Patent ID: 11940598
Assignee: LARGAN PRECISION CO., LTD.
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. A lens system comprising four lens elements, the four lens elements being, in order 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, and each of the four lens elements having an object-side surface facing toward the object side and an image-side surface facing toward the image side;
wherein the first lens element has negative refractive power, at least one of the object-side surface and the image-side surface of the first lens element has at least one inflection point, the object-side surface of the fourth lens element is convex in a paraxial region thereof, the image-side surface of the fourth lens element is concave in a paraxial region thereof, the lens system further comprises an aperture stop disposed between the second lens element and the third lens element, a central thickness of the third lens element is a maximum among central thicknesses of all lens elements of the lens system, and a total number of lens elements in the lens system is four;
wherein a minimum value among Abbe numbers of all lens elements of the lens system is Vdmin, a focal length of the lens system is f, an entrance pupil diameter of the lens system is EPD, and the following conditions are satisfied:

13.0<Vdmin<21.0; and

1.25<f/EPD<2.50.