Polymer-film-colour-to-thickness

In microfabrication, there is a process called spin coating. When you spin coat a polymer solution over a silicon surface, depending on the spining of the machine, different thicknesses of the polymer film can be obtained. With different thicknesses, the light reflection makes the polymer have different colours, the colour that is observed depends on the thickness of the film (different thickness = different light distance path). By having a reference colour chart (colour <=> thickness) I plan to make a calibration curve between the RGB colour scheme and film thickness, so that we can get the height profile of a random polymer film image.