Lens assembly
A lens assembly includes at least three lens elements. One lens element closest to an imaged object of the lens elements is a first lens element, which is made of an electromagnetic radiation absorbing material.
1. A lens assembly, comprising:
at least five lens elements, wherein one lens element closest to an imaged object of the lens elements is a first lens element, which is made of an electromagnetic radiation absorbing material and has an image-side surface being concave in a paraxial region thereof;
wherein an average transmittance of the electromagnetic radiation absorbing material for electromagnetic radiation with wavelengths in a range of 750 nm to 1100 nm is T_750, an average transmittance of the electromagnetic radiation absorbing material for electromagnetic radiation with wavelengths in a range of 350 nm to 700 nm is T_700, an f-number of the lens assembly is Fno, and the following conditions are satisfied:
50%<T_750;
T_700<20%; and
1.40<Fno≤2.25.
2. The lens assembly of claim 1 , wherein one lens element closest to an image surface of the lens elements is a last lens element, which has an image-side surface being concave in a paraxial region thereof, and the image-side surface of the last lens element comprises at least one convex shape in an off-axial region thereof.
3. The lens assembly of claim 1 , wherein the electromagnetic radiation absorbing material is made of a black dyed polycarbonate polymer.
4. The lens assembly of claim 1 , further comprising:
a housing made of a black dyed plastic material.
5. The lens assembly of claim 1 , wherein the average transmittance of the electromagnetic radiation absorbing material for electromagnetic radiation with wavelengths in the range of 350 nm to 700 nm is T_700, and the following condition is satisfied:
T_700<10%.
6. The lens assembly of claim 1 , wherein the average transmittance of the electromagnetic radiation absorbing material for electromagnetic radiation with wavelengths in the range of 750 nm to 1100 nm is T_750, and the following condition is satisfied:
70%<T_750.
7. The lens assembly of claim 1 , wherein the first lens element has positive refractive power, and the lens elements are all made of plastic materials.
8. The lens assembly of claim 7 , further comprising:
at least one electromagnetic radiation shield for blocking stray electromagnetic radiation.
9. The lens assembly of claim 1 , wherein a number of the lens elements of the lens assembly is N, and the following condition is satisfied:
5≤N≤7.
10. The lens assembly of claim 1 , wherein an axial distance between an object-side surface of the first lens element and an image surface is TTL, a focal length of the lens assembly is f, and the following conditions are satisfied:
1.0 mm<TTL<8.0 mm; and
0 mm<f<7.0 mm.
11. The lens assembly of claim 1 , wherein one lens element closest to an image surface of the lens elements is a last lens element, a maximum image height of the lens assembly is ImgH, an axial distance between an image-side surface of the last lens element and the image surface is BL, and the following condition is satisfied:
1.0<ImgH/BL<6.0.
12. A lens assembly, comprising:
at least five lens elements, wherein one lens element closest to an imaged object of the lens elements is a first lens element, which has an image-side surface being concave in a paraxial region thereof, one lens element closest to an image surface of the lens elements is a last lens element, which has an image-side surface being concave in a paraxial region thereof, the image-side surface of the last lens element is aspheric and comprises at least one convex shape in an off-axial region thereof, and at least one of the lens elements is made of an electromagnetic radiation absorbing material;
wherein an average transmittance of the electromagnetic radiation absorbing material for electromagnetic radiation with wavelengths in a range of 750 nm to 1100 nm is T_750, an average transmittance of the electromagnetic radiation absorbing material for electromagnetic radiation with wavelengths in a range of 350 nm to 700 nm is T_700, an f-number of the lens assembly is Fno, and the following conditions are satisfied:
50%<T_750;
T_700<20%;and
1.40<Fno<2.25.
13. The lens assembly of claim 12 , wherein the last lens element has negative refractive power.
14. The lens assembly of claim 12 , wherein an axial distance between an object-side surface of the first lens element and the image surface is TTL, a focal length of the lens assembly is f, and the following conditions are satisfied:
1.0 mm<TTL<8.0 mm; and
0 mm<f<7.0 mm.
15. The lens assembly of claim 12 , wherein a number of the lens elements of the lens assembly is N, and the following condition is satisfied:
5≤N≤7.
16. The lens assembly of claim 15 , wherein the number of the lens elements of the lens assembly is N, and the following condition is satisfied:
5≤N≤6.
17. The lens assembly of claim 12 , wherein the average transmittance of the electromagnetic radiation absorbing material for electromagnetic radiation with wavelengths in the range of 350 nm to 700 nm is T_700, and the following condition is satisfied:
T_700<10%.
18. The lens assembly of claim 12 , wherein the average transmittance of the electromagnetic radiation absorbing material for electromagnetic radiation with wavelengths in the range of 750 nm to 1100 nm is T_750,and the following condition is satisfied:
70%<T_750.
19. The lens assembly of claim 12 , wherein the first lens element has positive refractive power, and the lens elements are all made of plastic materials.
20. The lens assembly of claim 19 , wherein the electromagnetic radiation absorbing material is made of a black dyed polycarbonate polymer.