Optical imaging system

An optical imaging system, comprising a first lens element, a second lens element, a third lens element, a fourth lens element and a fifth lens element in order along an optical axis from an object side to an image side, wherein the first lens element to the fifth lens element each comprises an object-side surface facing towards the object side and allowing imaging rays to pass through and an image-side surface facing towards the image side and allowing the imaging rays to pass through, and wherein the first lens element is arranged to be a lens element in a first order from the object side to the image side, the second lens element is arranged to be a lens element in a second order from the object side to the image side, the third lens element is arranged to be a lens element in a third order from the object side to the image side, the fourth lens element is arranged to be a lens element in a fourth order from the object side to the image side, and the fifth lens element is arranged to be a lens element in a fifth order from the object side to the image side;

• the image-side surface of the first lens element having a concave portion in a vicinity of the optical axis, and the image-side surface of the first lens element having a concave portion in a vicinity of a periphery of the first lens element;
• the object-side surface of the second lens element having a convex portion in a vicinity of the optical axis, and the image-side surface of the second lens element having a concave portion in a vicinity of a periphery of the second lens element;
• the image-side surface of the third lens element having a concave portion in a vicinity of the optical axis;
• the image-side surface of the fourth lens element having a convex portion in a vicinity of the optical axis;
• lens elements of the optical imaging lens being only the five lens elements described above;
• the optical imaging system satisfying following conditions:
• TTL/EFL≤1.2, wherein TTL represents a distance from the object-side surface of the first lens element to an image plane of the optical imaging system along the optical axis, and EFL represents an effective focal length of the optical imaging system.

An optical imaging system, comprising a first lens element, a second lens element, a third lens element, a fourth lens element and a fifth lens element in order along an optical axis from an object side to an image side, wherein the first lens element to the fifth lens element each comprises an object-side surface facing towards the object side and allowing imaging rays to pass through and an image-side surface facing towards the image side and allowing the imaging rays to pass through, and wherein the first lens element is arranged to be a lens element in a first order from the object side to the image side, the second lens element is arranged to be a lens element in a second order from the object side to the image side, the third lens element is arranged to be a lens element in a third order from the object side to the image side, the fourth lens element is arranged to be a lens element in a fourth order from the object side to the image side, and the fifth lens element is arranged to be a lens element in a fifth order from the object side to the image side;

• the object-side surface of the second lens element having a convex portion in a vicinity of the optical axis, and the object-side surface of the second lens element having a convex portion in a vicinity of a periphery of the second lens element;
• the image-side surface of the third lens element having a concave portion in a vicinity of the optical axis, and the image-side surface of the third lens element having a concave portion in a vicinity of a periphery of the third lens element;
• the object-side surface of the fifth lens element having a concave portion in a vicinity of a periphery of the fifth lens element;
• lens elements of the optical imaging lens being only the five lens elements described above;
• the optical imaging system satisfying following conditions:
• TTL/EFL≤1.2 and AAG/(G12+G45)≤5.6, wherein TTL represents a distance from the object-side surface of the first lens element to an image plane of the optical imaging system along the optical axis, EFL represents an effective focal length of the optical imaging system, AAG represents a sum of four air gaps from the first lens element to the fifth lens element along the optical axis, G12 represents an air gap from the first lens element to the second lens element along the optical axis, and G45 represents an air gap from the fourth lens element to the fifth lens element along the optical axis.