For IR applications in the wavelength range from 780 - 3600 absorption can play a major role.
Absorption is the root cause of thermal lensing. The optimal performance depends on the absorption value of the specific fused silica grade. Metallic impurities and OH molecules are sources of absorption. A short video explaining the context can be found on the left side.
As the price of fused silica typically scales with increasing purity, it is economically important to make the right choice and not overspec. However, if the highest quality is needed, we can deliver it in large sizes too.
For details about our NIR fused silica grades, please check the following brochure: Fused Silica for Applications in the Near Infrared .