Lithium Fluoride(LiF)Double-Concave Lenses
Lithium fluoride (LiF) crystal is also one of the common infrared materials, it has the smallest refractive index in the infrared materials, its transmission spectrum range is 120nm-7000nm, usually used in thermal imaging systems, aerospace optical systems and excimer laser optical systems.
Lithium fluoride (LiF) double concave lens is similar to a plano-concave lens in that the focal length is negative, but the light incident in parallel diverges outward, and it’s often used for laser systems and infrared systems,such as optical instruments,laser device,optical measurement and inspection ect.
Our company can provide Lithium fluoride (LiF) double concave lens with diameters from 2-300mm.and thicknesses from 0.12-60mm (accuracy up to 20-10, 1/10L@633nm),coating AR, BBAR, AF or upon request.
Technical parameters of LiF Double-Concave Lens
Diameter | 2-300mm |
Focal length | 15-5000mm |
Thicknesses | 0.12-60mm |
Dimension tolerance | +0/-0.1mm |
Thickness tolerance | ±0.1mm |
Surface quality (scratch & dig) | 60-40, 40-20, or better |
Surface accuracy | λ/2, λ/4 or better |
Parallelism | 3' ,30'' |
Bevel | 0.1~0.3mm x 45 degree |
Clear aperture | >85%,>90% |
Coating | AR coating or cutom |
Material properties of LiF
| Optical Properties | |
| Transmission Range | 0.11-7μm |
| Transmittance | >94.8%@0.6μm |
| Reflection Loss | 5.2%@0.6μm(both surfaces) |
| Absorption Coefficienet | 5.9×10-3@4.3μm |
| Structure | Cubic Crystal System |
| Cleavage Planes | <100> |
| Physical Properties | |
| Density[g/cm3] | 2.639 |
| Melting Point [℃] | 848 |
| ThermalConductivity [W/(m×K)] | 11.3 @ 314K |
| Thermal Expansion [10-6/K] | 37.0 @ 283K |
| Knoop Hardness [kg/mm2] | 415 |
| Specific Heat Capacity [J/(kg×K)] | 1562 |
| Dielectric Constant | 7.33 @ 1 MHz |
| Young's Modulus (E) [GPa] | 64.79 |
| Shear Modulus(G) [GPa] | 55.14 |
| Bulk modulus(K) [GPa] | 62.03 |
| Poisson Coefficient | 0.22 |
| Chemical Properties | |
| Solubility / g/L | 2.7g @ 20℃ |
| Molecular Weight / g/mol | 25.9394 |
Transmission curve
Lithium fluoride crystals have a wide transmission band (110 to 6,600 nm) and a high transmittance, especially in the vacuum UV band, which is the highest among known materials. Therefore, it is used as an optical material in the ultraviolet band. Lithium fluoride double concave lenses are popular in many UV and IR applications.
