Infrared technique for measuring thickness of a flowing soap film

Citation
Xl. Wu et al., Infrared technique for measuring thickness of a flowing soap film, REV SCI INS, 72(5), 2001, pp. 2467-2471
Citations number
13
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Spectroscopy /Instrumentation/Analytical Sciences","Instrumentation & Measurement
Journal title
REVIEW OF SCIENTIFIC INSTRUMENTS
ISSN journal
0034-6748 → ACNP
Volume
72
Issue
5
Year of publication
2001
Pages
2467 - 2471
Database
ISI
SICI code
0034-6748(200105)72:5<2467:ITFMTO>2.0.ZU;2-3
Abstract
In conducting two-dimensional laminar and turbulence experiments, use of a vertical flowing soap film is often a good choice. However, one of the most frequently encountered and yet highly nontrivial problems is to measure th e thickness of the film precisely. We propose a solution to this problem ba sed on the strong absorbtion of infrared light by the water molecules in th e film. At lambda similar or equal to3 mum, a thin sheet of water is essent ially opaque. The extinction length of 0.9 mum serves as a precise ruler fo r gauging the film thickness. Although only the time-averaged, single-point measurements are presented, the technique is general and can be used for m ultipoint measurements to investigate turbulent driven spatiotemporal fluct uations of the film thickness. (C) 2001 American Institute of Physics.