Figure 4.

(a)–(d) Selected examples of implemented CGHs, (e)–(h) measured and (i)–(l) simulated intensity distributions in the focal plane for the situation where a discrete number of foci are located on an annulus of circumference $C=16d_{\mathit{min}}$. (m)–(p) show the corresponding comparisons of the azimuthal intensity distributions along the white dotted circles. Each column refers to a different configuration (from left to right): (a), (e), (i), (m) $N=8$, ${\Lambda }_1=2d_{\mathit{min}}$, $\uparrow \uparrow$; (b), (f), (j), (n) $N=16$, ${\Lambda }_2=4/3d_{\mathit{min}}$, $\uparrow \uparrow$; (c), (g), (k), (o) $N=16$, ${\Lambda }_2=4/3d_{\mathit{min}}$, $\uparrow \downarrow$; (d), (h), (l), (p) $N=32$, ${\Lambda }_3=2/3d_{\mathit{min}}$, $\uparrow \downarrow$. The scale bars in the top row refer to 10 µm.