Biomedical Engineering Reference
In-Depth Information
Figure 11.15
Experimentally measured Fourier-Hankel transforms of far-
field scattered radiation by (a)
μ
spiral and (b)
π
spiral, respectively,
summedovertheradialwavenumber
k
r
.Thenumbersinthefiguresindicate
the azimuthal Bessel order of the corresponding FHD peaks. Analytically
calculated Fourier-Hankel transforms of far-field scattered radiation by (c)
μ
spiral and (d)
π
spiral.
at numbers corresponding to the denominators of the rational
approximations (i.e., convergents) of the irrational divergence
angles used to generate the spirals, as previously discussed [51].
For the GA spiral, the encoding of the Fibonacci sequence up
to azimuthal number 144 was experimentally demonstrated in the
measured OAM spectrum. The
τ
spiral has a similar number of
convergentsinourregionofinterestandallowedustodemonstrate
however OAM peaks up to azimuthal number 169. However, these
peaks are significantly broadened by the aperturing of the beam
[51]. On the contrary, we can see in Fig. 11.15 that the
μ
and
