Light absorption is one of the causes of attenuation
A distinction is made between basic absorption and absorption due to impurities. Up to wavelengths of about 1,600 nm, basic absorption is decisive for attenuation and cannot be influenced by the manufacturing process. The situation is different for the absorption due to impurities. These must be reduced as much as possible in the quartz glass melt. The absorptions have a direct influence on the usable wavelength ranges, which are expressed in the optical windows.