Issue Information

Cover Photograph: Glass melts are considered commercially relevant once their melt size exceeds nominally 0.5 kg. Large melts are necessary when a particular glass system is selected to mass produce optical elements, such as windows, lenses, and filters. However, melt homogeneity and glass stability are sensitive to changes in melt size. In our study, a 2.5 kg glass plate (A) was manufactured by Amorphous Materials Inc., allowing the comparison of thermal behavior of this melt to previously demonstrated lab-scale melts. By segregating this plate into multiple cores (B), the material response to thermally-induced crystallization can be evaluated as a function of position within the plate. Individual specimens (C) were converted to glass-ceramics and their change in refractive index (relative to the base glass) was measured. Ongoing efforts seek to demonstrate index changes across the mid- and long-wave infrared, thus enabling dispersion engineering essential for designing imaging systems with reduced footprint and manufacturing costs.