Scanning-PIV using the drum scanner is employed to study the impingement of a vortex ring onto a solid surface. Both the wall-normal and wall-parallel planes are measured. The former reveals the expansion of the vortex ring and the generation of the secondary and even the tertiary rings in the impingement. The latter successfully visualised the development of the azimuthal instability in the primary and secondary rings. The well-understood long-wavelength instability is found to occur when the secondary ring moves into the primary one. Apart from the azimuthal instability of long-wavelength, another azimuthal instability phenomenon of short-wavelength is visualised. This shortwavelength instability along the primary ring happens when it approaches the surface and being stretched