Graded-index sphere lens with hemispherical rod cladding.
When a radially inhomogeneous sphere whose refractive-index profile decreases from center to periphery in a nearly parabolic manner is cladded with an additional hemispherical rod, the spherical aberration of the resultant lens (having a diameter of several millimeters) can be minimized to the diffraction limit for N.A. 0.45.
Kikuchi
K
K
Morikawa
T
T
Shimada
J
J
Sakurai
K
K