Optical measurement of liquid film thickness and wave velocity in liquid film flows

✍ Scribed by E. T. Hurlburt; T. A. Newell

• Publisher: Springer
• Year: 1996
• Tongue: English
• Weight: 795 KB
• Volume: 21
• Category: Article
• ISSN: 0723-4864
• DOI: 10.1007/bf00189056

✦ Synopsis

Two optical techniques are described for measurement of a liquid film's surface. Both techniques make use of the total internal reflection which occurs at a liquid-vapor interface due to the refractive index difference between a liquid and a vapor. The first technique is used for film thickness determination. A video camera records the distance between a light source and the rays which are reflected back from the liquid-vapor interface. This distance can be shown to be linearly proportional to film thickness. The second technique measures surface wave velocities. Two photo sensors, spaced a fixed distance apart, are used to record the time varying intensity of light reflected from the liquid-vapor interface. The velocity is then deduced from the time lag between the two signals.