Imaging lens
An imaging lens including an aperture stop, a first lens, a second lens and a third lens sequentially arranged along an optical axis from an object side to an image side is provided. The first lens is an aspheric glass lens and has positive refracting power. The second lens is an aspheric plastic lens. The third lens is an aspheric plastic lens. The imaging lens has the transmittance higher than 85% for light with a wavelength of 940 nm and has the field of view less than 90 degrees.
1. An imaging lens, from an object side to an image side along an optical axis, sequentially comprising:
a first lens, being an aspheric lens;
a second lens, being an aspheric plastic lens; and
a third lens, being an aspheric plastic lens,
wherein a diameter of the second lens is smaller than a diameter of a the third lens,
the imaging lens has a transmittance higher than 85% for light with a wavelength of 940 nm, and has a field of view less than 90 degrees, and
the imaging lens satisfies a condition of D 1 /LT<0.62, wherein LT is a distance along an optical axis between a surface of the first lens facing an object side and a surface of the third lens facing the image side, and D 1 is a diameter of an opening of an aperture stop.
2. The imaging lens as claimed in claim 1 , wherein a refracting power of the first lens is positive, and refracting powers of the second lens and the third lens are respectively positive and positive, negative and positive, or positive and negative.
3. The imaging lens as claimed in claim 1 , wherein the diameter of the third lens is greater than a diameter of the first lens.
4. The imaging lens as claimed in claim 1 , wherein the imaging lens satisfies a condition of D 1 /DL<0.6, and DL is an effective diameter of a surface of the imaging lens closest to the image side.
5. The imaging lens as claimed in claim 1 , wherein the imaging lens satisfies a condition of D 1 /LT<0.6.
6. The imaging lens as claimed in claim 1 , wherein the imaging lens satisfies a condition of DL/LT<1.2, wherein DL is an effective diameter of a surface of the imaging lens closest to the image side.
7. The imaging lens as claimed in claim 1 , wherein TTL of the imaging lens is 5.5 mm, a full field of view is within a range of 53° to 56°, IH is within a range of 2.25 mm to 2.27 mm, wherein TTL is a distance from an object side surface of the first lens close to the object side to an imaging plane, and IH is a maximum image height of the imaging lens.
8. The imaging lens as claimed in claim 1 , wherein a color of the first lens is black.
9. An imaging lens, comprising:
a first lens, being an aspheric-glass lens with a positive refracting power;
a second lens and a third lens, being two aspheric lenses; and
an aperture stop, located at an outermost side of all lenses of the imaging lens,
wherein a distance between outer surfaces of two outermost lenses of the imaging lens is less than 4.2 mm, and a field of view of the imaging lens is less than 90 degrees,
the imaging lens has a transmittance higher than 85% for light with a wavelength of 940 nm, and
the imaging lens satisfies a condition of 0.67<EFL1/EFL<1.11 and a condition of DL/LT<1.2, wherein ELF1 is an effective focal length of the first lens, ELF is an effective focal length of the imaging lens, DL is an effective diameter of a surface of the imaging lens closest to an image side, and LT is a distance along an optical axis between a surface of the first lens facing an object side and a surface of the third lens facing the image side.
10. The imaging lens as claimed in claim 9 , wherein the imaging lens satisfies a condition of 1.5<CT3/ET3<3, wherein CT3 is a center thickness of the third lens, and ET3 is an edge thickness of the third lens.
11. The imaging lens as claimed in claim 9 , wherein the imaging lens satisfies a condition of D 1 /DL<0.6, D 1 is a diameter of an opening of the aperture stop.
12. The imaging lens as claimed in claim 9 , wherein the imaging lens satisfies a condition of D 1 /LT<0.6, wherein D 1 is a diameter of an opening of the aperture stop.
13. The imaging lens as claimed in claim 9 , wherein the imaging lens satisfies a condition of LT<4.2 mm.
14. The imaging lens as claimed in claim 9 , wherein TTL of the imaging lens is 5.5 mm, a full field of view is within a range of 53° to 56°, IH is within a range of 2.25 mm to 2.27 mm, wherein TTL is a distance from an object side surface of the first lens close to the object side to an imaging plane, and IH is a maximum image height of the imaging lens.
15. An imaging lens, from an object side to an image side along an optical axis, sequentially comprising:
a first lens, a second lens and a third lens,
wherein the second lens and the third lens are both plastic lenses, and the first lens is a glass lens,
the imaging lens has a transmittance higher than 85% for light with a wavelength of 940 nm, and has a field of view less than 90 degrees, and
the imaging lens satisfies a condition of D 1 /LT<0.62, wherein D 1 is a diameter of an opening of an aperture stop, and LT is a distance along the optical axis between a surface of the first lens facing the object side and a surface of the third lens facing the image side.
16. The imaging lens as claimed in claim 15 , wherein the second lens is a convexo-concave lens.
17. The imaging lens as claimed in claim 15 , wherein the imaging lens satisfies a condition of D 1 /DL<0.6, DL is an effective diameter of a surface of the imaging lens closest to the image side.
18. The imaging lens as claimed in claim 15 , wherein the imaging lens satisfies a condition of D 1 /LT<0.6.
19. The imaging lens as claimed in claim 15 , wherein the surface of the third lens facing the image side has an inflection point.
20. The imaging lens as claimed in claim 19 , wherein a surface of the third lens facing the object side has an inflection point.