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LITHIUM FLUORIDE (LiF) OPTICS

Alkor Technologies manufactures LiF windows, lenses and prisms according to customer's specifications. Maximum size of LiF optics: Dia:100 mm x 40 mm.

Please contact us for more information.

LiF transmission

Lithium Fluoride is used for windows, lenses and prisms in the vacuum UV, UV, visible and infrared where transmission in the range 0.104mkm to 7mkm is desired. Modest precautions should be taken against moisture and high energy radiation damage.

LiF is attacked by atmospheric moisture at 400C, and softens at 600C. LiF is sensitive to thermal shock. Irradiation produces color centers. The material can be cleaved along (100) and less commonly (110). Although the optical characteristics are good the structure is not perfect and cleavage is difficult. VUV grade LiF windows are available. This is the best VUV transmitter available.

Main properties:

Chemical Formula LiF
Crystal Class Cubic
Lattice Constant, Å 4.03
Molecular Weight 25.94
Density, g/cm3 (20 °C) 2.60
Reflection Loss, % for two surfaces at 4 µm 4.4
Dielectric Constant for 102-1010 Hz at 298 K 9.0
Melting Temperature, K 1140
Thermal Conductivity, W/(m K) at 314 K 11.3
Thermal Expansion, 1/K at 300 K 34.4 x 10-6
Specific Heat, cal/(g K) at 283 K 0.37
Debye Temperature, K 732
Bandgap, eV 13.6
Solubility, g/100 g H2O at 291 K 0.27
Knoop Hardness, kg/mm2 100
Young's Modulus, GPa 64.77
Apparent Elastic Limit, MPa 11.2
Shear Modulus, GPa 55.12
Bulk Modulus, GPa 62.0
Poisson Ratio 0.326
 

Refractive index

Wavelength, µm 0.20 0.22 0.24 0.29 0.39 0.60 1.75 2.75 3.40
Refractive Index 1.44 1.43 1.42 1.41 1.40 1.39 1.38 1.37 1.36
 
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