Lens module

1. A lens module, comprising:

a barrel having a first sidewall, a light hole in the center of the first sidewall, a second sidewall extending from the first sidewall and a receiving room formed by the first sidewall and the second sidewall;

a first lens element disposed in the receiving room and connecting with the barrel for making the lens module have a first matching precision, the first lens having a first optical axis, a first surface, a second surface opposite to the first surface and partially engaging with the first sidewall, and a side surface connecting with the first surface and the second surface, the side surface engaging with the second sidewall, the first surface having a first portion arranged in the middle of the first surface, a first arc surface extending from the periphery of the first portion and a second portion extending from the periphery of the first arc surface;

a second lens element disposed in the receiving room and connecting with the first lens element for making the lens module have a second matching precision, the second lens element having a second optical axis, an upper surface near the first lens element, a lower surface opposite to the upper surface and a periphery surface connecting with the upper surface and the lower surface, the periphery surface keeping a distance with the second sidewall, the upper surface having a third portion arranged in the middle of the upper surface and centered about the second optical axis, a second arc surface extending from the periphery of the third portion and engaging with the first arc surface, and a fourth portion extending from the periphery of the second arc surface;

the first portion keeping a predetermined distance from the third portion and the second portion keeping a predetermined distance from the fourth portion, the second matching precision making the first optical axis and the second optical axis coincide with each other and the first matching precision making the center of the light hole be located on the optical axis of the first lens element and the second lens element.

2. The lens module as described in claim 1 , wherein the first portion comprises a first optical surface arranged in the middle of the first surface and centered about the first optical axis, a first extending surface extending from the periphery of the first optical surface, a connecting surface bended along from and extending from the periphery of the first extending surface, and a second extending surface extending from the periphery of the connecting surface.

3. The lens module as described in claim 2 , wherein, the second surface has a second optical surface arranged in the middle of the second surface and centered about the first optical axis, and a third extending surface extending from the periphery of the second optical surface and engaging with the first sidewall.

4. The lens module as described in claim 3 , wherein the third portion comprising a third optical surface arranged in the middle of the upper surface and centered about the second optical axis, and a first bearing surface extending from the third optical surface.

5. The lens module as described in claim 1 , wherein the first portion comprises a first optical surface arranged in the middle of the first surface and centered about the optical axis and a first extending surface extending from the periphery of the first optical surface.

6. The lens module as described in claim 5 , wherein the second surface comprises a second optical surface arranged in the middle of the second surface and centered about the first optical axis, and a second extending surface extending from the periphery of the second optical surface and engaging with the first sidewall.

7. The lens module as described in claim 6 , wherein the third portion comprises a third optical surface arranged in the middle of the upper surface and centered about the second optical axis, a first bearing surface extending from the periphery of the third optical surface, a transition surface bended from and extending from the periphery of the first bearing surface, and a second bearing surface extending from the periphery of the transition surface.

8. The lens module as described in claim 7 , wherein the first lens elements further comprises a side surface connecting with the first surface and the second surface, the side surface engages with the second sidewall, the second lens elements further comprises a periphery surface connecting with the upper surface and the lower surface, the periphery surface keeps a distance with the second sidewall.

9. The lens module as described in claim 1 , wherein the first portion comprises a first optical surface arranged in the middle of the first surface and centered about the first optical axis, a transition surface bended from and extending from the periphery of the first optical surface, and a first extending surface extending from the periphery of the transition surface.

10. The lens module as described in claim 9 , wherein the second surface has a second optical surface arranged in the middle of the second surface and centered about the optical axis, and a second extending surface extending from the periphery of the second optical surface and engaging with the first sidewall.

11. The lens module as described in claim 10 , wherein the third portion comprising a third optical surface arranged in the middle of the upper surface and centered about the second optical axis, and a first bearing surface extending from the third optical surface.

12. The lens module as described in claim 1 further comprising a light filter disposed between the first portion and the third portion.