Figure shows the transmittance T and reflectance R spectra of SiO 2 and CaF 2 . The transmission of the dielectric coatings deposited on a double-side polished Si substrate was measured with a Si substrate used as reference. The reflection spectra were measured by coating SiO 2 and CaF 2 on a thick gold films; thick Au mirror was used as reference. Both R, T values were logarithmically presented as transmittance and reflectance per micrometer of thickness.