Optical lens, fingerprint recognition module and mobile terminal

A fingerprint recognition module, comprising an optical lens, an image sensor, a memory and a processor, wherein the optical lens and the image sensor are cooperated to capture a fingerprint image, the memory is configured for storing at least one preset template and the captured fingerprint image, and the processor is configured for identifying whether the captured fingerprint image matches with the at least one preset template;

• wherein the optical lens, along an optical axis from an object side to an image side, sequentially comprises:
• a flat glass;
• a first lens having a negative refractive power, a concave surface facing an imaging surface, and a concave surface facing the object side and having at least one inflection point;
• a stop;
• a second lens having a positive refractive power and two convex surfaces;
• a third lens having a positive refractive power and a convex surface facing the imaging surface;
• an infrared filter;
• wherein the first lens, the second lens and the third lens each are plastic aspherical lenses, and each have a refractive index less than or equal to 1.70;
• wherein the optical lens meets the expression:
• 1.5<f3/f<2.2, f3 represents an effective focal length of the third lens, f represents an effective focal length of the optical lens.

A mobile terminal, comprising a housing, a display screen and a fingerprint recognition module, wherein the fingerprint recognition module and the display screen are engaged with the housing, the fingerprint recognition module comprises an optical lens, along an optical axis from an object side to an image side, the optical lens sequentially comprises:

• a flat glass;
• a first lens with a negative refractive power, an object side surface of the first lens adjacent to the optical axis being a concave surface and having at least one inflection point, an image side surface of the first lens being a concave surface;
• a stop;
• a second lens with a positive refractive power, an object side surface and an image side surface of the second lens both being convex surfaces;
• a third lens with a positive refractive power, an image side surface of the third lens being a convex surface;
• an infrared filter;
• wherein the first lens, the second lens and the third lens each have a refractive index less than or equal to 1.70;
• wherein the optical lens meets the expressions:
• 1.5<f3/f<2.2,
• 1.0 mm<f1+f2+f3<2.1 mm;
• −2.1<R11/f1<−1.5;
• where f3 represents an effective focal length of the third lens, f represents an effective focal length of the optical lens, f1 represents an effective focal length of the first lens, f2 represents an effective focal length of the second lens, R11 represents a radius of curvature of the object side surface of the first lens.