Optical lens

1. An optical lens, in order from an object side to an image-forming side, comprising: a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens, the first lens, the third lens and the fifth lens are first type lenses, the second lens, the fourth lens and the sixth lens are second type lenses; wherein the first type lenses are diverging lenses and the second type lenses are converging lenses, or the first type lenses are converging lenses and the second type lenses are diverging lenses; and the optical lens satisfies at least one of the following conditions: 0.5≦EFL/TTL, EFL/TTL≦1, 0.65 ≦F123/EFL and F123/EFL≦1, wherein EFL is an effective focal length of the optical lens, TTL is a distance between an object-side surface of the first lens and an imaging plane, and F123 is a total focal length of the first lens, the second lens and the third lens.

2. The optical lens as recited in claim 1 , wherein the first lens is a glass lens.

3. The optical lens as recited in claim 1 , wherein at least one of the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens is a plastic lens.

4. The optical lens as recited in claim 1 , wherein an imaging-side surface of the sixth lens is an aspheric surface with an infection point, a distance between the infection point and an optical axis is h 6 , a radius of the sixth lens is H 6 , and h 6 /H 6 <1.0.

5. The optical lens as recited in claim 1 , wherein a refractive index of the first lens is nd 1 and an Abbe number of the first lens is vd 1 , an Abbe number of the fourth lens is vd 4 , and 1.40≦nd 1 , 35≦vd 1 or vd 4 ≦40.

6. The optical lens as recited in claim 1 , wherein an Abbe number of the fifth lens is vd 5 , an Abbe number of the sixth lens is vd 6 , and |vd 5 −vd 6 |≦10.

7. An optical lens, in order from an object side to an image-forming side, comprising: a first lens having positive refractive power; a second lens having refractive power; a third lens having positive refractive power; a fourth lens having negative refractive power; a fifth lens having positive refractive power; and a sixth lens having negative refractive power; wherein the optical lens satisfies the following conditions: 0.5≦EFL/TTL, EFL/TTL≦1, 0.65≦F123/EFL, and F123/EFL≦1, wherein EFL is an effective focal length of the optical lens, TTL is a distance between an object-side surface of the first lens and an imaging plane, and F123 is a total focal length of the first lens, the second lens and the third lens.

8. The optical lens as recited in claim 7 , wherein the first lens is a glass lens.

9. The optical lens as recited in claim 7 , wherein at least one of the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens is a plastic lens.

10. The optical lens as recited in claim 7 , wherein at least one of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens is an aspheric lens.

11. The optical lens as recited in claim 7 , wherein an imaging-side surface of the sixth lens is an aspheric surface with an infection point, a distance between the infection point and an optical axis is h 6 , the sixth lens has a radius H 6 , and h 6 /H 6 <1.0.

12. The optical lens as recited in claim 7 , further comprises the optical lens satisfies at least one of the following conditions: 1.30≦Fno, Fno≦2.80 and TTL≦20.0 mm, wherein Fno is an F number of the optical lens.

13. The optical lens as recited in claim 7 , wherein a refractive index of the first lens is nd 1 and an Abbe number of the first lens is vd 1 , an Abbe number of the fourth lens is vd 4 , and 1.40≦nd 1 , 35≦vd 1 or vd 4 ≦40.

14. The optical lens as recited in claim 7 , wherein an Abbe number of the fifth lens is vd 5 , an Abbe number of the sixth lens is vd 6 , and |vd 5 −vd 6 |≦10.

15. The optical lens as recited in claim 7 , wherein an imaging-side surface of the first lens has positive refractive power or negative refractive power, and/or an object-side surface of the second lens has positive refractive power or negative refractive power.

16. An optical lens, in order from an object side to an image-forming side, comprising: a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens, the first lens, the third lens, and the fifth lens are first type lenses, and the second lens, the fourth lens and the sixth lens are second type lenses; wherein the first type lenses are diverging lenses and the second type lenses are converging lenses, or the first type lenses are converging lenses and the second type lenses are diverging lenses; wherein the optical lens satisfies at least one of the following conditions: 0.5≦EFL/TTL, EFL/TTL≦1, 0.65≦F123/EFL and F123 /EFL≦1, wherein EFL is an effective focal length of the optical lens, TTL is a distance between an object-side surface of the first lens and an imaging plane, F123 is a total focal length of the first lens, the second lens and the third lens, the first lens is a glass lens, and at least one of the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens is a plastic lens.

17. The optical lens as recited in claim 16 , wherein an imaging-side surface of the sixth lens is an aspheric surface with an infection point, a distance between the infection point and an optical axis is h 6 , a radius of the sixth lens is H 6 , and h 6 /H 6 <1.0.

18. The optical lens as recited in claim 16 , wherein a refractive index of the first lens is nd 1 and an Abbe number of the first lens is vd 1 , an Abbe number of the fourth lens is vd 4 , and 1.40≦nd 1 , 35≦vd 1 or vd 4 ≦40.

19. The optical lens as recited in claim 16 , wherein an Abbe number of the fifth lens is vd 5 , an Abbe number of the sixth lens is vd 6 , and |vd 5 −vd 6 |≦10.

20. The optical lens as recited in claim 16 , wherein an imaging-side surface of the first lens has positive refractive power or negative refractive power, and/or an object-side surface of the second lens has positive refractive power or negative refractive power.