An imaging lens of which optical performance does not deteriorate even in a high temperature environment, various aberrations are well corrected, optical length is short, and back focus is sufficiently secured; the imaging lens comprising: an aperture stop S; and a junction type compound lens 14 having a positive refractive power, characterized in that the aperture stop and the compound lens are arranged in this sequence from an object side to an image side. The junction type compound lens comprises a first lens L 1 , a second lens L 2 and a third lens L 3 , arranged in this sequence from the object side to the image side. The first lens and the third lens are formed of a curable resin material, and the second lens is formed of a high softening temperature optical glass material. The first lens and the second lens are bonded with adhesive, and the second lens and the third lens are bonded with adhesive. The object side face of the first lens and the image side face of the third lens are aspherical.
1. An imaging lens, comprising an aperture stop and a junction type compound lens having a positive refractive power, characterized in that
said aperture stop and said junction type compound lens are arranged in this sequence from an object side to an image side,
said junction type compound lens comprises a first lens, a second lens and a third lens arranged in this sequence from said object side to said image side,
said first lens and said third lens are formed of a curable resin material,
said second lens is formed of a high softening temperature optical glass material,
said first lens and said second lens are bonded with adhesive,
said second lens and said third lens are bonded with adhesive, and
following conditions (1) to (4) are satisfied:
0≦| N 3 −N 2 |≦0.1 (1)
0≦| N 3 −N 4 |≦0.1 (2)
0≦|ν 3 −ν 2 |≦30.0 (3)
0≦|ν 3 −ν 4 |≦30.0 (4)
where
N 2 : refractive index of said first lens
N 3 : refractive index of said second lens
N 4 : refractive index of said third lens
ν 2 : Abbe number of said first lens
ν 3 : Abbe number of said second lens
ν 4 : Abbe number of said third lens.
2. The imaging lens according to claim 1 , characterized in that
said second lens is an optical parallel plate,
said first lens is a plano-convex lens where an object side face of said first lens is a convex surface facing said object side, and
said third lens is a plano-convex lens where an image side face of said third lens is a convex surface facing said image side.
3. The imaging lens according to claim 1 , characterized in that
said second lens is an optical parallel plate,
said first lens is a piano-concave lens where an object side face of said first lens is a concave surface facing said object side, and
said third lens is a piano-convex lens where an image side face of said third lens is a convex surface facing said image side.
4. The imaging lens according to claim 1 , characterized in that
said second lens is a biconvex glass lens,
said first lens is a lens where an object side face of said first lens is a convex surface facing said object side, and
said third lens is a lens where an image side face of said third lens is a convex surface facing said image side.
5. The imaging lens according to claim 1 , characterized in that
said second lens is a biconvex glass lens,
said second lens is a lens where an object side face of said first lens is a concave surface facing said object side, and
said third lens is a lens where an image side face of said third lens is a convex surface facing said image side.
6. The imaging lens according to claim 1 , characterized in that
said second lens is a biconcave glass lens,
said first lens is a lens where an object side face of said first lens is a convex surface facing said object side, and
said third lens is a lens where an image side face of said third lens is a convex surface facing said image side.
7. The imaging lens according to claim 1 , characterized in that
said second lens is a biconcave glass lens,
said first lens is a lens where an object side face of said first lens is a concave surface facing said object side, and
said third lens is a lens where an image side face of said third lens is a convex surface facing said image side.
8. The imaging lens according to claim 1 , characterized in that said object side face of said first lens and said image side face of said third lens are aspherical.
9. The imaging lens according to claim 1 , characterized in that at least one surface of said second lens is coated.
10. The imaging lens according to claim 1 , characterized in that said curable resin material is a transparent high hardness silicon resin.
11. An imaging lens, comprising an aperture stop and a junction type compound lens having a positive refractive power, characterized in that
said aperture stop and said junction type compound lens are arranged in this sequence from an object side to an image side,
said junction type compound lens comprises a first lens, a second lens and a third lens arranged in this sequence from said object side to said image side,
said first lens, said second lens and said third lens are formed of a curable resin material,
said first lens and said second lens are directly bonded,
said second lens and said third lens are directly bonded, and
following conditions (1) to (4) are satisfied:
0≦| N 3 −N 2 |≦0.1 (1)
0 ≦|N 3 −N 4 |≦0.1 (2)
0≦|ν 3 −ν 2 |≦30.0 (3)
0≦|ν 3 −ν 4 |≦30.0 (4)
where
N 2 : refractive index of said first lens
N 3 : refractive index of said second lens
N 4 : refractive index of said third lens
ν 2 : Abbe number of said first lens
ν 3 : Abbe number of said second lens
ν 4 : Abbe number of said third lens.
12. The imaging lens according to claim 11 , characterized in that
said second lens is an optical parallel plate,
said first lens is a piano-convex lens where an object side face of said first lens is a convex surface facing said object side, and
said third lens is a piano-convex lens where an image side face of said third lens is a convex surface facing said image side.
13. The imaging lens according to claim 11 , characterized in that said object side face of said first lens and said image side face of said third lens are aspherical.
14. The imaging lens according to claim 11 , characterized in that said curable resin material is a transparent high hardness silicon resin.
15. An imaging lens, comprising an aperture stop and a junction type compound lens having a positive refractive index, characterized in that
said aperture stop and said junction type compound lens are arranged in this sequence from an object side to an image side,
said junction type compound lens comprises a first lens, a second lens and a third lens arranged in this sequence from said object side to said image side,
said first lens, said second lens and said third lens are formed of a curable resin material,
said first lens and said second lens are bonded with adhesive,
said second lens and said third lens are bonded with adhesive, and
following conditions (1) to (4) are satisfied:
0≦| N 3 −N 2 |≦0.1 (1)
0≦| N 3 −N 4 |≦0.1 (2)
0≦|ν 3 −ν 2 |≦30.0 (3)
0≦|ν 3 −ν 4 |≦30.0 (4)
where
N 2 : refractive index of said first lens
N 3 : refractive index of said second lens
N 4 : refractive index of said third lens
ν 2 : Abbe number of the said lens
ν 3 : Abbe number of said second lens
ν 4 : Abbe number of said third lens.
16. The imaging lens according to claim 15 , characterized in that
said second lens is an optical parallel plate,
said first lens is a piano-convex lens where an object side face of said first lens is a convex surface facing said object side, and
said third lens is a piano-convex lens where an image side face of said third lens is a convex surface facing said image side.
17. The imaging lens according to claim 15 , characterized in that said object side face of said first lens and said image side face of said third lens are aspherical.
18. The imaging lens according to claim 15 , characterized in that at least one surface of said second lens is coated.
19. The imaging lens according to claim 15 , characterized in that said curable resin material is a transparent high hardness silicon resin.