a) GUWs on aluminum plates with different thickness d₁ = 2.6 mm (red) and d₂ = 5.0 mm (black) are excited at different frequencies f_Exc = [60, 300] kHz in steps of 20 kHz. By means of digital holography, the surface deformation is then measured and evaluated with the structure function to determine the wavelength λ_m of the GUW, which is plotted against f_Exc ·⋅d. The thinner plate shows shorter wavelengths. b) The measured wavelengths are plotted against the resulting wavelengths from the simulation for the A0 mode λ_sim. The blue line marks the ideal result for the case of λ_m = λ_sim, corresponding to a slope of m = 1. The experimental results are in agreement with the simulation results for both samples. The corresponding slopes are m₁ = 0.95 and m₂ = 1.08. This successfully qualifies our measurement method for the measurement and characterization for GUWs.