Ideal Vacuum Cube Replacement Window for 6x6 Viewing Window Plate, 3/8" Fused Silica

This is a fused silica replacement window for the Ideal Vacuum Cube 6x6 Viewing Window AssembIy. Use it to replace or upgrade a scratched, hazed or discolored glass window. It replaces the viewing window pane used on our 6x6x6 or 6x6x12 Cubes.

Our high purity fused silica replacement windows are ground and polished to optical grade on both sides with a total thickness variation (TTV) of <10µm, a surface finish of S/D 40/20, and a surface roughness of Ra < 1 nm. These windows have appreciably improved transmittance, and a wider useful wavelength range than standard glass. Characteristics include extraordinarily low refractive index variations, low birefringence values, and an ultra-low thermal expansion coefficient. Fused silica is used for transmissive optics where a high laser damage threshold is required. Fused silica is used for optics operating in the deep UV, visible, and the near infrared wavelength range.

We also offer standard tempered glass window replacements which are commonly used for general, direct observation of roughing or high-vacuum chamber processes and can be used to facilitate optical alignments of chamber components, observe degassing of fluids, or used to help teach in-vacuo processes by direct observation. The glass material is 3/8" thick, tempered, low-iron, high-clarity glass. Surface quality and flatness is Q4 per ASTM 1036-06 and 1048-04. The low iron content of the glass results in it having a slight blueish tint. This economical glass is unsuitable for high power laser experiments.


Newer versions of the viewing window assembly are field upgradeable. Please download the IVP Cube Viewing Window Assembly Manual for instructions.

If you have an older viewing window plate assembly (does not have a bare aluminum window frame), we will upgrade the entire viewing window assembly at no charge to our latest version when you order a replacement window. The latest version includes thicker glass and is more leak resistant. When you purchase the new replacement window, just let us know (by phone or email) that you have an older model. We will provide an RMA and return shipping label for you to send us your old viewing window plate assembly. Once we receive the old plate assembly, we will send you a complete, fully tested, updated assembly. Old plate assemblies will not be returned.

NOTE: All viewing windows or viewports are inherently fragile, should be handled carefully, and always inspected before use. Ideal Vacuum viewing windows are designed and rated for VACUUM ONLY and can be susceptible to thermal shock if exposed to rapid temperature changes (>10° C /min). If directing a laser beam through the window, make sure the laser’s wavelength can be reasonably transmitted through the window’s material. Please download and read all the safety warnings in the IVP Cube Viewing Window Assembly Manual.