Folded camera lens designs
Folded lens modules and assemblies characterized by low height and large entrance pupil (clear aperture), designed for folded cameras in consumer electronics and specifically in mobile phones. In some embodiments, a folded lens assembly comprises a plurality of lens elements that include, in order for an object side to an image side, a first lens element L 1 with a clear aperture CA(S 1 ) and a second lens element L 2 with a clear aperture CA(S 3 ), wherein CA(S 1 )/CA(S 3 )>1.2 and wherein the lens assembly has a ratio between an image sensor diagonal length SDL and a clear aperture of a last lens element surface CA(S 2N ), SDL/CA(S 2N )>1.5.
1 . A lens assembly, comprising:
N≥4 lens elements; and
an image sensor having an image sensor diagonal length SDL,
wherein with a first lens element L 1 faces an object and a last lens element L N faces the image sensor, wherein the lens assembly has an effective focal length (EFL), a total track length (TTL) defined as the distance from a first surface S 1 of L 1 to the image sensor and a back focal length (BFL) defined as the distance from a last surface S 2N of L N to the image sensor,
wherein a ratio between SDL and a clear aperture CA(S 2N ) of S 2N fulfills SDL/CA(S 2N )>1.5,
wherein the lens assembly has a f number f/#<3,
wherein a ratio BFL/TTL>0.35, and
wherein the lens assembly is included in a folded camera.
2 . The lens assembly of claim 1 , wherein N=4, 5.
3 . The lens assembly of claim 1 , wherein f/#<2.75.
4 . The lens assembly of claim 1 , wherein f/#<2.6.
5 . The lens assembly of claim 1 , wherein f/# is in a range of 2.148 to 2.819.
6 . The lens assembly of claim 1 , wherein SDL/CA(S 2N )>1.6.
7 . The lens assembly of claim 1 , wherein SDL/CA(S 2N )>1.8.
8 . The lens assembly of claim 1 , wherein the first surface S 1 of L 1 has a clear aperture CA(S 1 ), wherein a first surface S 3 of a second lens element L 2 has a clear aperture CA(S 3 ), and wherein CA(S 1 )/CA(S 3 )>1.076.
9 . The lens assembly of claim 1 , wherein L 1 has positive refractive power and wherein a second lens element L 2 has negative refractive power.
10 . The lens assembly of claim 9 , wherein a third lens element L 3 has positive refractive power.
11 . The lens assembly of claim 1 , wherein SDL/EFL>0.4.
12 . The lens assembly of claim 1 , wherein SDL/EFL is in the range of 0.389 to 0.74.
13 . The lens assembly of claim 1 , wherein the lens assembly has a 35 mm equivalent focal length calculated by (43.3 mm×EFL)/SDL, and wherein the 35 mm equivalent focal length is in the range of 90.2 mm to 119.3 mm.
14 . The lens assembly of claim 13 , wherein the 35 mm equivalent focal length is in the range of 92.5 mm to 110.8 mm.
15 . The lens assembly of claim 1 , wherein L 1 has a focal length f 1 , and wherein a ratio f 1 /EFL<0.6.
16 . The lens assembly of claim 1 , wherein L 1 has a focal length f 1 , wherein a second lens element L 2 has a focal length f 2 , and wherein a magnitude of a ratio |f 2 /f 1 | is in the range of 0.421 to 0.886.
17 . The lens assembly of claim 16 , wherein |f 2 /f 1 | is in the range of 0.697 to 0.862.
18 . The lens assembly of claim 1 , wherein BFL/TTL>0.5.
19 . The lens assembly of claim 1 , wherein a ratio TTL/EFL<1.
20 . The lens assembly of claim 1 , wherein L 1 has a first lens element thickness T 1 , and wherein a ratio of T 1 /TTL>0.1.
21 . The lens assembly of claim 1 , wherein the lens assembly is included in a mobile phone.