| 摘要 |
The diffractive structure of an intra-ocular lens is adjusted in the central zone so that the lens displays an intermediate focus as well as a near and a far focus. This may be achieved by having consecutive zone boundaries with steps of differential heights giving phase delays greater than 1/20 of a wavelength, or different surface curvatures of the diffractive zones, or a surface asphericity of at least one of the diffractive zones. (62) Divided Out of 560258
|
