Sapphire viewports are selected for their superior optical transmission properties in the IR spectrum. Windows are silver-brazed to Kovar® sleeves. They are mounted in stainless steel tube-weld adapters and CF type flanges for use below 1x10-11, or ISO type Kwik-Flange® or Large Flange® for intermediate vacuum ranges.
Sapphire window surfaces which are extremely hard and scratch resistant offer a minimum of distortion and provide maximum light transmission suitable for most applications. UV grade viewports have a 90° crystal orientation normal to the optical axis.