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An optical technique is described for determining, in a physically nondisturbing manner, the thickness of a thin flowing liquid film. The technique is based on measurement of the fluorescent emission induced in the liquid film by absorption of a focused laser beam. Although the technique was developed for measuring liquid film thicknesses on the prefilming surface of an airblast fuel atomizer, it is not limited to this application.
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Driscoll et al. (1992) studied this question.
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