KF63 Vacuum Viewport — KF63 Sight Glass for High Vacuum

KF63 Vacuum Viewport — KF63 Sight Glass for High Vacuum

KF63 vacuum sight glass (ISO-KF63) for high-vacuum systems. Available in borosilicate, fused silica and sapphire. Compact, quick-install KF flange, optional AR coatings and custom sizes.

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Description

A KF-63 vacuum sight glass (KF63 viewport) is a compact ISO-KF (NW63) flanged vacuum window designed for high-vacuum and process observation applications. These viewports provide a reliable optical interface for monitoring, alignment, and inspection inside vacuum chambers. The window is sealed to a stainless-steel flange using high-vacuum compatible methods such as Viton O-rings or metal gaskets, ensuring excellent vacuum integrity and repeatable sealing performance.Typical window materials include borosilicate glass, fused silica (quartz), or sapphire, depending on transmission wavelength, thermal resistance, and process conditions.

Key Benefits

  • KF 63 flange — compatible with standard KF hardware (clamps, centering rings, and O-rings) for quick installation and removal.
  • High-vacuum compatible sealing — O-ring or metal-sealed construction ensures low leak rate and repeatable performance.
  • Material options — optical borosilicate, fused silica (quartz) for UV, or sapphire for the highest mechanical/thermal robustness.
  • Compact and easy to use — ideal for small systems or quick-access optical ports.
  • Custom sizes and materials — KF25 / KF40 / KF50 versions also available; CAD drawings and small-batch manufacturing supported.

Why choose the KF 63 viewport？

The KF63 vacuum viewport is widely used for visual observation and optical access in compact vacuum setups. Its simple clamp-style connection allows fast assembly and maintenance without complex tools.
Sapphire and quartz versions can withstand elevated bakeout temperatures and offer excellent transmission for laser, spectroscopy, and plasma monitoring applications.

By specifying your operating pressure, temperature, and optical wavelength, our engineering team can recommend the optimal window material and sealing configuration.

Typical Technical Specifications

Product model KF63
Product vacuum degree 1E*10-12 pa·m³/s
Flange material 304
Glass material Borosilicate / Quartz (Fused Silica) / Sapphire / Barium Fluoride / Calcium Fluoride / Zinc Selenide
Surface quality 60/40, 50/20, 20/10
Optical surface type 1/2 – 1/10
Visible diameter (mm) 63
Heat resistance range 150 ～ 230℃
Surface treatment Electrolytic polishing
Transmittance 1.45 ～ 1.76
Outer diameter (mm) 87
Inner diameter (mm) 63
Product Height(mm) 49
Glass thickness 6

Applications & industries

  • Semiconductor equipment (process monitoring, plasma observation).

  • Vacuum coating & thin-film deposition systems.

  • Laboratory and R&D vacuum chambers.

  • Laser alignment & spectroscopy setups.

  • Analytical and measurement instruments.

  • Optical diagnostics in high-vacuum environments.

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