LARGE-APERTURE LENS Russian patent published in 2011 - IPC G02B9/36 G02B13/14 

FIELD: physics.

SUBSTANCE: lens comprises four-series arranged components. The first and fourth components are positive menisci. The second component is a negative meniscus. The third component is a plane-concave lens whose concave side faces the object, and its optical power is minus (0.1-0.5) times the optical power of the large-aperture lens. The fourth component can move along the optical axis and its optical power is (1-2) times the optical power of the large-aperture lens. The following conditions are satisfied: N₁=N₄, N₂=N₃, υ₁=υ₄, υ₂=υ₃, where N and υ is the refraction index and the dispersion of the components, respectively.

EFFECT: high aperture ratio of the lens, easy assembling with optical workpieces and simple design of the lens, while preserving good optical properties.

1 dwg, 1 tbl