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.
R
R
Oron
J L
JL
Guedalia
N
N
Davidson
A A
AA
Friesem
E
E
Hasman