Spatial and temporal film thickness measurement of a soap bubble based on large lateral shearing displacement interferometry

Abstract

The film thickness of a hanging soap bubble has been studied along its gravitational orientation after its birth and before its bursting using large lateral shearing displacement interferometry, with a theoretical error of less than 0.325λ. The results show that the spatial distribution of the film thickness could be approximated with an exponential model in all captured frames, especially in the lower half of the soap bubble. Before its bursting, a special zone, where the water layer has drained out while the surfactant solution layer remains, will occur at the top of the soap bubble and gradually expand toward the bottom. Moreover, the simulated fringe patterns based on the computed values match well with the experimentally observed ones.

Single bubble and drop techniques for characterizing foams and emulsions

“…In many scenarios involving foam and emulsion films, it is necessary to measure the film thickness at both high temporal and spatial resolutions. This has motivated a number of researchers to perform studies with custom built thin film interferometry apparatuses [8,9,17,39,42,43,67,70,78,80,[101][102][103][104][105][106][107][108][109][110][111][112][113][114][115].…”

Recent Progress on Optical Tomographic Technology for Measurements and Inspections of Film Structures

“…However, most of the research works for film metrology using interferometry have been focused on low-coherence interferometry (LCI) [ 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 ], which has the significant benefit to obtain absolute distances and lengths, and it is suitable for measuring the thicknesses of transparent plates and film layers. LCI can be typically categorized as a scanning interferometer and a spectral interferometer by the operating principle.…”

Optical behavior of surface bubbles

“…The Cartesian components of such unit vectors are given by the respective direction cosines. For meridional rays, equation (6) directly reduces to equation (5); for skew rays, equation (6) also expresses the belonging of the refracted ray ¢  r to the incidence plane defined by rˆand â.…”