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LiF Optics

LiF (Lithium Fluoride) crystal shows excellent transmittance in the VUV region. It is used for windows, prisms, and lenses in the visible and infrared in 0.105 μm – 6 μm. LiF (Lithium Fluoride) crystal is sensitive to thermal shock and would be attacked by atmospheric moisture at 400°C. In addition, irradiation produces color centers. Modest precautions should be taken against moisture and high energy radiation damage. Besides LiF (Lithium Fluoride) softens at 600°C and is slightly plastic that can be bent into radius plates. The material can be cleaved along (100) plane and less commonly (110) plane. The optical characteristics are good and yet the structure is not perfect and cleavage is difficult. Honour Optics is the professional VUV grade LiF optics manufacturer,buy China LiF optics, welcome to consult wholesale LiF optics.

LiF (Lithium Fluoride) has the lowest refractive index of all common infrared materials. It also possesses the highest UV transmission of any material, being able to transmit significantly into the VUV region at the hydrogen Lyman-alpha line (121nm). Transmission is about 40% at 121nm; this is one of the most popular materials for deep UV spectrum. It is slightly soluble in water while being soluble in HDF and other acids. However, it can be cleaned with pure alcohol. welcome to consult custom LiF optics latest price.

High purity LiF optics birefringence should be taken into consideration before selection of this material in optical design. It is resistant to thermal and mechanical shock. It is twice as hard as CaF2 but only half as hard as Ge. It is significantly more expensive than CaF2 and BaF2, but usually not more expensive than MgF2. LiF is diamond turnable. welcome to consult custom LiF optics latest price.

Products manufactured: Lenses, Aspheric lenses, Windows, Wedges, Prisms.

Surface finish: Typical specifications for surface quality in the infrared are a 40-20 scratch-dig in the 0.75 to μm spectral region and 60-40 or 80-50 scratch-dig for the 3-7μm area depending upon system performance requirements.

Surface figure: In the infrared, typical surface figure ranges from 1/2 wave to 4 waves @0.6328μm depending upon system performance requirements.

AR coating options: LiF can be AR coated for use in the infrared, but generally without much improvement in transmission due to its low index of refraction and already high transmission

Tab. 1.Main Properties of LiF

Optical Properties
Transmission Range 105 nm to 6 μm
Transmittance >90% at 300 nm to 4.5 μm
Refractive Index 1.3733at 2.5 μm;

1.6240 at 121 nm

Reflection Loss 4.4% at 4 μm (both surfaces)
Physical Properties
Density 2.64 g/cm3
Melting Point 845℃
Thermal Conductivity 11.3 Wm-1K-1 at 314K
Thermal Expansion 37 x 10-6 /℃
Mohs Hardness 113 with 600g indenter (kg/mm2)
Specific Heat Capacity 1562 J/(kg.k)
Dielectric Constant 9.0 at 100 Hz
Youngs Modulus (E) 64.79 GPa
Shear Modulus (G) 55.14 GPa
Bulk Modulus (K) 62.03 GPa
Rupture Modulus 10.8 MPa
Elastic Coefficient C11=112; C12=45.6; C44=63.2
Chemical Properties
Solubility 0.27 g/ 100g water at 18℃
Molecular Weight 25.94
Structure Cubic Crystal
Cleavage Plane (100)

Tab. 2.Refraction index of LiF, No = Ordinary Ray

µm No µm No µm No
0.106 1.9130 0.108 1.8330 0.110 1.7770
0.121 1.6240 0.130 1.5690 0.140 1.5300
0.150 1.5030 0.160 1.4840 0.170 1.4690
0.180 1.4850 0.190 1.4455 0.200 1.4391
0.220 1.4291 0.250 1.4189 0.260 1.4164
0.270 1.4141 0.280 1.4121 0.290 1.4103
0.300 1.4087 0.310 1.4073 0.320 1.4060
0.330 1.4048 0.340 1.4037 0.350 1.4028
0.360 1.4019 0.400 1.3989 0.500 1.3943
0.600 1.3918 0.700 1.3902 0.800 1.3890
0.900 1.3880 1.000 1.3871 1.500 1.3832
2.000 1.3788 2.500 1.37327 3.000 1.3666
3.500 1.3587 4.000 1.3494 4.500 1.3388
5.000 1.3266 5.100 1.3240 5.200 1.3213
5.300 1.3186 5.400 1.3158 5.500 1.3129
5.600 1.3099 5.700 1.3069 5.800 1.3038
5.900 1.3007 6.000 1.2975

Tab. 3.Specification of LiF options

Specification Typical Level High precision
Sizes 2mm-150mm 2mm-180mm
Diameter tolerance +/-0.1mm +/-0.05mm
Thickness tolerance +/-0.1mm +/-0.05mm
Surface quality, scr/dig 60/40 20/10
Surface flatness(lambda) 2 L/4
Parallelism 3 arc min 10 arc sec
Clear Aperture 80% 90%
Chamfer 0.25mm at 45 deg 0.15mm at 45 deg
Coating As requested As requested

Transmission Spectrum

China LiF optics transmission spectrum

High purity LiF optics shows good optical properties. It can be used for windows, prisms, and lenses in the VUV, UV, visible and infrared where the desired transmission is in the 0.11μm~6μm range. Because of its particular lattice structure, LiF (Lithium Fluoride) can also be used as X-ray diffraction devices. Honour Optics is the professional VUV grade LiF optics manufacturer,buy China LiF optics, welcome to consult wholesale LiF optics.

Main specifications summarized as follows:

7.Excimer lasers
8.X-ray fluorescence instruments

Honour Optics is the professional manufacturer of LiF (Lithium Fluoride) with ROHS environmental protection requirements. Honour Optics could provide:
UV and IR level LiF (Lithium Fluoride) optical components with different shapes, such as rod, square, step, wedge, prism, spherical, cylindrical and so on.
Good quality LiF (Lithium Fluoride) crystal, maximum size is about 180mm
Orientation: <100>, <110>, <111>