It has been well known that laser-induced damage in optical thin films depends on the applied test laser beam diameter, if the damage initiation is dominated by inclusions and defects. This correlation has been subject of numerous discussions and has also been implemented in the corresponding ISO standard (ISO 11254-2). There, a minimum beam diameter is advised which further reduction affects the result significantly. Previous work indicates, depending on sample properties, a constant damage threshold towards large beam diameters. However, experimental data for this behavior is limited. This paper presents a detailed investigation within the ns-timescale on a series of four comparable sample sets of HfO2 /SiO2 high reflectors. The respective samples are designed and manufactured for ISO damage testing at 1ω, 2ω, 3ω, and 4ω irradiation of the Nd:YAG laser.