Mobile device and optical imaging lens thereof

An optical imaging lens comprising, sequentially from an object side to an image side:

• a first lens element;
• a second lens element;
• a third lens element;
• and
• a fourth lens element, each of the first, second, third, and fourth lens elements having an object-side surface facing toward the object side and an image-side surface facing toward the image side, wherein:
• the object-side surface of the first lens element comprises a convex portion in a vicinity of the optical axis and a convex portion in a vicinity of a periphery of the first lens element, and the image-side surface of the first lens element comprises a convex portion in the vicinity of the optical axis;
• the image-side surface of the second lens element comprises a concave portion in a vicinity of the optical axis, and the object-side surface of the second lens element is convex;
• the object-side surface of the third lens element comprises a concave portion in a vicinity of the optical axis and 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 and a convex portion in a vicinity of a periphery of the fourth lens element;
• an air gap between the first lens element and the second lens element along the optical axis is G12;
• the optical imaging lens as a whole has refracting power;
• a distance between the object-side surface of the first lens element and an image plane along the optical axis is TTL, a thickness of the first lens element along the optical axis is T1, and TTL and T1 satisfy the equation:
• 7.021≦TTL/T1≦11.307;
• and
• a sum of the thickness of all four lens elements along the optical axis is ALT, an air gap between the third lens element and the fourth lens element along the optical axis is G34, and ALT and G34 satisfy the equation:
• 13.7≦(ALT/G34)≦26.0.