Using a standard optical microscope, researchers from China's Harbin Institute of Technology developed a quick, cheap and efficient way of measuring graphene's thickness. The researchers have shown that the thickness of graphene (and other 2D materials, by the way) can be calculated by reflecting light from the material's surface and measuring the red, green and blue components.
The contrast of red, green and blue values between the substrate on which the sample is placed and the sample itself increases with the thickness of the sample. Using Raman spectroscopy and atomic force microscopy, the researchers confirmed their measurements.were used to confirm the researchers' thickness measurements. They tested their method on mechanically exfoliated graphene, graphene oxide, nitrogen-doped graphene and molybdenuym disulphide.