LARGE-APERTURE LENS Russian patent published in 2010 - IPC G02B9/60 G02B13/14 

FIELD: physics.

SUBSTANCE: lens consists of four components. The first component is made from separate biconvex and concave-plane lenses. The second component is a separate convex-plane lens whose flat side faces the image. The third component is a positive lens made from a biconvex and a biconcave lens. The fourth component is a positive meniscus whose concave side faces the image and whose radius of curvature of the convex surface is greater than the radius of curvature of the concave surface. In the first component, the modulus of the radius of curvature of the second surface of biconvex lens is greater than the radius of curvature of the first surface of the concave-plane lens. Each biconvex lens is symmetrical. The refraction index of the fourth component is greater than 1.64 and less than 1.9 for line e. The refraction index of the biconvex lens of the fourth component is greater than 1.56 and less than 1.63 for line e and is less than the refraction index of the biconvex lens of the first component. The following condition is satisfied: 0.5f' <d₄<f', where: f' is focal distance of the lens; d₄ is distance between the first and second components.

EFFECT: wider angular field of view and miniaturisation with high image quality.

2 cl, 1 dwg, 2 tbl