Modified UV-VIS-NIR spectrophotometric investigation method for unprepared glass samples

We report about practical experience in industrial glass production control by a slightly modified ultraviolet and visible near infrared (UV-VIS-NIR) spectrophotometric method. A key element for the successful implementation of the method has been identified in the photodiode used as detector in the commercially available spectrophotometers. With some software tools and a specific sample holder it is possible to implement an accurate measurement of spectral features on a commercial glass sample without significant physical preparation. The glass making process can be kept under tight control without the need of laboratory technicans. We show that by the carefully chosen combination of detector and data-handling tools glass quality determining factors (e.g. redox equilibria) can be measured quickly and accurately for quality assurance of the final product. In the case of flint glasses it is possible to calculate the concentrations of key polyvalent elements (Fe 2+ , Fe 3+ , Cr 3+ ) as well as derived parameters of technological relevance