ZnS windows are perfect for a wide variety of infrared applications including thermal imaging, FLIR, and medical systems. This chemical vapor deposited material has extensive usage in high power CO2 laser systems because of its low absorption coefficient and high resistance to thermal shock. Zinc Selenide (ZnSe) is a relatively soft material that scratches easily, and it is not recommended in harsh environments because its Knoop Hardness is only 120. When handling, apply uniform pressure and wear Latex finger cots or gloves to prevent contamination.
ZnS windows are available off-the-shelf with three anti-reflection coating options: 3 – 5μm for mid-infrared applications, 3 – 12μm for broadband multispectral applications, or 8 – 12μm for thermal imaging applications. Due to its high index of refraction (around 4.0 from 2 – 14μm), an anti-reflection coating is recommended for these ZnS windows for sufficient transmission in the region of interest. Germanium is subject to thermal runaway, meaning that the transmission decreases as temperature increases. As such, these ZnS windows should be used at temperatures below 100°C. Germanium’s high density (5.33 g/cm3) should be considered when designing for weight-sensitive systems. The Knoop Hardness of germanium (780) is approximately twice that of magnesium fluoride, making it ideal for infrared applications requiring rugged optics.
This article comes from hypoptics edit released