CN215264201U

CN215264201U - Fixed focus lens

Info

Publication number: CN215264201U
Application number: CN202121130736.2U
Authority: CN
Inventors: 何剑炜; 姚晨; 张磊
Original assignee: Dongguan Yutong Optical Technology Co Ltd
Current assignee: Dongguan Yutong Optical Technology Co Ltd
Priority date: 2021-05-25
Filing date: 2021-05-25
Publication date: 2021-12-21
Anticipated expiration: 2031-05-25

Abstract

The embodiment of the utility model discloses tight shot is disclosed. The fixed-focus lens comprises a first lens with negative focal power, a second lens with negative focal power, a third lens with positive focal power, a fourth lens with positive focal power, a fifth lens with negative focal power, a sixth lens with negative or positive focal power, a seventh lens with positive focal power, an eighth lens with negative or positive focal power and a ninth lens with positive focal power which are sequentially arranged from an object side to an image side along an optical axis; the focal lengths of the second lens and the third lens satisfy that: | f2/f | is more than or equal to 4.3 and less than or equal to 9.5; | f3/f | is more than or equal to 1.0 and less than or equal to 4.4; where f is the focal length of the fixed focus lens, and f2 and f3 represent the focal lengths of the second lens and the third lens, respectively. The utility model discloses can realize the black light camera lens of wide angle, high definition, super large target surface, applicable 1/1.2 "super large target surface sensitization chip uses under-40 ~ 80 ℃ of environment and guarantees that the resolving power satisfies the imaging requirement.

Description

Fixed focus lens

Technical Field

The embodiment of the utility model provides a relate to optical lens technical field, especially relate to a tight shot.

Background

In recent years, with the development of security protection, the monitoring lens technology brings a new revolution for realizing networking of cameras, and the most obvious revolution of the lens is embodied in two aspects: high cleaning and large target area. In the era of networking and digitalization, the pursuit of high definition for monitoring makes the size requirement of a camera on a target surface higher and higher. Generally, the larger the area of the photosensitive device, the better the photosensitive performance, and the higher the signal-to-noise ratio, the better the imaging effect. In order to improve the picture quality, high-definition network camera products often adopt a photosensitive chip with a large target surface. However, most of the fixed focus lenses on the market at present cannot meet the requirements of a large aperture and a large target surface, and are not favorable for the networked development of monitoring lenses.

SUMMERY OF THE UTILITY MODEL

The utility model provides a prime lens to a wide angle, high definition, the black light camera lens of super large target surface, applicable 1/1.2 "super large target surface sensitization chip adopts the glass to mould the mixed structure and can satisfy the service condition of-40 ℃ -80 ℃.

The embodiment of the present invention provides a fixed focus lens, including a first lens with negative focal power, a second lens with negative focal power, a third lens with positive focal power, a fourth lens with positive focal power, a fifth lens with negative focal power, a sixth lens with negative or positive focal power, a seventh lens with positive focal power, an eighth lens with negative or positive focal power, and a ninth lens with positive focal power, which are arranged in sequence from an object side to an image side along an optical axis;

the focal lengths of the second lens and the third lens satisfy the following condition:

4.3≤|f2/f|≤9.5；

1.0≤|f3/f|≤4.4；

wherein f is the focal length of the fixed focus lens, and f2 and f3 represent the focal lengths of the second lens and the third lens, respectively.

Optionally, focal lengths of the first lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, and the ninth lens satisfy the following condition:

0.8≤|f1/f|≤4.2；

1.7≤|f4/f|≤6.8；

1.6≤|f5/f|≤6.5；

4.2≤|f6/f|≤85.0；

1.8≤|f7/f|≤6.6；

2.0≤|f8/f|≤18.6；

2.1≤|f9/f|≤12.8；

4.2≤|(f1+f2)/f3|≤13.8；

5.9≤|(f4+f5+f6)/f|≤85.7；

0.08≤|(f8+f9)/f|≤10.3；

wherein f1, f4, f5, f6, f7, f8, f9 represent focal lengths of the first lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, and the ninth lens, respectively, in this order.

Optionally, focal lengths of the fourth lens, the fifth lens and the sixth lens satisfy the following condition:

5.9≤|(f4+f5+f6)/f|≤85.7。

optionally, the focal lengths of the eighth lens and the ninth lens satisfy the following condition:

0.08≤|(f8+f9)/f|≤10.3。

optionally, the first lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are glass spherical lenses, the second lens, the seventh lens, the eighth lens, and the ninth lens are plastic aspherical lenses, and a diaphragm is disposed between the third lens and the fourth lens.

Optionally, the refractive indices of the first to seventh lenses satisfy the following condition:

1.63≤n1≤1.90；

n2≤1.80；

1.70≤n3≤2.01；

1.50≤n4≤1.78；

n5≤1.95；

1.40≤n6；

1.53≤n7≤1.78；

wherein n1, n2, n3, n4, n5, n6 and n7 sequentially represent refractive indexes of the first lens to the seventh lens, respectively.

Optionally, the aperture F of the fixed-focus lens satisfies the following condition:

1.0≤F≤1.4。

optionally, the field angle FOV of the fixed-focus lens satisfies the following condition:

90°≤FOV≤120°。

optionally, the maximum clear aperture D1 of the first lens, the distance TTL from the front surface of the first lens to the image plane, and the distance BFL from the ninth lens to the image plane satisfy the following conditions:

BFL/TTL＞0.02，D1/TTL＜0.55。

optionally, the focal length f and the image plane diameter IH of the fixed-focus lens satisfy the following condition:

1.1≤|IH/f|≤2.5。

the present invention provides a fixed focus lens, which includes a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element, a sixth lens element, a seventh lens element, an eighth lens element and a ninth lens element sequentially disposed from an object side to an image side along an optical axis; the first lens, the second lens and the fifth lens are negative focal power lenses, and the third lens, the fourth lens, the seventh lens and the ninth lens are positive focal power lenses; meanwhile, the focal length of the second lens is set to be equal to or more than 4.3 and equal to or less than 9.5 in absolute f2/f, the focal length of the third lens is set to be equal to or more than 1.0 and equal to or less than 4.4 in absolute f3/f, a black light lens with a wide angle, high definition and an oversized target surface can be realized, and the black light lens is suitable for a 1/1.2' -oversized target surface photosensitive chip and is used under the environment of-40 to 80 ℃ to ensure that the resolving power meets the imaging requirement.

Drawings

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 plot for the fixed focus lens of FIG. 1;

FIG. 3 is a light fan diagram of the fixed focus lens of FIG. 1;

FIG. 4 is a diagram of a spot arrangement of the fixed focus lens shown in FIG. 1;

FIG. 5 is a field curvature distortion diagram of the fixed focus lens shown in FIG. 1;

FIG. 6 is a vertical axis chromatic aberration diagram of the fixed focus lens shown in FIG. 1;

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

FIG. 8 is a spherical aberration plot for the fixed focus lens of FIG. 7;

FIG. 9 is a light fan diagram of the fixed focus lens of FIG. 7;

FIG. 10 is a diagram of a spot arrangement of the fixed focus lens shown in FIG. 7;

FIG. 11 is a field curvature distortion diagram of the fixed focus lens shown in FIG. 7;

FIG. 12 is a vertical axis chromatic aberration diagram of the fixed focus lens shown in FIG. 7;

fig. 13 is a schematic structural diagram of a fixed-focus lens according to a third embodiment of the present invention;

FIG. 14 is a spherical aberration plot for the fixed focus lens of FIG. 13;

FIG. 15 is a light fan diagram of the fixed focus lens of FIG. 13;

fig. 16 is a dot array diagram of the fixed-focus lens shown in fig. 13;

fig. 17 is a field curvature distortion diagram of the fixed-focus lens shown in fig. 13;

fig. 18 is a vertical axis chromatic aberration diagram of the fixed focus lens shown in fig. 13.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

Fig. 1 is a schematic structural diagram of a fixed focus lens according to a first embodiment of the present invention, and referring to fig. 1, the fixed focus lens includes a first lens 11 having a negative focal power, a second lens 12 having a negative focal power, a third lens 13 having a positive focal power, a fourth lens 14 having a positive focal power, a fifth lens 15 having a negative focal power, a sixth lens 16 having a negative or positive focal power, a seventh lens 17 having a positive focal power, an eighth lens 18 having a negative or positive focal power, and a ninth lens 19 having a positive focal power, which are sequentially arranged from an object side to an image side along an optical axis; the focal lengths of the second lens 12 and the third lens 13 satisfy the following condition: | f2/f | is more than or equal to 4.3 and less than or equal to 9.5; | f3/f | is more than or equal to 1.0 and less than or equal to 4.4; where f is the focal length of the fixed focus lens, and f2 and f3 represent the focal lengths of the second lens 12 and the third lens 13, respectively.

Therein, it is understood that the optical power is equal to the difference between the image-side and object-side convergence, which characterizes the ability of the optical system to deflect 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. In the fixed focus lens shown in figure 1,

the first lens 11, the second lens 12 and the fifth lens 15 are negative focal power lenses, the third lens 13, the fourth lens 14, the seventh lens 17 and the ninth lens 19 are positive focal power lenses, the field angle can be increased by the first lens 11, light convergence and light divergence can be performed by other lenses, and on-axis aberration, off-axis aberration and the like can be corrected, so that the imaging quality is improved, and a large-aperture and infrared confocal lens can be realized. Specifically, the focal power of the first lens 11 and the second lens 12 is set to be negative, which can cooperate to control the incident angle of the optical system, thereby realizing a large field angle; on the basis, the chromatic power of other lenses is matched, so that aberrations such as spherical aberration correction, magnification chromatic aberration, axial chromatic aberration correction and the like of the fixed-focus lens can be corrected, and the fixed-focus lens is ensured to have higher resolving power.

On the basis of the above lens combination, the second lens 12 plays a role in converging light and reducing light height, and is mainly responsible for correcting spherical aberration, chromatic aberration of magnification and axial chromatic aberration, so that the focal length f2 of the second lens 12 and the focal length f of the prime lens in the embodiment satisfy | f2/f | < 4.3 ≦ 9.5, which can effectively correct spherical aberration, chromatic aberration of magnification, axial chromatic aberration, and the like, and better balance aberrations. In addition, the third lens 13 is used as a main element of light rays on a convergence axis in the whole fixed-focus lens, and the focal length f3 of the third lens 13 and the focal length f of the fixed-focus lens are set to satisfy | f3/f | -4.4 which is more than or equal to 1.0, so that whether the fixed-focus lens is in virtual focus in a high-temperature and low-temperature state can be greatly influenced, and the generation of virtual focus can be effectively avoided.

With continued reference to fig. 1, in the fixed focus lens, the focal lengths of the optional first lens 11, fourth lens 14, fifth lens 15, sixth lens 16, seventh lens 17, eighth lens 18, and ninth lens 19 satisfy the following condition:

0.8≤|f1/f|≤4.2；

1.7≤|f4/f|≤6.8；

1.6≤|f5/f|≤6.5；

4.2≤|f6/f|≤85.0；

1.8≤|f7/f|≤6.6；

2.0≤|f8/f|≤18.6；

2.1≤|f9/f|≤12.8；

4.2≤|(f1+f2)/f3|≤13.8；

5.9≤|(f4+f5+f6)/f|≤85.7；

0.08≤|(f8+f9)/f|≤10.3；

wherein f1, f4, f5, f6, f7, f8 and f9 represent focal lengths of the first lens 11, the fourth lens 14, the fifth lens 15, the sixth lens 16, the seventh lens 17, the eighth lens 18 and the ninth lens 19, respectively, in this order.

Further, the focal lengths of the optional fourth lens 14, fifth lens 15, and sixth lens 16 satisfy the following condition: less than or equal to 5.9 (f4+ f5+ f 6)/less than or equal to 85.7.

The fourth lens 14, the fifth lens 15 and the sixth lens 16 can form a cemented lens group in a cemented form, at this time, the fourth lens 14, the fifth lens 15 and the sixth lens 16 can realize correction of chromatic aberration of magnification and axial chromatic aberration, so that aberration balance under high and low temperature conditions is ensured, and the focal length ratio satisfies the above conditions and can generate great help for correction of tolerance.

Still further, the focal lengths of the optional eighth lens 18 and the ninth lens 19 satisfy the following condition: less than or equal to 0.08 (f8+ f 9)/less than or equal to 10.3. At this time, the eighth lens 18 and the ninth lens 19 can correct aberrations such as spherical aberration, curvature of field, astigmatism, and coma aberration.

In the embodiment of the present invention, the first lens 11, the third lens 13, the fourth lens 14, the fifth lens 15 and the sixth lens 16 can be selected as glass spherical lenses, the second lens 12, the seventh lens 17, the eighth lens 18, and the ninth lens 19 are plastic aspheric lenses, and a diaphragm is disposed between the third lens 13 and the fourth lens 14. The prime lens of 5G4P is realized, the prime lens is formed by mixing 5 glass lenses and 4 plastic lenses, the number of glass aspheric lenses can be reduced, the manufacturing difficulty of the lenses is reduced, the production cost is effectively improved, the aberration can be corrected by using the limited plastic aspheric lenses, the infrared confocal is realized by using the glass lenses, the high resolution of the lens is ensured, the lens is suitable for the working environment of-40 ℃ to 80 ℃, and the characteristics of low distortion, low distortion and miniaturization of the lens are realized.

Alternatively, the refractive indices of the first lens to the seventh lens in the present embodiment satisfy the following conditions:

1.63≤n1≤1.90；

n2≤1.80；

1.70≤n3≤2.01；

1.50≤n4≤1.78；

n5≤1.95；

1.40≤n6；

1.53≤n7≤1.78；

On the basis of the above embodiment, the utility model discloses light ring F that can set up the tight shot satisfies following condition: f is more than or equal to 1.0 and less than or equal to 1.4, and meanwhile, the field angle FOV of the fixed-focus lens can be set to meet the following conditions: the FOV is more than or equal to 90 degrees and less than or equal to 120 degrees, and at the moment, the fixed-focus lens can meet the requirements of a large aperture and a large field angle, so that the fixed-focus lens is suitable for a photosensitive chip with an oversized target surface.

In a preferred embodiment, the maximum clear aperture D1 of the first lens, the distance TTL from the front surface of the first lens to the image plane, and the distance BFL from the ninth lens to the image plane may be further set to satisfy the following conditions: BFL/TTL is more than 0.02, D1/TTL is less than 0.55. At this time, the fixed focus lens can ensure that the lens does not interfere with the base and the shell when being installed.

In a preferred embodiment, the focal length f and the image plane diameter IH of the fixed-focus lens can be set to satisfy the following condition: IH/f is more than or equal to 1.1 and less than or equal to 2.5. At the moment, the fixed-focus lens can ensure better matching degree and image surface imaging effect with the photosensitive chip.

The following describes the fixed focus lens with specific embodiments. As shown in fig. 1, in the first embodiment, the fixed-focus lens includes, in order from the object side to the image side along the optical axis, a first lens 11 having negative optical power, a second lens 12 having negative optical power, a third lens 13 having positive optical power, a fourth lens 14 having positive optical power, a fifth lens 15 having negative optical power, a sixth lens 16 having positive optical power, a seventh lens 17 having positive optical power, an eighth lens 18 having negative optical power, and a ninth lens 19 having positive optical power; the focal lengths of the second lens 12 and the third lens 13 satisfy the following condition: | f2/f | is more than or equal to 4.3 and less than or equal to 9.5; | f3/f | is more than or equal to 1.0 and less than or equal to 4.4; where f is the focal length of the fixed focus lens, and f2 and f3 represent the focal lengths of the second lens 12 and the third lens 13, respectively.

In this embodiment one, respective design values of the first lens 11 to the ninth lens 19 are shown in table 1 below.

Table 1 shows design values (aperture F1.1) of a fixed focus lens in the first embodiment

Number of noodles	Surface type	Radius of curvature	Thickness of	Material (nd)	Coefficient of K
						S1	Spherical surface	-154.7	1.4	1.71
S2	Spherical surface	11.3	6.8
						S3	Aspherical surface	-9.9	5.2	1.63	-0.2
S4	Aspherical surface	-16.2	3.2		-0.7
						S5	Spherical surface	22.6	4.0	2.00
S6	Spherical surface	-121.5	6.7
						STO/S7	PL	Infinity	-1.4
S8	Spherical surface	14.3	4.8	1.59
						S9	Spherical surface	-15.9	0.9	1.84
S10	Spherical surface	16.8	3.0	1.43
						S11	Spherical surface	-20.1	0.1
S12	Aspherical surface	33.0	3.3	1.63	-40.7
						S13	Aspherical surface	-33.4	1.3		13.8
S14	Aspherical surface	-8.8	3.6	1.66	-11.5
						S15	Aspherical surface	-21.6	0.1		-48.5
S16	Aspherical surface	7.3	3.5	1.53	-4.1
						S17	Aspherical surface	11.5	3.6		0

The surface numbers in table 1 are numbered according to the surface order of the respective lenses, where "S1" represents the front surface of the first lens, "S2" represents the rear surface of the first lens, and so on; the curvature radius represents the bending degree of the surface of the lens, a positive value represents that the surface is bent to the image surface side, and a negative value represents that the surface is bent to the object surface side; the thickness represents the central axial distance from the current surface to the next surface, the refractive index represents the deflection capability 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 K value represents the magnitude of the best fitting conic coefficient for the aspheric surface. Note that the stop is disposed between S6 and S8, that is, the stop is located between the rear surface of the third lens and the front surface of the fourth lens.

The aspheric conic coefficients can be defined by the following aspheric equation, but are not limited to the following representation:

Z＝cy²/{1+√[1-(1+k)c²y²]}+Ay⁴+By⁶+Cy⁸+Dy¹⁰+Ey¹²+Fy¹⁴；

wherein Z is the distance rise from the vertex of the aspheric surface when the aspheric surface is at the position with the height of y along the optical axis direction; c is 1/R, R represents the paraxial radius of curvature of the mirror surface; k is the cone coefficient; A. b, C, D, E, F are high-order aspheric coefficients.

In the first embodiment, the aspheric surface parameters are shown in table 2:

table 2 shows design values of aspheric coefficients in a fixed-focus lens in the first embodiment

Wherein, exemplarily, 1.46E-04 represents that the coefficient A with the surface number S3 is 1.46 x 10^-4。

Table 3 is a data list of each parameter in the first embodiment of the present invention

FIG. 2 is a spherical aberration plot for the fixed focus lens of FIG. 1; FIG. 3 is a light fan diagram of the fixed focus lens of FIG. 1; FIG. 4 is a diagram of a spot arrangement of the fixed focus lens shown in FIG. 1; FIG. 5 is a field curvature distortion diagram of the fixed focus lens shown in FIG. 1; fig. 6 is a vertical axis chromatic aberration diagram of the fixed focus lens shown in fig. 1. As can be seen from FIG. 2, the axial chromatic aberration of the fixed-focus lens is not greater than 0.035 μm for different wavelengths of light (0.436 μm, 0.486 μm, 0.545 μm, 0.587 μm and 0.656 μm). As can be seen from the sector diagrams and the histogram shown in fig. 3 and 4, the imaging ranges of different wavelengths under different field angles are within ± 20 μm, so that the aberration differences of different field areas are ensured to be small, that is, the fixed-focus lens corrects the aberration of the optical system well, and the imaging quality is good. As can be seen from FIG. 5, the field curvature in the meridional and sagittal directions generated by the fixed focus lens for light is within + -0.06 mm, and the maximum distortion is within-10%. As can be seen from FIG. 6, the axial chromatic aberration generated by the light with different wavelengths is within + -0.07 μm, and the vertical chromatic aberration is within the Airy spots. In conclusion, the embodiment of the present invention provides a fixed focus lens, which not only can better correct chromatic aberration, but also can ensure that there is less difference in the imaging chromatic aberration of infrared light and visible light, thereby facilitating the confocal of visible light and infrared light, and providing high-resolution and high-quality images.

The prime lens in the first embodiment achieves the following technical indexes: image plane diameter/focal length: IH/f 1.71; aperture value: f is 1.1; the field angle: 2w is more than or equal to 108 degrees; resolution ratio: can be adapted to 800 ten thousand pixel high resolution CCD or CMOS cameras.

Fig. 7 is a schematic structural diagram of a fixed focus lens according to a second embodiment of the present invention, referring to fig. 7, the fixed focus lens includes a first lens 11 having a negative focal power, a second lens 12 having a negative focal power, a third lens 13 having a positive focal power, a fourth lens 14 having a positive focal power, a fifth lens 15 having a negative focal power, a sixth lens 16 having a positive focal power, a seventh lens 17 having a positive focal power, an eighth lens 18 having a positive focal power, and a ninth lens 19 having a positive focal power, which are sequentially arranged from an object side to an image side along an optical axis; the focal lengths of the second lens 12 and the third lens 13 satisfy the following condition: | f2/f | is more than or equal to 4.3 and less than or equal to 9.5; | f3/f | is more than or equal to 1.0 and less than or equal to 4.4; where f is the focal length of the fixed focus lens, and f2 and f3 represent the focal lengths of the second lens 12 and the third lens 13, respectively.

In this second embodiment, respective design values of the first lens 11 to the ninth lens 19 are shown in table 4 below.

Table 4 shows design values (aperture F1.0) of the fixed focus lens in example two

Number of noodles	Surface type	Radius of curvature	Thickness of	Material (nd)	Coefficient of K
						S1	Spherical surface	231.3	1.4	1.80
S2	Spherical surface	11.4	7.6
						S3	Aspherical surface	-7.3	4.2	1.63	-0.5
S4	Aspherical surface	-11.7	1.2		-0.9
						S5	Spherical surface	28.5	3.3	1.95
S6	Spherical surface	-57.9	12.6
						STO/S7	PL	Infinity	-2.3
S8	Spherical surface	11.8	5.0	1.61
						S9	Spherical surface	-13.7	1.3	1.74
S10	Spherical surface	11.4	3.7	1.49
						S11	Spherical surface	-26.6	0.05
S12	Aspherical surface	43.8	2.3	1.58	-180.5
						S13	Aspherical surface	-34.2	0.9		-31.9
S14	Aspherical surface	-5.1	2.5	1.63	-6.6
						S15	Aspherical surface	-8.1	0.05		-6.5
S16	Aspherical surface	5.8	2.5	1.53	-4.8
						S17	Aspherical surface	8.8	4.1		-6.9

As shown in table 4, among others, the stop STO is disposed between the fourth lens 14 and the fifth lens 15, and may be particularly disposed on the front surface S7 of the fourth lens.

The aspheric surface type parameters in the second embodiment are shown in table 5:

table 5 shows design values of aspheric coefficients in the fixed-focus lens in the second embodiment

Table 6 is a data list of each parameter in the second embodiment of the present invention

FIG. 8 is a spherical aberration plot for the fixed focus lens of FIG. 7; FIG. 9 is a light fan diagram of the fixed focus lens of FIG. 7; FIG. 10 is a diagram of a spot arrangement of the fixed focus lens shown in FIG. 7; FIG. 11 is a field curvature distortion diagram of the fixed focus lens shown in FIG. 7; fig. 12 is a vertical axis chromatic aberration diagram of the fixed focus lens shown in fig. 7. As can be seen from FIG. 8, the axial chromatic aberration of the different wavelengths of light (0.436 μm, 0.486 μm, 0.545 μm, 0.587 μm and 0.656 μm) in the prime lens is not greater than 0.035 μm. As can be seen from the sector diagrams and the histogram shown in fig. 9 and 10, the imaging ranges of different wavelengths under different field angles are within ± 20 μm, so that the aberration differences of different field areas are ensured to be small, that is, the fixed-focus lens corrects the aberration of the optical system well, and the imaging quality is good. As can be seen from FIG. 11, the field curvature in the meridional and sagittal directions generated by the fixed focus lens for light is within + -0.08 mm, and the maximum distortion is within-5%. As can be seen from FIG. 12, the axial chromatic aberration generated by the light with different wavelengths is within + -0.05 μm, and the homeotropic chromatic aberration is within the Airy spots. In conclusion, the embodiment of the present invention provides a fixed focus lens, which not only can better correct chromatic aberration, but also can ensure that there is less difference in the imaging chromatic aberration of infrared light and visible light, thereby facilitating the realization of confocal imaging of visible light and infrared light, and providing high-resolution and high-quality images.

The fixed-focus lens in the second embodiment achieves the following technical indexes: image plane diameter/focal length: IH/f is 1.82 mm; aperture value: f is 1.0; the field angle: 2w is more than or equal to 108 degrees; resolution ratio: can be adapted to 800 ten thousand pixel high resolution CCD or CMOS cameras.

Fig. 13 is a schematic structural diagram of a fixed focus lens according to a third embodiment of the present invention, and referring to fig. 13, the fixed focus lens includes a first lens 11 having a negative focal power, a second lens 12 having a negative focal power, a third lens 13 having a positive focal power, a fourth lens 14 having a positive focal power, a fifth lens 15 having a negative focal power, a sixth lens 16 having a negative focal power, a seventh lens 17 having a positive focal power, an eighth lens 18 having a positive focal power, and a ninth lens 19 having a positive focal power, which are sequentially arranged from an object side to an image side along an optical axis; the focal lengths of the second lens 12 and the third lens 13 satisfy the following condition: | f2/f | is more than or equal to 4.3 and less than or equal to 9.5; | f3/f | is more than or equal to 1.0 and less than or equal to 4.4; where f is the focal length of the fixed focus lens, and f2 and f3 represent the focal lengths of the second lens 12 and the third lens 13, respectively.

In the third embodiment, respective design values of the first lens 11 to the ninth lens 19 are shown in table 7 below.

Table 7 shows design values (aperture F1.4) of the fixed focus lens in the third embodiment

Number of noodles	Surface type	Radius of curvature	Thickness of	Material (nd)	Coefficient of K
						1	Spherical surface	-181.9	1.4	1.79
2	Spherical surface	10.9	7.9
						3	Aspherical surface	-8.9	4.7	1.64	-0.6
4	Aspherical surface	-14.3	0.7		-1.0
						5	Spherical surface	24.9	4.5	1.95
6	Spherical surface	-56.9	9.8
						STO/S7	PL	Infinity	-1.4
8	Spherical surface	12.0	5.3	1.62
						9	Spherical surface	-11.8	1.5	1.74
10	Spherical surface	7.8	3.5	1.50
						11	Spherical surface	-37.6	0.1
12	Aspherical surface	65.8	2.4	1.60	-70.6
						13	Aspherical surface	-22.7	0.7		-109.4
14	Aspherical surface	-6.4	2.5	1.64	-11.5
						15	Aspherical surface	-8.1	0.1		-5.7
16	Aspherical surface	6.0	1.9	1.53	-6.1
						17	Aspherical surface	6.6	4.9		-6.2

As shown in table 7, among others, the stop STO is disposed between the fourth lens 14 and the fifth lens 15, and may be particularly disposed on the front surface S7 of the fourth lens.

The aspheric surface type parameters in the third embodiment are shown in table 8:

table 8 shows design values of aspheric coefficients in fixed-focus lens in the third embodiment

Serial number

A

B

C

D

E

F

3

1.27E-04

1.03E-06

-7.33E-09

1.66E-10

-1.14E-12

7.02E-15

4

6.09E-05

3.60E-07

-1.18E-09

2.62E-11

-1.84E-13

1.07E-15

12

-4.35E-04

-1.48E-05

4.90E-08

-3.79E-09

1.27E-10

1.34E-12

13

-2.15E-04

-8.76E-06

9.66E-08

1.56E-09

5.88E-12

5.72E-15

14

9.67E-05

8.19E-06

-5.65E-08

1.58E-09

-1.90E-11

7.19E-14

15

-3.31E-04

4.61E-06

8.53E-09

-6.19E-10

1.38E-11

1.28E-13

16

-2.32E-04

-4.06E-06

-4.40E-07

1.37E-08

-9.55E-11

-2.48E-13

17

-5.02E-05

-1.39E-05

-1.24E-08

6.28E-09

-4.76E-11

-2.11E-13

Table 9 is a data list of each parameter in the third embodiment of the present invention

FIG. 14 is a spherical aberration plot for the fixed focus lens of FIG. 13; FIG. 15 is a light fan diagram of the fixed focus lens of FIG. 13; fig. 16 is a dot array diagram of the fixed-focus lens shown in fig. 13; fig. 17 is a field curvature distortion diagram of the fixed-focus lens shown in fig. 13; fig. 18 is a vertical axis chromatic aberration diagram of the fixed focus lens shown in fig. 13. As can be seen from FIG. 14, the axial chromatic aberration in the prime lens is not greater than 0.030 μm for the different wavelengths of light (0.436 μm, 0.486 μm, 0.545 μm, 0.587 μm, and 0.656 μm). As can be seen from the sector diagrams and the histogram shown in fig. 15 and 16, the imaging ranges of different wavelengths under different field angles are within ± 20 μm, so that the aberration differences of different field areas are ensured to be small, that is, the fixed-focus lens corrects the aberration of the optical system well, and the imaging quality is good. As can be seen from FIG. 17, the field curvature in the meridional and sagittal directions generated by the fixed focus lens for light is within + -0.03 mm, and the maximum distortion is within-8%. As can be seen from FIG. 18, the axial chromatic aberration generated by the light with different wavelengths is within + -0.06 μm, and the vertical chromatic aberration is within the Airy spots. Therefore, the embodiment of the present invention provides a fixed focus lens, which not only can better correct chromatic aberration, but also can ensure that there is less difference in the imaging chromatic aberration of infrared light and visible light, thereby facilitating the confocal of visible light and infrared light, and providing high-resolution and high-quality images.

The prime lens in the third embodiment achieves the following technical indexes: image plane diameter/focal length: IH/f is 1.74; aperture value: f is 1.4; the field angle: 2w is more than or equal to 108 degrees; resolution ratio: can be adapted to 800 ten thousand pixel high resolution CCD or CMOS cameras.

It should be noted that the foregoing is only a preferred embodiment of the present invention and the technical principles applied. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious modifications, rearrangements, combinations and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail with reference to the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the scope of the present invention.

Claims

1. A fixed focus lens is characterized by comprising a first lens with negative focal power, a second lens with negative focal power, a third lens with positive focal power, a fourth lens with positive focal power, a fifth lens with negative focal power, a sixth lens with negative or positive focal power, a seventh lens with positive focal power, an eighth lens with negative or positive focal power and a ninth lens with positive focal power which are sequentially arranged from an object side to an image side along an optical axis;

4.3≤|f2/f|≤9.5；

1.0≤|f3/f|≤4.4；

2. The prime lens according to claim 1, wherein the focal lengths of the first lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, and the ninth lens satisfy the following condition:

0.8≤|f1/f|≤4.2；

1.7≤|f4/f|≤6.8；

1.6≤|f5/f|≤6.5；

4.2≤|f6/f|≤85.0；

1.8≤|f7/f|≤6.6；

2.0≤|f8/f|≤18.6；

2.1≤|f9/f|≤12.8；

4.2≤|(f1+f2)/f3|≤13.8；

5.9≤|(f4+f5+f6)/f|≤85.7；

0.08≤|(f8+f9)/f|≤10.3；

3. The prime lens according to claim 2, wherein the focal lengths of the fourth lens, the fifth lens and the sixth lens satisfy the following condition:

5.9≤|(f4+f5+f6)/f|≤85.7。

4. the prime lens according to claim 2, wherein the focal lengths of the eighth lens and the ninth lens satisfy the following condition:

0.08≤|(f8+f9)/f|≤10.3。

5. the prime lens according to claim 1, wherein the first lens, the third lens, the fourth lens, the fifth lens and the sixth lens are glass spherical lenses, the second lens, the seventh lens, the eighth lens and the ninth lens are plastic aspherical lenses, and a stop is provided between the third lens and the fourth lens.

6. The prime lens according to claim 1, wherein refractive indices of the first to seventh lenses satisfy the following condition:

1.63≤n1≤1.90；

n2≤1.80；

1.70≤n3≤2.01；

1.50≤n4≤1.78；

n5≤1.95；

1.40≤n6；

1.53≤n7≤1.78；

7. The prime lens according to claim 1, wherein the aperture F of the prime lens satisfies the following condition:

1.0≤F≤1.4。

8. the fixed focus lens according to claim 1, wherein a field angle FOV of the fixed focus lens satisfies the following condition:

90°≤FOV≤120°。

9. the prime lens according to claim 1, wherein the maximum clear aperture D1 of the first lens, the distance TTL from the front surface of the first lens to the image plane, and the distance BFL from the ninth lens to the image plane satisfy the following conditions:

BFL/TTL＞0.02，D1/TTL＜0.55。

10. the fixed focus lens according to claim 1, wherein a focal length f and an image plane diameter IH of the fixed focus lens satisfy the following condition:

1.1≤|IH/f|≤2.5。