Optical components inside the vacuum

Windows

Typ: Broadband precision wedged window (https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=8430&pn=WW11050-C)
Ordering No.: WW11050-C
Wavelength: 1050 - 1700 nm
Wedge Angle: 30 +/- 10 arcim
Subsrtate: N-BK7 (Datasheet: https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=6973&tabname=N-BK7)
Diameter: Ø1“ 25.4 mm +0.0/-0.2mm
Thickness 5.0 mm +/- 0.1mm
Clear Aperture: >= Ø22.86 mm
Surface Flatness: ≤λ/20 Over Central Ø10 mm; ≤λ/10 Over Entire Clear Aperture
Surface Quality: 20-10 Scratch-Dig
Reflectance Over AR Coating Range: R_avg < 0.5% @ 0° AOI
Temperature:
- Question: What is the maximum (continuous) temperature which the AR coatings are able to withstand? What is the maximum temperature gradient that can be applied (continuously) between the two faces of the 1/2“ 3mm BK7 and fused silica windows?
- Response from Jeremy at Thorlabs: The maximum temperature will be around 200°C or so. We do not spec a maximum temperature gradient since it can depend on the thermal boundary conditions and geometrical boundary conditions of the window. However, I would recommend UVFS over N-BK7 because of its much lower coefficient of thermal coefficient.