This paper reports an experimental study of spray characteristics in rotary slinger atomizers using different laser diagnostic tools. The main objective of the present study is to investigate the effect of size of the slinger orifices on liquid breakup dynamics and droplet size distribution over a wide range of rotational speed (5000–45,000 rpm) and liquid flow rates (0.2–2 lpm). Three different slinger discs having the same number of orifices but different sizes (d0 = 1, 1.5, and 2 mm) are considered. The primary liquid breakup visualization is achieved using volumetric laser-induced fluorescence (VLIF) technique; whereas, the droplet size is measured by interferometric laser imaging for droplet sizing (ILIDS) technique. The results demonstrate critical role of orifice size on liquid breakup mode and droplet size up to rotational speed about 30,000 rpm, beyond which the aerodynamic force dominates the atomization process such that neither the orifice size nor rate of rotation has strong influence. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.