What are the properties of lithium fluoride (LiF)?
Wide spectral transmittance: high transmittance from UV (0.11um) to IR (7um).
Low refractive index: refractive index of about 1.39, suitable for low reflection optical design.
High Damage Threshold: can withstand high power lasers, suitable for laser applications.
Chemical stability: corrosion-resistant, but prone to deliquescence, requires moisture-proof treatment.
Mechanical properties: low hardness, easy to process but need to be handled with care.

Applications of LiF lenses
Lithium fluoride lenses are used for windows, prisms and lenses in the vacuum ultraviolet, visible and infrared.