Anomaly in a high-numerical-aperture diffractive focusing lens.
We show an anomalous behavior in a diffractive lens in which the spot size at the focus reaches a minimum at a numerical aperture of ~0.5 and then increases significantly at higher values. Theoretical and experimental results are presented, along with a comparison with refractive aplanatic lenses, in which the anomaly does not appear to exist.
Oron
R
R
Guedalia
J L
JL
Davidson
N
N
Friesem
A A
AA
Hasman
E
E