“…Input-detection-free FRF measurements with reliability factors for underwater structures 2.1. Underwater LA excitation force LA has various applications, such as in microfabrication (McCann et al, 2016), propulsion of flying objects (Yabe et al, 2002), peening (Hatamleh, 2008), laserinduced bubbles in inside liquids (Lazic et al, 2012), vibration testing (Kajiwara and Hosoya, 2011;Hosoya et al, 2012Hosoya et al, , 2016a, acoustic analysis (Hosoya et al, 2014), and damage detection (Huda et al, 2013;Hosoya et al, 2016cHosoya et al, , 2016dHosoya et al, , 2017a. Figure 1 shows the principle of underwater LA excitation force generation (Hosoya et al, 2016a).…”