Liquid Film Thickness Measurements by Means of Internally Reflected Light

The objective of this project is to establish the feasibility of measuring the thickness of a thin dynamic liquid film using internally reflected light. The principle of the sensor operation is demonstrated through static calibration curves. The influence of various liquids is also explored by testing water, motor oil, Stoddard fluid, and finally skim milk to show the effect of a semi-opaque liquid. The response of the system to 1.25 millisecond impulse of light caused by a 500 Hz square wave is examined to demonstrate the dynamic range of the device. A wave machine is used to demonstrate the dynamic response of the sensor. These measurements are made with the early version of the film thickness sensor.