Optical imaging lens

1. An optical imaging lens, sequentially from an object side to an image side along an optical axis, comprising first, second, third, fourth, fifth and sixth lens elements, each of said first, second, third, fourth, fifth and sixth lens elements having refracting power, an object-side surface facing toward said object side and an image-side surface facing toward said image side, wherein:

said image-side surface of said first lens element comprises a concave portion in a vicinity of the optical axis;

said image-side surface of said second lens element comprises a concave portion in a vicinity of the optical axis;

said object-side surface of said third lens element comprises a convex portion in a vicinity of the optical axis;

said object-side surface of said fourth lens element comprises a concave portion in a vicinity of a periphery of said fourth lens element;

at least one of said object-side surface and said image-side surface of said fifth lens element is an aspherical surface;

both said object-side surface and said image-side surface of said sixth lens element are aspherical surfaces;

said optical imaging lens comprises no other lenses having refracting power beyond said first, second, third, fourth, fifth and sixth lens elements;

a distance between said object-side surface of said first lens element and an image plane along the optical axis is represented by TTL, a distance from said object-side surface of said first lens element to said image-side surface of said sixth lens element along the optical axis is represented by TL, a distance from said image-side surface of said second lens element to said object-side surface of said third lens element along the optical axis is represented by G23, a distance from said image-side surface of said third lens element to said object-side surface of said fourth lens element along the optical axis is represented by G34, a distance from said image-side surface of said fourth lens element to said object-side surface of said fifth lens element along the optical axis is represented by G45, and TTL, TL, G23, G34, G45 satisfy the equations: TTL≤6.5 mm and TL/(G23+G34+G45)≤2.7.

2. The optical imaging lens according to claim 1 , wherein an Abbe number of said third lens element is represented by V3, an Abbe number of said fourth lens element is represented by V4, and V3 and V4 satisfy the equation: 16≤V3−V4≤50.

3. The optical imaging lens according to claim 1 , wherein a central thickness of said second lens element along the optical axis is represented by T2, a central thickness of said third lens element along the optical axis is represented by T3, a central thickness of said fourth lens element along the optical axis is represented by T4, a central thickness of said fifth lens element along the optical axis is represented by T5, and T2, T3, T4, T5 and G23 satisfy the equation: (T2+T3+T4+T5)/G23≤34.

4. The optical imaging lens according to claim 1 , wherein a central thickness of said sixth lens element along the optical axis is represented by T6, and TTL and T6 satisfy the equation: TTL/T6≤20.

5. The optical imaging lens according to claim 1 , wherein an effective focal length of said optical imaging lens is represented by EFL, a central thickness of said sixth lens element along the optical axis is represented by T6, and EFL and T6 satisfy the equation: EFL/T6≤20.

6. The optical imaging lens according to claim 1 , wherein a sum of all air gaps between all lens elements along the optical axis is represented by AAG, a central thickness of said first lens element along the optical axis is represented by T1, a central thickness of said sixth lens element along the optical axis is represented by T6, and AAG, T1 and T6 satisfy the equation: AAG/(T1+T6)≤2.

7. The optical imaging lens according to claim 1 , wherein a central thickness of said first lens element along the optical axis is represented by T1, a central thickness of said second lens element along the optical axis is represented by T2, a central thickness of said third lens element along the optical axis is represented by T3, a central thickness of said fourth lens element along the optical axis is represented by T4, a central thickness of said fifth lens element along the optical axis is represented by T5, and T1, T2, T3, T4, T5, G23 and G34 satisfy the equation: (T1+T2+T3+T4+T5)/(G23+G34)≤3.

8. An optical imaging lens, sequentially from an object side to an image side along an optical axis, comprising first, second, third, fourth, fifth and sixth lens elements, each of said first, second, third, fourth, fifth and sixth lens elements having refracting power, an object-side surface facing toward said object side and an image-side surface facing toward said image side, wherein:

said image-side surface of said first lens element comprises a concave portion in a vicinity of the optical axis;

said image-side surface of said second lens element comprises a concave portion in a vicinity of a periphery of said second lens element;

said object-side surface of said third lens element comprises a convex portion in a vicinity of the optical axis;

said object-side surface of said fourth lens element comprises a concave portion in a vicinity of a periphery of said fourth lens element;

at least one of said object-side surface and said image-side surface of said fifth lens element is an aspherical surface;

both said object-side surface and said image-side surface of said sixth lens element are aspherical surfaces;

said optical imaging lens comprises no other lenses having refracting power beyond said first, second, third, fourth, fifth and sixth lens elements;

a distance between said object-side surface of said first lens element and an image plane along the optical axis is represented by TTL, a distance from said object-side surface of said first lens element to said image-side surface of said sixth lens element along the optical axis is represented by TL, a distance from said image-side surface of said second lens element to said object-side surface of said third lens element along the optical axis is represented by G23, a distance from said image-side surface of said third lens element to said object-side surface of said fourth lens element along the optical axis is represented by G34, a distance from said image-side surface of said fourth lens element to said object-side surface of said fifth lens element along the optical axis is represented by G45, and TTL, TL, G23, G34, G45 satisfy the equations: TTL≤6.5 mm and TL/(G23+G34+G45)≤2.7.

9. The optical imaging lens according to claim 8 , wherein a central thickness of said first lens element along the optical axis is represented by T1, and T1 and G23 satisfy the equation: T1/G23≤10.

10. The optical imaging lens according to claim 8 , wherein a central thickness of said first lens element along the optical axis is represented by T1, a central thickness of said second lens element along the optical axis is represented by T2, a central thickness of said third lens element along the optical axis is represented by T3, a central thickness of said fourth lens element along the optical axis is represented by T4, a central thickness of said fifth lens element along the optical axis is represented by T5, and T1, T2, T3, T4, T5 and G45 satisfy the equation: (T1+T2+T3+T4+T5)/G45≤5.5.

11. The optical imaging lens according to claim 8 , wherein a central thickness of said first lens element along the optical axis is represented by T1, a central thickness of said fifth lens element along the optical axis is represented by T5, a distance from said image-side surface of said first lens element to said object-side surface of said second lens element along the optical axis is represented by G12, a distance from said image-side surface of said fifth lens element to said object-side surface of said sixth lens element along the optical axis is represented by G56, and T1, T5, G12, G45 and G56 satisfy the equation: (T1+G12+T5+G56)/G45≤2.

12. The optical imaging lens according to claim 8 , wherein a sum of the central thicknesses of all lens elements is represented by ALT, a central thickness of said sixth lens element along the optical axis is represented by T6, and ALT and T6 satisfy the equation: ALT/T6≤8.7.

13. The optical imaging lens according to claim 8 , wherein a central thickness of said first lens element along the optical axis is represented by T1, a central thickness of said sixth lens element along the optical axis is represented by T6, and TL, T1 and T6 satisfy the equation: TL/(T1+T6)≤4.

14. An optical imaging lens, sequentially from an object side to an image side along an optical axis, comprising first, second, third, fourth, fifth and sixth lens elements, each of said first, second, third, fourth, fifth and sixth lens elements having refracting power, an object-side surface facing toward said object side and an image-side surface facing toward said image side, wherein:

said image-side surface of said first lens element comprises a concave portion in a vicinity of the optical axis;

at least one of said object-side surface and said image-side surface of said second lens element is an aspherical surface;

said object-side surface of said third lens element comprises a convex portion in a vicinity of a periphery of said third lens element;

said object-side surface of said fourth lens element comprises a concave portion in a vicinity of a periphery of said fourth lens element;

at least one of said object-side surface and said image-side surface of said fifth lens element is an aspherical surface;

both said object-side surface and said image-side surface of said sixth lens element are aspherical surfaces;

said optical imaging lens comprises no other lenses having refracting power beyond said first, second, third, fourth, fifth and sixth lens elements;

a distance between said object-side surface of said first lens element and an image plane along the optical axis is represented by TTL, a distance from said object-side surface of said first lens element to said image-side surface of said sixth lens element along the optical axis is represented by TL, a distance from said image-side surface of said second lens element to said object-side surface of said third lens element along the optical axis is represented by G23, a distance from said image-side surface of said third lens element to said object-side surface of said fourth lens element along the optical axis is represented by G34, a distance from said image-side surface of said fourth lens element to said object-side surface of said fifth lens element along the optical axis is represented by G45, and TTL, TL, G23, G34, G45 satisfy the equations: TTL≤6.5 mm and TL/(G23+G34+G45)≤2.7.

15. The optical imaging lens according to claim 14 , wherein a sum of all air gaps between all lens elements along the optical axis is represented by AAG, a central thickness of the sixth lens element along the optical axis is represented by T6, and AAG and T6 satisfy the equation: AAG/T6≤8.1.

16. The optical imaging lens according to claim 14 , wherein a back focal length of the optical imaging lens is represented by BFL, and BFL and G23 satisfy the equation: BFL/G23≤10.

17. The optical imaging lens according to claim 14 , wherein a central thickness of said first lens element along the optical axis is represented by T1, a central thickness of said second lens element along the optical axis is represented by T2, a central thickness of said third lens element along the optical axis is represented by T3, a central thickness of said fourth lens element along the optical axis is represented by T4, a central thickness of said fifth lens element along the optical axis is represented by T5, and T1, T2, T3, T3, T4, T5, G23 and G45 satisfy the equation: (T1+T2+T3+T4+T5)/(G23+G45)≤5.

18. The optical imaging lens according to claim 14 , wherein a central thickness of said first lens element along the optical axis is represented by T1, a central thickness of said second lens element along the optical axis is represented by T2, a central thickness of said third lens element along the optical axis is represented by T3, a central thickness of said fourth lens element along the optical axis is represented by T4, a central thickness of said fifth lens element along the optical axis is represented by T5, and T1, T2, T3, T3, T4, T5, G34 and G45 satisfy the equation: (T1+T2+T3+T4+T5)/(G34+G45)≤1.4.

19. The optical imaging lens according to claim 14 , wherein a distance from said image-side surface of said first lens element to said object-side surface of said second lens element along the optical axis is represented by G12, a distance from said image-side surface of said fifth lens element to said object-side surface of said sixth lens element along the optical axis is represented by G56, and G12, G23, G34 and G56 satisfy the equation: (G12+G34+G56)/G23≤20.

20. The optical imaging lens according to claim 14 , wherein an effective focal length of said optical imaging lens is represented by EFL, a central thickness of said first lens element along the optical axis is represented by T1, a central thickness of said sixth lens element along the optical axis is represented by T6, and EFL, T1 and T6 satisfy the equation: EFL/(T1+T6)≤5.