Critical-angle scattering of laser light from bubbles was photographed, and angular structures in the far-zone intensity are compared with models. The radii of the freely rising bubbles were in the 26.4–814-µm range. Deviation from sphericity for the rising bubbles is considered. Diffraction effects make simple geometric optics inadequate near the critical angle. Coarse-structure intensity oscillations show agreement with a physical-optics approximation and with Mie theory. Measurements agree with derived expressions for the angular spacings of fine structure and contrast modulations. Uses of these structures in different bubblesizing methods are discussed. The locations of scattered-wave virtual sources are modeled.
© 1984 Optical Society of America
Dean S. Langley and Philip L. Marston, "Critical-angle scattering of laser light from bubbles in water: measurements, models, and application to sizing of bubbles," Appl. Opt. 23, 1044-1054 (1984)