Lens assembly

Information

  • Patent Grant
  • 11536933
  • Patent Number
    11,536,933
  • Date Filed
    Thursday, August 13, 2020
    4 years ago
  • Date Issued
    Tuesday, December 27, 2022
    2 years ago
Abstract
A lens assembly includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens, all of which are arranged in order from an object side to an image side along an optical axis. The first lens is with positive refractive power and includes a convex surface facing the object side. The second lens is with negative refractive power and includes a concave surface facing the image side. The third lens is with refractive power and includes a convex surface facing the image side. The fourth, fifth, and sixth lenses are with refractive power. The lens assembly satisfies: 2 mm
Description
BACKGROUND OF THE INVENTION
Field of the Invention

The invention relates to a lens assembly.


Description of the Related Art

The current development trend of a lens assembly is toward miniaturization. Additionally, the lens assembly is developed to have small field of view and high resolution capability in accordance with different application requirements. However, the known lens assembly can't satisfy such requirements. Therefore, the lens assembly needs a new structure in order to meet the requirements of miniaturization, small field of view, and high resolution at the same time.


BRIEF SUMMARY OF THE INVENTION

The invention provides a lens assembly to solve the above problems. The lens assembly of the invention is provided with characteristics of a shortened total lens length, a smaller field of view, a higher resolution, and still has a good optical performance.


The lens assembly in accordance with an exemplary embodiment of the invention includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens, all of which are arranged in order from an object side to an image side along an optical axis. The first lens is with positive refractive power and includes a convex surface facing the object side. The second lens is with negative refractive power and includes a concave surface facing the image side. The third lens is with refractive power and includes a convex surface facing the image side. The fourth, fifth, and sixth lenses are with refractive power. The lens assembly satisfies: 2 mm<f5+f6<35 mm, wherein f5 is an effective focal length of the fifth lens and f6 is an effective focal length of the sixth lens.


The lens assembly in accordance with another exemplary embodiment of the invention includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens, all of which are arranged in order from an object side to an image side along an optical axis. The first lens is with positive refractive power and includes a convex surface facing the object side. The second lens is with negative refractive power and includes a concave surface facing the image side. The third lens is with refractive power and includes a convex surface facing the image side. The fourth, fifth, and sixth lenses are with refractive power. The lens assembly satisfies: −21.5≤(R41−R42)/(R41+R42)≤3.5, wherein R41 is a radius of curvature of an object side surface of the fourth lens and R42 is a radius of curvature of an image side surface of the fourth lens.


The lens assembly in accordance with yet another exemplary embodiment of the invention includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a stop. The first lens is with positive refractive power and includes a convex surface facing an object side. The second lens is with negative refractive power and includes a concave surface facing an image side. The third lens is with refractive power and includes a convex surface facing the image side. The fourth, fifth, and sixth lenses are with refractive power. The first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are arranged in order from the object side to the image side along an optical axis. The stop is disposed between the object side and the third lens. The lens assembly satisfies: 4 mm<TTL−SL<9 mm, wherein TTL is an interval from the convex surface of the first lens to an image plane along the optical axis and SL is an interval from the convex surface of the first lens to the stop along the optical axis.


In another exemplary embodiment, the third lens is with positive refractive power and the fourth lens is with negative refractive power.


In yet another exemplary embodiment, the fifth lens is with positive refractive power and the sixth lens is with negative refractive power.


In another exemplary embodiment, the second lens further includes another concave surface facing the object side, the third lens further includes another convex surface facing the object side, the fourth lens is a biconcave lens, the sixth lens is a biconcave lens.


In yet another exemplary embodiment, the fifth lens is a biconvex lens.


In another exemplary embodiment, the first lens further includes a concave surface facing the image side.


In yet another exemplary embodiment, the first lens further includes another convex surface facing the image side.


In another exemplary embodiment, the fifth lens is a meniscus lens.


In yet another exemplary embodiment, the first lens further includes a concave surface facing the image side.


In another exemplary embodiment, the first lens further includes another convex surface facing the image side.


In yet another exemplary embodiment, the lens assembly satisfies: −21.5≤(R41−R42)/(R41+R42)≤3.5, wherein R41 is a radius of curvature of an object side surface of the fourth lens and R42 is a radius of curvature of an image side surface of the fourth lens.


In another exemplary embodiment, the lens assembly further includes a stop disposed between the object side and the third lens, wherein the lens assembly satisfies: 4 mm<TTL−SL<9 mm, wherein TL is an interval from the convex surface of the first lens to an image plane along the optical axis and SL is an interval from the convex surface of the first lens to the stop along the optical axis.


In yet another exemplary embodiment, the lens assembly satisfies: f1+f2<−1 mm, wherein f1 is an effective focal length of the first lens and f2 is an effective focal length of the second lens.


In another exemplary embodiment, the lens assembly satisfies: −4≤−f/f≤0, wherein f2 is an effective focal length of the second lens and f is an effective focal length of the lens assembly.


In yet another exemplary embodiment, the lens assembly satisfies: 25<V1−V2<38, wherein V1 is an Abbe number of the first lens and V2 is an Abbe number of the second lens.


In another exemplary embodiment, the lens assembly satisfies: −25 mm<f2+f4<−1.5 mm, wherein f2 is an effective focal length of the second lens and f4 is an effective focal length of the fourth lens.


In yet another exemplary embodiment, the lens assembly satisfies: FOV≤56°, wherein FOV is a field of view of the lens assembly.


In yet another exemplary embodiment, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are aspheric lenses.


A detailed description is given in the following embodiments with reference to the accompanying drawings.





BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:



FIG. 1 is a lens layout and optical path diagram of a lens assembly in accordance with a first embodiment of the invention;



FIG. 2A depicts a longitudinal spherical aberration of the lens assembly in accordance with the first embodiment of the invention;



FIG. 2B is an astigmatic field curves diagram of the lens assembly in accordance with the first embodiment of the invention;



FIG. 2C is a distortion diagram of the lens assembly in accordance with the first embodiment of the invention;



FIG. 3 is a lens layout and optical path diagram of a lens assembly in accordance with a second embodiment of the invention;



FIG. 4A depicts a longitudinal spherical aberration of the lens assembly in accordance with the second embodiment of the invention;



FIG. 4B is an astigmatic field curves diagram of the lens assembly in accordance with the second embodiment of the invention;



FIG. 4C is a distortion diagram of the lens assembly in accordance with the second embodiment of the invention;



FIG. 5 is a lens layout and optical path diagram of a lens assembly in accordance with a third embodiment of the invention;



FIG. 6A depicts a field curvature diagram of the lens assembly in accordance with the third embodiment of the invention;



FIG. 6B is a distortion diagram of the lens assembly in accordance with the third embodiment of the invention:



FIG. 6C is a modulation transfer function diagram of the lens assembly in accordance with the third embodiment of the invention;



FIG. 7 is a lens layout and optical path diagram of a lens assembly in accordance with a fourth embodiment of the invention:



FIG. 8A depicts a field curvature diagram of the lens assembly in accordance with the fourth embodiment of the invention;



FIG. 8B is a distortion diagram of the lens assembly in accordance with the fourth embodiment of the invention;



FIG. 8C is a modulation transfer function diagram of the lens assembly in accordance with the fourth embodiment of the invention;



FIG. 9 is a lens layout and optical path diagram of a lens assembly in accordance with a fifth embodiment of the invention:



FIG. 10A depicts a field curvature diagram of the lens assembly in accordance with the fifth embodiment of the invention;



FIG. 10B is a distortion diagram of the lens assembly in accordance with the fifth embodiment of the invention; and



FIG. 10C is a modulation transfer function diagram of the lens assembly in accordance with the fifth embodiment of the invention.





DETAILED DESCRIPTION OF THE INVENTION

The following description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.


Referring to FIG. 1, FIG. 1 is a lens layout and optical path diagram of a lens assembly in accordance with a first embodiment of the invention. The lens assembly 1 includes a stop ST1, a first lens L11, a second lens L12, a third lens L13, a fourth lens L14, an optical filter OF1, and a cover glass CG1, all of which are arranged in order from an object side to an image side along an optical axis OA1. In operation, an image of light rays from the object side is formed at an image plane IMA1.


The first lens L11 is a meniscus lens with positive refractive power and made of glass material, wherein the object side surface S12 is a convex surface, the image side surface S13 is a concave surface, and both of the object side surface S12 and image side surface S13 are aspheric surfaces.


The second lens L12 is a meniscus lens with negative refractive power and made of plastic material, wherein the object side surface S14 is a convex surface, the image side surface S15 is a concave surface, and both of the object side surface S14 and image side surface S15 are aspheric surfaces.


The third lens L13 is a meniscus lens with negative refractive power and made of plastic material, wherein the object side surface S16 is a concave surface, the image side surface S17 is a convex surface, and both of the object side surface S16 and image side surface S17 are aspheric surfaces.


The fourth lens L14 is a meniscus lens with positive refractive power and made of plastic material, wherein the object side surface S18 is a convex surface, the image side surface S19 is a concave surface, and both of the object side surface S18 and image side surface S19 are aspheric surfaces.


Both of the object side surface S110 and image side surface S111 of the optical filter OF1 are plane surfaces.


Both of the object side surface S112 and image side surface S113 of the cover glass CG1 are plane surfaces.


In order to maintain excellent optical performance of the lens assembly in accordance with the first embodiment of the invention, the lens assembly 1 satisfies at least one of the following conditions:

FOV1≤56°  (1)
4 mm<TTL1−SL1<9 mm  (2)
f11+f12<−1 mm  (3)
−4≤f12/f1≤0  (4)
25<V11−V12<38  (5)
−21.5≤(R141−R142)/(R141+R142)≤3.5  (6)
−25 mm<f12+f14<−1.5 mm  (7)


wherein FOV1 is a field of view in degree for the lens assembly 1, TTL1 is an interval from the object side surface S12 of the first lens L11 to the image plane IMA1 along the optical axis OA1, SL1 is an interval from the object side surface S12 of the first lens L11 to the stop ST1 along the optical axis OA, f11 is an effective focal length of the first lens L11, f12 is an effective focal length of the second lens L12, f14 is an effective focal length of the fourth lens L14, f1 is an effective focal length of the lens assembly 1, V11 is an Abbe number of the first lens L11, V12 is an Abbe number of the second lens L12, R141 is a radius of curvature of the object side surface S18 of the fourth lens L14, and R142 is a radius of curvature of the image side surface S19 of the fourth lens L14.


By the above design of the lenses, stop ST1, and satisfies at least one of the conditions (1)-(7), the lens assembly 1 is provided with an effective shortened total lens length, an effective decreased field of view, an increased resolution, and an effective corrected aberration.


In order to achieve the above purposes and effectively enhance the optical performance, the lens assembly 1 in accordance with the first embodiment of the invention is provided with the optical specifications shown in Table 1, which include the effective focal length, F-number, total lens length, field of view, radius of curvature of each lens surface, thickness between adjacent surface, refractive index of each lens, Abbe number of each lens, and effective focal length of each lens. Table 1 shows that the effective focal length is equal to 5.4619 mm, F-number is equal to 4.5, total lens length is equal to 6.688 mm, and field of view is equal to 43.9779 degrees for the lens assembly 1 of the first embodiment of the invention.









TABLE 1







Effective Focal Length = 5.4619 mm F-number = 4.5


Total Lens Length = 6.688 mm Field of View = 43.9779 Degrees


















Effective




Radius of



Focal


Surface
Curvature
Thickness


Length


Number
(mm)
(mm)
Nd
Vd
(mm)
Remark
















S11

0.000



Stop ST1


S12
1.852
0.395
1.589
61.2
3.51310
The First








Lens L11


S13
16.186
0.050


S14
2.591
0.500
1.636
23.9
−6.02370
The Second








Lens L12


S15
1.429
1.578


S16
−0.853
0.500
1.636
23.9
−5.11500
The Third








Lens L13


S17
−1.420
0.050


S18
2.103
1.030
1.535
55.7
4.1985
The Fourth








Lens L14


S19
27.234
0.500


S110

0.210
1.517
64.2

Optical








Filter OF1


S111

1.426


S112

0.400
1.517
64.2

Cover








Glass CG1


S113

0.050









The aspheric surface sag z of each lens in table 1 can be calculated by the following formula:

z=ch2/{1+[1−(k+1)c2h2]1/2}+Ah4+Bhb+Ch8+Dh10

where c is curvature, h is the vertical distance from the lens surface to the optical axis, k is conic constant and A, B, C and D are aspheric coefficients.


In the first embodiment, the conic constant k and the aspheric coefficients A, B, C, D of each surface are shown in Table 2.













TABLE 2







Surface






Number
S12
S13
S14
S15





K
−3.5527E−01 
0.0000E+00
−1.6190E+00 
−2.9888E−02 


A
3.8319E−03
−8.7036E−03 
−2.2288E−03 
−5.4284E−02 


B
−4.7768E−03 
1.7903E−05
6.5077E−03
6.2554E−03


C
0.0000E+00
6.5897E−03
1.1869E−04
8.6668E−03


D
0.0000E+00
0.0000E+00
7.0890E−05
9.8377E−03





Surface



Number
S16
S17
S18
S19





K
−2.3851E+00
−2.1665E+00
−9.4074E+00
0.0000E+00


A
−5.1997E−02
−1.2031E−02
−1.1391E−02
−2.9667E−02 


B
−2.0059E−02
 2.2708E−03
 4.4922E−03
3.3095E−03


C
 3.5820E−02
 5.3712E−03
−1.0136E−03
6.4504E−04


D
−1.7535E−02
−2.0000E−03
 1.1801E−04
−1.1033E−04 









Table 3 shows the parameters and condition values for conditions (1)-(7). As can be seen from Table 3, the lens assembly 1 of the first embodiment satisfies the conditions (1)-(7).

















TABLE 3







FOV1
43.9779
Degrees
TTL1
6.688
mm
SL1
0
mm


f11
3.5131
mm
f12
−6.02370
mm
f14
4.1985
mm













f1
5.4619
mm
V11
61.2 
V12
23.9















R141
2.103
mm
R142
27.234
mm





FOV1
43.9779
Degrees
TTL1 − SL1
6.688
mm
f11 + f12
−2.511
mm













f12 + f14
−1.825
mm
f12/f1
−1.103
V11 − V12
37.3














(R141 − R142)/(R141 + R142)
−0.857









By the above arrangements of the lenses and stop ST1, the lens assembly 1 of the first embodiment can meet the requirements of optical performance as seen in FIGS. 2A-2C, wherein FIG. 2A shows a longitudinal spherical aberration diagram of the lens assembly 1 in accordance with the first embodiment of the invention, FIG. 2B shows an astigmatic field curves diagram of the lens assembly 1 in accordance with the first embodiment of the invention, and FIG. 2C shows a distortion diagram of the lens assembly 1 in accordance with the first embodiment of the invention.


It can be seen from FIG. 2A that the longitudinal spherical aberration in the lens assembly 1 of the first embodiment ranges from −0.005 mm to 0.013 mm for the wavelength of 435.8300 nm, 546.0700 nm, and 656.2800 nm.


It can be seen from FIG. 2B that the astigmatic field curves of tangential direction and sagittal direction in the lens assembly 1 of the first embodiment ranges from −0.005 mm to 0.005 mm for the wavelength of 546.0700 nm.


It can be seen from FIG. 2C that the distortion in the lens assembly 1 of the first embodiment ranges from 0% to 0.5% for the wavelength of 546.0700 nm.


It is obvious that the longitudinal spherical aberration, the astigmatic field curves, and the distortion of the lens assembly 1 of the first embodiment can be corrected effectively. Therefore, the lens assembly 1 of the first embodiment is capable of good optical performance.


Referring to FIG. 3, FIG. 3 is a lens layout and optical path diagram of a lens assembly in accordance with a second embodiment of the invention. The lens assembly 2 includes a stop ST2, a first lens L21, a second lens L22, a third lens L23, a fourth lens L24, an optical filter OF2, and a cover glass CG2, all of which are arranged in order from an object side to an image side along an optical axis OA2. In operation, an image of light rays from the object side is formed at an image plane IMA2.


The first lens L21 is a meniscus lens with positive refractive power and made of glass material, wherein the object side surface S22 is a convex surface, the image side surface S23 is a concave surface, and both of the object side surface S22 and image side surface S23 are aspheric surfaces.


The second lens L22 is a meniscus lens with negative refractive power and made of plastic material, wherein the object side surface S24 is a convex surface, the image side surface S25 is a concave surface, and both of the object side surface S24 and image side surface S25 are aspheric surfaces.


The third lens L23 is a meniscus lens with negative refractive power and made of plastic material, wherein the object side surface S26 is a concave surface, the image side surface S27 is a convex surface, and both of the object side surface S26 and image side surface S27 are aspheric surfaces.


The fourth lens L24 is a biconvex lens with positive refractive power and made of plastic material, wherein the object side surface S28 is a convex surface, the image side surface S29 is a convex surface, and both of the object side surface S28 and image side surface S29 are aspheric surfaces.


Both of the object side surface S210 and image side surface S211 of the optical filter OF2 are plane surfaces.


Both of the object side surface S212 and image side surface S213 of the cover glass CG2 are plane surfaces.


In order to maintain excellent optical performance of the lens assembly in accordance with the second embodiment of the invention, the lens assembly 2 satisfies at least one of the following conditions:

FOV2≤56°  (8)
4 mm<TTL2−SL2<9 mm  (9)
f21+f22<−1 mm  (10)
−4≤f22/f1≤0  (11)
25<V21−V22<38  (12)
−21.5≤(R241−R242)/(R241+R242)≤3.5  (13)
−25 mm<f22+f24<−1.5 mm  (14)


The definition of FOV2, TTL2, SL2, f21, f22, f24, f2, V21, V22, R241, and R242 are the same as that of FOV1, TTL1, SL1, f11, f12, f14, f1, V11, V12, R141, and R142 in the first embodiment, and is not described here again.


By the above design of the lenses, stop ST2, and satisfies at least one of the conditions (8)-(14), the lens assembly 2 is provided with an effective shortened total lens length, an effective decreased field of view, an increased resolution, and an effective corrected aberration.


In order to achieve the above purposes and effectively enhance the optical performance, the lens assembly 2 in accordance with the second embodiment of the invention is provided with the optical specifications shown in Table 4, which include the effective focal length, F-number, total lens length, field of view, radius of curvature of each lens surface, thickness between adjacent surface, refractive index of each lens, Abbe number of each lens, and effective focal length of each lens. Table 4 shows that the effective focal length is equal to 5.4246 mm, F-number is equal to 4.5, total lens length is equal to 7.412 mm, and field of view is equal to 44.0706 degrees for the lens assembly 2 of the second embodiment of the invention.









TABLE 4







Effective Focal Length = 5.4246 mm F-number = 4.5


Total Lens Length = 7.412 mm Field of View = 44.0706 Degrees


















Effective




Radius of



Focal


Surface
Curvature
Thickness


Length


Number
(mm)
(mm)
Nd
Vd
(mm)
Remark
















S21

−0.090



Stop ST2


S22
2.066
0.500
1.589
61.2
5.59480
The First








Lens L21


S23
5.037
0.453


S24
2.097
0.300
1.636
23.9
−19.03600
The Second








Lens L22


S25
1.688
0.682


S26
−0.635
0.300
1.636
23.9
−3.00140
The Third








Lens L23


S27
−1.126
0.100


S28
2.442
1.006
1.535
55.7
2.8826
The Fourth








Lens L24


S29
−3.585
0.500


S210

0.210
1.517
64.2

Optical








Filter OF2


S211

3.001


S212

0.400
1.517


Cover








Glass CG2


S213

0.050









The aspheric surface sag z of each lens in table 4 can be calculated by the following formula:

z=ch2/{1+[1−(k+1)c2h2]1/2}+Ah4+Bhb+Ch8+Dh10

where c is curvature, h is the vertical distance from the lens surface to the optical axis, k is conic constant and A, B, C and D are aspheric coefficients.


In the second embodiment, the conic constant k and the aspheric coefficients A, B, C, D of each surface are shown in Table 5.













TABLE 5







Surface






Number
S22
S23
S24
S25





K
3.0921E−03
 0.0000E+00
−6.3202E+00
−1.8255E+00


A
6.7904E−03
−2.4248E−02
−1.2011E−02
−3.9700E−02


B
−4.9964E−03 
−2.4752E−03
−3.8126E−02
 2.6612E−02


C
−1.5750E−04 
−1.6603E−02
 9.0336E−03
 2.3417E−03


D
0.0000E+00
 0.0000E+00
−3.5095E−03
−1.2144E−03





Surface



Number
S26
S27
S28
S29





K
−2.1224E+00
−2.8806E+00 
−2.2729E+01
 0.0000E+00


A
−5.2106E−02
1.4819E−02
−1.7987E−02
−8.0327E−03


B
 1.6977E−02
7.5686E−03
 6.6630E−03
 1.0811E−03


C
 6.4081E−02
2.5693E−03
−2.7596E−03
−7.5699E−04


D
−1.5156E−02
−3.5407E−03 
−5.3512E−04
−7.3260E−05









Table 6 shows the parameters and condition values for conditions (8)-(14). As can be seen from Table 6, the lens assembly 2 of the second embodiment satisfies the conditions (8)-(14).

















TABLE 6







FOV2
44.0706
Degrees
TTL2
7.412
mm
SL2
0.09
mm


f21
5.5948
mm
f22
−19.03600
mm
f24
2.8826
mm













f2
5.4246
mm
V21
61.2 
V22
23.9















R241
2.442
mm
R242
−3.582
mm





FOV2
44.070
Degrees
TTL2 − SL2
7.322
mm
f21 + f22
−13.4412
mm













f22 + f24
−16.153
mm
f22/f2
−3.509
V21 − V22
37.3














(R241 − R242)/(R241 + R242)
−5.274









By the above arrangements of the lenses and stop ST2, the lens assembly 2 of the second embodiment can meet the requirements of optical performance as seen in FIGS. 4A-4C, wherein FIG. 4A shows a longitudinal spherical aberration diagram of the lens assembly 2 in accordance with the second embodiment of the invention, FIG. 4B shows an astigmatic field curves diagram of the lens assembly 2 in accordance with the second embodiment of the invention, and FIG. 4C shows a distortion diagram of the lens assembly 2 in accordance with the second embodiment of the invention.


It can be seen from FIG. 4A that the longitudinal spherical aberration in the lens assembly 2 of the second embodiment ranges from 0.00 mm to 0.030 mm for the wavelength of 435.8300 nm, 546.0700 nm, and 656.2800 nm.


It can be seen from FIG. 4B that the astigmatic field curves of tangential direction and sagittal direction in the lens assembly 2 of the second embodiment ranges from −0.015 mm to 0.018 mm for the wavelength of 546.0700 nm.


It can be seen from FIG. 4C that the distortion in the lens assembly 2 of the second embodiment ranges from 0% to 1.3% for the wavelength of 546.0700 nm.


It is obvious that the longitudinal spherical aberration, the astigmatic field curves, and the distortion of the lens assembly 2 of the second embodiment can be corrected effectively. Therefore, the lens assembly 2 of the second embodiment is capable of good optical performance.


Referring to FIG. 5, FIG. 5 is a lens layout and optical path diagram of a lens assembly in accordance with a third embodiment of the invention. The lens assembly 3 includes a stop ST3, a first lens L31, a second lens L32, a third lens L33, a fourth lens L34, a fifth lens L35, a sixth lens L36, and an optical filter OF3, all of which are arranged in order from an object side to an image side along an optical axis OA3. In operation, an image of light rays from the object side is formed at an image plane IMA3.


The first lens L31 is a meniscus lens with positive refractive power and made of plastic material, wherein the object side surface S32 is a convex surface, the image side surface S33 is a concave surface, and both of the object side surface S32 and image side surface S33 are aspheric surfaces.


The second lens L32 is a biconcave lens with negative refractive power and made of plastic material, wherein the object side surface S34 is a concave surface, the image side surface S35 is a concave surface, and both of the object side surface S34 and image side surface S35 are aspheric surfaces.


The third lens L33 is a biconvex lens with positive refractive power and made of plastic material, wherein the object side surface S36 is a convex surface, the image side surface S37 is a convex surface, and both of the object side surface S36 and image side surface S37 are aspheric surfaces.


The fourth lens L34 is a biconcave lens with negative refractive power and made of plastic material, wherein the object side surface S38 is a concave surface, the image side surface S39 is a concave surface, and both of the object side surface S38 and image side surface S39 are aspheric surfaces.


The fifth lens L35 is a biconvex lens with positive refractive power and made of plastic material, wherein the object side surface S310 is a convex surface, the image side surface S311 is a convex surface, and both of the object side surface S310 and image side surface S311 are aspheric surfaces.


The sixth lens L36 is a biconcave lens with negative refractive power and made of plastic material, wherein the object side surface S312 is a concave surface, the image side surface S313 is a concave surface, and both of the object side surface S312 and image side surface S313 are aspheric surfaces


Both of the object side surface S314 and image side surface S315 of the optical filter OF3 are plane surfaces.


In order to maintain excellent optical performance of the lens assembly in accordance with the third embodiment of the invention, the lens assembly 3 satisfies at least one of the following conditions:

FOV3≤56°  (15)
4 mm<TTL3−SL3<9 mm  (16)
f31+f32<−1 mm  (17)
−25 mm<f32+f34<−1.5 mm  (18)
−4≤f32/f3≤0  (19)
2 mm<f35+f36<35 mm  (20)
25<V31−V32<38  (21)
−21.5≤(R341−R342)/(R341+R342)≤3.5  (22)


The definition of FOV3, TTL3, SL3, f31, f32, f34, f3, V31, V32, R341, and R342 are the same as that of FOV1, TTL1, SL1, f11, f12, f14, f1, V11, V12, R141, and R142 in the first embodiment, and is not described here again, f35 is an effective focal length of the fifth lens L35 and f36 is an effective focal length of the sixth lens L36.


By the above design of the lenses, stop ST3, and satisfies at least one of the conditions (15)-(22), the lens assembly 3 is provided with an effective shortened total lens length, an effective decreased field of view, an increased resolution, and an effective corrected aberration.


In order to achieve the above purposes and effectively enhance the optical performance, the lens assembly 3 in accordance with the third embodiment of the invention is provided with the optical specifications shown in Table 7, which include the effective focal length, F-number, total lens length, field of view, radius of curvature of each lens surface, thickness between adjacent surface, refractive index of each lens, Abbe number of each lens, and effective focal length of each lens. Table 7 shows that the effective focal length is equal to 5.574 mm, F-number is equal to 2.8, total lens length is equal to 5.88 mm, and field of view is equal to 55.5 degrees for the lens assembly 3 of the third embodiment of the invention.









TABLE 7







Effective Focal Length = 5.574 mm F-number = 2.8


Total Lens Length = 5.88 mm Field of View = 55.5 Degrees


















Effective




Radius of



Focal


Surface
Curvature
Thickness


Length


Number
(mm)
(mm)
Nd
Vd
(mm)
Remark
















S31

−0.316



Stop ST3


S32
1.7608
0.591
1.535
56.115
3.423
The First Lens L31


S33
38.585
0.026


S34
−2512.54
0.35
1.636
23.972
−6.364
The Second Lens L32


S35
4.064
0.6


S36
8.398
1.083
1.535
56.115
7.624
The Third Lens L33


S37
−7.599
0.159


S38
−5.616
0.266
1.544
56.093
−5.354
The Fourth Lens L34


S39
6.171
0.031


S310
4.21
0.777
1.535
56.115
6.588
The Fifth Lens L35


S311
−20.468
0.791


S312
−3.319
0.295
1.535
56.115
−3.847
The Sixth Lens L36


S313
5.609
0.345


S314

0.21
1.517
64.167

Optical Filter OF3


S315

0.396









The aspheric surface sag z of each lens in table 7 can be calculated by the following formula:

z=ch2/{1+[1−(k+1)c2h2]1/2}+Ah4+Bhb+Ch8+Dh10+Eh12+Fh14+Gh16

where c is curvature, h is the vertical distance from the lens surface to the optical axis, k is conic constant and A, B, C, D, E, F and G are aspheric coefficients.


In the third embodiment, the conic constant k and the aspheric coefficients A, B, C, D, E, F, G of each surface are shown in Table 8.













TABLE 8





Surface
k
A
B
C


Number
D
E
F
G







S32
   0.024
 8.24E−03
−4.99E−03
 8.59E−03



−4.32E−03
−4.69E−04
−2.01E−03
−1.12E−03


S33
0
−8.55E−03
 8.54E−03
 8.86E−03



 1.05E−02
−1.84E−04
−2.31E−03
−1.12E−02


S34
0
−2.40E−02
 2.59E−02
 2.08E−02



 1.46E−02
−8.56E−03
−5.08E−03
−1.09E−03


S35
  −1.101
−9.52E−03
 5.91E−02
−7.41E−03



 3.23E−02
−1.01E−02
−2.66E−02
 3.80E−02


S36
   3.316
−3.62E−02
−1.80E−03
 7.05E−03



 1.08E−02
−5.64E−03
−1.37E−02
 7.73E−03


S37
0
−1.12E−01
 1.07E−02
−2.49E−02



−7.59E−03
 8.03E−03
 7.83E−03
−6.23E−03


S38
0
−5.86E−02
−2.50E−02
−9.50E−03



−5.81E−03
−3.53E−03
−1.59E−03
 1.41E−03


S39
  −0.904
−3.41E−02
 1.26E−02
 1.38E−03



−2.64E−03
−1.61E−03
−6.45E−04
−2.98E−04


S310
   4.469
−6.85E−02
 1.93E−02
−1.29E−02



 1.03E−03
 8.80E−04
−3.64E−04
−1.23E−08


S311
−1002.23  
 3.17E−02
 6.87E−04
−3.47E−03



−5.00E−04
 4.84E−05
 1.45E−04
−2.39E−05


S312
   1.759
−3.46E−02
 4.98E−04
 9.89E−03



−7.83E−04
−7.24E−04
−4.02E−05
 4.00E−05


S313
  −10.386
−6.64E−02
 1.42E−02
−2.36E−03



 2.26E−04
−1.74E−05
−5.58E−06
 4.41E−07









Table 9 shows the parameters and condition values for conditions (15)-(22). As can be seen from Table 8, the lens assembly 3 of the third embodiment satisfies the conditions (15)-(22).

















TABLE 9







FOV3
55.5
Degrees
TTL3
5.88
mm
SL3
0.316
mm


f31
3.42
mm
f32
−6.364
mm
f34
−5.354
mm


f35
6.588
mm
f36
−3.847
mm
f3
5.574
mm













V31
56.115
V32
23.972
R341
−5.616
mm















R342
6.171
mm








FOV3
55.5
Degrees
TTL3 − SL3
5.564
mm
f31 + f32
−2.941
mm














f32 + f34
−11.718
mm
f32/f3
−1.142
f35 + f36
2.741
mm













V31 − V32
32.143
(R341 − R342)/(R341 + R342)
−21.238 









By the above arrangements of the lenses and stop ST3, the lens assembly 3 of the third embodiment can meet the requirements of optical performance as seen in FIGS. 6A-6C, wherein FIG. 6A shows a field curvature diagram of the lens assembly 3 in accordance with the third embodiment of the invention, FIG. 6B shows a distortion diagram of the lens assembly 3 in accordance with the third embodiment of the invention, and FIG. 6C shows a modulation transfer function diagram of the lens assembly 3 in accordance with the third embodiment of the invention.


It can be seen from FIG. 6A that the field curvature of tangential direction and sagittal direction in the lens assembly 3 of the third embodiment ranges from −0.06 mm to 0.05 mm for the wavelength of 0.439 μm, 0.546 μm, 0.573 μm, 0.587 μm, and 0.656 μm.


It can be seen from FIG. 6B that the distortion in the lens assembly 3 of the third embodiment ranges from 0% to 1.8% for the wavelength of 0.439 μm, 0.546 μm, 0.573 μm, 0.587 μm, and 0.656 μm.


It can be seen from FIG. 6C that the modulation transfer function of tangential direction and sagittal direction in the lens assembly 3 of the third embodiment ranges from 0.38 to 1.0 wherein the wavelength ranges from 0.4385 μm to 0.6563 μm, the fields respectively are 0.0000 mm, 0.5867 mm, 1.1734 mm, 1.4668 mm, 2.0535 mm, 2.6402 mm, and 2.9335 mm, and the spatial frequency ranges from 0 lp/mm to 125 lp/mm.


It is obvious that the field curvature and the distortion of the lens assembly 3 of the third embodiment can be corrected effectively, and the resolution of the lens assembly 3 of the third embodiment can meet the requirement. Therefore, the lens assembly 3 of the third embodiment is capable of good optical performance.


Referring to FIG. 7, FIG. 7 is a lens layout and optical path diagram of a lens assembly in accordance with a fourth embodiment of the invention. The lens assembly 4 includes a first lens L41, a stop ST4, a second lens L42, a third lens L43, a fourth lens L44, a fifth lens L45, a sixth lens L46, and an optical filter OF4, all of which are arranged in order from an object side to an image side along an optical axis OA4. In operation, an image of light rays from the object side is formed at an image plane IMA4.


The first lens L41 is a meniscus lens with positive refractive power and made of plastic material, wherein the object side surface S41 is a convex surface, the image side surface S42 is a concave surface, and both of the object side surface S41 and image side surface S42 are aspheric surfaces.


The second lens L42 is a biconcave lens with negative refractive power and made of plastic material, wherein the object side surface S43 is a concave surface, the image side surface S44 is a concave surface, and both of the object side surface S43 and image side surface S44 are aspheric surfaces.


The third lens L43 is a biconvex lens with positive refractive power and made of plastic material, wherein the object side surface S45 is a convex surface, the image side surface S46 is a convex surface, and both of the object side surface S45 and image side surface S46 are aspheric surfaces.


The fourth lens L44 is a biconcave lens with negative refractive power and made of plastic material, wherein the object side surface S47 is a concave surface, the image side surface S48 is a concave surface, and both of the object side surface S47 and image side surface S48 are aspheric surfaces.


The fifth lens L45 is a meniscus lens with positive refractive power and made of plastic material, wherein the object side surface S49 is a convex surface, the image side surface S410 is a concave surface, and both of the object side surface S49 and image side surface S410 are aspheric surfaces.


The sixth lens L46 is a biconcave lens with negative refractive power and made of plastic material, wherein the object side surface S411 is a concave surface, the image side surface S412 is a concave surface, and both of the object side surface S411 and image side surface S412 are aspheric surfaces


Both of the object side surface S413 and image side surface S414 of the optical filter OF4 are plane surfaces.


In order to maintain excellent optical performance of the lens assembly in accordance with the fourth embodiment of the invention, the lens assembly 4 satisfies at least one of the following conditions:

FOV4≤56°  (23)
4 mm<TTL4−SL4<9 mm  (24)
f41+f42<−1 mm  (25)
−25 mm<f42+f44<−1.5 mm  (26)
−4≤f42/f4≤0  (27)
2 mm<f45+f46<35 mm  (28)
25<V41−V42<38  (29)
−21.5≤(R441−R442)/(R441+R442)≤3.5  (30)


The definition of FOV4, TTL4, SL4, f41, f42, f44, f45, f46, f4, V41, V42, R441, and R442 are the same as that of FOV3, TTL3, SL3, f31, f32 f34, f35, f36, f3, V31, V32, R341, and R342 in the third embodiment, and is not described here again.


By the above design of the lenses, stop ST4, and satisfies at least one of the conditions (23)-(30), the lens assembly 4 is provided with an effective shortened total lens length, an effective decreased field of view, an increased resolution, and an effective corrected aberration.


In order to achieve the above purposes and effectively enhance the optical performance, the lens assembly 4 in accordance with the fourth embodiment of the invention is provided with the optical specifications shown in Table 10, which include the effective focal length, F-number, total lens length, field of view, radius of curvature of each lens surface, thickness between adjacent surface, refractive index of each lens, Abbe number of each lens, and effective focal length of each lens. Table 10 shows that the effective focal length is equal to 7.082 mm, F-number is equal to 2.8, total lens length is equal to 7.7 mm, and field of view is equal to 45 degrees for the lens assembly 4 of the fourth embodiment of the invention.









TABLE 10







Effective Focal Length = 7.082 mm F-number = 2.8


Total Lens Length = 7.7 mm Field of View = 45 Degrees


















Effective




Radius of



Focal


Surface
Curvature
Thickness


Length


Number
(ram)
(mm)
Nd
Vd
(mm)
Remark
















S41
2.347197
0.910177
1.535
56.115
4.547
The First Lens L41


S42
54.93809
0.046326



Stop ST4


S43
−20.1212
0.249992
1.636
23.972
−7.392
The Second Lens L42


S44
6.184075
0.108445


S45
7.374668
1.184192
1.535
56.115
9.335
The Third Lens L43


S46
−14.6877
0.274388


S47
−11.0451
0.913223
1.544
56.093
−6.845
The Fourth Lens L44


S48
5.799714
0.02497


S49
4.304854
1.69802
1.535
56.115
9.369
The Fifth Lens L45


S410
26.00662
1.176473


S411
−3.46793
0.309922
1.535
56.115
−4.533
The Sixth Lens L46


S412
8.369748
0.4


S413

0.21
1.517
64.167

Optical Filter OF4


S414

0.195235









The aspheric surface sag z of each lens in table 10 can be calculated by the following formula:

z=ch2/{1+[1−(k+1)c2h2]1/2}+Ah4+Bhb+Ch8+Dh10+Eh12+Fh14+Gh16

where c is curvature, his the vertical distance from the lens surface to the optical axis k is conic constant and A, B, C, D, E, F and are aspheric coefficients.


In the fourth embodiment, the conic constant k and the aspheric coefficients A, B, C, D, E, F, G of each surface are shown in Table 11.













TABLE 11





Surface
k
A
B
C


Number
D
E
F
G







S41
   0.024
 1.76E−03
−3.29E−03 
 5.27E−03



−3.55E−03
−1.46E−03
1.76E−03
−4.44E−04


S42
0
 2.24E−02
4.43E−03
−4.83E−03



 6.44E−03
 1.79E−04
−3.88E−03 
 2.56E−04


S43
0
 9.51E−03
1.78E−02
 1.17E−02



−2.62E−03
−4.35E−03
1.77E−03
−1.16E−03


S44
  −1.101
−1.02E−02
5.70E−02
−1.67E−03



 1.29E−02
−5.04E−03
−1.22E−02 
 5.30E−03


S45
   3.316
−1.12E−02
1.43E−02
 2.27E−02



−1.14E−02
−9.35E−03
4.35E−03
−2.56E−03


S46
0
−1.14E−01
4.02E−03
−3.38E−03



−2.41E−03
−1.00E−03
5.70E−03
−3.28E−03


S47
0
−1.66E−01
−1.16E−02 
 3.32E−02



−4.85E−03
−1.50E−02
9.61E−03
−4.51E−04


S48
  −0.904
−3.12E−02
2.29E−02
 1.67E−03



−4.93E−03
−8.00E−04
1.21E−03
−1.43E−04


S49
   4.469
 1.05E−02
1.80E−03
−4.87E−03



−7.58E−04
 8.69E−05
3.40E−04
−9.80E−05


S410
−1002.23  
 2.79E−02
−4.18E−03 
 1.76E−03



−3.52E−04
−6.09E−05
2.60E−05
−1.55E−06


S411
   1.759
−7.58E−02
2.53E−02
−3.34E−04



−1.07E−03
−9.58E−05
2.59E−05
 1.15E−05


S412
  −10.386
−5.33E−02
1.12E−02
−4.96E−04



−2.72E−04
 3.17E−07
7.68E−06
−5.92E−07









Table 12 shows the parameters and condition values for conditions (23)-(30). As can be seen from Table 12, the lens assembly 4 of the fourth embodiment satisfies the conditions (23)-(30).

















TABLE 12







FOV4
45
Degrees
TTL4
7.7
mm
SL4
0.910
mm


f41
4.547
mm
f42
−7.392
mm
f44
−6.845
mm


f45
9.369
mm
f46
−4.533
mm
f4
7.082
mm













V41
56.115
V42
23.972
R441
−11.0451
mm















R442
5.799714
mm








FOV4
45
Degrees
TTL4 − SL4
6.79
mm
f41 + f42
−2.845
mm














f42 + f44
−14.237
mm
f42/f4
−1.044
f45 + f46
4.836
mm













V41 − V42
32.143
(R441 − R442)/(R441 + R442)
 3.211









By the above arrangements of the lenses and stop ST4, the lens assembly 4 of the fourth embodiment can meet the requirements of optical performance as seen in FIGS. 8A-8C, wherein FIG. 8A shows a field curvature diagram of the lens assembly 4 in accordance with the fourth embodiment of the invention, FIG. 8B shows a distortion diagram of the lens assembly 4 in accordance with the fourth embodiment of the invention, and FIG. 8C shows a modulation transfer function diagram of the lens assembly 4 in accordance with the fourth embodiment of the invention.


It can be seen from FIG. 8A that the field curvature of tangential direction and sagittal direction in the lens assembly 4 of the fourth embodiment ranges from −0.03 mm to 0.05 mm for the wavelength of 0.439 μm, 0.546 μm, 0.573 μm, 0.587 μm, and 0.656 μm.


It can be seen from FIG. 8B that the distortion in the lens assembly 4 of the fourth embodiment ranges from 0% to 2.0% for the wavelength of 0.439 μm, 0.546 μm, 0.573 μm, 0.587 μm, and 0.656 μm.


It can be seen from FIG. 8C that the modulation transfer function of tangential direction and sagittal direction in the lens assembly 4 of the fourth embodiment ranges from 0.38 to 1.0 wherein the wavelength ranges from 0.4385 μm to 0.6563 μm, the fields respectively are 0.0000 mm, 0.5867 mm, 1.1734 mm, 1.4668 mm, 2.0535 mm, 2.6402 mm, and 2.9335 mm, and the spatial frequency ranges from 0 lp/mm to 125 lp/mm.


It is obvious that the field curvature and the distortion of the lens assembly 4 of the fourth embodiment can be corrected effectively, and the resolution of the lens assembly 4 of the fourth embodiment can meet the requirement. Therefore, the lens assembly 4 of the fourth embodiment is capable of good optical performance.


Referring to FIG. 9, FIG. 9 is a lens layout and optical path diagram of a lens assembly in accordance with a fifth embodiment of the invention. The lens assembly 5 includes a first lens L51, a second lens L52, a stop ST5, a third lens L53, a fourth lens L54, a fifth lens L55, a sixth lens L56, and an optical filter OF5, all of which are arranged in order from an object side to an image side along an optical axis OA5. In operation, an image of light rays from the object side is formed at an image plane IMA5.


The first lens L51 is a biconvex lens with positive refractive power and made of plastic material, wherein the object side surface S51 is a convex surface, the image side surface S52 is a convex surface, and both of the object side surface S51 and image side surface S52 are aspheric surfaces.


The second lens L52 is a biconcave lens with negative refractive power and made of plastic material, wherein the object side surface S53 is a concave surface, the image side surface S54 is a concave surface, and both of the object side surface S53 and image side surface S54 are aspheric surfaces.


The third lens L53 is a biconvex lens with positive refractive power and made of plastic material, wherein the object side surface S56 is a convex surface, the image side surface S57 is a convex surface, and both of the object side surface S56 and image side surface S57 are aspheric surfaces.


The fourth lens L54 is a biconcave lens with negative refractive power and made of plastic material, wherein the object side surface S58 is a concave surface, the image side surface S59 is a concave surface, and both of the object side surface S58 and image side surface S59 are aspheric surfaces.


The fifth lens L55 is a meniscus lens with positive refractive power and made of plastic material, wherein the object side surface S510 is a concave surface, the image side surface S511 is a convex surface, and both of the object side surface S510 and image side surface S511 are aspheric surfaces.


The sixth lens L56 is a biconcave lens with negative refractive power and made of plastic material, wherein the object side surface S512 is a concave surface, the image side surface S513 is a concave surface, and both of the object side surface S512 and image side surface S513 are aspheric surfaces


Both of the object side surface S514 and image side surface S515 of the optical filter OF5 are plane surfaces.


In order to maintain excellent optical performance of the lens assembly in accordance with the fifth embodiment of the invention, the lens assembly 5 satisfies at least one of the following conditions:

FOV5≤56°  (31)
4 mm<TTL5−SL5<9 mm  (32)
f51+f52<−1 mm  (33)
−25 mm<f52+f54<−1.5 mm  (34)
−4≤f52/f5≤0  (35)
2 mm<f55+f56<35 mm  (36)
25<V51−V52<38  (37)
−21.5≤(R541−R542)/(R541+R542)≤3.5  (38)


The definition of FOV5, TTL5, SL5, f51, f52, f54, f55, f56, f5, V51, V52, R541, and R542 are the same as that of FOV3. TTL3, SL3, f31, f32, f34, f35, f36, f3, V31, V32, R341, and R342 in the third embodiment, and is not described here again.


By the above design of the lenses, stop ST5, and satisfies at least one of the conditions (31)-(38), the lens assembly 5 is provided with an effective shortened total lens length, an effective decreased field of view, an increased resolution, and an effective corrected aberration.


In order to achieve the above purposes and effectively enhance the optical performance, the lens assembly 5 in accordance with the fifth embodiment of the invention is provided with the optical specifications shown in Table 13, which include the effective focal length, F-number, total lens length, field of view, radius of curvature of each lens surface, thickness between adjacent surface, refractive index of each lens, Abbe number of each lens, and effective focal length of each lens. Table 13 shows that the effective focal length is equal to 7.0767 mm, F-number is equal to 2.8, total lens length is equal to 7.533 mm, and field of view is equal to 45 degrees for the lens assembly 5 of the fifth embodiment of the invention.









TABLE 13







Effective Focal Length = 7.076 mm F-number = 2.8


Total Lens Length = 7.533 mm Field of View = 45 Degrees


















Effective




Radius of



Focal


Surface
Curvature
Thickness


Length


Number
(mm)
(mm)
Nd
Vd
(mm)
Remark
















S51
2.341
2.13
1.535
56.115
4.275
The First Lens L51


S52
−73.615
0.04


S53
−351.363
0.48
1.661
28.800
−6.395
The Second Lens L52


S54
4.3
0.31


S55

0.07



Stop ST5


S56
8.459
1.37
1.661
26.800
8.134
The Third Lens L53


S57
−13.970
0.21


S58
−7.870
0.39
1.661
24.700
−9.582
The Fourth Lens L54


S59
33.838
0.46


S510
−6.000
0.40
1.661
20.373
27.959
The Fifth Lens L55


S511
−4.655
0.24


S512
−6.795
0.50
1.661
20.373
−5.431
The Sixth Lens L56


S513
7.905
0.27


S514

0.21
1.517
64.167

Optical Filter OF5


S515

0.44









The aspheric surface sag z of each lens in table 13 can be calculated by the following formula:

z=ch2/{1+[1−(k+1)c2h2]1/2}+Ah4+Bhb+Ch8+Dh10+Eh12+Fh14+Gh16

where c is curvature, h is the vertical distance from the lens surface to the optical axis, k is conic constant and A, B, C, D, E, F and G are aspheric coefficients.


In the fifth embodiment, the conic constant k and the aspheric coefficients A, B, C, D, E, F, G of each surface are shown in Table 14.













TABLE 14





Surface
k
A
B
C


Number
D
E
F
G







S51
  −0.627
 3.62E−03
−4.44E−04 
2.79E−04



−8.98E−05
 0.00E+00
0.00E+00
0.00E+00


S52
0
−1.91E−02
1.44E−02
−4.36E−03 



 3.99E−04
 0.00E+00
0.00E+00
0.00E+00


S53
0
−2.79E−04
1.88E−02
−3.93E−03 



 6.12E−04
 0.00E+00
0.00E+00
0.00E+00


S54
  14.006
−8.88E−03
1.20E−02
−4.76E−03 



−2.79E−03
 0.00E+00
0.00E+00
0.00E+00


S56
0
−2.97E−02
−2.54E−02 
5.65E−02



−2.84E−02
−8.93E−02
1.60E−01
−7.94E−02 


S57
0
−1.69E−01
3.93E−02
−2.05E−02 



 1.68E−02
 1.44E−02
−5.70E−03 
−2.51E−03 


S58
  24.344
−2.12E−01
1.84E−02
1.70E−02



 4.91E−02
−4.10E−03
−2.07E−02 
5.78E−03


S59
  488.898
−2.37E−02
1.75E−02
−8.86E−04 



−1.91E−03
 1.26E−03
−5.86E−04 
1.01E−04


S510
  −49.446
 3.31E−02
1.62E−02
−2.43E−02 



 7.66E−03
 1.45E−04
−6.97E−04 
1.23E−04


S511
  −25.672
−6.38E−03
1.08E−02
−7.99E−04 



−7.18E−04
 9.13E−05
−1.66E−05 
4.43E−06


S512
  −3.722
−5.61E−02
1.13E−02
5.35E−03



−9.31E−04
−2.79E−04
4.40E−05
1.08E−06


S513
   4.931
−7.33E−02
2.37E−02
−5.01E−03 



 5.34E−04
 8.33E−06
−1.03E−05 
7.74E−07









Table 15 shows the parameters and condition values for conditions (31)-(38). As can be seen from Table 15, the lens assembly 5 of the fifth embodiment satisfies the conditions (31)-(38).

















TABLE 15







FOV5
45
Degrees
TTL5
7.533
mm
SL5
2.960
mm


f51
4.275
mm
f52
−6.395
mm
f54
−9.582
mm


f55
27.959
mm
f56
−5.431
mm
f5
7.076
mm













V51
56.115
V52
28.800
R541
−7.870
mm















R542
33.838
mm








FOV5
45
Degrees
TTL5 − SL5
4.573
mm
f51 + f52
−2.12
mm














f52 + f54
−15.977
mm
f52/f5
−0.904
f55 + f56
22.528
mm













V51 − V52
35.74 
(R541 − R542)/(R541 + R542)
−1.606









By the above arrangements of the lenses and stop ST5, the lens assembly 5 of the fifth embodiment can meet the requirements of optical performance as seen in FIGS. 10A-10C, wherein FIG. 10A shows a field curvature diagram of the lens assembly 5 in accordance with the fifth embodiment of the invention, FIG. 10B shows a distortion diagram of the lens assembly 5 in accordance with the fifth embodiment of the invention, and FIG. 10C shows a modulation transfer function diagram of the lens assembly 5 in accordance with the fifth embodiment of the invention.


It can be seen from FIG. 10A that the field curvature of tangential direction and sagittal direction in the lens assembly 5 of the fifth embodiment ranges from −0.035 mm to 0.035 mm for the wavelength of 0.436 μm, 0.546 μm, 0.573 μm, 0.587 μm, and 0.656 μm.


It can be seen from FIG. 10B that the distortion in the lens assembly 5 of the fifth embodiment ranges from −0.8% to 0.2% for the wavelength of 0.436 μm, 0.546 μm, 0.573 μm, 0.587 μm, and 0.656 μm.


It can be seen from FIG. 10C that the modulation transfer function of tangential direction and sagittal direction in the lens assembly 5 of the fifth embodiment ranges from 0.41 to 1.0 wherein the wavelength ranges from 0.4358 μm to 0.6563 μm, the fields respectively are 0.0000 mm, 0.5867 mm, 1.1734 mm, 1.4668 mm, 2.0535 mm, 2.6402 mm, and 2.9335 mm, and the spatial frequency ranges from 0 lp/mm to 120 lp/mm.


It is obvious that the field curvature and the distortion of the lens assembly 5 of the fifth embodiment can be corrected effectively, and the resolution of the lens assembly 5 of the fifth embodiment can meet the requirement. Therefore, the lens assembly 5 of the fifth embodiment is capable of good optical performance.


Referring to Table 16 and Table 17, Table 16 provides optical specifications in accordance with a sixth embodiment of the invention; Table 17 provides aspheric coefficients of each surface in Table 16.


The figure which depicts the lens layout diagram of the lens assembly in accordance with the sixth embodiment of the invention is similar to the figure which depicts the lens layout diagram of the lens assembly in accordance with the third embodiment of the invention, thus the figure which depicts the lens layout diagram of the lens assembly in accordance with the sixth embodiment of the invention is omitted.


Table 16 shows that the effective focal length is equal to 7.076 mm, F-number is equal to 2.8, total lens length is equal to 7.7533 mm, and field of view is equal to 45 degrees for the lens assembly of the sixth embodiment of the invention.









TABLE 16







Effective Focal Length = 7.076 mm F-number = 2.8


Total Lens Length = 7.7533 mm Field of View = 45 Degrees


















Effective




Radius of



Focal


Surface
Curvature
Thickness


Length


Number
(mm)
(mm)
Nd
Vd
(mm)
Remark
















S61

−0.346



Stop ST6


S62
2.087953
0.684262
1.535218
56.11525
3.849
The First Lens L61


S63
−154.0975
0.150804


S64
−16.56542
0.324744
1.661342
28.8
−5.817
The Second Lens L62


S65
5.076681
0.065043


S66
7.150339
1.594457
1.661342
26.8
5.011
The Third Lens L63


S67
−3.914118
0.029974


S68
−5.237808
1.100006
1.661342
24.7
−7.414
The Fourth Lens L64


S69
89.06507
0.041966


S610
26.85975
1.238261
1.662342
20.3729
29.636
The Fifth Lens L65


S611
−72.18347
0.678644


S612
−13.26351
0.499951
1.661342
20.3729
−3.702
The Sixth Lens L66


S613
3.062019
0.27


S614

0.21
1.5168
64.16734

Optical Filter OF6


S615

0.437948









The aspheric surface sag z of each lens in table 16 can be calculated by the following formula:

z=ch2/{1+[1−(k+1)c2h2]1/2}+Ah4+Bhb+Ch8+Dh10+Eh12+Fh14+Gh16

where c is curvature, h is the vertical distance from the lens surface to the optical axis, k is conic constant and A, B, C, D, E, F and G are aspheric coefficients.


In the sixth embodiment, the conic constant k and the aspheric coefficients A, B, C, D, E, F, G of each surface are shown in Table 17.













TABLE 17





Surface
K
A
B
C


Number
D
E
F
G







S62
0
0.00E+00
0.00E+00
0.00E+00



0.00E+00
0.00E+00
0.00E+00
0.00E+00


S63
0
0.00E+00
0.00E+00
0.00E+00



0.00E+00
0.00E+00
0.00E+00
0.00E+00


S64
0
0.00E+00
0.00E+00
0.00E+00



0.00E+00
0.00E+00
0.00E+00
0.00E+00


S65
0
0.00E+00
0.00E+00
0.00E+00



0.00E+00
0.00E+00
0.00E+00
0.00E+00


S66
0
0.00E+00
0.00E+00
0.00E+00



0.00E+00
0.00E+00
0.00E+00
0.00E+00


S67
    3.341941
0.00E+00
0.00E+00
0.00E+00



0.00E+00
0.00E+00
0.00E+00
0.00E+00


S68
0
0.00E+00
0.00E+00
0.00E+00



0.00E+00
0.00E+00
0.00E+00
0.00E+00


S69
0
0.00E+00
0.00E+00
0.00E+00



0.00E+00
0.00E+00
0.00E+00
0.00E+00


S610
0
0.00E+00
0.00E+00
0.00E+00



0.00E+00
0.00E+00
0.00E+00
0.00E+00


S611
−21025.33  
0.00E+00
0.00E+00
0.00E+00



0.00E+00
0.00E+00
0.00E+00
0.00E+00


S612
   36.54096
0.00E+00
0.00E+00
0.00E+00



0.00E+00
0.00E+00
0.00E+00
0.00E+00


S613
    −0.898173
0.00E+00
0.00E+00
0.00E+00



0.00E+00
0.00E+00
0.00E+00
0.00E+00









The difference between the above sixth embodiment of the lens assembly and the third embodiment of the lens assembly is that the image side surface S63 of the first lens L61 is a convex surface for the sixth embodiment of the lens assembly, however, the image side surface S33 of the first lens L31 is a concave surface for the third embodiment of the lens assembly.


The above field curvature (figure is omitted) and distortion (figure is omitted) for the sixth embodiment of the lens assembly can be corrected effectively, and the resolution for the sixth embodiment of the lens assembly can meet the requirement. Therefore, the lens assembly of the sixth embodiment is capable of good optical performance.


While the invention has been described by way of example and in terms of the preferred embodiment(s), it is to be understood that the invention is not limited thereto. On the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures.

Claims
  • 1. A lens assembly comprising: a first lens which is with positive refractive power and comprises a convex surface facing an object side;a second lens which is with negative refractive power and comprises a concave surface facing an image side;a third lens which is with refractive power and comprises a convex surface in a paraxial region facing the image side;a fourth lens which is with refractive power;a fifth lens which is with refractive power; anda sixth lens which is with refractive power;wherein the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are arranged in order from the object side to the image side along an optical axis;wherein the lens assembly satisfies: 2 mm<f5+f6<35 mm,wherein f5 is an effective focal length of the fifth lens and f6 is an effective focal length of the sixth lens.
  • 2. The lens assembly as claimed in claim 1, wherein the third lens is with positive refractive power and the fourth lens is with negative refractive power.
  • 3. The lens assembly as claimed in claim 2, wherein the fifth lens is with positive refractive power and the sixth lens is with negative refractive power.
  • 4. The lens assembly as claimed in claim 1, wherein the second lens further comprises another concave surface facing the object side, the third lens further comprises another convex surface facing the object side, the fourth lens is a biconcave lens, and the sixth lens is a biconcave lens.
  • 5. The lens assembly as claimed in claim 4, wherein the fifth lens is a biconvex lens.
  • 6. The lens assembly as claimed in claim 5, wherein the first lens further comprises a concave surface facing the image side.
  • 7. The lens assembly as claimed in claim 5, wherein the first lens further comprises another convex surface facing the image side.
  • 8. The lens assembly as claimed in claim 4, wherein the fifth lens is a meniscus lens.
  • 9. The lens assembly as claimed in claim 8, wherein the first lens further comprises a concave surface facing the image side.
  • 10. The lens assembly as claimed in claim 8, wherein the first lens further comprises another convex surface facing the image side.
  • 11. The lens assembly as claimed in claim 2, wherein the lens assembly satisfies: −21.5≤(R141−R142)/(R141+R142)≤3.5,wherein R41 is a radius of curvature of an object side surface of the fourth lens and R42 is a radius of curvature of an image side surface of the fourth lens.
  • 12. The lens assembly as claimed in claim 3, further comprising a stop disposed between the object side and the third lens, wherein the lens assembly satisfies: 4 mm<TTL−SL<9 mm,wherein TTL is an interval from the convex surface of the first lens to an image plane along the optical axis and SL is an interval from the convex surface of the first lens to the stop along the optical axis.
  • 13. The lens assembly as claimed in claim 4, wherein the lens assembly satisfies: f1+f2<−1 mm,wherein f1 is an effective focal length of the first lens and f2 is an effective focal length of the second lens.
  • 14. The lens assembly as claimed in claim 13, wherein the lens assembly satisfies: −4≤f2/f≤0,wherein f2 is an effective focal length of the second lens and f is an effective focal length of the lens assembly.
  • 15. The lens assembly as claimed in claim 3, wherein the lens assembly satisfies: 25<V1−V2<38,wherein V1 is an Abbe number of the first lens and V2 is an Abbe number of the second lens.
  • 16. The lens assembly as claimed in claim 2, wherein the lens assembly satisfies: −25 mm<f2+f4<−1.5 mm,wherein f2 is an effective focal length of the second lens and f4 is an effective focal length of the fourth lens.
  • 17. The lens assembly as claimed in claim 15, wherein the lens assembly satisfies: FOV≤56°,wherein FOV is a field of view of the lens assembly.
  • 18. The lens assembly as claimed in claim 1, wherein the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are aspheric lenses.
  • 19. A lens assembly comprising: a first lens which is with positive refractive power and comprises a convex surface facing an object side;a second lens which is with negative refractive power and comprises a concave surface facing an image side;a third lens which is with refractive power and comprises a convex surface facing the image side;a fourth lens which is with refractive power;a fifth lens which is with refractive power; anda sixth lens which is with refractive power;wherein the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are arranged in order from the object side to the image side along an optical axis;wherein the lens assembly satisfies: f1+f2<−1 mm,wherein f1 is an effective focal length of the first lens and f2 is an effective focal length of the second lens.
  • 20. A lens assembly comprising: a first lens which is with positive refractive power and comprises a convex surface facing an object side;a second lens which is with negative refractive power and comprises a concave surface facing an image side;a third lens which is with refractive power and comprises a convex surface facing the image side;a fourth lens which is with refractive power;a fifth lens which is with refractive power;a sixth lens which is with refractive power; anda stop;wherein the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are arranged in order from the object side to the image side along an optical axis;wherein the stop is disposed between the object side and the third lens;wherein the lens assembly satisfies: −25 mm<f2+f4<−1.5 mm,wherein f2 is an effective focal length of the second lens and f4 is an effective focal length of the fourth lens.
Priority Claims (1)
Number Date Country Kind
201710303279.4 May 2017 CN national
CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No. 15/859,842, filed Jan. 2, 2018 and entitled “Lens Assembly”, issued on Sep. 22, 2020 as U.S. Pat. No. 10,782,503.

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Related Publications (1)
Number Date Country
20200371313 A1 Nov 2020 US
Continuations (1)
Number Date Country
Parent 15859842 Jan 2018 US
Child 16992216 US