Depends on the infrared band they're using but normal glass or acrylic should stop most of it. Edit: looks like they're using SWIR (~1500nm) so glass/acrylic/p

Depends on the infrared band they're using but normal glass or acrylic should stop most of it. Edit: looks like they're using SWIR (~1500nm) so glass/acrylic/polycarbonate will pass it just fine.