Laser triangulation for liquid film thickness measurements through multiple interfaces

Laser triangulation is used to measure the thickness of a liquid film in a test section consisting of a quartz viewing window, a water layer, and a hydrophobic membrane. The triangulation sensor acquires measurements to the bounding surfaces of the film while peering through multiple interfaces. This allows the difference between the two measurements to constitute the local film thickness. A refraction model is developed and applied to the analysis of data collected from the experiment. For verification, an empirical method is also developed and compared to the analytical approach. The measurement technique is intended to assess the stability of liquid films for use as gas-liquid contactors. (C) 2006 Optical Society of America.