“Thermal radiation does not pass through standard glass lenses, as glass is opaque to the long-wavelength infrared radiation detected by thermal sensors. Special materials such as germanium are used for thermal camera lenses because they allow infrared radiation to pass through.”

— Axis Communications Academy, Thermal Imaging, 2022

“Conventional glass lenses are not suitable for thermal imaging cameras because they block the wavelengths of infrared energy that thermal sensors use. Therefore, thermal lenses are made from materials like germanium.”

— Axis Communications, Thermal Cameras Technology