Thin films on transparent substrates are of increased interest in advanced technologies like flexible displays, but this often raises the question of how to suppress disturbing backside reflections in a non-destructive manner. Knife edge illumination is a very effective tool to cope with this issue without damaging the sample.
Knife edge illumination is a non-destructive technique that allows to measure layers on thin transparent substrates without any manipulation of the sample, or the substrate. Usually on transparent substrates, the top side reflection is overlayed by the reflection from the bottom side of the substrate that distorts the measurement. In order to avoid this effect, we place a knife edge close to the sample, which results in partly shading the back side of the sample substrate.
