Near-infrared lens for cameras in mobile devices

Abstract

A first optical imaging system includes, in order from the object side to the image side, a first lens element, a second lens element, and a third lens element, arranged along an optical axis. A second optical imaging system includes, in order from the object side to the image side, a first lens element, a second lens element, a third lens element, and a fourth lens element, arranged along an optical axis. A third optical imaging system is a telecentric lens system having only lens elements having a refractive power and a chief ray angle smaller than 1 degree. The lens elements of the optical imaging systems may be made of the same material having absorption in visible wavelengths and high transmission in near infrared radiation. The lens elements may be coated with an antireflective coating that is optimized for near infrared radiation.

What is claimed is: 
     
         1 . An optical imaging lens system comprising, sequentially in order from an object side to an image side, an aperture stop, a first lens element, a second lens element, a third lens element, and a fourth lens element arranged along an optical axis, 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 image-side surface of the first lens element comprises a convex portion in a vicinity of its periphery;   the object-side surface of the second lens element comprises a concave portion in a vicinity of a periphery of the second lens element;   the object-side surface of the fourth lens element comprises a convex portion in a vicinity of the optical axis and a concave portion in a vicinity of its periphery; wherein:   an absolute value of a difference between an Abbe number V 1  of the first lens and an Abbe number V 4  of the fourth lens is defined as |V 1 −V 4 |, a thickness of the fourth lens element at the optical axis is defined as T 4 , a distance measured from the object side surface of the first lens element to an image plane along the optical axis is defined as TTL, a sum of thicknesses of the first, second, third, and fourth lens elements is defined as ALT, a sum of air gaps between the first lens element through the fourth lens element along the optical axis is defined as AAG, a thickness of the first lens element at the optical axis is defined as T 1 , a thickness of the second lens element at the optical axis is defined as T 2 , an air gap between the first and second lens elements at the optical axis is defined as G 12 , and |V 1 −V 4 |, T 1 , T 2 , T 4 , TTL, AAG, ALT, and G 12  satisfy the relations:
   0≤| V 1− V 4|≤20.00;
 
   6.50≤ TTL/T 4≤10.00;
 
   3.15≤ ALT/T 1≤3.50;
 
   3.15≤ ALT/AAG≤ 3.50;
 
   1.50≤ T 2/ G 12≤2.10; and
 
   1.44≤ T 4/ T 2≤1.60.
 
   
     
     
         2 . The optical imaging lens system of  claim 1  wherein a distance between the image side of the fourth lens element and the image plane along the optical axis is defined as a BFL, and ALT and BFL satisfy the relation:
   1.175≤ ALT/BFL≤ 1.751.
 
 
     
     
         3 . The optical imaging lens system of  claim 2  wherein:
   0.862≤ T 1/ T 2≤2.244.
 
 
     
     
         4 . The optical imaging lens system of  claim 2  wherein the image-side surface of the second lens element comprises a convex portion in a vicinity of its periphery. 
     
     
         5 . The optical imaging lens system of  claim 1  wherein:
   0.450≤ T 2/ T 1≤1.148.
 
 
     
     
         6 . The optical imaging lens system of  claim 5  wherein a distance between the image side of the fourth lens element and the image plane along the optical axis is defined as a BFL, and BFL and T 4  satisfy the relation:
   2.237≤ BFL/T 4≤3.765.
 
 
     
     
         7 . The optical imaging lens system of  claim 1  wherein an air gap between the second lens element and the third lens elements measured at the optical axis is defined as G 23 , and ALT and G 23  satisfy the relation:
   5.116≤ ALT/G 23≤5.699.
 
 
     
     
         8 . The optical imaging lens system of  claim 1  wherein a thickness of the third lens element at the optical axis is defined as T 3 , a distance between the image side of the fourth lens element and the image plane along the optical axis is defined as a BFL, and an air gap between the second lens element and the third lens elements measured at the optical axis is defined as G 23 , and T 3 , BFL, and G 23  satisfy the relation:
   5.079≤( T 3+ BFL )/ G 23≤6.125.
 
 
     
     
         9 . The optical imaging lens system of  claim 1  wherein a distance between the image side of the fourth lens element and the image plane along the optical axis is defined as a BFL and an air gap between the second lens element and the third lens elements measured at the optical axis is defined as G 23 , and BFL and G 23  satisfy the relation:
   3.766≤ BFL/G 23≤4.366.
 
 
     
     
         10 . The optical imaging lens system of  claim 1  wherein an air gap between the second lens element and the third lens elements measured at the optical axis is defined as G 23 , and TTL, T 1 , and G 23  satisfy the relation:
   4.107≤ TTL /( T 1+ G 23)≤4.322.
 
 
     
     
         11 . The optical imaging lens system of  claim 1  wherein an air gap between the second lens element and the third lens elements measured at the optical axis is defined as G 23 , and ALT, T 1  and G 23  satisfy the relation:
   1.973≤ ALT /( T 1− G 23)≤2.092.
 
 
     
     
         12 . The optical imaging lens system of  claim 1  wherein an air gap between the second lens element and the third lens elements measured at the optical axis is defined as G 23 , and TTL, G 12 , and G 23  satisfy the relation:
   6.921≤ TTL /( G 12+ G 23)≤8.077.
 
 
     
     
         13 . The optical imaging lens system of  claim 1  wherein an air gap between the second lens element and the third lens elements measured at the optical axis is defined as G 23 , and ALT, G 12 , and G 23  satisfy the relation:
   3.324≤ ALT /( G 12+ G 23)≤3.909.
 
 
     
     
         14 . The optical imaging lens system of  claim 1  wherein a thickness of the third lens element at the optical axis is defined as T 3 , a distance between the image side of the fourth lens element and the image plane along the optical axis is defined as a BFL, and an air gap between the second lens element and the third lens elements measured at the optical axis is defined as G 23 , and T 3 , BFL, G 12 , and G 23  satisfy the relation:
   3.300≤( T 3+ BFL )/( G 12+ G 23)≤4.202.
 
 
     
     
         15 . The optical imaging lens system of  claim 1  wherein a thickness of the third lens element at the optical axis is defined as T 3  and an air gap between the third lens element and the fourth lens elements measured at the optical axis is defined as G 34 , and T 1 , T 2 , T 3 , and G 34  satisfy the relation:
   1.658≤( T 1+ T 2+ G 34)/ T 3≤2.053.
 
 
     
     
         16 . The optical imaging lens system of  claim 1  wherein an air gap between the third lens element and the fourth lens elements measured at the optical axis is defined as G 34 , and T 1 , T 2 , T 4 , and G 34  satisfy the relation:
   2.013≤( T 1+ T 2+ G 34)/ T 4≤2.285.
 
 
     
     
         17 . The optical imaging lens system of  claim 1  wherein an air gap between the second lens element and the third lens elements measured at the optical axis is defined as G 23  and an air gap between the third lens element and the fourth lens elements measured at the optical axis is defined as G 34 , and T 1 , T 2 , G 23 , and G 34  satisfy the relation:
   2.696≤( T 1+ T 2+ G 34)/ G 23≤2.915.
 
 
     
     
         18 . The optical imaging lens system of  claim 1  wherein an air gap between the third lens element and the fourth lens elements measured at the optical axis is defined as G 34 , and T 1 , T 2 , T 4 , and G 34  satisfy the relation:
   1.431≤( T 2+ G 34+ T 4)/ T 1≤1.530.
 
 
     
     
         19 . The optical imaging lens system of  claim 1  wherein an air gap between the third lens element and the fourth lens elements measured at the optical axis is defined as G 34 , and T 4 , G 12 , and G 34  satisfy the relation:
   2.914≤( G 34+ T 4)/ G 12≤3.335.
 
 
     
     
         20 . The optical imaging lens system of  claim 1  wherein an air gap between the third lens element and the fourth lens elements measured at the optical axis is defined as G 34 , and T 2 , T 4 , and G 34  satisfy the relation:
   1.624≤( G 34+ T 4)/ T 2≤1.806.