Vacuum Viewports

Ultrahigh Ultra High In-Vacuum UHV HV Viewports, drawing

UHV Vacuum Viewport Windows

Vacuum viewport flanges (windows) are available in several window materials and construction types for both high (HV) and ultrahigh (UHV) vacuum chamber viewport applications. Both fused and demountable vacuum viewport glass designs are available to choose from. Window materials include Corning 7056 borosilicate glass, proprietary Accu-Sol™ glass, Synthetic Fused Silica (Quartz), and crystalline Sapphire. Demountable substrate windows also offer various coating options.

Viewport Material Selection

Corning 7056 / Borosilicate Glass

  • 7056 Borosilicate viewports are commonly used for observation
  • These glass vacuum viewport windows offer transmission greater than 90% over the 375nm to 1900nm wavelength range and are used in many standard viewport vacuum chamber assemblies.
  • The most commonly used in-vacuum viewports window material in the industry.

Demountable Substrate Accu-Sol™ Glass and/or Coated Fused Silica

  • Demountable substrate vacuum viewports are an economical "alternative" to fused and/or brazed viewports.
  • High transmission glass with greater than 90% transmission from 350nm to 1500nm wavelength range.
  • Removable substrate viewports offer easy access for maintenance and/or use with optional BBAR coated synthetic fused silica (quartz) windows. Available coatings are optimized for UV (290~370nm), Type-A (350~700nm), Type-B (650~1050nm) and Type-C (1050~1620nm). Uncoated fused silica viewport glass is also available.
  • A great alternative to the most commonly used vacuum window material in the industry.

Fused Silica

  • Great transparency to ultraviolet radiation.
  • The ultraviolet grade material is suitable for most applications and is certified to meet > 80%/cm at 185nm external transmittance.
  • Deep ultraviolet grade is equivalent to Supersil-1® and similar to the ultraviolet grade except for inclusion specifications.


  • Sapphire vacuum viewports are constructed using 90° crystal orientation, where the crystal orientation is parallel to the window surface.  Sapphire is a synthetic, hexagonal single crystal anisotropic material which displays substantially different physical, thermal, dielectric and optical characteristics when measured along different axes.  Poor surface finish can contribute as much as 10% to a window's total transmission loss.  Accu-Glass sapphire viewports are supplied with flat faces polished to a 50-20 scratch-DIG.

Leaded Glass / X-Ray Viewport Shields

  • Leaded Glass Viewport Shields mount, or 'piggyback' onto CF flanges from 1.33 to 8 inch diameters. The Lead Glass Viewport Shield is a safety accessory used to block harmful X-Ray radiation while allowing a safe and clear view into the vacuum system. The shield is mounted on the atmosphere side of a standard CF type Zero-Length viewport using longer than standard bolts (zero-length viewports and long fasteners are not included... and must be purchased separately). Please note that the 'Leaded Glass Viewport Shield' glass thickness may vary as needed to attain the specified 2mm lead shielding equivalence. Furthermore, customers are responsible for determining the appropriate, safe level of X-ray radiation shielding required for their specific applications.