These Fused-silica Windows are in UV grade material (Spectrosil B or equivalent) and usable down to 170nm. They have excellent chemical and radiation resistance, and are usable up to 1050°C, and have very low fluorescence. They are listed both coated and with a multiplayer AR-coating for 248-400nm.
When the broadest transmission spectrum is required (from 185nm to over 2 microns) together with high durability, all for a reasonable cost, these windows are ideal. Fused silica is physically robust and resists chipping and scratches. The coefficient of thermal expansion is quite low, so these windows maybe subjected to higher levels of thermal shock than glass or sapphire can withstand. Circular, square and rectangular shapes available.
 

Standard Specification

Material: BK7 grade A optical glass
Diameter Tolerance: +0.0, -0.1mm
Thickness Tolerance: ± 0.2mm
Clear Aperture> 85%
Parallelism<1 arc minute
Surface Quality: 60-40 scratch and dig
Flatness: λ/4 per 25mm @632.8nm
Wavefront Distortion: λ/4 per 25mm @632.8nm
Bevel: 0.25mm x 45°
High precision specification and coaitng are available upon request