Advanced industrial metrology used for qualification of high-quality optical materials

Schott Glass is producing and developing the optical material for various specialized applications in photonics, optical and microlithography technology. In order to achieve the specifications several of metrology R&D activities have been done and hardware has been installed in the metrology labs. Today special diagnostics are available to qualify materials for the absolute refractive index, the transmissin, radiation durability and inner quality to ensure the quality of the produced materials. Methods used for this qualifications are minimum deviation, precision spectral photometer, in-situ transmission measurements using UV lasers and Rayleigh Scattering. The optical material quality requirements of such materials are extremely high and still increasing. Therefore further development and implementation of diagnostics have been iniatiated, e.g. Raman Scattering, fluorescence and refractive index measurements. We present the status of R&D activities for metrology, which is necessary to visualize the status and the improvement of the optical quality with the help of new and improved metrology.