Optical lens

Abstract

The application discloses an optical lens, which comprises, along an optical axis from an object side to an imaging plane, a first lens with negative focal power, the object side of which is a convex surface and the image side of which is a concave surface; a second lens with negative focal power, the object side and the image side of which are both concave surfaces; a third lens with positive focal power, the object side and the image side of which are both convex surfaces; a fourth lens with positive focal power, the object side of which is a convex surface and the image side of which is a concave surface; a voltage-driven zoom lens; a fifth lens with positive focal power, the object side and the image side of which are both convex surfaces; a sixth lens with negative focal power, the object side and the image side of which are both concave surfaces; a seventh lens with positive focal power, the object side of which is a concave surface and the image side of which is a convex surface; and an eighth lens with positive focal power, the object side and the image side of which are both convex surfaces. The optical lens has the advantages of fast focusing, small size, high image quality and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of imaging lens, in particular to an optical lens. BACKGROUND

[0002] Since 2010, China has achieved explosive growth in the field of machine vision, and with the development of camera technology, the camera module has gradually developed from the initial focal system with limited camera conditions to the zoom system that can switch between different camera conditions.

[0003] The existing zoom system generally changes the distance between lenses by driving part of the lens to move relatively through the voice coil motor to change the focal length of the zoom system, so as to realize the function of automatic focusing in various different shooting distances, and then to adapt to different object distances, depth of field, shooting range and other camera requirements while ensuring a certain imaging quality. At the same time, in order to obtain higher quality images, the existing zoom system gradually uses higher and higher pixel CCD or CMOS photosensitive chips.

[0004] However, in order to match the high pixel of the photosensitive chip with the image quality of the zoom system, it is usually necessary to increase the number of lenses, which increases the weight and volume of the lens; at the same time, for high-speed applications or precision applications that require rapid refocusing, the existing zoom system is difficult to shoot clear and accurate images, that is, the focusing speed is slow and the image quality is not high. SUMMARY

[0005] Therefore, the purpose of the present application is to provide an optical lens, which at least has the advantages of fast focusing, small volume and high image quality.

[0006] The present application achieves the above-mentioned purpose through the following technical solutions.

[0007] This invention provides an optical lens comprising, along the optical axis from the object side to the image plane: a first lens with negative optical power, wherein the object side of the first lens is convex and the image side is concave; a second lens with negative optical power, wherein both the object side and the image side of the second lens are concave; a third lens with positive optical power, wherein both the object side and the image side of the third lens are convex, and the second lens and the third lens form a first cemented lens group; and a fourth lens with positive optical power, wherein the object side of the fourth lens is convex and the image side is concave. The lens comprises: a concave surface; a voltage-driven zoom lens; a fifth lens with positive optical power, wherein both the object-side and image-side surfaces of the fifth lens are convex; a sixth lens with negative optical power, wherein both the object-side and image-side surfaces of the sixth lens are concave, and the fifth and sixth lenses together form a second cemented lens group; a seventh lens with positive optical power, wherein both the object-side and image-side surfaces of the seventh lens are concave, and the image-side surface of the seventh lens is convex; and an eighth lens with positive optical power, wherein both the object-side and image-side surfaces of the eighth lens are convex; wherein the voltage-driven zoom lens contains an aperture stop.

[0008] Compared to existing technologies, the optical lens provided by this invention uses eight lenses with specific shapes and employs a specific combination of optical power and surface profile to achieve high pixel count while maintaining a small weight and size. At the same time, it uses a voltage-driven zoom lens, which can achieve fast zooming and focusing as well as maintain high image quality under different working distances and temperature environments. Attached Figure Description

[0009] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0010] Figure 1 This is a schematic diagram of the structure of an optical lens provided in the first embodiment of the present invention;

[0011] Figure 2 A transverse chromatic aberration diagram of an optical lens provided in the first embodiment of the present invention;

[0012] Figure 3 The MTF diagram of the optical lens provided in the first embodiment of the present invention;

[0013] Figure 4 The distortion diagram of the optical lens provided in the first embodiment of the present invention;

[0014] Figure 5 This is a schematic diagram of the structure of an optical lens provided in the second embodiment of the present invention;

[0015] Figure 6 A transverse chromatic aberration diagram of an optical lens provided in the second embodiment of the present invention;

[0016] Figure 7 MTF diagram of the optical lens provided for the second embodiment of the present application;

[0017] Figure 8 Distortion diagram of the optical lens provided for the second embodiment of the present application;

[0018] Figure 9 Structure schematic diagram of the optical lens provided for the third embodiment of the present application;

[0019] Figure 10 Vignetting diagram of the optical lens provided for the third embodiment of the present application;

[0020] Figure 11 MTF diagram of the optical lens provided for the third embodiment of the present application;

[0021] Figure 12 Distortion diagram of the optical lens provided for the third embodiment of the present application. DETAILED DESCRIPTION

[0022] In order to make the objects, features and advantages of the present application more clear and easy to understand, the specific embodiments of the present application are described in detail below with reference to the drawings. The drawings show several embodiments of the present application. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terminology used in the description of the present application is only for the purpose of describing the specific embodiments and is not intended to limit the present application. Throughout the description and claims of this specification, the same reference numerals in different drawings represent the same elements.

[0024] The present application provides an optical lens, which comprises, in sequence along the optical axis from the object side to the imaging surface, a first lens, a second lens, a third lens, a fourth lens, a voltage-driven zoom lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens and a filter, and the optical centers of the lenses are located on the same straight line.

[0025] The voltage-driven zoom lens is provided with a diaphragm therein.

[0026] The first lens has a negative focal power, 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.

[0027] The second lens has a negative focal power, and the object side surface and the image side surface of the second lens are both concave surfaces.

[0028] The third lens has positive refractive power, both the object side surface and the image side surface of the third lens are convex, and the second lens and the third lens form a first cemented lens group;

[0029] The fourth lens has positive refractive power, the object side surface of the fourth lens is convex, and the image side surface of the fourth lens is concave;

[0030] The fifth lens has positive refractive power, both the object side surface and the image side surface of the fifth lens are convex;

[0031] The sixth lens has negative refractive power, both the object side surface and the image side surface of the sixth lens are concave, and the fifth lens and the sixth lens form a second cemented lens group;

[0032] The seventh lens has positive refractive power, the object side surface of the seventh lens is concave, and the image side surface of the seventh lens is convex;

[0033] The eighth lens has positive refractive power, both the object side surface and the image side surface of the eighth lens are convex.

[0034] In some embodiments, the optical lens satisfies the following conditional expression:

[0035] 4.0 < U / f < 5.5; (1)

[0036] wherein U represents the voltage of the voltage-driven zoom lens at a working object distance, and f represents the effective focal length of the optical lens. Satisfying the above conditional expression (1) can achieve good image quality at different working object distances, and by adjusting the voltage of the voltage-driven zoom lens to change the curvature thereof, the effective focal length of the optical lens can be changed, thereby realizing fast focusing of the optical lens.

[0037] In some embodiments, the optical lens satisfies the following conditional expression:

[0038] 0.25 < IH / TTL < 0.35; (2)

[0039] wherein TTL represents the total optical length of the optical lens, and IH represents the image height of the optical lens. When the value of IH / TTL exceeds the upper limit, the refractive power of each lens is too large, the lens aberration correction is difficult, and the resolution capability is significantly reduced. When the value of IH / TTL exceeds the lower limit, the total length of the lens is too long, and it is difficult to meet the demand for miniaturization; or the target surface is too small in the case that the total length of the lens is small enough, and it is difficult to match a larger chip.

[0040] In some embodiments, the optical lens satisfies the following conditional expression:

[0041] 10 < Vd3-Vd2 < 40; (3)

[0042] Vd3 / Vd2> 1.5, wherein Vd3 represents the Abbe number of the third lens, and Vd2 represents the Abbe number of the second lens. By selecting appropriate lens materials and reasonably matching the second lens and the third lens to satisfy the above condition formula (3), chromatic aberration correction of the optical system is facilitated, and resolution is improved.

[0043] In some embodiments, the optical lens satisfies the following condition formula:

[0044] |Φ41 / R41-Φ42 / R42| / 4 > 0.07; (4)

[0045] wherein Φ41 represents the effective clear aperture of the object side of the fourth lens, R41 represents the curvature radius of the object side of the fourth lens, Φ42 represents the effective clear aperture of the image side of the fourth lens, and R42 represents the curvature radius of the image side of the fourth lens. Satisfying the above condition formula (4) can reduce the processing difficulty and cost of the fourth lens.

[0046] In some embodiments, the optical lens satisfies the following condition formula:

[0047] 0.05 < CT45 / TTL < 0.2; (5)

[0048] wherein CT45 represents the air gap between the fourth lens and the fifth lens, and TTL represents the total optical length of the optical lens. By reasonably controlling the air gap between the fourth lens and the fifth lens to satisfy the above condition formula (5), the resolving power of the optical lens can be ensured while meeting the installation requirements of the optical lens. When the value of CT45 / TTL exceeds the upper limit, the gap between the fourth lens and the fifth lens is too large, which is not conducive to the voltage-driven zoom lens to present the captured image on the imaging surface after adjusting the focal length, resulting in a decrease in the resolution and poor image quality of the optical lens. When the value of CT45 / TTL exceeds the lower limit, there is not enough gap between the fourth lens and the fifth lens to install the voltage-driven zoom lens, which makes it difficult to assemble the optical lens.

[0049] In some embodiments, the optical lens satisfies the following condition formula:

[0050] 2.5 < f7 / f < 3.5; (6)

[0051] wherein f7 represents the effective focal length of the seventh lens, and f represents the effective focal length of the optical lens. Satisfying the above condition formula (6) can make the seventh lens bear part of the optical power of the optical system, which is conducive to the correction of spherical aberration of the optical system and provides better resolving power.

[0052] In some embodiments, the optical lens satisfies the following condition formula:

[0053] 25 < Vd5-Vd6 < 55; (7)

[0054] 30 < Vd7-Vd8 < 60; (8)

[0055] wherein Vd5 represents the Abbe number of the fifth lens, Vd6 represents the Abbe number of the sixth lens, Vd7 represents the Abbe number of the seventh lens, and Vd8 represents the Abbe number of the eighth lens. By selecting appropriate lens materials, the fifth lens, the sixth lens, the seventh lens and the eighth lens can bear part of the optical power of the optical system, which helps to correct aberration of the optical system and improve resolving power, by satisfying the above conditional expression (7) and conditional expression (8).

[0056] In some embodiments, the optical lens satisfies the following conditional expression:

[0057] 1.9 < Nd4 < 2.0; (10)

[0058] 10 < Vd4 < 40; (11)

[0059] wherein Vd4 represents the Abbe number of the fourth lens, and Nd4 represents the refractive index of the fourth lens. By selecting appropriate lens materials, the fourth lens can bear part of the optical power of the optical system, which helps to correct aberration of the optical system and improve resolving power, by satisfying the above conditional expression (10) and conditional expression (11).

[0060] In some embodiments, the optical lens satisfies the following conditional expression:

[0061] 28.0 mm < TTL < 32.0 mm; (12)

[0062] 7.65 mm ≤ f ≤ 8.35 mm; (13)

[0063] wherein TTL represents the total track length of the optical lens, and f represents the effective focal length of the optical lens. By satisfying the above conditional expression (12) and conditional expression (13), the total track length and the effective focal length of the optical lens can be reasonably controlled, and miniaturization of the optical lens can be achieved.

[0064] The application will be further described in the following embodiments. In each embodiment, the thickness, the radius of curvature and the material selection of each lens in the optical lens are different, and the specific differences can be seen from the parameter table of each embodiment. The following embodiments are only preferred embodiments of the application, but the embodiments of the application are not limited to the following embodiments only, and any changes, substitutions, combinations or simplifications made without departing from the innovative points of the application should be regarded as equivalent replacement methods, and are included in the protection scope of the application.

[0065] First embodiment

[0066] Referring to Figure 1 A structure diagram of the optical lens 100 provided by the first embodiment of the present application is shown in the figure, the optical lens 100 comprises, along the optical axis from the object side to the imaging surface, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a voltage-driven zoom lens VFL, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8 and a filter L9, and the optical centers of the lenses are located on the same line.

[0067] The first lens L1 has negative focal power, the object side S1 of the first lens is a convex surface, and the image side S2 of the first lens is a concave surface; the second lens L2 has negative focal power, the object side S3 of the second lens is a concave surface, and the image side of the second lens is a concave surface; the third lens L3 has positive focal power, the object side of the third lens is a convex surface, and the image side S5 of the third lens is a convex surface, and the second lens L2 and the third lens L3 form a first cemented lens group, and the image side of the second lens and the object side of the third lens form a cemented surface S4; the fourth lens L4 has positive focal power, the object side S6 of the fourth lens is a convex surface, and the image side S7 of the fourth lens is a concave surface; the voltage-driven zoom lens VFL is provided with a diaphragm; the fifth lens L5 has positive focal power, the object side S8 of the fifth lens is a convex surface, and the image side of the fifth lens is a convex surface; the sixth lens L6 has negative focal power, the object side of the sixth lens is a concave surface, and the image side S10 of the sixth lens is a concave surface, and the fifth lens L5 and the sixth lens L6 form a second cemented lens group, and the image side of the fifth lens and the object side of the sixth lens form a cemented surface S9; the seventh lens L7 has positive focal power, the object side S11 of the seventh lens is a concave surface, and the image side S12 of the seventh lens is a convex surface; the eighth lens L8 has positive focal power, and the object side S13 and the image side S14 of the eighth lens are both convex surfaces; the object side of the filter L9 is S15, and the image side is S16.

[0068] The related parameters of the lenses of the optical lens 100 provided by the embodiment are shown in Table 1.

[0069] Table 1

[0070]

[0071]

[0072] Referring to Figure 2 The figure shows the axial chromatic aberration diagram of the optical lens 100 in the embodiment, and it can be seen from the figure that the offset of the axial chromatic aberration is controlled within ±1 microns, which indicates that the optical lens 100 can effectively correct the axial chromatic aberration.

[0073] Referring to Figure 3The figure shows the MTF diagram of the optical lens 100 in this embodiment. As can be seen from the figure, the MTF value of the lens is above 0.25 at a spatial frequency of 180 lp / mm, indicating that the optical lens 100 has a high resolution.

[0074] Please see Figure 4 The figure shows the F-Theta distortion of the optical lens 100 in this embodiment. As can be seen from the figure, the F-Theta distortion of the lens is small and less than ±2%, indicating that the distortion of the optical lens 100 is well corrected.

[0075] Second Embodiment

[0076] Please see Figure 5 The diagram shown is a structural schematic of the optical lens 200 provided in this embodiment. The surface shape of each lens in the optical lens 200 in this embodiment is roughly the same as that in the optical lens 100 in the first embodiment. The difference is that the radius of curvature, thickness and air gap between each lens are different.

[0077] The relevant parameters of each lens of the optical lens 200 provided in this embodiment are shown in Table 2.

[0078] Table 2

[0079]

[0080]

[0081] Please see Figure 6 The figure shows the chromatic aberration diagram of the optical lens 200 in this embodiment. As can be seen from the figure, the offset of the chromatic aberration is controlled within ±0.5 micrometers, indicating that the optical lens 200 can effectively correct the chromatic aberration.

[0082] Please see Figure 7 The figure shows the MTF diagram of the optical lens 200 in this embodiment. As can be seen from the figure, the MTF value of the lens is above 0.3 at a spatial frequency of 180 lp / mm, indicating that the optical lens 200 has a high resolution.

[0083] Please see Figure 8 The figure shows the F-Theta distortion of the optical lens 200 in this embodiment. As can be seen from the figure, the F-Theta distortion of the lens is small and less than ±2%, indicating that the distortion of the optical lens 200 is well corrected.

[0084] Third Embodiment

[0085] Please see Figure 9The diagram shown is a structural schematic of the optical lens 300 provided in this embodiment. The surface shape of each lens in the optical lens 300 in this embodiment is roughly the same as that in the optical lens 100 in the first embodiment. The difference is that the radius of curvature, thickness and air gap between each lens are different.

[0086] The relevant parameters of each lens of the optical lens 300 provided in this embodiment are shown in Table 3.

[0087] Table 3

[0088]

[0089]

[0090] Please see Figure 10 The figure shows the chromatic aberration diagram of the optical lens 300 in this embodiment. As can be seen from the figure, the offset of the chromatic aberration is controlled within ±1.2 micrometers, indicating that the optical lens 300 can effectively correct the chromatic aberration.

[0091] Please see Figure 11 The figure shows the MTF diagram of the optical lens 300 in this embodiment. As can be seen from the figure, the MTF value of the lens is above 0.3 at a spatial frequency of 180 lp / mm, indicating that the optical lens 300 has a high resolution.

[0092] Please see Figure 12 The figure shows the F-Theta distortion of the optical lens 300 in this embodiment. As can be seen from the figure, the F-Theta distortion of the lens is small and less than ±2%, indicating that the distortion of the optical lens 300 is well corrected.

[0093] Please refer to Table 4, which shows the optical characteristics of the optical lenses provided in the three embodiments above, including the total optical length TTL, aperture number F#, effective focal length f, field of view FOV, and image height IH of the optical lens, as well as the relevant values ​​corresponding to each condition in the above conditional expressions.

[0094] Table 4

[0095]

[0096]

[0097] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the patent scope of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. An optical lens characterized in that, The optical lens comprises eight lenses and one voltage-driven zoom lens, and from the object side to the imaging surface along the optical axis, they are in sequence: a first lens with negative refractive power, the object side surface of the first lens is convex, and the image side surface of the first lens is concave; a second lens with negative refractive power, the object side surface and the image side surface of the second lens are both concave; a third lens with positive refractive power, the object side surface and the image side surface of the third lens are both convex, and the second lens and the third lens form a first cemented lens group; a fourth lens with positive refractive power, the object side surface of the fourth lens is convex, and the image side surface of the fourth lens is concave; the voltage-driven zoom lens, the curvature of the voltage-driven zoom lens is changed by adjusting the voltage of the voltage-driven zoom lens; a fifth lens with positive refractive power, the object side surface and the image side surface of the fifth lens are both convex; a sixth lens with negative refractive power, the object side surface and the image side surface of the sixth lens are both concave, and the fifth lens and the sixth lens form a second cemented lens group; a seventh lens with positive refractive power, the object side surface of the seventh lens is concave, and the image side surface of the seventh lens is convex; an eighth lens with positive refractive power, the object side surface and the image side surface of the eighth lens are both convex.

2. The optical lens of claim 1, wherein, The optical lens satisfies the following conditional expression: 4.0 < U / f < 5.5; wherein U represents the voltage of the voltage-driven zoom lens at the working object distance, and f represents the effective focal length of the optical lens.

3. The optical lens of claim 1, wherein, The optical lens satisfies the following conditional expression: 0.25 < IH / TTL < 0.35; wherein TTL represents the total optical length of the optical lens, and IH represents the image height of the optical lens.

4. The optical lens of claim 1, wherein, The optical lens satisfies the following conditional expression: 10 < Vd3-Vd2 < 40; wherein Vd3 represents the Abbe number of the third lens, and Vd2 represents the Abbe number of the second lens.

5. The optical lens of claim 1, wherein, The optical lens satisfies the following conditional expression: |Φ41 / R41-Φ42 / R42| / 4 > 0.07; wherein Φ41 represents the effective light aperture of the object side surface of the fourth lens, R41 represents the curvature radius of the object side surface of the fourth lens, Φ42 represents the effective light aperture of the image side surface of the fourth lens, and R42 represents the curvature radius of the image side surface of the fourth lens.

6. The optical lens of claim 1, wherein, The optical lens satisfies the following conditional expression: 0.05 < CT45 / TTL < 0.2; wherein CT45 represents the air gap between the fourth lens and the fifth lens, and TTL represents the total optical length of the optical lens.

7. The optical lens of claim 1, wherein, The optical lens satisfies the following conditional expression: 2.5 < f7 / f < 3.5; wherein f7 represents the effective focal length of the seventh lens, and f represents the effective focal length of the optical lens.

8. The optical lens of claim 1, wherein, The optical lens satisfies the following conditional expression: 25 < Vd5-Vd6 < 55; 30 < Vd7-Vd8 < 60; wherein Vd5 represents the Abbe number of the fifth lens, Vd6 represents the Abbe number of the sixth lens, Vd7 represents the Abbe number of the seventh lens, and Vd8 represents the Abbe number of the eighth lens.

9. The optical lens of claim 1, wherein, A diaphragm is arranged in the voltage-driven zoom lens.

10. The optical lens of claim 1, wherein, The optical lens satisfies the following conditional expression: 28.0 mm < TTL < 32.0 mm; 7.65 mm < f < 8.35 mm; wherein TTL represents an optical total track length of the optical lens, and f represents an effective focal length of the optical lens.

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