Figure 4
From: Generating Bessel beams with broad depth-of-field by using phase-only acoustic holograms
Axial field distribution for a zero-th order Bessel beam as a function of the excitation frequency of (a) a fraxicon and (b) phase-only hologram of F = 50 mm, a = 25 mm and for a design frequency of f0 = 1.112 MHz. The focus of the n-th diffraction order, Fn, is shown in dotted-dashed white lines. (c–e) Axial field distributions at 1.392 MHz, 970 MHz and 522 kHz, respectively. The focus of the n-th diffraction order, Fn, is shown in dotted-dashed black lines.
