CN114265185B - Optical lens and imaging device - Google Patents

Abstract

The application discloses an optical lens, which comprises a third lens, a fourth lens and a fifth lens, wherein the third lens is a positive focal power glass spherical lens, and both the object plane side and the image plane side of the third lens are convex surfaces; the fourth lens and the fifth lens form a cemented lens; the object plane side and the image plane side of the fourth lens are convex surfaces; the object plane side and the image plane side of the fifth lens are concave surfaces; the light rays sequentially pass through the third lens, the fourth lens and the fifth lens. Has high resolution and small distortion; the problems of low relative illumination of an external view field, serious ghost images and the like are solved; has the advantages of simple structure and low cost.

Description

Optical lens and imaging device

Technical Field

The present disclosure relates to the field of optical imaging technologies, and in particular, to an optical lens and an imaging device.

Background

With the rapid development of automobile driving assistance systems, optical lenses play an increasingly important role therein. Particularly, the vehicle-mounted lens is arranged in or outside an automobile cab, and monitors the front situation of the automobile through an image imaged on a Sensor by the lens. The in-vehicle lens plays an important role in an automatic driving system. Because of safety concerns, optical lenses for automotive applications have more stringent requirements for certain optical parameters, and in particular, for their resolution performance.

Chinese patent application "an ultra wide angle high definition high speed photographic lens optical system", application number: CN201420218382.0 discloses that the optical system is composed of a first lens (L1) with negative power, a second lens (L2) with negative power, a third lens (L3) with positive power, a diaphragm, a fourth lens (L4) with positive power, a fifth lens (L5) with negative power, a sixth lens (L6) with positive power and a day and night optical filter (L7), which are sequentially arranged from the object to the image plane side along the optical axis, and the objects with different distances can be imaged clearly at the image plane through the overall movement of the lens. The optical system has the characteristics of ultra wide angle, large aperture, visible light wave band and near infrared wave band, and clear imaging, and the optical system lens adopts spherical lenses, uses common crown glass or flint glass, has low cost, and is suitable for batch production.

Chinese patent application "a fish-eye lens", application number: CN201821462930.9 discloses a lens comprising a first lens with convex-concave negative focal power, a second lens with biconcave negative focal power, a third lens with biconvex positive focal power, a fourth lens with biconvex positive focal power, a fifth lens with biconcave negative focal power, and a sixth lens with biconvex positive focal power, which are arranged in sequence from an object side to an image side, wherein the first and second lenses are glass lenses, and the third and fifth sixth lenses are plastic aspheric lenses. By reasonably distributing the focal power, the visual field of the invention can reach ultra wide angle, visible and infrared confocal, 4K imaging is realized, and meanwhile, the resolution power is kept unchanged in a high-low temperature environment of-40-85 ℃.

However, the resolution of the optical lens still has a space for improvement, and the optical lens has larger distortion or higher cost and larger volume. And the external view field has low relative illumination and serious ghost images.

Disclosure of Invention

An object of the present invention is to provide an optical lens and an imaging apparatus having high resolution, less distortion, and high relative illuminance.

Another object of the present application is to provide an optical lens and an imaging apparatus, which solve the problems of low relative illuminance of an external field, serious ghost images, and the like.

Another object of the present invention is to provide an optical lens and an imaging apparatus, which have the advantages of simple structure and low cost.

The technical scheme that this application adopted is: an optical lens comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and an optical filter which are sequentially arranged from an object side to an imaging side along an optical axis; the third lens is a glass spherical lens with positive focal power, and the object plane side and the image plane side of the third lens are convex surfaces; the fourth lens and the fifth lens form a cemented lens; the object plane side and the image plane side of the fourth lens are convex surfaces; the object plane side and the image plane side of the fifth lens are concave surfaces.

Compared with the prior art, the lens has the advantages that the third lens adopts the spherical lens of the glass with positive focal power, is not defocused at high and low temperatures, and can still maintain the excellent performance in the high and low temperature environment of-40 ℃ to 85 ℃. The object plane side and the image plane side of the third lens are convex surfaces, and can converge and properly compress divergent light rays, so that the light rays smoothly transition in trend and smoothly enter the rear optical system. The structure can effectively control the generation of the ghost images, so that the lens has fewer ghost images.

And the fourth lens and the fifth lens form a cemented lens, and the cemented lens can be used for minimizing chromatic aberration or eliminating chromatic aberration. And the whole structure of the optical system is compact, the miniaturization requirement is met, and the tolerance sensitivity problem of the lens unit caused by inclination/eccentric core and the like in the assembling process is reduced. The use of the cemented lens in the optical lens can improve the image quality and reduce the reflection loss of light energy, thereby improving the imaging definition of the lens. In addition, the use of the cemented lens can also simplify the assembly procedure in the lens manufacturing process.

According to the high-definition imaging device, the lens shape is optimally set, the focal power is reasonably distributed, and the number of spherical surfaces and aspherical mirror surfaces is properly set, so that high-definition imaging can be realized. Meanwhile, the requirements of miniaturization, small distortion, high resolution, low cost, good temperature adaptability and the like of the lens can be met. The application requirements of miniaturization and high resolution of the vehicle-mounted side view lens are met. On the basis, the third lens and the bonding lens in the optical lens are mutually matched, so that the influence of temperature change on the focal length of the lens is effectively compensated, and the stability of the resolving power of the lens at different temperatures is further improved.

In some embodiments of the present application, the present application further includes a first lens.

The first lens is a glass spherical lens with negative focal power, the object plane side of the first lens is a convex surface, and the image plane side of the first lens is a concave surface;

the focal length value F1 of the first lens satisfies the following relationship: -8 is more than or equal to F1 is more than or equal to-6; the optical refractive index Nd1 and abbe constant Vd1 of the first lens respectively satisfy: 2.0 Nd1 is more than or equal to 1.75, vd1 is more than or equal to 40 and 35.

The first lens is arranged in a meniscus shape protruding to the object side, so that light rays with a large field of view can be collected as much as possible, the light rays enter the rear optical system, and the light passing amount is increased. In practical application, the design of the meniscus shape protruding to the object side is beneficial to the sliding of water drops and reduces the influence on imaging in consideration of the fact that the outdoor installation and use environment of the vehicle-mounted lens can be in bad weather such as rain and snow.

In some embodiments of the present application, the present application further includes a second lens.

The second lens is a plastic aspheric lens with negative focal power, and the object plane side and the image plane side of the second lens are concave surfaces;

the focal length value of the second lens satisfies the following relationship: -4 is more than or equal to F2 is more than or equal to-3;

the optical refractive index Nd2 and abbe constant Vd2 of the second lens satisfy the following relationship: 1.6 Nd2 is more than or equal to 1.5, vd2 is more than or equal to 60 and is more than or equal to 50.

The second lens has a lower refractive index (relative to the third lens), and the matching of the high refractive index and the low refractive index is beneficial to the rapid transition of the front light, increases the aperture of the diaphragm and meets the night vision requirement. The second lens has negative focal power, the third lens close to the image side has positive focal power, and the front light can be diverged and then is converged quickly and then transited to the rear through the arrangement of the front negative film and the rear positive film, so that the optical path of the rear light is reduced, and the short TTL is realized.

In some embodiments of the present application, the focal length value F3 of the third lens (3) satisfies the following relationship: 5. more than or equal to F3 is more than or equal to 3; the optical refractive index Nd3 and Abbe constant Vd3 of the third lens (3) respectively satisfy: 1.9 Nd3 is more than or equal to 1.7, vd3 is more than or equal to 30 and more than or equal to 20.

In some embodiments of the present application, the following relationship is satisfied between the center thickness h3 of the third lens and the total optical length TTL of the optical lens: h3/TTL <0.3. If the third lens thickness is larger than the upper limit value, processing and realization of a small TTL are not facilitated.

In some embodiments of the present application, the optical system further comprises an optical stop, wherein the optical stop is arranged between the third lens and the fourth lens;

a diaphragm for restricting the light beam is provided to further improve the imaging quality of the lens. When the diaphragm is arranged between the third lens and the fourth lens, light entering the optical system can be effectively converged, and the caliber of the lens of the optical system is reduced.

In some embodiments of the present application, the fourth lens is a positive power plastic aspherical lens, and the fourth lens focal length value F4 satisfies the following relationship: 4. f4 is more than or equal to 2; the optical refractive index Nd4 and abbe constant Vd4 of the fourth lens satisfy the following relationship: 1.6 Nd4 is more than or equal to 1.5, vd4 is more than or equal to 60 and more than or equal to 50.

After the aperture diaphragm is arranged, the fourth lens with positive focal power is used, so that aberration generated by the front lens group can be further corrected, meanwhile, light beams are converged again, the aperture of the lens can be increased, the total length of the lens can be shortened, the optical system is more compact, and the optical system has a relatively short total length of the lens.

In some embodiments of the present application, the fifth lens is a negative power plastic aspherical lens; the fifth lens focal length value F5 satisfies the following relationship: -3 is more than or equal to F5 is more than or equal to-2; the optical refractive index Nd5 and abbe constant Vd5 of the fifth lens satisfy the following relationship: 1.7 Nd5 is more than or equal to 1.6, vd5 is more than or equal to 25 and more than or equal to 20.

The fourth lens with positive focal power is arranged in front, and the fifth lens with negative focal power is arranged in back, so that light passing through the third lens can be smoothly transited to the fifth lens, and the overall length of the optical system is reduced.

In some embodiments of the present application, the focal length F4&5 of the cemented lens composed by the fourth lens and the fifth lens satisfies the following relationship: -15.5 is greater than or equal to F4 and 5 is greater than or equal to-16.5.

The adoption of the cemented lens effectively reduces the chromatic aberration of the system, ensures that the whole structure of the optical system is compact, meets the miniaturization requirement, and simultaneously reduces the tolerance sensitivity problem of the lens unit caused by inclination/core shift and the like in the assembling process. Because if the discrete lenses are positioned at the light turning positions, the sensitivity is easy to be caused by processing/assembling errors, and the sensitivity is effectively reduced by the arrangement of the cemented lens group.

The focal length formed by combining the fourth lens and the fifth lens can well improve the resolution of the optical lens. By adopting the structure, the optical lens can further have smaller chromatic aberration through the light refractive index of each lens and the matching of the corresponding Abbe constant, so that the optical lens has good resolving power and the occurrence of ghost images in the optical lens is effectively controlled.

In some embodiments of the present application, the present application further comprises a sixth lens; the sixth lens is a plastic aspheric lens with positive focal power, and the object plane side and the image plane side are both convex surfaces.

The focal length value of the sixth lens satisfies the following relationship: 4. f6 is more than or equal to 3;

the optical refractive index Nd and abbe constant Vd of the sixth lens satisfy the following relationship: 1.6 Nd6 is more than or equal to 1.5, vd6 is more than or equal to 60 and more than or equal to 50;

the sixth lens can be an aspheric lens so as to smoothly transition the light rays passing through the fifth lens to the imaging surface, and the total length of the system is reduced; various aberrations of the optical system are sufficiently corrected, and on the premise of compact structure, the resolution can be improved, and the optical performances such as distortion, CRA and the like can be optimized.

In some embodiments of the present application, the present application further includes an optical filter sequentially arranged from the object side to the imaging side along the optical axis: a first lens, a second lens, a third lens, a diaphragm, a fourth lens, a fifth lens, a sixth lens and a filter; the light after passing through the filter falls on the imaging surface. A filter disposed between the sixth lens and the imaging surface to filter light rays having different wavelengths; and may further include a protective glass disposed between the optical filter and the imaging plane to prevent internal elements (e.g., chips) of the optical lens from being damaged.

Through the combination of two glass spherical lenses and four plastic aspherical lenses and the combination of the structures of the lenses, the purposes of high resolution of the lens, small distortion, improvement of the relative illumination of an external visual field and reduction of ghost images can be achieved; the positions of the glass lens and the plastic lens ensure that the optical lens still has higher resolution power when the temperature changes, thereby ensuring that the optical lens has higher temperature adaptability; the structure of the second lens and the third lens can effectively control the generation of ghost images, so that the lens has fewer ghost images. The optical structure can achieve the purposes of high resolution, small distortion, improvement of the relative illumination of the external field and reduction of ghost images, and the purpose of reducing the volume of the optical lens is further achieved by avoiding additional optical components.

In some embodiments of the present application, the first lens and the third lens are spherical lenses.

In some embodiments of the present application, the second lens, the fourth lens, the fifth lens and the sixth lens are plastic aspherical lenses, and satisfy an aspherical definition equation:

wherein Z represents the sagittal height along the optical axis (9), c represents the curvature corresponding to the radius of the lens, r represents the radial coordinates of the lens, k represents conic constant, and A, B, C, D, E, F, G represents the aspheric coefficient.

The thermal expansion coefficient of the lens made of plastic is larger, and when the ambient temperature used by the lens is changed greatly, the lens made of plastic can cause larger optical back focal change of the lens. The aspherical lens is characterized in that: the curvature varies continuously from the center to the periphery of the lens. Unlike a spherical lens having a constant curvature from the center to the periphery of the lens, an aspherical lens has a better radius of curvature characteristic, and has advantages of improving distortion aberration and improving astigmatic aberration. After the aspheric lens is adopted, aberration generated during imaging can be eliminated as much as possible, and therefore imaging quality of the lens is improved. The arrangement of the aspheric lens is helpful for correcting system aberration and improving resolution.

In some embodiments of the present application, the following relationship is satisfied between the total optical length TTL of the optical lens and the maximum imaging plane circle diameter D: TTL/D <4.3. In this application, the threshold value of the length of the TTL is further defined. The optical lens is suitable for the optical lens with smaller product volume, and the optical framework is adopted to realize high resolution, small distortion and high relative illumination. For larger optical lenses, other more advantageous optical architectures may be employed due to the small size constraints.

An image forming apparatus, characterized in that: the imaging element is used for converting an optical image formed by the optical lens into an electric signal.

The imaging element is a photosensitive element that receives light, called Sensor. The light is incident on the lens and forms refraction in the lens. The Sensor is re-incident through six lenses. The object is imaged at Sensor.

Drawings

The present application will be described in further detail below in conjunction with the drawings and preferred embodiments, but it will be appreciated by those skilled in the art that these drawings are drawn for the purpose of illustrating the preferred embodiments only and thus should not be taken as limiting the scope of the present application. Moreover, unless specifically indicated otherwise, the drawings are merely schematic representations, not necessarily to scale, of the compositions or constructions of the described objects and may include exaggerated representations.

FIG. 1 is a schematic view of an optical structure of an optical lens according to the present invention;

FIG. 2 is a graph of relative illuminance of an optical lens according to the present invention;

FIG. 3 is a graph showing the resolution of an optical lens according to the present invention at different angles;

FIG. 4 is a graph showing a field variation of an optical lens according to the present invention;

FIG. 5 is an f- θ distortion curve of an optical lens of the present invention;

as shown in the figure: 1. a first lens; 2. a second lens; 3. a third lens; 4. a diaphragm; 5. a fourth lens; 6. a fifth lens; 7. a sixth lens; 8. a light filter; 9. an optical axis; 10. an imaging surface.

Detailed Description

The present application will be described in detail with reference to the accompanying drawings.

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the present application.

Embodiment one: as shown in fig. 1: an optical lens comprises a first lens 1, a second lens 2, a third lens 3, a fourth lens 5, a fifth lens 6, a sixth lens 7 and an optical filter 8 which are sequentially arranged from an object side to an imaging side along an optical axis 9; the third lens 3 is a glass spherical lens with positive focal power, and the object plane side and the image plane side of the third lens are convex surfaces; the third lens 3 adopts a glass spherical lens with positive focal power, is not defocused at high and low temperatures, and can still maintain the excellent performance in a high and low temperature environment of-40 ℃ to 85 ℃. The object plane side and the image plane side of the third lens 3 are both convex surfaces, which can converge divergent light rays, and properly compress the divergent light rays, so that the light rays smoothly transition and smoothly enter the rear optical system.

The fourth lens 5 and the fifth lens 6 form a cemented lens; the cemented lens may be used to minimize chromatic aberration or eliminate chromatic aberration. And the whole structure of the optical system is compact, the miniaturization requirement is met, and the tolerance sensitivity problem of the lens unit caused by inclination/eccentric core and the like in the assembling process is reduced. The object plane side and the image plane side of the fourth lens 5 are convex surfaces; the aberration generated by the front lens group can be further corrected by using a fourth lens 5 having positive power, while converging the light beam again. The object plane side and the image plane side of the fifth lens 6 are concave surfaces; the fourth lens 5 with positive power is in front and the fifth lens 6 with negative power is in back, which is beneficial to smoothly transition the light passing through the third lens 3 to the fifth lens 6 and reduce the overall length of the optical system. The light rays sequentially pass through the third lens 3, the fourth lens 5 and the fifth lens 6. The third lens 3 and the glued lens in the optical lens are mutually matched, so that the influence of temperature change on the focal length of the lens can be effectively compensated, and the stability of the resolving power of the lens at different temperatures can be further improved.

According to the high-definition imaging device, the lens shape is optimally set, the focal power is reasonably distributed, and the number of spherical surfaces and aspherical mirror surfaces is properly set, so that high-definition imaging can be realized. Meanwhile, the requirements of miniaturization, small distortion, high resolution, low cost, good temperature adaptability and the like of the lens can be met. The application requirements of miniaturization and high resolution of the vehicle-mounted side view lens are met.

Embodiment two: as shown in fig. 1, the present application further includes a diaphragm 4, where the diaphragm 4 is disposed between the third lens 3 and the fourth lens 5; sequentially arranged from the object side to the imaging side along the optical axis 9 are: a first lens 1, a second lens 2, a third lens 3, a diaphragm 4, a fourth lens 5, a fifth lens 6, a sixth lens 7, and a filter 8; the first lens 1 is a glass spherical lens; the second lens 2 is a plastic aspheric lens; the sixth lens 7 is a plastic aspherical lens. A stop 4 for limiting the light beam is provided to further improve the imaging quality of the lens. When the diaphragm 4 is arranged between the third lens 3 and the fourth lens 5, the light entering the optical system can be effectively converged, and the aperture of the lens of the optical system can be reduced.

The light after passing through the filter 8 falls on the imaging surface 10. A filter 8 disposed between the sixth lens 7 and the imaging surface 10 to filter light rays having different wavelengths; and may further include a cover glass disposed between the optical filter 8 and the imaging plane 10 to prevent internal elements (e.g., chips) of the optical lens from being damaged.

Through the combination of two glass spherical lenses and four plastic aspherical lenses and the combination of the structures of the lenses, the purposes of high resolution of the lens, small distortion, improvement of the relative illumination of an external visual field and reduction of ghost images can be achieved; the positions of the glass lens and the plastic lens ensure that the optical lens still has higher resolution power when the temperature changes, thereby ensuring that the optical lens has higher temperature adaptability; the structures of the second lens 2 and the third lens 3 can effectively control the occurrence of ghost images, so that the lens has fewer ghost images. The optical structure can achieve the purposes of high resolution, small distortion, improvement of the relative illumination of the external field and reduction of ghost images, and the purpose of reducing the volume of the optical lens is further achieved by avoiding additional optical components.

The other contents of the second embodiment are the same as those of the first embodiment.

Embodiment III: as shown in fig. 1, the first lens is a glass spherical lens with negative focal power, the object plane side is a convex surface, and the image plane side is a concave surface; the focal length value F1 of the first lens satisfies the following relationship: -8 is more than or equal to F1 is more than or equal to-6; the optical refractive index Nd1 and abbe constant Vd1 of the first lens respectively satisfy: 2.0 Nd1 is more than or equal to 1.75, vd1 is more than or equal to 40 and 35.

The second lens is a plastic aspheric lens with negative focal power, and the object plane side and the image plane side of the second lens are concave surfaces; the focal length value of the second lens satisfies the following relationship: -4 is more than or equal to F2 is more than or equal to-3; the optical refractive index Nd2 and abbe constant Vd2 of the second lens satisfy the following relationship: 1.6 Nd2 is more than or equal to 1.5, vd2 is more than or equal to 60 and is more than or equal to 50.

The focal length F3 of the third lens satisfies the following relationship: 5. more than or equal to F3 is more than or equal to 3; the optical refractive index Nd3 and abbe constant Vd3 of the third lens respectively satisfy: 1.9 Nd3 is more than or equal to 1.7, vd3 is more than or equal to 30 and more than or equal to 20. The following relationship is satisfied between the center thickness h3 of the third lens and the total optical length TTL of the optical lens: h3/TTL <0.3.

The fourth lens is a plastic aspheric lens with positive focal power, and the focal length value F4 of the fourth lens meets the following relation: f4 is more than or equal to 4 and more than or equal to 2; the optical refractive index Nd4 and abbe constant Vd4 of the fourth lens satisfy the following relationship: 1.6 Nd4 is more than or equal to 1.5, vd4 is more than or equal to 60 and more than or equal to 50.

The fifth lens is a plastic aspheric lens with negative focal power; the fifth lens focal length value F5 satisfies the following relationship: -3 is more than or equal to F5 is more than or equal to-2; the optical refractive index Nd5 and abbe constant Vd5 of the fifth lens satisfy the following relationship: 1.7 Nd5 is more than or equal to 1.6, vd5 is more than or equal to 25 and more than or equal to 20.

The focal length F4&5 of the cemented lens composed by the fourth lens and the fifth lens satisfies the following relationship: -15.5 is greater than or equal to F4 and 5 is greater than or equal to-16.5.

The sixth lens is a plastic aspheric lens with positive focal power, and the object plane side and the image plane side are both convex surfaces.

The focal length value of the sixth lens satisfies the following relationship: 4. f6 is more than or equal to 3; the optical refractive index Nd6 and abbe constant Vd6 of the sixth lens satisfy the following relationship: 1.6 Nd6 is more than or equal to 1.5, vd6 is more than or equal to 60 and more than or equal to 50;

the optical performance of the present application can be achieved by the lens structure having a value within the above-mentioned optical specification range. However, the optical specification is beyond the above range, and there is a problem that the optical performance of the present application cannot be achieved.

The first lens and the third lens are spherical lenses. The second lens, the fourth lens, the fifth lens and the sixth lens are plastic aspheric lenses and satisfy the aspheric definition equation:

wherein Z represents a direction along the optical axis (9)The sagittal elevation, c, represents the curvature corresponding to the radius of the lens, r represents the radial coordinates of the lens, k represents the conic constant, and A, B, C, D, E, F, G represents the aspheric coefficient.

The surface of the plastic aspherical lens meets the following conditions:

surface of the body

c

k

A

B

C

D

E

P2R1

-0.03571

35.1730

-1.1238E-03

6.2053E-05

6.9410E-07

0.0000E+00

0.0000E+00

P2R1

0.526316

-0.8763

1.8832E-03

-3.7065E-04

3.1577E-05

6.1943E-08

0.0000E+00

P4R1

0.714286

1.0672

-3.7635E-03

-2.6200E-04

2.4413E-04

1.4726E-05

-3.3613E-06

P4R2

-0.45455

0.3382

-1.5550E-02

3.8489E-02

-2.1384E-02

3.8534E-03

-8.8773E-05

P5R1

-0.45455

0.3382

-1.5550E-02

3.8489E-02

-2.1384E-02

3.8534E-03

-8.8773E-05

P5R2

0.25641

-15.3260

2.1645E-02

1.3499E-03

-1.2732E-03

1.8890E-04

-1.5882E-06

P6R1

0.285714

-7.0701

-8.3680E-04

1.2305E-03

-6.3377E-05

6.0992E-06

-4.4145E-08

P6R2

-0.27778

-1.1218

1.0303E-03

3.6111E-04

1.1166E-05

2.2233E-05

2.7934E-07

Wherein: p2 is the second lens, P4 is the 4 th lens, P5 is the 5 th lens, P6 is the 6 th lens;

g1 R1 is the first surface radius of curvature of the glass sphere of the first lens, G1R 2 is the second surface radius of curvature of the glass sphere of the first lens, P2R 1 is the first surface radius of curvature of the plastic aspherical surface of the second lens, P2R 2 is the second surface radius of curvature of the plastic aspherical surface of the second lens, G3R 1 is the first surface radius of curvature of the glass sphere of the third lens, G3R 2 is the second surface radius of curvature of the glass sphere of the third lens, P4R 1 is the first surface radius of curvature of the plastic aspherical surface of the fourth lens, P4R 2 is the second surface radius of curvature of the plastic aspherical surface of the fourth lens, P5R 1 is the first surface radius of curvature of the plastic aspherical surface of the fifth lens, P5R 2 is the first surface radius of curvature of the plastic aspherical surface of the sixth lens, P6R 1 is the second surface radius of curvature of the plastic aspherical surface of the sixth lens, P6R 2 is the second surface of curvature of the plastic aspherical surface of the sixth lens

Further, TTL is the total length of the imaging lens, that is, the distance from the center of curvature of the first surface of the glass spherical lens of the first lens to the imaging surface in the optical axis direction.

The following relation is satisfied between the total optical length TTL of the optical lens and the maximum imaging plane circle diameter D: TTL/D <4.3.

The other matters of the third embodiment are the same as those of the embodiment.

Embodiment four: an imaging device comprises an imaging element and the optical lens, wherein the imaging element is used for converting an optical image formed by the optical lens into an electric signal. The imaging element is a photosensitive element that receives light, called Sensor. The light is incident on the lens and forms refraction in the lens. The Sensor is re-incident through six lenses. The object is imaged at Sensor.

Other matters of the fourth embodiment may be the same as those of any of the above-described embodiments.

The foregoing has outlined rather broadly the principles and embodiments of the present application in order that the detailed description of the invention may be better understood, and in order that the present application may be better understood. It should be noted that it would be obvious to those skilled in the art that various improvements and modifications can be made to the present application without departing from the principles of the present application, and such improvements and modifications fall within the scope of the claims of the present application.

Claims (8)

1. An optical lens comprises a first lens (1), a second lens (2), a third lens (3), a fourth lens (5), a fifth lens (6), a sixth lens (7) and an optical filter (8) which are sequentially arranged from an object side to an imaging side along an optical axis (9); the method is characterized in that: the third lens (3) is a glass spherical lens with positive focal power, and the object plane side and the image plane side of the third lens are convex surfaces; the fourth lens (5) and the fifth lens (6) form a cemented lens; the object plane side and the image plane side of the fourth lens (5) are convex surfaces; the object plane side and the image plane side of the fifth lens (6) are concave surfaces;

the fourth lens (5) is a plastic aspheric lens with positive focal power, the fifth lens (6) is a plastic aspheric lens with negative focal power, and the focal length value F5 of the fifth lens (6) meets the following relation: -3 is more than or equal to F5 is more than or equal to-2; the optical refractive index Nd5 and Abbe constant Vd5 of the fifth lens (6) satisfy the following relationship: 1.7 Nd5 is more than or equal to 1.6,25, vd5 is more than or equal to 20; the object plane side of the glued lens is a convex surface and the image plane side is a concave surface; the focal length value F4&5 of the cemented lens composed by the fourth lens (5) and the fifth lens (6) satisfies the following relationship: -15.5 is greater than or equal to F4 and 5 is greater than or equal to-16.5.

2. An optical lens according to claim 1, characterized in that the focal length value F3 of the third lens (3) satisfies the following relationship: 5. more than or equal to F3 is more than or equal to 3; the optical refractive index Nd3 and Abbe constant Vd3 of the third lens (3) respectively satisfy: 1.9 Nd3 is more than or equal to 1.7, vd3 is more than or equal to 30 and more than or equal to 20.

3. An optical lens according to claim 1, wherein: the following relationship is satisfied between the center thickness h3 of the third lens (3) and the total optical length TTL of the optical lens: h3/TTL <0.3.

4. An optical lens according to claim 1 or 3, wherein: the following relation is satisfied between the total optical length TTL of the optical lens and the maximum imaging plane circle diameter D: TTL/D <4.3.

5. An optical lens according to claim 1, wherein: the fourth lens (5) focal length value F4 satisfies the following relationship: 4. f4 is more than or equal to 2; the focal length value F5 of the fifth lens (6) satisfies the following relationship: -3 is more than or equal to F5 is more than or equal to-2; the optical refractive index Nd4 and Abbe constant Vd4 of the fourth lens (5) satisfy the following relationship: 1.6 Nd4 is more than or equal to 1.5, vd4 is more than or equal to 60 and more than or equal to 50; the optical refractive index Nd5 and Abbe constant Vd5 of the fifth lens (6) satisfy the following relationship: 1.7 Nd5 is more than or equal to 1.6, vd5 is more than or equal to 25 and more than or equal to 20.

6. An optical lens according to claim 1, wherein: the lens system further comprises a diaphragm (4), wherein the diaphragm (4) is arranged between the third lens (3) and the fourth lens (5); the first lens (1) is a glass spherical lens with negative focal power, the object plane side of the first lens is a convex surface, and the image plane side of the first lens is a concave surface; the second lens (2) is a plastic aspheric lens with negative focal power, and the object plane side and the image plane side of the second lens are concave surfaces; the sixth lens (7) is a plastic aspheric lens with positive focal power, and the object plane side and the image plane side are both convex surfaces.

7. An optical lens according to claim 1, wherein: the second lens (2), the fourth lens (5), the fifth lens (6) and the sixth lens (7) are plastic aspheric lenses and satisfy an aspheric definition equation:

wherein Z represents the sagittal height along the optical axis (9), c represents the curvature corresponding to the radius of the lens, r represents the radial coordinates of the lens, k represents conic constant, and A, B, C, D, E, F, G represents the aspheric coefficient.

8. An image forming apparatus, characterized in that: comprising an imaging element for converting an optical image formed by the optical lens into an electrical signal, and the optical lens of any one of claims 1-7.

Images