Lithium fluoride (LiF) crystal has the smallest refractive index in the common infrared optical materials. lts transmissionspectrum ranges from 120nm to 7000nm. lt is usually used for lenses, prisms and windows of thermal imaging systems.space optical systems and excimer laser optical systems. lt has high water solubility and high coeficient of thermalexpansion, When used in atmospheric environment, special measures should be taken to prevent its delicuescence ancdeformation.
