Distributor: Accu-Glass Products, Inc.
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Standard Length Fused Silica Viewports

Standard length quartz

Larson Electronic Glass’s standard length fused silica viewports are constructed using a Kovar sleeve brazed to a stainless steel weld end. The result is a robust window assembly that can be used in vacuum mounted normally or inverted. It is this design Larson uses when making custom configuration inverted windows.

While both fused silica and quartz viewports are both silicon dioxide (SiO2), synthetically-grown fused silica is superior to quartz in most regards. A fused silica viewport will not fluoresce when exposed to UV radiation at 253.7 µm, as does a quartz viewport.

NOTE: Maximum bakeout temperature limited to 200°C due to a low temperature braze alloy.

Fused silica viewports are offered without flanges, with CF type, ISO type Kwik-Flange® and Large-Flange®. Viewport window surfaces offer a minimum of distortion and provide maximum transmission for most applications.


  • Available in 1-1/2” and 2-1/2” view diameter
  • 304 stainless steel weld mount, KOVAR® brazed to fused silica
  • >90% Transmission from 230nm to 2000nm
  • CF and Weld mount bakeable to 200°C, 25°C/Min gradient
  • Kwik-Flange® and Large-Flange® bakeable to 200°C, 25°C/Min gradient

Request a quote on the standard length fused silica viewports you need, or contact Larson Electronic Glass to learn more.

Larson Electronic Glass offers "Standard Length Fused Silica Viewports" available in 2 standard sizes 1-1/2 inch and 2-1/2 inch with a variety of flange options. Dimensions are in inches unless otherwise noted.

ImageStandard Length Fused Silica ViewportsFlangeView diameter (V)Metal endHeight (H)Glass thickness (T)Major diameter (D)Model NumberPart NumberPrice
1-1/2" Standard Length Fused Silica Viewport1-1/2" Standard Length Fused Silica Viewport-1.37"1-1/2" Tube.85".125"1.76"VQ-150-T122161$320
2-1/2" Standard Length Fused Silica Viewport-2.37"2-1/2" Tube1.10".250"2.88"VQ-250-T122211$620