Material: Germanium optical grade
Type: circular plane-parallel window
Diameter: 38.1 mm (+0.0/-0.1 mm)
Thickness: 4 mm (+/-0.1 mm)
Surface quality: 60/40 scr/dig
Flatness: please specify your standard
Parallelism: <= 3 arc minutes
Clear aperture: >= 90% of diameter
Coating: AR/AR coating at 8-14 microns