Glass viewing window?

Assumed the viewing window would be made of polycarbonate as it is light, break-resistant and blocks the wavelength of CO2 lasers; however, there have been numerous mentions of a glass window. Will the window be made of glass and can you publish the transmittance curve for the glass you’ll be using? Just wondering how it performs in the near-IR and UV ranges.

It is indeed very thick glass, not polycarbonate. We’re not sharing any of the materials specifications though.