  We study the optical transmittance of multilayer graphene films up to 65
layers thick. By combing large-scale tight-binding simulation and optical
measurement on CVD multilayer graphene, the optical transmission through
graphene films in the visible region is found to be solely determined by the
number of graphene layers. We argue that the optical transmittance measurement
is more reliable in the determination of the number of layers than the commonly
used Raman Spectroscopy. Moreover, optical transmittance measurement can be
applied also to other 2D materials with weak van der Waals interlayer
interaction.
