Validation of bubble sizes obtained with incoherent imaging on a sloped viewing window

摘要: Abstract A sampling-followed-by-imaging technique for sizing bubbles in flotation systems has been developed (Proceedings of the 34th Annual Meeting Canadian Mineral Processors, pp. 389–402, Miner. Eng. 17 (2004) 53). The directs a sample into viewing chamber where they are exposed and digitally imaged using incoherent backlighting. images automatically analyzed by means threshold criterion. is sloped to spread over surface (glass) window, configuration chosen reduce bubble overlap facilitate definition focal plane. design also that defocus distance (object plane) small always negative (the object lies between plane light source). This simplifies fundamental assessment factors contributing image size. Measurements from were compared with standard sizes obtained displaced-volume method. Thresholding at half intensity level, systematically underestimated bias was correlated size, increasing 0.3% ca. 0.7 mm 2% 4 mm. evidence reflected rays slightly towards underestimating size whereas inclined window causes overestimation due flattening. These two effects similar magnitude tend cancel. Consequently, underestimation trend can be attributed distance. semi-empirical correction procedure suggested which uses method Bongiovanni et al. (Exp. Fluids 23 (1997) 209) correct system optics along an empirical approach compensate