Optical lens
An optical lens includes a first lens, a second lens, a third lens, a fourth lens and a cemented lens. The first lens is closest to a magnified side as compared with any other lens of the optical lens, one of the second lens and the third lens is a first aspheric lens, and the fourth lens is a second aspheric lens and disposed between the cemented lens and a minified side of the optical lens. The optical lens satisfies the condition: 1.0<D 1 /DL<4.0, where D 1 denotes a lens diameter of the first lens and DL denotes a lens diameter of the fourth lens.
1. An optical lens, comprising:
a first lens, a second lens, a third lens, a fourth lens and a cemented lens, the first lens being closest to a magnified side of the optical lens, one of the second lens and the third lens being a first aspheric lens, and the fourth lens being a second aspheric lens and disposed between the cemented lens and a minified side of the optical lens; and
an aperture stop disposed between the second lens and the cemented lens, the cemented lens being disposed between the fourth lens and the aperture stop, a full field of view of the optical lens being in the range between 150 degrees and 180 degrees, a total number of lenses with refractive powers in the optical lens being no more than eight, a thermal drift of the optical lens measured by a shift distance between a focal plane at 25 degrees and a focal plane at 105 degrees being smaller than or equal to 10 um, the optical lens having at most two plastic lens, and the optical lens satisfying the condition:
1.0<D 1 /DL<4.0, where D 1 denotes a lens diameter of the first lens and DL denotes a lens diameter of the fourth lens.
2. The optical lens as claimed in claim 1 , wherein the first lens and the second lens are spherical lenses.
3. The optical lens as claimed in claim 1 , wherein no lens with a refractive power is disposed between the aperture stop and the first aspheric lens.
4. The optical lens as claimed in claim 1 , wherein a displacement between a focal plane for 450 nm visible light and a focal plane for 550 nm visible light is smaller than or equal to 15 um.
5. The optical lens as claimed in claim 1 , wherein the optical lens satisfies one of the following conditions:
(1) the cemented lens is a cemented doublet;
(2) all lenses of the optical lens are glass lenses.
6. The optical lens as claimed in claim 1 , wherein the optical lens has six lenses, and the six lenses of the optical lens have respective refractive powers of negative, negative, positive, positive, negative and positive in order from the magnified side to the minified side.
7. The optical lens as claimed in claim 1 , wherein the optical lens has six lenses, and the six lenses of the optical lens have respective shapes of meniscus, meniscus, aspheric, biconvex, biconcave and aspheric in order from the magnified side to the minified side.
8. The optical lens as claimed in claim 1 , wherein the optical lens satisfies one of the following conditions:
(1) a difference in Abbe number between two lenses of the cemented lens is greater than 40;
(2) a difference in Abbe number between two lenses of the cemented lens is greater than 50.
9. The optical lens as claimed in claim 1 , wherein a full field of view of the optical lens is in the range between 150 degrees and 170 degrees.
10. The optical lens as claimed in claim 1 , wherein an F-number of the optical lens being smaller than or equal to 2.
11. The optical lens as claimed in claim 1 , wherein a total number of lenses with refractive powers in the optical lens ranges from 6 to 8.
12. The optical lens as claimed in claim 1 , wherein the optical lens comprises at least one plastic lens.
13. The optical lens as claimed in claim 1 , wherein the optical lens further comprises a fifth lens disposed between the third lens and the cemented lens.
14. The optical lens as claimed in claim 1 , wherein the optical lens has seven lenses, and the seven lenses of the optical lens have respective refractive powers of negative, negative, positive, positive, positive, negative and positive in order from a magnified side to a minified side.
15. The optical lens as claimed in claim 1 , wherein the optical lens has seven lenses, and the seven lenses of the optical lens have respective shapes of meniscus, meniscus, aspheric, biconvex, biconvex, meniscus and aspheric in order from a magnified side to a minified side.
16. The optical lens as claimed in claim 1 , wherein the optical lens has six lenses, and the six lenses of the optical lens have respective shapes of meniscus, aspheric, meniscus, biconvex, meniscus and aspheric in order from a magnified side to a minified side.
17. The optical lens as claimed in claim 1 , wherein the first lens has a negative refractive power, the second lens has a negative refractive power, the third lens has a positive refractive power, the fourth lens with a positive refractive power, and the cemented lens comprises a lens with a positive refractive power and a lens with a negative refractive power.
18. The optical lens as claimed in claim 17 , wherein the optical lens satisfies one of the following conditions:
(1) the cemented lens is a cemented doublet;
(2) all lenses of the optical lens are glass lenses.
19. The optical lens as claimed in claim 17 , wherein the optical lens comprises at least one plastic lens.