HALO View Replacement Window for Non-illuminated Viewport, ISO-250, LF250, 3/8 in. Fused Silica

This is a replacement fused silica window for the Ideal Vacuum ISO-63 non-illuminated HALO View Window. It can be replaced in the field. Please see the HALO View Window User Manual, available in downloads for instructions on replacing the window media.

These replacement fused silica 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. They 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 complete HALO Viewports and replacement panes with standard low-iron tempered glass. This economical glass is most 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. This media is unsuitable for laser experiments below visible or beyond near-infrared (NIR) wavelengths.

Please see the graph below for the transmissivity curves of tempered glass and fused silica:

HALO Viewport replacement windows are available in ISO 63, 80, 100, 160, 200 and 250 sizes and are used in place of blank ISO flanges. Like other ISO fittings, these ISO flanged windows use either single or double claw clamps along with a centering ring fitted with an O-ring. Use double claw clamps on ISO-K to ISO-K connections. Use single claw clamps on ISO-K to ISO-F (bolted) connections. The recommended number and type of claw clamps and the centering ring required is shown in the table below:

Our ISO viewing windows employ an innovative, zero metal-to-glass contact design that holds the 3/8” thick window pane to a stainless steel mounting flange. This cushioned window mounting system ensures operator safety and is less prone to leakage than other viewport window configurations, even at high-vacuum pressures. Ideal Vacuum ISO HALO viewing windows are delivered fully assembled and use Viton O-rings and Teflon spacers. Bakeout temperatures to 150 °C are permissible.

NOTE: All viewing windows or ports 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 HALO View Window User Manual.