Pyrocarbon optical properties in reflected light

A new accurate method is presented for measuring the extinction angle of pyrocarbons and their related anisotropy. The method permits also the extraction of the main optical parameters. Firstly, it established that the wavelength of the measurement must be controlled. Secondly, the origin of the optical phase shift when a polarized beam is reflected by such an absorbing media is derived. Then, the physical meaning of the extinction angle is discussed on the basis of calculations in an ideal case. The optical phase shift, as well as the ordinary and extraordinary reflectance were obtained by fitting the experimental data to the theoretical model. The reflectance coefficients obtained are very close to those measured by a more common method. Finally, the extinction angle Ae and phase shift are proposed to distinguish the various families of pyrocarbons.