Biomedical Engineering Reference
In-Depth Information
Figure 11.9
(a,b) Analytically calculated far-field radiation patterns of GA
and
π
spiral with 2000 particles at a wavelength of 633 nm for structures
with
a
0
=
14.5
μ
m. The far-field radiation patterns have been truncated
with an angular aperture of 4
◦
and 3
◦
, respectively. (c,d) Fourier-Hankel
transforms of far-field scattered radiation by GA and
spiral, respectively,
summedovertheradialwavenumber
k
r
.Thenumbersinthefiguresindicate
the azimuthal Bessel order of the corresponding FHD peaks.
π
review several unique aspects related to the Fresnel diffraction of
optical fields by Vogel spirals with well-defined chirality in the next
section.
11.3.1
Diffracted Beam Propagation from Aperiodic Chiral
Spirals
In this section, we will show that the interplay between the struc-
tural disorder and the well-defined CCW chirality of the
α
1
spiral
givesrisetofascinatingwavediffractionandself-imagingproperties
thatcanbeofinteresttoanumberofapplicationsinsingularoptics.
In particular, we will discuss the evolution of a scattered plane
wave as it propagates away from the plane of a diffracting array
of apertures with
α
1
chiral geometry toward the far-field region.
