Large-aperture optical lens with three lens pieces
View Patent ↗An optical lens is provided with three lens pieces. The optical lens includes a diaphragm, a first lens piece having positive focal power, a second lens piece having negative focal power and a third lens piece having positive focal power, arranged in sequence. The first lens piece has an S 1 surface and an S 2 surface. The second lens piece has an S 3 surface and an S 4 surface. The third lens piece has an S 5 surface and an S 6 surface. An S 7 surface is provided on a side of the S 6 surface away from the S 5 surface. A lens frame is provided at the S 6 surface or between the S 6 and S 7 surfaces. The calibers of the Si to S 7 surfaces sequentially decrease. An equivalent focal length of the first lens piece is larger than that of the third lens piece. A numerical aperture of the lens is larger than 0.6.
1. A large-aperture optical lens, comprising:
a diaphragm ( 10 ),
a first lens piece ( 20 ) having positive focal power,
a second lens piece ( 30 ) having negative focal power, and
a third lens piece ( 40 ) having positive focal power, which are arranged in sequence, wherein
two surfaces of the first lens piece ( 20 ) are an S 1 surface ( 21 ) and an S 2 surface ( 22 ) respectively, two surfaces of the second lens piece ( 30 ) are an S 3 surface ( 31 ) and an S 4 surface ( 32 ) respectively, and two surfaces of the third lens piece ( 40 ) are an S 5 surface ( 41 ) and an S 6 surface ( 42 ) respectively; the S 1 surface ( 21 ), the S 2 surface ( 22 ), the S 3 surface ( 31 ), the S 4 surface ( 32 ), the S 5 surface ( 41 ) and the S 6 surface ( 42 ) are arranged in sequence; an S 7 surface ( 50 ) is provided on a side of the S 6 surface ( 42 ) away from the S 5 surface ( 41 ), and a lens frame ( 60 ) is provided at the S 6 surface ( 42 ) or between the S 6 surface ( 42 ) and the S 7 surface ( 50 ); the S 1 surface ( 21 ), the S 2 surface ( 22 ) and the S 5 surface ( 41 ) are all convex surfaces, and the S 3 surface ( 31 ) is a concave surface;
a distance between the diaphragm ( 10 ) and an object focus of the lens is |ST−F obj |, and an equivalent focal length of the lens is f 0 , |ST−F obj |<0.5f 0 ;
the calibers of the S 1 surface ( 21 ) to the S 7 surface ( 50 ) sequentially decrease progressively; a curvature radius of the S 3 surface ( 31 ) is r 3 , and a curvature radius of the S 4 surface ( 32 ) is r 4 , |r 3 |<|r 4 |; a curvature radius of the S 5 surface ( 41 ) is r 5 , and a curvature radius of the S 6 surface ( 42 ) is r 6 , |r 5 |<|r 6 |; an equivalent focal length of the first lens piece ( 20 ) is greater than an equivalent focal length of the third lens piece ( 40 ); and
a center distance between the first lens piece ( 20 ) and the second lens piece ( 30 ) is G 12 , and a center distance between the second lens piece ( 30 ) and the third lens piece ( 40 ) is G 23 , G 12 <G 23 ; a back focal length of the lens is greater than 5 mm; and a numerical aperture of the lens is greater than 0.6.
2. The large-aperture optical lens according to claim 1 , wherein the S 4 surface ( 32 ) is a concave surface.
3. The large-aperture optical lens according to claim 1 , wherein the S 6 surface ( 42 ) is a convex surface.
4. The large-aperture optical lens according to claim 1 , wherein the S 1 surface ( 21 ), the S 2 surface ( 22 ), the S 3 surface ( 31 ), the S 4 surface ( 32 ), the S 5 surface ( 41 ) and the S 6 surface ( 42 ) are spherical surfaces or aspherical surfaces.
5. The large-aperture optical lens according to claim 1 , wherein the first lens piece ( 20 ), the second lens piece ( 30 ) and the third lens piece ( 40 ) are single lens pieces or cemented lens pieces.
6. The large-aperture optical lens according to claim 1 , wherein the first lens piece ( 20 ), the second lens piece ( 30 ) and the third lens piece ( 40 ) are glass lens pieces or plastic lens pieces.
7. The large-aperture optical lens according to claim 1 , wherein an Abbe number of the first lens piece ( 20 ) is Vd 1 ; an Abbe number of the second lens piece ( 30 ) is Vd 2 ; and an Abbe number of the first lens piece ( 40 ) is Vd 3 , Vd 1 −Vd 2 >25, Vd 3 −Vd 2 >25.
8. The large-aperture optical lens according to claim 1 , wherein a distance between the S 6 surface ( 42 ) and the S 7 surface ( 50 ) is greater than 5 mm.