A case study of optical methods for measuring thickness of liquid sheets

We demonstrate that the usual optical methods can be applied in a simple way to quickly estimate thickness of liquid sheets on sub-millimetre scales. It is shown that an approximate linear relation can be obtained between gap thickness and several of the usual RBG and HSV variables (red and green pixel values in the RBG case and saturation in the HSV case). The method we use is viable as long as the sheet does not become too thin and is much simpler than other dye-based optical methods for determining the thickness