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 and fifth lens elements, each of the first, second, third, fourth and fifth lens elements having refracting power, an object-side surface facing toward the object side and an image-side surface facing toward the image side and a central thickness defined along the optical axis, wherein:

the first lens element has negative refracting power;

the second lens element has negative refracting power;

the object-side surface of the third lens element comprises a concave portion in a vicinity of a periphery of the third lens element;

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

the object-side surface of the fourth lens element comprises a convex portion in a vicinity of a periphery of the fourth lens element and the image-side surface of the fourth lens element comprises a concave portion in a vicinity of the optical axis;

the fifth lens element is constructed by plastic material;

the optical imaging lens comprises no other lenses having refracting power beyond the five lens elements; and

a sum of all four air gaps from the first lens element to the fifth lens element along the optical axis is represented by Gaa, the central thickness of the fourth lens element is represented by T4, the central thickness of the first lens element is represented by T1, and Gaa, T4 and T1 satisfy the inequality:

Gaa /( T 4+ T 1)≤1.5.

2. The optical imaging lens according to claim 1 , wherein the central thickness of the fifth lens element is represented by T5, the central thickness of the third lens element is represented by T3, and T5, T3 and T4 satisfy the inequality:

( T 5+ T 3)/ T 4≤6.2.

3. The optical imaging lens according to claim 1 , wherein a distance between the object-side surface of the first lens element and the image-side surface of the fifth lens element along the optical axis is represented by TL, an air gap between the third lens element and the fourth lens element along the optical axis is represented by G3, and TL, T4 and G3 satisfy the inequality:

TL /( T 4+ G 3)≤13.8.

4. The optical imaging lens according to claim 1 , wherein an air gap between the second lens element and the third lens element along the optical axis is represented by G2, an air gap between the third lens element and the fourth lens element along the optical axis is represented by G3, and G2, T4 and G3 satisfy the inequality:

G 2/( T 4+ G 3)≤1.7.

5. The optical imaging lens according to claim 1 , wherein an air gap between the first lens element and the second lens element along the optical axis is represented by G1, the central thickness of the third lens element is represented by T3, an air gap between the second lens element and the third lens element along the optical axis is represented by G2, and G1, T3 and G2 satisfy the inequality:

( G 1+ T 3)/ G 2≥2.8.

6. The optical imaging lens according to claim 1 , wherein a sum of the central thicknesses of all five lens elements is represented by ALT, the central thickness of the fifth lens element is represented by T5, an air gap between the third lens element and the fourth lens element along the optical axis is represented by G3, and ALT, T5 and G3 satisfy the inequality:

ALT /( T 5+ G 3)≤5.

7. The optical imaging lens according to claim 1 , wherein a distance between the object-side surface of the first lens element and an image plane along the optical axis is represented by TTL, the central thickness of the fifth lens element is represented by T5, an air gap between the third lens element and the fourth lens element along the optical axis is represented by G3, and TTL, T5 and G3 satisfy the inequality:

TTL /( T 5+ G 3)≤8.5.

8. The optical imaging lens according to claim 1 , wherein the central thickness of the second lens element is represented by T2, and T2 and T4 satisfy the inequality:

T 2/ T ≤2.2.

9. The optical imaging lens according to claim 1 , wherein the central thickness of the fifth lens element is represented by T5, the central thickness of the third lens element is represented by T3, and T5 and T3 satisfy the inequality:

T 5/ T 3≥0.7.

10. The optical imaging lens according to claim 1 , wherein a distance between the object-side surface of the first lens element and the image-side surface of the fifth lens element along the optical axis is represented by TL, the central thickness of the fifth lens element is represented by T5, an air gap between the third lens element and the fourth lens element along the optical axis is represented by G3, and TL, T5 and G3 satisfy the inequality:

TL /( T 5+ G 3)≤6.8.

11. The optical imaging lens according to claim 1 , wherein an air gap between the second lens element and the third lens element along the optical axis is represented by G2, an air gap between the first lens element and the second lens element along the optical axis is represented by G1, and T1, G2 and G1 satisfy the inequality:

( T 1+ G 2)/ G 1≤2.

12. The optical imaging lens according to claim 1 , wherein an air gap between the first lens element and the second lens element along the optical axis is represented by G1, and G1 and T1 satisfy the inequality:

G 1/ T 1≥0.8.

13. The optical imaging lens according to claim 1 , wherein a distance between the object-side surface of the first lens element and the image-side surface of the fifth lens element along the optical axis is represented by TL, an air gap between the first lens element and the second lens element along the optical axis is represented by G1, the central thickness of the fifth lens element is represented by T5, and TL, G1 and T5 satisfy the inequality:

TL /( G 1+ T 5)≤3.3.

14. The optical imaging lens according to claim 1 , wherein a sum of the central thicknesses of all five lens elements is represented by ALT, an air gap between the first lens element and the second lens element along the optical axis is represented by G1, the central thickness of the fifth lens element is represented by T5, and ALT, G1 and T5 satisfy the inequality:

ALT /( G 1+ T 5)≤2.2.

15. The optical imaging lens according to claim 1 , wherein a sum of the central thicknesses of all five lens elements is represented by ALT, an air gap between the third lens element and the fourth lens element along the optical axis is represented by G3, and ALT, T4 and G3 satisfy the inequality:

ALT /( T 4+ G 3)≤9.2.

16. The optical imaging lens according to claim 1 , wherein a distance between the object-side surface of the first lens element and an image plane along the optical axis is represented by TTL, an air gap between the third lens element and the fourth lens element along the optical axis is represented by G3, and TTL, T4 and G3 satisfy the inequality:

TTL /( T 4+ G 3)≤16.

17. The optical imaging lens according to claim 1 , wherein a distance between the object-side surface of the first lens element and an image plane along the optical axis is represented by TTL, an air gap between the first lens element and the second lens element along the optical axis is represented by G1, the central thickness of the fifth lens element is represented by T5, and TTL, G1 and T5 satisfy the inequality:

TTL /( G 1+ T 5)≤3.8.

18. The optical imaging lens according to claim 1 , wherein the central thickness of the second lens element is represented by T2, the central thickness of the fifth lens element is represented by T5, and T2 and T5 satisfy the inequality:

T 2/ T 5≤1.

19. The optical imaging lens according to claim 1 , wherein the central thickness of the fifth lens element is represented by T5, an air gap between the third lens element and the fourth lens element along the optical axis is represented by G3, an air gap between the second lens element and the third lens element along the optical axis is represented by G2, and T5, G3 and G2 satisfy the inequality:

( T 5+ G 3)/ G 2≥1.5.

20. The optical imaging lens according to claim 1 , wherein the central thickness of the fifth lens element is represented by T5, an air gap between the second lens element and the third lens element along the optical axis is represented by G2, and T5, G2 and T4 satisfy the inequality:

( T 5+ G 2)/ T 4≤5.5.

21. An optical imaging lens, sequentially from an object side to an image side along an optical axis, comprising first, second, third, fourth and fifth lens elements, each of the first, second, third, fourth and fifth lens elements having refracting power, an object-side surface facing toward the object side and an image-side surface facing toward the image side and a central thickness defined along the optical axis, wherein:

the first lens element has negative refracting power;

the second lens element has negative refracting power;

the object-side surface of the third lens element comprises a concave portion in a vicinity of a periphery of the third lens element;

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

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

the fifth lens element is constructed by plastic material;

the optical imaging lens comprises no other lenses having refracting power beyond the five lens elements;

a sum of all four air gaps from the first lens element to the fifth lens element along the optical axis is represented by Gaa, the central thickness of the fourth lens element is represented by T4, the central thickness of the first lens element is represented by T1, and Gaa, T4 and T1 satisfy the inequality:

Gaa /( T 4+ T 1)≤1.5; and

the central thickness of the fifth lens element is greater than the central thickness of the second lens element.