Optical imaging lens

An optical imaging lens, sequentially from an object side to an image side along an optical axis, comprising first, second, third, and fourth lens elements, each of the first, second, third, and fourth lens elements having a 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 an optical axis, wherein:

• the image-side surface of the first lens element comprises a concave portion in a vicinity of the optical axis;
• the second lens element has a positive refracting power;
• the object-side surface of the third lens element comprises a convex portion in a vicinity of a periphery of the third lens element, the image-side surface of said third lens element comprises a convex portion in a vicinity of a periphery of the third lens element;
• 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;
• a sum of a central thicknesses of all four lens elements along the optical axis is represented by ALT, an air gap between the first lens element and the second lens element along the optical axis is represented by G12, an air gap between the second lens element and the third lens element along the optical axis is represented by G23, an air gap between the third lens element and the fourth lens element along the optical axis is represented by G34, a sum of G12, G23, and G34 is represented by AAG, ALT and AAG satisfy the equation:
• ALT/AAG≤1.25;
• a central thickness of the third lens element is represented by T3, G12 and T3 satisfy the equation:
• G12/T3≤1.8;
• and
• wherein the optical imaging lens comprises no other lenses having refracting power beyond the first, second, third, and fourth lens elements.