CN217332984U - Fixed focus lens - Google Patents

Abstract

The utility model discloses a fixed focus lens, which comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens and a ninth lens which are sequentially arranged from an object plane to an image plane along an optical axis, wherein the focal power of each lens satisfies that phi 1/phi is more than or equal to 0.02 and less than or equal to 0.08; phi 2/phi is less than or equal to-0.40 and is less than or equal to-1.10; phi 3/phi is less than or equal to-0.40 and is less than or equal to-1.10; phi 4/phi is more than or equal to 0.20 and less than or equal to 1.00; phi 5/phi is more than or equal to 0.20 and less than or equal to 0.90; phi 6/phi is more than or equal to 0.05 and less than or equal to 0.60; phi 7/phi is more than or equal to minus 0.60 and less than or equal to minus 0.05; phi 8/phi is more than or equal to 0.10 and less than or equal to 0.70; phi 9/phi is more than or equal to 0.05 and less than or equal to 0.60. The embodiment of the utility model provides a tight shot adopts 9 pieces of lens, through the focal power of the 9 pieces of lens of reasonable collocation, has realized the tight shot of low cost, little volume, big target surface, low distortion.

Description

Fixed focus lens

Technical Field

The utility model relates to an optical device technical field especially relates to a tight shot.

Background

Along with the development of trade, the demand of market to the lens performance is also more and more diversified, and the current camera lens ubiquitous has the too big problem of distortion for image processing's the degree of difficulty in next step promotes, but the image plane of current low distortion camera lens is all less, and the camera lens that generally can accomplish big target surface and low distortion all has with high costs, bulky scheduling problem.

SUMMERY OF THE UTILITY MODEL

The utility model provides a fixed focus lens to realize the fixed focus lens of low cost, small, big target surface, low distortion.

The utility model provides a fixed focus lens, which comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens and a ninth lens which are arranged in sequence from an object plane to an image plane along an optical axis;

the first lens has a positive optical power, the second lens has a negative optical power, the third lens has a negative optical power, the fourth lens has a positive optical power, the fifth lens has a positive optical power, the sixth lens has a positive optical power, the seventh lens has a negative optical power, the eighth lens has a positive optical power, and the ninth lens has a positive optical power;

the focal power of the first lens is phi 1, the focal power of the second lens is phi 2, the focal power of the third lens is phi 3, the focal power of the fourth lens is phi 4, the focal power of the fifth lens is phi 5, the focal power of the sixth lens is phi 6, the focal power of the seventh lens is phi 7, the focal power of the eighth lens is phi 8, the focal power of the ninth lens is phi 9, and the focal power of the fixed-focus lens is phi, wherein:

0.02≤φ1/φ≤0.08；-1.10≤φ2/φ≤-0.40；-1.10≤φ3/φ≤-0.40；

0.20≤φ4/φ≤1.00；0.20≤φ5/φ≤0.90；0.05≤φ6/φ≤0.60；

-0.60≤φ7/φ≤-0.05；0.10≤φ8/φ≤0.70；0.05≤φ9/φ≤0.60。

optionally, the sixth lens and the seventh lens form a double cemented lens group.

Optionally, the focal power of the double cemented lens group is phi 10, wherein phi 10/phi is more than or equal to 0.02 and less than or equal to 0.07.

Optionally, the first lens, the second lens, the fourth lens, the sixth lens, the seventh lens and the ninth lens are glass spherical lenses; the eighth lens is a plastic aspheric lens; the third lens is a glass spherical lens or a plastic aspherical lens; the fifth lens is a glass spherical lens or a plastic aspherical lens.

Optionally, the refractive index of the first lens is Nd1, and the abbe number is Vd 1; the refractive index of the second lens is Nd2, and the Abbe number is Vd 2; the refractive index of the third lens is Nd3, and the Abbe number is Vd 3; the refractive index of the fourth lens is Nd4, and the Abbe number is Vd 4; the refractive index of the fifth lens is Nd5, and the Abbe number is Vd 5; the refractive index of the sixth lens is Nd6, and the Abbe number is Vd 6; the refractive index of the seventh lens is Nd7, and the Abbe number is Vd 7; the refractive index of the eighth lens is Nd8, and the Abbe number is Vd 8; the refractive index of the ninth lens is Nd9, and the Abbe number is Vd 9; wherein:

1.45≤Nd1≤1.75；52.9≤Vd1≤78.0；

1.65≤Nd2≤2.10；16.0≤Vd2≤35.0；

1.45≤Nd3≤1.65；43.6≤Vd3≤66.1；

1.65≤Nd4≤2.10；16.0≤Vd4≤35.0；

1.45≤Nd5≤1.65；45.0≤Vd5≤66.6；

1.59≤Nd6≤1.79；40.2≤Vd6≤70.0；

1.62≤Nd7≤1.84；18.3≤Vd7≤37.0；

1.45≤Nd8≤1.69；44.6≤Vd8≤57.0；

1.63≤Nd9≤1.75；49.9≤Vd9≤75.0。

optionally, the radius of curvature of the object-side surface of the first lens is R11, the radius of curvature of the image-side surface of the first lens is R12, the radius of curvature of the object-side surface of the second lens is R21, and the radius of curvature of the image-side surface of the second lens is R22; wherein:

0.24≤︱R11/R12︱≤0.70；2.43≤︱R21/R22︱≤4.33。

optionally, a central thickness of the first lens on the optical axis is CT1, a clear aperture of the first lens is D1, a central thickness of the second lens on the optical axis is CT2, a clear aperture of the second lens is D2, a central thickness of the fourth lens on the optical axis is CT4, a clear aperture of the fourth lens is D4, a central thickness of the ninth lens on the optical axis is CT9, and a clear aperture of the ninth lens is D9; wherein:

0.18≤︱CT1/D1︱≤0.40；0.39≤︱CT2/D2︱≤0.64；

0.42≤︱CT4/D4︱≤1.68；0.35≤︱CT9/D9︱≤0.53。

optionally, the image plane diameter of the fixed focus lens is IC, and the total optical length of the fixed focus lens is TTL; wherein IC/TTL is more than or equal to 0.13.

Optionally, a distance between an optical axis center of an image side surface of the ninth lens element and an image plane is BFL, and an optical total length of the fixed-focus lens is TTL, where BFL/TTL is greater than 0.10 and less than 0.35.

Optionally, the fixed-focus lens further includes a diaphragm;

the diaphragm is located in an optical path between the fifth lens and the sixth lens.

The embodiment of the utility model provides a tight shot adopts 9 pieces of lenses, and lens quantity is less to less volume and length have. Through the focal power of 9 pieces of lens of reasonable collocation, better correction the aberration to realized higher definition and less optical distortion under the lower condition of cost, simultaneously, this prime lens can match 1/1.2 "target surface sensor chip at most, has satisfied big target surface demand.

It should be understood that the statements herein are not intended to identify key or critical features of any embodiment of the present invention, nor are they intended to limit the scope of the invention. Other features of the present invention will become apparent from the following description.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a fixed-focus lens according to a first embodiment of the present invention;

fig. 2 is a spherical aberration curve chart of a fixed focus lens according to a first embodiment of the present invention;

fig. 3 is a light fan diagram of a fixed focus lens according to a first embodiment of the present invention;

fig. 4 is a distortion curve diagram of a fixed focus lens according to a first embodiment of the present invention;

fig. 5 is a schematic structural diagram of a fixed-focus lens provided in the second embodiment of the present invention;

fig. 6 is a spherical aberration curve chart of the fixed focus lens provided in the second embodiment of the present invention;

fig. 7 is a light fan diagram of a fixed-focus lens provided in the second embodiment of the present invention;

fig. 8 is a distortion curve diagram of a fixed focus lens provided in the second embodiment of the present invention;

fig. 9 is a schematic structural diagram of a fixed-focus lens provided in the third embodiment of the present invention;

fig. 10 is a spherical aberration curve chart of the fixed-focus lens provided in the third embodiment of the present invention;

fig. 11 is a light fan diagram of a fixed-focus lens provided in the third embodiment of the present invention;

fig. 12 is a distortion curve diagram of a fixed-focus lens according to a third embodiment of the present invention.

Detailed Description

In order to make the technical solution of the present invention better understood, the technical solution of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts shall belong to the protection scope of the present invention.

It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

Example one

Fig. 1 is a schematic structural diagram of a fixed focus lens according to an embodiment of the present invention, as shown in fig. 1, the fixed focus lens according to an embodiment of the present invention includes a first lens 110, a second lens 120, a third lens 130, a fourth lens 140, a fifth lens 150, a sixth lens 160, a seventh lens 170, an eighth lens 180, and a ninth lens 190, which are sequentially arranged from an object plane to an image plane along an optical axis. The first lens 110 has positive power, the second lens 120 has negative power, the third lens 130 has negative power, the fourth lens 140 has positive power, the fifth lens 150 has positive power, the sixth lens 160 has positive power, the seventh lens 170 has negative power, the eighth lens 180 has positive power, and the ninth lens 190 has positive power. The focal power of the first lens 110 is phi 1, the focal power of the second lens 120 is phi 2, the focal power of the third lens 130 is phi 3, the focal power of the fourth lens 140 is phi 4, the focal power of the fifth lens 150 is phi 5, the focal power of the sixth lens 160 is phi 6, the focal power of the seventh lens 170 is phi 7, the focal power of the eighth lens 180 is phi 8, the focal power of the ninth lens 190 is phi 9, and the focal power of the fixed focus lens is phi, wherein:

0.02≤φ1/φ≤0.08；-1.10≤φ2/φ≤-0.40；-1.10≤φ3/φ≤-0.40；0.20≤φ4/φ≤1.00；0.20≤φ5/φ≤0.90；0.05≤φ6/φ≤0.60；-0.60≤φ7/φ≤-0.05；0.10≤φ8/φ≤0.70；0.05≤φ9/φ≤0.60。

wherein, the focal power is equal to the difference between the convergence of the image side light beam and the convergence of the object side light beam, which characterizes the capability of the optical system to deflect the light. The larger the absolute value of the focal power is, the stronger the bending ability to the light ray is, and the smaller the absolute value of the focal power is, the weaker the bending ability to the light ray is. When the focal power is positive, the refraction of the light is convergent; when the focal power is negative, the refraction of the light is divergent. The optical power can be suitable for representing a certain refractive surface of a lens (namely, a surface of the lens), can be suitable for representing a certain lens, and can also be suitable for representing a system (namely a lens group) formed by a plurality of lenses together.

In the fixed focus lens provided in this embodiment, each lens can be fixed in a lens barrel (not shown in fig. 1), by setting the first lens 110 as a positive power lens, the second lens 120 as a negative power lens, the third lens 130 as a negative power lens, the fourth lens 140 as a positive power lens, the fifth lens 150 as a positive power lens, the sixth lens 160 as a positive power lens, the seventh lens 170 as a negative power lens, the eighth lens 180 as a positive power lens, and the ninth lens 190 as a positive power lens, and by setting the ratio relationship between the powers of the first lens 110, the second lens 120, the third lens 130, the fourth lens 140, the fifth lens 150, the sixth lens 160, the seventh lens 170, the eighth lens 180, and the ninth lens 190 and the fixed focus lens together, the powers of the system are shared reasonably through the powers of the positive power lens and the negative power lens, the aberration can be corrected, the fixed-focus lens can be guaranteed to achieve high definition, and the tolerance of the system structure is favorably corrected, so that the sensitivity of the lens is reduced, and the production possibility is improved.

Simultaneously, this tight shot can match 1/1.2 "target surface sensor chip the most, satisfies big target surface demand, simultaneously, F-Tan (theta) distortion is less than or equal to | 5.0% |, satisfies low distortion demand, and this tight shot only adopts 9 pieces of lens, and total optical length TTL can satisfy: the TTL is less than or equal to 40.6mm, the volume is smaller, the number of lenses is less, and the cost of the fixed-focus lens is reduced.

To sum up, the embodiment of the utility model provides a tight shot adopts 9 pieces of lenses, and lens quantity is less to have less volume and length. Through the focal power of 9 pieces of lens of reasonable collocation, better correction the aberration to realized higher definition and less optical distortion under the lower condition of cost, simultaneously, this prime lens can match 1/1.2 "target surface sensor chip at most, has satisfied big target surface demand.

As a possible implementation, as shown in fig. 1, the sixth lens 160 and the seventh lens 170 constitute a double cemented lens group 200.

By arranging the sixth lens 160 and the seventh lens 170 to form the double cemented lens assembly 200, the air space between the sixth lens 160 and the seventh lens 170 can be effectively reduced, thereby further reducing the total lens length. In addition, the double-cemented lens assembly 200 can reduce chromatic aberration or eliminate chromatic aberration to the utmost extent, so that various aberrations of the fixed-focus lens can be fully corrected, on the premise of compact structure, the resolution can be improved, the optical performance such as distortion can be optimized, the light quantity loss caused by reflection between lenses can be reduced, the illumination intensity can be improved, the image quality can be improved, and the imaging definition of the lens can be improved. In addition, the use of the dual cemented lens assembly 200 can also reduce the number of assembling parts between the two lenses, simplify the assembling procedure in the lens manufacturing process, reduce the cost, and reduce the tolerance sensitivity problems of the lens units such as tilt/decentration generated in the assembling process.

As a possible implementation, the focal power of the doublet 200 is φ 10, wherein 0.02 ≦ φ 10/φ ≦ 0.07.

Wherein, through reasonably setting the ratio relationship between the focal power phi 10 of the double cemented lens group 200 and the focal power phi of the fixed focus lens, the aberration can be better corrected, so that the fixed focus lens has higher definition.

As a possible embodiment, the first lens 110, the second lens 120, the fourth lens 140, the sixth lens 160, the seventh lens 170, and the ninth lens 190 are glass spherical lenses, and the eighth lens 180 is a plastic aspherical lens; the third lens 130 is a glass spherical lens or a plastic aspherical lens; the fifth lens 150 is a glass spherical lens or a plastic aspherical lens.

Wherein, the eighth lens 180 and the like are arranged to adopt a plastic aspheric lens, so that the high-level aberration of the system can be corrected, and the imaging quality of the system is improved.

In addition, since the cost of the plastic lens is much lower than that of the glass lens, the prime lens provided by this embodiment has good image quality, low cost and light weight by providing at least 1 plastic aspheric lens.

Simultaneously, the tight shot adopts glass to mould the structure collocation of mixing, because of two kinds of materials have the compensation effect of each other, can promote the imaging quality of system effectively, still can satisfy the tight shot use simultaneously and do not lose burnt in high low temperature environment, guarantees that the tight shot still can normal use under high low temperature environment.

It should be noted that the above plastic aspheric lens may be made of various plastics known to those skilled in the art, and the glass spherical lens may be made of various types of glass known to those skilled in the art, which is neither described nor limited in this embodiment.

As a possible embodiment, the refractive index of the first lens 110 is Nd1, and the abbe number is Vd 1; the refractive index of the second lens 120 is Nd2, and the Abbe number is Vd 2; the refractive index of the third lens 130 is Nd3, and the Abbe number is Vd 3; the refractive index of the fourth lens 140 is Nd4, and the Abbe number is Vd 4; the refractive index of the fifth lens 150 is Nd5, and the Abbe number is Vd 5; the refractive index of the sixth lens 160 is Nd6, and the abbe number is Vd 6; the refractive index of the seventh lens 170 is Nd7, and the abbe number is Vd 7; the refractive index of the eighth lens 180 is Nd8, and the Abbe number is Vd 8; the refractive index of the ninth lens 190 is Nd9, and the abbe number is Vd 9; wherein:

1.45≤Nd1≤1.75；52.9≤Vd1≤78.0；1.65≤Nd2≤2.10；16.0≤Vd2≤35.0；1.45≤Nd3≤1.65；43.6≤Vd3≤66.1；1.65≤Nd4≤2.10；16.0≤Vd4≤35.0；1.45≤Nd5≤1.65；45.0≤Vd5≤66.6；1.59≤Nd6≤1.79；40.2≤Vd6≤70.0；1.62≤Nd7≤1.84；18.3≤Vd7≤37.0；1.45≤Nd8≤1.69；44.6≤Vd8≤57.0；1.63≤Nd9≤1.75；49.9≤Vd9≤75.0。

the refractive index is the ratio of the propagation speed of light in vacuum to the propagation speed of light in the medium, and is mainly used for describing the refractive power of materials to light, and the refractive indexes of different materials are different. The abbe number is an index for expressing the dispersion capability of the transparent medium, and the more severe the dispersion of the medium is, the smaller the abbe number is; conversely, the more slight the dispersion of the medium, the greater the abbe number.

In this embodiment, the refractive index and abbe number of each lens are set in a matching manner, which is beneficial to realizing the miniaturization design of the fixed-focus lens and enabling the fixed-focus lens to have higher pixel resolution.

As a possible embodiment, the curvature radius of the object-side surface of the first lens 110 is R11, the curvature radius of the image-side surface of the first lens 110 is R12, the curvature radius of the object-side surface of the second lens 120 is R21, and the curvature radius of the image-side surface of the second lens 120 is R22; wherein:

0.24≤︱R11/R12︱≤0.70；2.43≤︱R21/R22︱≤4.33。

the proportional relationship between the curvature radius of the object-side surface of the first lens element 110 and the curvature radius of the image-side surface of the first lens element 110 is reasonably set, so that the shape of the object-side surface of the first lens element 110 is more curved than that of the image-side surface on the basis of meeting the focal power of the first lens element 110, which is beneficial to correcting the aberration of the optical system and improving the image quality.

Meanwhile, by reasonably setting the proportional relationship between the curvature radius of the object side surface of the second lens element 120 and the curvature radius of the image side surface of the second lens element 120, the incidence angle of the chief ray on the optical surface of the third lens element 130 can be reduced on the basis of meeting the focal power of the second lens element 120, so that the light can smoothly enter the optical system, the aberration of the off-axis field can be corrected, and the image resolution quality of the system can be improved.

As a possible embodiment, the central thickness of the first lens 110 on the optical axis is CT1, the clear aperture of the first lens 110 is D1, the central thickness of the second lens 120 on the optical axis is CT2, the clear aperture of the second lens 120 is D2, the central thickness of the fourth lens 140 on the optical axis is CT4, the clear aperture of the fourth lens 140 is D4, the central thickness of the ninth lens 190 on the optical axis is CT9, and the clear aperture of the ninth lens 190 is D9; wherein:

0.18≤︱CT1/D1︱≤0.40；0.39≤︱CT2/D2︱≤0.64；

0.42≤︱CT4/D4︱≤1.68；0.35≤︱CT9/D9︱≤0.53。

by restricting the relationship between the clear aperture and the center thickness of the first lens 110, the second lens 120, the fourth lens 140, and the ninth lens 190, the spherical aberration of the imaging system can be eliminated better, and higher imaging quality can be obtained.

As a possible implementation manner, the image plane diameter of the fixed-focus lens is IC, and the total optical length of the fixed-focus lens is TTL; wherein IC/TTL is more than or equal to 0.13.

In this embodiment, the relationship between the image plane diameter IC of the fixed focus lens and the total optical length TTL of the fixed focus lens is set reasonably, so that the fixed focus lens has better imaging quality and clearer picture, and meanwhile, the total lens length of the fixed focus lens is reduced, so that the fixed focus lens has smaller volume.

As a possible implementation manner, the distance from the optical axis center of the image-side surface of the ninth lens element 190 to the image plane is BFL, and the total optical length of the fixed-focus lens is TTL, where 0.10 < BFL/TTL < 0.35.

In this embodiment, the distance BFL from the optical axis center of the image-side surface of the ninth lens 190 to the image plane can be understood as the back focal length of the fixed-focus lens, and the relationship between the back focal length of the fixed-focus lens and the total optical length of the fixed-focus lens is reasonably set, so that the compression of the total optical length of the fixed-focus lens is facilitated, and the fixed-focus lens has a smaller volume.

As a possible implementation, the fixed focus lens further includes an optical stop 300, and the optical stop 300 is located in an optical path between the fifth lens 150 and the sixth lens 160.

The propagation direction of the light beam can be adjusted by additionally arranging the diaphragm 300, which is beneficial to improving the imaging quality. The diaphragm 300 may be located in the optical path between the fifth lens 150 and the sixth lens 160, but the specific location of the diaphragm 300 is not limited by the embodiments of the present invention.

As a possible implementation manner, as shown in fig. 1, the prime lens provided in an embodiment of the present invention further includes an optical filter 400, and the optical filter 400 is disposed on the image-side surface side of the ninth lens element 190.

The filter 400 is disposed on the image-side surface of the ninth lens element 190, so that the imaging sensor can be protected. Meanwhile, the optical filter 400 can also filter out unwanted stray light, so as to improve the image quality of the fixed-focus lens, for example, the optical filter 400 filters out infrared light in the daytime to improve the imaging quality of the fixed-focus lens.

As a feasible implementation mode, the aperture F # of the fixed-focus lens meets the condition that the F # is more than or equal to 1.6 and less than or equal to 2.5.

The aperture F # of the fixed-focus lens reaches 1.6-2.5, and the requirement for throughput can be met, so that the monitoring requirement under the low-illumination condition is met.

For example, table 1 illustrates specific optical physical parameters of each lens in a fixed focus lens provided by an embodiment of the present invention in a practical implementation manner, where the fixed focus lens in table 1 corresponds to the fixed focus lens shown in fig. 1.

TABLE 1 design values of optical physical parameters of fixed-focus lens

Wherein, the surface numbers are numbered according to the surface sequence of each lens, for example, the surface number "S1" represents the object side surface of the first lens 110, the surface number "S2" represents the image side surface of the first lens 110, and so on; the curvature radius represents the bending degree of the lens surface, a positive value represents that the surface is bent to the image surface side, a negative value represents that the surface is bent to the object surface side, and the 'PL' represents that the surface is a plane and the curvature radius is infinite; the thickness represents the central axial distance from the current surface to the next surface; the refractive index Nd represents the deflection capacity of the material between the current surface and the next surface to light, the blank space represents that the current position is air, and the refractive index is 1; the abbe number Vd represents the dispersion characteristic of the material between the current surface and the next surface to light, and a blank space represents that the current position is air; the K value represents the numerical value of the best fitting cone coefficient of the aspheric surface; "STO" represents a diaphragm; IMA stands for image plane.

The aspheric conic coefficient can be defined by the following aspheric formula, but is not limited to the following expression method:

wherein Z is the axial rise of the aspheric surface in the Z direction; r is the height of the aspheric surface; c is the curvature of the fitting sphere, and the numerical value is the reciprocal of the curvature radius; k is a fitting cone coefficient; A-F are coefficients of 4 th, 6 th, 8 th, 10 th, 12 th and 14 th order terms of the aspheric polynomial.

Illustratively, table 2 details the aspheric coefficients of the lenses of the first embodiment in a possible implementation manner.

TABLE 2 designed values of aspherical coefficients of respective lenses in fixed-focus lens

Number of noodles

A

B

C

D

E

F

S9

4.101736E-04

3.303087E-04

-6.081673E-05

8.686298E-06

-4.366575E-07

1.170382E-08

S10

-7.250207E-04

4.261438E-04

-4.527993E-05

4.198746E-06

-1.269960E-07

3.022680E-08

S15

1.033344E-03

3.924685E-05

4.371936E-07

-6.679241E-08

-2.963230E-09

1.558886E-10

S16

1.641687E-03

3.294943E-05

6.055889E-06

-1.883954E-07

2.597395E-09

-4.790300E-11

Wherein 4.101736E-04 indicates that the coefficient A with the surface number of S9 is 4.101736 x 10 ^-4 And so on.

The focal length F of the prime lens provided by the embodiment is 5.92mm, and the aperture F # is 2.19.

Further, fig. 2 is a spherical aberration curve diagram of a fixed focus lens provided in the embodiment of the present invention, as shown in fig. 2, the spherical aberration of the fixed focus lens under different wavelengths (0.436 μm, 0.487 μm, 0.555 μm, 0.587 μm, and 0.656 μm) is all within 0.02mm, and different wavelength curves are relatively concentrated, which indicates that the axial aberration of the fixed focus lens is small, thereby knowing that the fixed focus lens provided in the embodiment of the present invention can better correct the aberration.

Fig. 3 is a light fan diagram of a fixed focus lens according to an embodiment of the present invention, as shown in fig. 3, imaging ranges of light rays with different wavelengths (0.436 μm, 0.487 μm, 0.546 μm, 0.587 μm, and 0.656 μm) at different angles of view of the fixed focus lens are all within 20 μm and curves are very concentrated, so as to ensure that aberrations of different fields of view are small, that is, it is explained that the fixed focus lens better corrects aberrations of an optical system.

Fig. 4 is a distortion curve diagram of a prime lens according to an embodiment of the present invention, as shown in fig. 4, a horizontal coordinate represents a distortion magnitude, and a unit is; the vertical coordinate represents the normalized image height, with no units; as can be seen from fig. 4, the distortion of the fixed-focus lens provided by the embodiment is better corrected, the imaging distortion is smaller, and the requirement of low distortion is met.

Example two

Fig. 5 is a schematic structural diagram of a fixed focus lens according to a second embodiment of the present invention, as shown in fig. 5, the fixed focus lens according to the second embodiment of the present invention includes a first lens 110, a second lens 120, a third lens 130, a fourth lens 140, a fifth lens 150, a sixth lens 160, a seventh lens 170, an eighth lens 180, and a ninth lens 190, which are sequentially arranged from an object plane to an image plane along an optical axis. The sixth lens 160 and the seventh lens 170 constitute a double cemented lens group 200. An aperture 300 is located in the optical path between the fifth lens 150 and the sixth lens 160. The filter 400 is disposed on the image-side surface side of the ninth lens 190.

For example, table 3 illustrates specific optical physical parameters of each lens in the fixed-focus lens provided by embodiment two of the present invention in a practical implementation manner, where the fixed-focus lens in table 3 corresponds to the fixed-focus lens shown in fig. 5.

TABLE 3 design values of optical physical parameters of fixed-focus lens

The surface numbers are numbered according to the surface sequence of the lenses, for example, the surface number "S1" represents the object side surface of the first lens 110, the surface number "S2" represents the image side surface of the first lens 110, and so on; the curvature radius represents the bending degree of the lens surface, a positive value represents that the surface is bent to the image surface side, a negative value represents that the surface is bent to the object surface side, and the 'PL' represents that the surface is a plane and the curvature radius is infinite; thickness represents the central axial distance from the current surface to the next surface; the refractive index Nd represents the deflection capacity of the material between the current surface and the next surface to light, the blank space represents that the current position is air, and the refractive index is 1; the abbe number Vd represents the dispersion characteristic of the material between the current surface and the next surface to light, and a blank space represents that the current position is air; the K value represents the numerical value of the best fitting cone coefficient of the aspheric surface; "STO" represents a diaphragm; IMA stands for image plane.

The aspheric conic coefficient can be defined by the following aspheric formula, but is not limited to the following expression method:

wherein Z is the axial rise of the aspheric surface in the Z direction; r is the height of the aspheric surface; c is the curvature of the fitting sphere, and the numerical value is the reciprocal of the curvature radius; k is a fitting cone coefficient; A-F are coefficients of 4 th, 6 th, 8 th, 10 th, 12 th and 14 th order terms of the aspheric polynomial.

Table 4 illustrates aspheric coefficients of each lens in the second embodiment in a possible implementation manner.

TABLE 4 designed values of aspherical coefficients of respective lenses in fixed-focus lens

wherein-3.400468E-04 represents that the coefficient A with the surface number of S5 is-3.400468 x 10 ^-4 And so on.

The focal length F of the fixed-focus lens provided in this embodiment is 5.94mm, and the aperture F # is 2.14.

Furthermore, fig. 6 is a spherical aberration curve chart of the fixed focus lens provided by the second embodiment of the present invention, as shown in fig. 6, the spherical aberration of the fixed focus lens at different wavelengths (0.436 μm, 0.487 μm, 0.555 μm, 0.587 μm, and 0.656 μm) is all within 0.01mm, and different wavelength curves are relatively concentrated, which indicates that the axial aberration of the fixed focus lens is small, so as to know that the fixed focus lens provided by the embodiment of the present invention can better correct the aberration.

Fig. 7 is a light fan diagram of a fixed focus lens according to the second embodiment of the present invention, as shown in fig. 7, imaging ranges of light rays with different wavelengths (0.436 μm, 0.487 μm, 0.555 μm, 0.587 μm, and 0.656 μm) under different angles of view of the fixed focus lens are all within 20 μm and curves are very concentrated, so as to ensure that aberrations of different fields of view are small, that is, it is explained that the fixed focus lens better corrects aberrations of an optical system.

Fig. 8 is a distortion curve diagram of a fixed-focus lens provided in the second embodiment of the present invention, as shown in fig. 8, a horizontal coordinate represents the magnitude of distortion, and the unit is; the vertical coordinate represents the normalized image height, with no units; as can be seen from fig. 8, the distortion of the fixed-focus lens provided by this embodiment is better corrected, the imaging distortion is smaller, and the requirement of low distortion is met.

EXAMPLE III

Fig. 9 is a schematic structural diagram of a fixed focus lens according to a third embodiment of the present invention, as shown in fig. 9, the fixed focus lens according to the third embodiment of the present invention includes a first lens 110, a second lens 120, a third lens 130, a fourth lens 140, a fifth lens 150, a sixth lens 160, a seventh lens 170, an eighth lens 180, and a ninth lens 190, which are sequentially arranged from an object plane to an image plane along an optical axis. The sixth lens 160 and the seventh lens 170 constitute a double cemented lens group 200. An aperture 300 is located in the optical path between the fifth lens 150 and the sixth lens 160. The filter 400 is disposed on the image-side surface side of the ninth lens 190.

Illustratively, table 5 illustrates specific optical physical parameters of each lens in the fixed-focus lens provided by the third embodiment of the present invention in a feasible implementation manner, where the fixed-focus lens in table 5 corresponds to the fixed-focus lens shown in fig. 9.

TABLE 5 design values of optical physical parameters of fixed-focus lens

The surface numbers are numbered according to the surface sequence of the lenses, for example, the surface number "S1" represents the object side surface of the first lens 110, the surface number "S2" represents the image side surface of the first lens 110, and so on; the curvature radius represents the bending degree of the lens surface, a positive value represents that the surface is bent to the image surface side, a negative value represents that the surface is bent to the object surface side, and the 'PL' represents that the surface is a plane and the curvature radius is infinite; the thickness represents the central axial distance from the current surface to the next surface; the refractive index Nd represents the deflection capacity of the material between the current surface and the next surface to light, the blank space represents that the current position is air, and the refractive index is 1; the abbe number Vd represents the dispersion characteristic of the material between the current surface and the next surface to light, and a blank space represents that the current position is air; the K value represents the numerical value of the best fitting cone coefficient of the aspheric surface; "STO" represents a diaphragm; IMA stands for image plane.

The aspheric conic coefficient can be defined by the following aspheric formula, but is not limited to the following expression method:

wherein Z is the axial rise of the aspheric surface in the Z direction; r is the height of the aspheric surface; c is the curvature of the fitting sphere, and the numerical value is the reciprocal of the curvature radius; k is a fitting cone coefficient; A-F are coefficients of 4 th, 6 th, 8 th, 10 th, 12 th and 14 th order terms of the aspheric polynomial.

Table 6 illustrates aspheric coefficients of each lens in the third embodiment in a possible implementation manner.

TABLE 6 designed values of aspherical coefficients of respective lenses in fixed-focus lens

Noodle sequence number

A

B

C

D

E

F

S5

-1.560578E-04

8.032082E-06

3.731353E-07

1.911154E-08

-1.685419E-09

4.681498E-12

S6

-1.000943E-03

-5.728350E-05

6.582588E-07

2.025915E-07

-1.011974E-08

-7.473542E-10

S15

1.008907E-03

3.356945E-05

8.083559E-07

-1.865116E-08

1.547744E-09

-3.637443E-11

S16

1.596237E-03

2.415067E-05

5.625307E-06

-2.482864E-07

7.307521E-09

2.457193E-12

wherein-1.560578E-04 represents that the coefficient A with the surface number of S5 is-1.560578 x 10 ^-4 And so on.

The focal length F of the prime lens provided by the embodiment is 5.91mm, and the aperture F # is 2.16.

Further, fig. 10 is a spherical aberration curve chart of a fixed focus lens provided by the third embodiment of the present invention, as shown in fig. 10, the spherical aberration of the fixed focus lens under different wavelengths (0.436 μm, 0.487 μm, 0.555 μm, 0.587 μm, and 0.656 μm) is all within 0.02mm, and different wavelength curves are relatively concentrated, which indicates that the axial aberration of the fixed focus lens is small, so that it can be known that the fixed focus lens provided by the embodiment of the present invention can better correct the aberration.

Fig. 11 is a light fan diagram of a fixed focus lens according to a third embodiment of the present invention, as shown in fig. 11, imaging ranges of light rays with different wavelengths (0.436 μm, 0.487 μm, 0.555 μm, 0.587 μm, and 0.656 μm) at different angles of view of the fixed focus lens are all within 20 μm and curves are very concentrated, so as to ensure that aberrations of different fields of view are small, that is, it is described that the fixed focus lens better corrects aberrations of an optical system.

Fig. 12 is a distortion curve diagram of a fixed-focus lens according to a third embodiment of the present invention, as shown in fig. 12, a horizontal coordinate represents the magnitude of distortion, and the unit is; the vertical coordinate represents the normalized image height, with no units; as can be seen from fig. 12, the distortion of the fixed-focus lens provided by the embodiment is better corrected, the imaging distortion is smaller, and the requirement of low distortion is met.

For more clear description of the above embodiments, table 7 details specific optical physical parameters of each lens in the fixed-focus lenses provided in the first to third embodiments of the present invention and other feasible optical physical parameters.

TABLE 7 design values of optical physical parameters of fixed-focus lens

The above detailed description does not limit the scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions may be made in accordance with design requirements and other factors. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A prime lens is characterized by comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens and a ninth lens which are sequentially arranged from an object plane to an image plane along an optical axis;

the first lens has a positive optical power, the second lens has a negative optical power, the third lens has a negative optical power, the fourth lens has a positive optical power, the fifth lens has a positive optical power, the sixth lens has a positive optical power, the seventh lens has a negative optical power, the eighth lens has a positive optical power, and the ninth lens has a positive optical power;

the focal power of the first lens is phi 1, the focal power of the second lens is phi 2, the focal power of the third lens is phi 3, the focal power of the fourth lens is phi 4, the focal power of the fifth lens is phi 5, the focal power of the sixth lens is phi 6, the focal power of the seventh lens is phi 7, the focal power of the eighth lens is phi 8, the focal power of the ninth lens is phi 9, and the focal power of the fixed-focus lens is phi, wherein:

0.02≤φ1/φ≤0.08；-1.10≤φ2/φ≤-0.40；-1.10≤φ3/φ≤-0.40；

0.20≤φ4/φ≤1.00；0.20≤φ5/φ≤0.90；0.05≤φ6/φ≤0.60；

-0.60≤φ7/φ≤-0.05；0.10≤φ8/φ≤0.70；0.05≤φ9/φ≤0.60。

2. the prime lens according to claim 1,

the sixth lens and the seventh lens form a double cemented lens group.

3. The prime lens according to claim 2,

the focal power of the double cemented lens group is phi 10, wherein phi 10/phi is more than or equal to 0.02 and less than or equal to 0.07.

4. The prime lens according to claim 1,

the first lens, the second lens, the fourth lens, the sixth lens, the seventh lens and the ninth lens are glass spherical lenses; the eighth lens is a plastic aspheric lens; the third lens is a glass spherical lens or a plastic aspherical lens; the fifth lens is a glass spherical lens or a plastic aspherical lens.

5. The prime lens according to claim 1,

the refractive index of the first lens is Nd1, and the Abbe number is Vd 1; the refractive index of the second lens is Nd2, and the Abbe number is Vd 2; the refractive index of the third lens is Nd3, and the Abbe number is Vd 3; the refractive index of the fourth lens is Nd4, and the Abbe number is Vd 4; the refractive index of the fifth lens is Nd5, and the Abbe number is Vd 5; the refractive index of the sixth lens is Nd6, and the Abbe number is Vd 6; the refractive index of the seventh lens is Nd7, and the Abbe number is Vd 7; the refractive index of the eighth lens is Nd8, and the Abbe number is Vd 8; the refractive index of the ninth lens is Nd9, and the Abbe number is Vd 9; wherein:

1.45≤Nd1≤1.75；52.9≤Vd1≤78.0；

1.65≤Nd2≤2.10；16.0≤Vd2≤35.0；

1.45≤Nd3≤1.65；43.6≤Vd3≤66.1；

1.65≤Nd4≤2.10；16.0≤Vd4≤35.0；

1.45≤Nd5≤1.65；45.0≤Vd5≤66.6；

1.59≤Nd6≤1.79；40.2≤Vd6≤70.0；

1.62≤Nd7≤1.84；18.3≤Vd7≤37.0；

1.45≤Nd8≤1.69；44.6≤Vd8≤57.0；

1.63≤Nd9≤1.75；49.9≤Vd9≤75.0。

6. the prime lens according to claim 1,

the curvature radius of the object side surface of the first lens is R11, the curvature radius of the image side surface of the first lens is R12, the curvature radius of the object side surface of the second lens is R21, and the curvature radius of the image side surface of the second lens is R22; wherein:

0.24≤︱R11/R12︱≤0.70；2.43≤︱R21/R22︱≤4.33。

7. the prime lens according to claim 1,

the central thickness of the first lens on the optical axis is CT1, the clear aperture of the first lens is D1, the central thickness of the second lens on the optical axis is CT2, the clear aperture of the second lens is D2, the central thickness of the fourth lens on the optical axis is CT4, the clear aperture of the fourth lens is D4, the central thickness of the ninth lens on the optical axis is CT9, and the clear aperture of the ninth lens is D9; wherein:

0.18≤︱CT1/D1︱≤0.40；0.39≤︱CT2/D2︱≤0.64；

0.42≤︱CT4/D4︱≤1.68；0.35≤︱CT9/D9︱≤0.53。

8. the prime lens according to claim 1,

the image surface diameter of the fixed focus lens is IC, and the optical total length of the fixed focus lens is TTL; wherein IC/TTL is more than or equal to 0.13.

9. The prime lens according to claim 1,

the distance from the center of an optical axis of the image side surface of the ninth lens to the image surface is BFL, the total optical length of the fixed-focus lens is TTL, and the BFL/TTL is more than 0.10 and less than 0.35.

10. The prime lens according to claim 1,

the fixed-focus lens further comprises a diaphragm;

the diaphragm is located in an optical path between the fifth lens and the sixth lens.

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