of the present invention;

FIG. 3 is a graph showing F-Theta distortion of an optical lens according to embodiment 1 of the present invention;

fig. 4 is a schematic structural diagram of an optical lens system according to embodiment 2 of the present invention;

fig. 5 is a contrast chart of the optical lens system according to embodiment 2 of the present invention;

FIG. 6 is a graph showing F-Theta distortion of an optical lens in embodiment 2 of the present invention;

fig. 7 is a schematic structural diagram of an optical lens system according to embodiment 3 of the present invention;

fig. 8 is a contrast chart of the optical lens system according to embodiment 3 of the present invention;

FIG. 9 is a graph showing F-Theta distortion of an optical lens according to embodiment 3 of the present invention;

fig. 10 is a schematic structural diagram of an optical lens system according to embodiment 4 of the present invention;

fig. 11 is a contrast chart of the optical lens system according to embodiment 4 of the present invention;

fig. 12 is a graph showing the F-Theta distortion of the optical lens in embodiment 4 of the present invention.

Description of the main element symbols:

the following detailed description will further illustrate the invention in conjunction with the above-described figures.

Detailed Description

For a better understanding of the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It should be understood that the detailed description is merely illustrative of embodiments of the application and does not limit the scope of the application in any way. Like reference numerals refer to like elements throughout the specification. The expression "and/or" includes any and all combinations of one or more of the associated listed items.

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

In the drawings, the thickness, size, and shape of the lens have been slightly exaggerated for convenience of explanation. In particular, the shapes of the spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shape of the spherical surface or the aspherical surface is not limited to the shape of the spherical surface or the aspherical surface shown in the drawings. The figures are purely diagrammatic and not drawn to scale.

Herein, the paraxial region refers to a region 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 surface of each lens closest to the object is called the object side surface of the lens, and the surface of each lens closest to the imaging surface is called the image side surface of the lens.

It will be further understood that the terms "comprises," "comprising," "has," "having," "includes" and/or "including," when used in this specification, specify the presence of stated features, elements, and/or components, but do not preclude the presence or addition of one or more other features, elements, components, and/or groups thereof. Moreover, when a statement such as "at least one of" appears after a list of listed features, the entirety of the listed features is modified rather than modifying individual elements in the list. Furthermore, when describing embodiments of the present application, the use of "may" mean "one or more embodiments of the present application. Also, the term "exemplary" is intended to refer to an example or illustration.

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

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

An optical lens according to an embodiment of the present application includes, in order from an object side to an image side: the lens comprises a first lens, a second lens, a diaphragm, a third lens, a fourth lens and a fifth lens.

The first lens has negative focal power, and the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface. The first lens is in a meniscus shape with the convex surface facing the object side, can collect large view field light rays as far as possible to enter a rear optical system, increases the light flux, and is beneficial to realizing the whole large view field range. The first lens can use high refractive index material, for example, the refractive index of the first lens satisfies Nd1 ≧ 1.5, so as to facilitate reduction of the front end aperture and improvement of the imaging quality.

The second lens has positive focal power, and the object-side surface and the image-side surface of the second lens are convex surfaces. The second lens is a biconvex lens, which is beneficial to converging light rays, so that the diverging light rays smoothly enter a rear optical system after being converged, and the miniaturization is facilitated. In addition, the lens with positive focal power can balance the spherical aberration introduced by the front lens and improve the imaging quality of the optical lens.

The third lens has positive focal power, and the object side surface of the third lens is a concave surface while the image side surface of the third lens is a convex surface. The third lens can converge the divergent light to the rear optical system, and can shorten the optical path of the peripheral light to the imaging surface, thereby improving the resolution quality.

The fourth lens has negative focal power, and the object side surface of the fourth lens is a convex surface and the image side surface of the fourth lens is a concave surface.

The fifth lens has positive focal power, and the object-side surface and the image-side surface of the fifth lens are both convex surfaces.

The image side surface of the fourth mirror is cemented with the object side surface of the fifth mirror, and the fourth mirror and the fifth mirror are combined into a cemented lens, which is favorable for eliminating chromatic aberration influence, reducing field curvature and correcting coma; meanwhile, the cemented lens may also retain a part of chromatic aberration to balance the entire chromatic aberration of the optical system. In the cemented lens, the fourth lens near the object side has negative power, the fifth lens near the image side has positive power, and the positive and negative lenses are cemented to reduce aberration and optical total length. In addition, the gluing of the lens can reduce tolerance sensitivity problems of inclination, core deviation and the like of the lens unit caused in the assembling process.

The fourth lens with negative focal power is arranged in front of the optical lens, the fifth lens with positive focal power is arranged behind the optical lens, the light rays converged by the fourth lens at the front end can be diverged and transited firstly, and then the fifth lens with positive focal power is used for further correcting aberration and converging the light rays to an imaging surface. In the embodiment of the application, the opening angle of the bonding surface can be increased, which is beneficial to the quick focusing of peripheral light rays and improves the imaging quality.

In some embodiments, a diaphragm for limiting the light beam is arranged between the second lens and the third lens, so as to further improve the imaging quality of the lens. When the diaphragm is arranged between the second lens and the third lens, the diaphragm can be beneficial to effectively collecting light rays entering the optical system and reducing the aperture of the optical lens. It should be noted, however, that the positions of the diaphragms disclosed herein are merely examples and not limitations; in alternative embodiments, the diaphragm may be disposed at other positions according to actual needs.

In some embodiments, the maximum field angle FOV of the optical lens satisfies: the FOV is more than or equal to 80 degrees and less than or equal to 100 degrees. Satisfying the above range, the optical lens can be ensured to have a characteristic of a large angle of view.

In some embodiments, the aperture value FNO of the optical lens satisfies: FNO is less than or equal to 1.1. Satisfying the above range, the optical lens can be ensured to have a characteristic of a large aperture.

In some embodiments, the total optical length TTL and the effective focal length f of the optical lens satisfy: TTL/f is more than 3.5 and less than 5.0. The optical total length of the optical lens can be effectively shortened under the condition of fixed focal length, and the miniaturization of the optical lens is facilitated.

In some embodiments, the total optical length TTL of the optical lens and the image height IH corresponding to the maximum field angle satisfy: TTL/IH is more than 2.7 and less than 3.0. The optical lens system meets the conditional expression, can effectively shorten the optical total length of the optical lens while considering good imaging quality, and is beneficial to miniaturization of the optical lens.

In some embodiments, the maximum field angle FOV of the optical lens and the aperture value FNO satisfy: 70 < FOV/FNO < 100. The condition formula is satisfied, the field angle of the optical lens is favorably enlarged, the aperture of the optical lens is enlarged, the large field angle and the large aperture characteristic are realized, the realization of the large field angle characteristic is favorable for the optical lens to acquire more scene information, the requirement of large-range detection is satisfied, the realization of the large aperture characteristic is favorable for improving the problem that the relative brightness of the edge is reduced rapidly caused by the large field angle, and therefore the acquisition of more tasting-up information is also favorable.

In some embodiments, the relative illuminance RI corresponding to the maximum field angle of the optical lens satisfies: RI > 85%. The condition formula is satisfied, the illumination of the edge field of view is favorably improved, and the shooting effect of the optical lens in a dark light environment is enhanced.

In some embodiments, the effective focal length f of the optical lens satisfies, with the radius of curvature R3 of the object-side surface of the second lens and the radius of curvature R4 of the image-side surface of the second lens: f/(R3-R4) < 0.15 < 0.25. The astigmatism of the system can be effectively controlled by meeting the conditional expression, and the imaging quality of the edge field can be improved.

In some embodiments, a radius of curvature R5 of the third lens object-side surface and a radius of curvature R6 of the third lens image-side surface of the optical lens satisfy: 4.5 < R5/R6 < 6.5. The angle of the principal ray incidence image surface of the peripheral field angle can be reduced by satisfying the conditional expression, the spherical aberration is reduced, the aberration of the peripheral field angle is corrected, and the imaging quality of the peripheral field angle can be improved.

In some embodiments, the effective focal length f of the optical lens and the focal length f3 of the third lens satisfy: f3/f is more than 2.0 and less than 3.0. The light source satisfies the condition formula, can realize the smooth transition of light, and is favorable for realizing a large-aperture diaphragm.

In some embodiments, the effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: 2.2 < f5/f < 3.5. The condition formula is satisfied, so that the fifth lens of the last lens has a short focal length, light convergence is facilitated, and the light transmission amount of the optical lens is ensured.

In some embodiments, the total optical length TTL of the optical lens and the separation distance T23 on the optical axis between the second lens and the third lens satisfy: 0.06 < T23/TTL < 0.12. Satisfying the above conditions, the optical total length of the optical lens can be effectively shortened, which is beneficial to the miniaturization of the optical lens.

The optical lens according to the above-described embodiment of the present application employs, for example, five lenses, and at least one of advantageous effects of downsizing, large aperture, good temperature performance, high relative illuminance, and the like of the optical lens is achieved by optimally setting the shapes of the lenses and reasonably distributing the focal powers of the lenses.

In the following embodiments, the thickness, the curvature radius, and the material selection of each lens in the optical lens are different, and specific differences can be referred to in the parameter tables of the embodiments.

Example 1

Referring to fig. 1, a schematic structural diagram of an optical lens 100 according to embodiment 1 of the present invention is shown, the optical lens sequentially includes, from an object side to an image plane along an optical axis: a first lens L1, a second lens L2, an aperture stop ST, a third lens L3, a fourth lens L4, a fifth lens L5, and a filter G1.

The first lens element L1 has negative power, and has a convex object-side surface S1 and a concave image-side surface S2;

the second lens L2 has positive focal power, and both the object side surface S3 and the image side surface S4 are convex surfaces;

the third lens element L3 has positive power, and has a concave object-side surface S5 and a convex image-side surface S6;

the fourth lens element L4 has negative power, and has a convex object-side surface S7 and a concave image-side surface;

the fifth lens L5 has positive focal power, the object-side surface and the image-side surface S9 of the fifth lens are convex surfaces, the fourth lens L4 and the fifth lens L5 are mutually cemented to form a cemented lens, namely the cemented surface of the image-side surface of the fourth lens L4 and the object-side surface of the fifth lens L5 is S8;

the first lens L1, the second lens L2, the third lens L3, the fourth lens L4 and the fifth lens L5 are all glass spherical lenses.

Table 1 shows the relevant parameters of each lens of the optical lens 100 provided in this embodiment.

TABLE 1

In the present embodiment, the relative illuminance graph and the F-Theta distortion graph of the optical lens 100 are shown in fig. 2 and 3, respectively.

Referring to fig. 2, a graph of relative illuminance of the optical lens of the present embodiment is shown, in which the horizontal axis represents the Y field angle (unit: °), and the vertical axis represents the relative illuminance (unit:%) of different field angles on the image plane. As can be seen from fig. 2, the relative contrast value of the optical lens is still greater than 92% at the maximum half field angle, indicating that the relative contrast of the optical lens is high.

Referring to fig. 3, a graph of F-Theta distortion of the optical lens of the present embodiment is shown, in which the F-Theta distortion of the light with the central wavelength at different image heights on the image plane is shown, the horizontal axis shows the F-Theta distortion (unit:%), and the vertical axis shows the Y field angle (unit:%). As can be seen from fig. 3, the F-Theta distortion of the optical lens is controlled within 6% at the maximum half field angle, which indicates that the F-Theta distortion of the optical lens is well corrected.

Example 2

Referring to fig. 4, a schematic structural diagram of an optical lens 200 according to embodiment 2 of the present invention is shown, the optical lens sequentially includes, from an object side to an image plane along an optical axis: a first lens L1, a second lens L2, an aperture stop ST, a third lens L3, a fourth lens L4, a fifth lens L5, and a filter G1.

The first lens element L1 has negative power, and has a planar object-side surface S1 and a concave image-side surface S2;

the fifth lens L5 has positive focal power, the object side surface and the image side surface S9 are convex surfaces, and the fourth lens and the fifth lens are mutually cemented to form a cemented lens;

the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 are all glass spherical lenses, that is, a bonding surface between an image side surface of the fourth lens L4 and an object side surface of the fifth lens L5 is S8;

Table 2 shows the parameters related to each lens of the optical lens 200 provided in this embodiment.

TABLE 2

In the present embodiment, the relative illuminance graph and the F-Theta distortion graph of the optical lens 200 are shown in fig. 5 and 6, respectively.

Referring to fig. 5, a graph of relative illuminance of the optical lens of the present embodiment is shown, in which the horizontal axis represents the Y field angle (unit: °), and the vertical axis represents the relative illuminance (unit:%) of different field angles on the image plane. As can be seen from fig. 5, the contrast value of the optical lens is still greater than 90% at the maximum half field angle, which indicates that the contrast of the optical lens is high.

Fig. 6 is a graph showing F-Theta distortion of the optical lens of the present embodiment, wherein the F-Theta distortion is shown at different image heights of the light beam with the central wavelength on the image plane, the horizontal axis shows the F-Theta distortion (unit:%), and the vertical axis shows the Y field angle (unit:%). As can be seen from fig. 3, the F-Theta distortion of the optical lens is controlled within 3% at the maximum half field angle, which indicates that the F-Theta distortion of the optical lens is well corrected.

Example 3

Referring to fig. 7, a schematic structural diagram of an optical lens 300 according to embodiment 3 of the present invention is shown, the optical lens sequentially includes, from an object side to an image plane along an optical axis: a first lens L1, a second lens L2, an aperture stop ST, a third lens L3, a fourth lens L4, a fifth lens L5, and a filter G1.

Table 3 shows the parameters related to each lens of the optical lens 300 according to the present embodiment.

TABLE 3

In the present embodiment, the relative illuminance graph and the F-Theta distortion graph of the optical lens 300 are shown in fig. 8 and 9, respectively.

Fig. 8 is a graph showing relative illuminance of the optical lens of the present embodiment, wherein the graph shows relative illuminance values of different viewing angles on the image plane, the horizontal axis shows the Y viewing angle (unit: °), and the vertical axis shows the relative illuminance (unit:%). As can be seen from fig. 8, the relative contrast value of the optical lens is still greater than 89% at the maximum half field angle, which indicates that the relative contrast of the optical lens is high.

Fig. 9 is a graph showing F-Theta distortion of the optical lens of the present embodiment, wherein the F-Theta distortion is shown at different image heights of the light beam with the central wavelength on the image plane, the horizontal axis shows the F-Theta distortion (unit:%), and the vertical axis shows the Y field angle (unit:%). As can be seen from fig. 9, the F-Theta distortion of the optical lens is controlled within 5% at the maximum half field angle, which indicates that the F-Theta distortion of the optical lens is well corrected.

Example 4

Referring to fig. 10, a schematic structural diagram of an optical lens 400 according to embodiment 4 of the present invention is shown, the optical lens sequentially includes, from an object side to an image plane along an optical axis: a first lens L1, a second lens L2, an aperture stop ST, a third lens L3, a fourth lens L4, a fifth lens L5, and a filter G1.

Table 4 shows the parameters related to each lens of the optical lens 400 provided in this embodiment.

TABLE 4

In the present embodiment, the relative illuminance graph and the F-Theta distortion graph of the optical lens 400 are shown in fig. 11 and 12, respectively.

Fig. 11 is a graph showing relative illuminance of the optical lens of the present embodiment, wherein the graph shows relative illuminance values of different viewing angles on an image plane, the horizontal axis shows Y viewing angle (unit:%), and the vertical axis shows relative illuminance (unit:%). As can be seen from fig. 11, the contrast value of the optical lens at the maximum half field angle is still greater than 86%, which indicates that the contrast of the optical lens is high.

Fig. 12 is a graph showing F-Theta distortion of the optical lens of the present embodiment, wherein the F-Theta distortion is shown at different image heights of the light beam with the central wavelength on the image plane, the horizontal axis shows the F-Theta distortion (unit:%), and the vertical axis shows the Y field angle (unit:%). As can be seen from FIG. 12, the F-Theta distortion of the optical lens is controlled within 6% at the maximum half field angle, which shows that the F-Theta distortion of the optical lens is well corrected

Please refer to table 5, which shows the optical characteristics of the optical lens provided in each of the above four embodiments, mainly including the total optical length TTL, the effective focal length f, the f-stop FNO, the image height IH corresponding to the field angle FOV and the maximum field angle of the optical lens, and the values corresponding to each of the aforementioned conditional expressions.

TABLE 5

In summary, the optical lens provided in the embodiments of the present invention employs five glass lenses, and by optimally setting the shapes of the lenses and reasonably allocating the focal powers of the lenses, at least one of the beneficial effects of miniaturization, large aperture, good temperature performance, high relative illumination, and the like of the optical lens is achieved.

The above examples are merely illustrative of several embodiments of the present invention, and the description thereof is more specific and detailed, but not to be construed as limiting the scope of the invention. It should be noted that, for those skilled in the art, various changes and modifications can be made without departing from the spirit of the invention, and these changes and modifications are all within the scope of the invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims

1. An optical lens system includes five lenses, in order from an object side to an image plane along an optical axis:

the image side surface of the first lens is a concave surface;

a second lens having a positive refractive power, both the object-side surface and the image-side surface of the second lens being convex;

a diaphragm;

a fourth lens element with negative refractive power having a convex object-side surface and a concave image-side surface;

the fourth lens and the fifth lens are mutually glued to form a cemented lens;

2. An optical lens according to claim 1, wherein the total optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: TTL/f is more than 3.5 and less than 5.0.

3. An optical lens according to claim 1, wherein the maximum field angle FOV of the optical lens and the aperture value FNO of the optical lens satisfy: 70 < FOV/FNO < 100.

4. An optical lens as claimed in claim 1, characterized in that the effective focal length f of the optical lens satisfies, together with a radius of curvature R3 of the object-side surface of the second lens and a radius of curvature R4 of the image-side surface of the second lens: f/(R3-R4) < 0.15 < 0.25.

5. An optical lens as claimed in claim 1, characterized in that the radius of curvature R5 of the object-side surface of the third lens and the radius of curvature R6 of the image-side surface of the third lens satisfy: 4.5 < R5/R6 < 6.5.

6. An optical lens according to claim 1, characterized in that the effective focal length f of the optical lens and the focal length f3 of the third lens satisfy: f3/f is more than 2.0 and less than 3.0.

7. An optical lens according to claim 1, characterized in that the effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: 2.2 < f5/f < 3.5.

8. An optical lens as claimed in claim 1, wherein the total optical length TTL of the optical lens and the distance T23 between the second lens and the third lens on the optical axis satisfy: 0.06 < T23/TTL < 0.12.

9. An optical lens according to claim 1, wherein the first lens to the fifth lens are all glass spherical lenses.