Chloride (NaCl) is used for windows, lenses and prisms where transmission
in the 0.25 - 16 µm range is desired. Because of its low absorption,
Sodium Chloride is being used in high power laser systems. Polished
surfaces must be protected from moisture by exposing it to only dry
atmosphere or by using a heating element to maintain the Sodium Chloride
above the ambient temperature. Sodium Chloride can be used up to 400°C.
The material is sensitive to thermal shock. Irradiation generates color
Potassium Chloride (KCl) is used for infrared windows,
lenses and prisms when transmission in the 0.3 - 20 µm range is
desired (transmission extends beyond that of Sodium Chloride). Potassium
Chloride is soluble in water, and polished surfaces must be protected
from moisture. Maximum use temperature is 400°C.
Potassium Bromide (KBr) is used as IR spectroscopic
components, beamsplitters, and for CO2 -lasers. KBr is water soluble
and must be protected against moisture degradation of polished surfaces.
The material cleaves readily, and can be used at temperature of up to
300 °C. Irradiation of KBr produces color centers.
Cesium Iodide (CsI) is useful for infrared, having
transmission through the visible out to 70 µm in a 2 mm thickness.
It is principally used for infrared prisms, cell windows and as a beamsplitter
or as interferometer plates. Cesium Iodide is also furnished as Thallium
activated Cesium Iodide for scintillation crystals. Being relatively
soft, this material has found application in satellite-borne radiation
detectors, which must withstand extreme shock and vibration along with
rapid temperature changes. Cesium Iodide precipitated powders are used
in solid phase pelleting of samples for infrared spectroscopy. Cesium
Iodide is highly water soluble and polished faces of this material may
be damaged by moisture in the atmosphere when relative humidity is higher
than 35%. CsI can be cut with a band saw. Standard polishing techniques
can be used.