These ultra-high vacuum (UHV) viewports employ window materials such as Zinc Selenide, Magnesium Fluoride and Calcium Fluoride. All-metal-sealed, extended-range optics are available in 1 inch and 2 inch view diameters with a combined transmission range of 120nm to 20 microns. Coatings which enhance the transmission performance of many of these viewports are offered as standard options. Many nonstandard materials, coatings and optical specifications may be reviewed and quoted to meet custom application requirements.