Fused quartz is glass which contains only SiO2, and no other ingredients, and has a low index of refraction, high Abbe number, low coefficient of thermal expansion, and a high maximum operating temperature (Edmund Optics). Any impurities in the glass can impact these qualities, which is why a high purity raw material is essential for the optical industry. As you can see from the index of refraction graph below, taken from Heraeus, even high purity quartz can have variations in qualities due to different impurities/doping agents (Heraeus).
The low index of refraction means that the light passing through the glass will not be distorted or discoloured, while the relatively high Abbe number means that there is less colour dispersion and a reduction in colour aberration. Additionally, quartz has a high coefficient of thermal expansion and high maximum operating temperature. Fused quartz, therefore, is very suited for use in high end optics and fibre optic cables, as well as any applications which are used in extreme environments (Edmund Optics).
However, just because quartz glass can be used for a variety of applications does not mean any quartz sand will do. The glass used in high end applications needs to be checked and factors taken into consideration must include optical homogeneity, transmission and absorption, bubble and inclusion content, refractive index and dispersion, residual strain, fluorescence, resistance to light induced defects or irradiation, and cost (Heraeus).
The Quartz Corp’s high purity quartz products are mined from the world’s purest quartz deposits. Because of the unique geological properties of the mine at Spruce Pine, our products are some of the purest available on the market today, making them ideal for use in all manner of optical glass items. To find out more, please download our datasheets or contact us directly.