It works on ice, water, oil, and a variety of other clear or semi-opaque materials. It can measure very rapid changes in film thickness. The film thickness sensor measures the depth of fluid over a surface as shown in Figure 1. The sensor is imbedded in the surface. Optical fibers transmit light from a laser to the sensor, and a cone of light is formed over the sensor.
Light is reflected back to the sensor by the surface of the fluid.
Optical fibers transmit reflected light from the sensor to the detector. This system responds quickly to changes in thickness because it is based upon light and a fast-acting detector. Application of the film thickness sensor. Principle of Operation Figure 2 shows the configuration of the film thickness sensor. Light enters through the transmitting fibers which are placed around the perimeter of the sensor.