Lens assembly and electronic device including the same
According to an embodiment of the disclosure, there may be provided an electronic device, comprising the lens assembly including a plurality of lenses arranged along a direction of an optical axis from an object side to an image side; an optical member disposed closer to the object side than the lens assembly and configured to reflect or refract external light incident in a direction crossing the optical axis to be incident on the lens assembly along the direction of the optical axis; and an image sensor. The electronic device may implement a telephoto lens with reduced chromatic aberration.
1 . An electronic device comprising:
a lens assembly including a plurality of lenses arranged along a direction of an optical axis from an object side to an image side;
at least one optical member disposed closer to the object side than the lens assembly and configured to reflect or refract external light incident in a direction crossing the optical axis to be incident on the lens assembly along the direction of the optical axis; and
an image sensor;
wherein the plurality of lenses include a first lens, a second lens, a third lens, and a fourth lens sequentially arranged along the direction of the optical axis, and wherein the lens assembly satisfies conditional equation 1, conditional equation 2 and conditional equation 4,
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∑
f
f
t
v
d
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≤
0.05
[
conditional
equation
1
]
FOV
≤
25
deg
[
conditional
equation
2
]
where ‘f’ is a focal length of each of the lenses except for a lens closest to the image side among the lenses included in the lens assembly, ‘f t ’ is a focal length of an optical system, and ‘v d ’ is an Abbe's number of the first lens, the second lens, the third lens, and the fourth lens, and ‘FOV’ is a field of view of the optical system
0.99 <R _ L 1 S 2 /R _ L 3 S 6<1.15 [conditional equation 4]
where:
R_L1S2 is a radius of curvature of an object-side surface of the first lens and
R_L3S6 is a radius of curvature of an object-side surface of the third lens,
wherein the at least one optical member comprises a first optical member (R) configured to change a first light path of light incident in a direction crossing the optical axis to a second light path, and a second optical member (W) disposed closer to the object side than the first optical member and is configured to cause chromic aberration and capable of changing an incident angle of the first light path,
wherein the first optical member (R) is configured to correct the chromic aberration caused by the second optical member, and
wherein the plurality of lenses included in the lens assembly, the first optical member, or the second optical member are configured to stabilize an image provided to the image sensor,
wherein the first optical member includes a mirror or a right-angled prism having a triangular cross section, and wherein the second optical member includes a prism having a wedge-shaped cross section or includes a prism transformable into a wedge shape.
2 . The electronic device of claim 1 , wherein the lens assembly further includes a fifth lens disposed between the fourth lens and the image sensor.
3 . The electronic device of claim 2 , wherein the electronic device satisfies conditional equation 3,
vdl> 50 [conditional equation 3]
where ‘vdl’ is an Abbe's number of a lens closest to the image side in the lens assembly.
4 . The electronic device of claim 1 , wherein the electronic device satisfies conditional equation 5,
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∑
i
=
1
n
f
i
f
t
v
i
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"\[RightBracketingBar]"
≤
0.5
[
conditional
equation
5
]
where:
‘f i ’ is a focal length of each lens included in the lens assembly,
‘f t ’ is focal length of the optical system,
‘v i ’ is an Abbe's number of each lens.
5 . The electronic device of claim 1 , wherein the first lens has a positive refractive power,
the second lens has a negative refractive power,
the third lens has a positive refractive power, and
the fourth lens has a negative refractive power.
6 . The electronic device of claim 1 , further comprising a third optical member disposed between a lens closest to the image side in the lens assembly and the image sensor.
7 . An electronic device including a lens assembly, comprising:
a lens assembly including:
a first lens having a positive refractive power,
a second lens having a negative refractive power,
a third lens having a positive refractive power,
a fourth lens having a negative refractive power, and
a fifth lens,
wherein the first lens, second lens, third lens, fourth lens, and fifth lens are sequentially arranged along a direction of an optical axis from an object side to an image side; and
an image sensor;
wherein the lens assembly satisfies conditional equation 1, conditional equation 2, and conditional equation 5,
❘
"\[LeftBracketingBar]"
∑
f
f
t
v
d
❘
"\[RightBracketingBar]"
≤
0.05
[
conditional
equation
1
]
FOV
≤
25
deg
[
conditional
equation
2
]
where ‘f’ is a focal length of each of the lenses except for the fifth lens, ‘f t ’ is a focal length of an optical system, and ‘v d ’ is an Abbe's number of the first lens, the second lens, the third lens, and the fourth lens, and ‘FOV’ is a field of view of the optical system
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"\[LeftBracketingBar]"
∑
i
=
1
n
f
i
f
t
v
i
❘
"\[RightBracketingBar]"
≤
0.5
,
[
conditional
equation
5
]
where:
‘f i ’ is a focal length of each lens included in the lens assembly,
‘v i ’ is an Abbe's number of each lens, and
a first optical member (R) configured to change a first light path of light incident in a direction crossing the optical axis to a second light path, and a second optical member (W) disposed closer to the object side than the first optical member, is capable of changing an incident angle of the first light path, and is configured to cause chromic aberration and capable of changing an incident angle of the first light path,
wherein the first optical member (R) is configured to correct the chromic aberration caused by the second optical member,
wherein the lens assembly, the first optical member, or the second optical member are configured to stabilize an image provided to the image sensor, and
wherein the first optical member includes a mirror or a right-angled prism having a triangular cross section, and wherein the second optical member includes a prism having a wedge-shaped cross section or includes a prism transformable into a wedge shape.
8 . The electronic device of claim 7 , wherein the electronic device satisfies conditional equation 3,
vdl> 50 [conditional equation 3]
where ‘vdl’ is an Abbe's number of the fifth lens.
9 . The electronic device of claim 7 , wherein the electronic device satisfies conditional equation 4,
0.8 <R _ L 1 S 2 /R _ L 3 S 6<2 [conditional equation 4]
where:
R_L1S2 is a radius of curvature of an object-side surface of the first lens, and
R_L3S6 is a radius of curvature of an object-side surface of the third lens.
10 . The electronic device of claim 7 , further comprising:
at least one optical member disposed adjacent to the lens assembly; and
wherein the lens assembly and at least one optical member form a folded optical device.
11 . The electronic device of claim 10 , further comprising:
another optical member disposed closer to the object side than the lens assembly and configured to reflect or refract external light incident in a direction crossing the optical axis to be incident on the lens assembly along the direction of the optical axis.
12 . The electronic device of claim 7 , wherein the at least one optical member includes a mirror or a triangular prism, and
wherein the another optical member includes a wedge-shaped prism or includes a prism transformable into a wedge shape.
13 . The electronic device of claim 11 , further comprising a third optical member disposed between the fifth lens in the lens assembly and the image sensor.