Patent ID: 10901181

Abstract:
An optical imaging system includes, in a sequential 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. 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. The optical imaging system satisfies the relations 2.13°≤HFOV/Fno≤8.75°, and 0.56≤G23/T1≤1.54, where HFOV is the half field of view and Fno is the F number of the optical imaging system, G23 is an air gap between the second and third lens elements along the optical axis, and T1 is a thickness of the first lens element along the optical axis.