Alfa Chemistry uses lithium fluoride (LiF) material for custom infrared optics. This is a colorless, crystalline substance that transmits light throughout a wide range of wavelengths, from VUV to IR, however it is most frequently employed in specialist UV optics because of its deep UV transmission. All custom LiF optics are rigorously tested by skilled experts at cutting-edge metrology facilities, giving customers the peace of mind that their needs will be met. Contact us as soon as possible to provide you with customer service!
Our Services
Alfa Chemistry provides high-quality customization of LiF parts, such as windows, lenses, and prisms, that can be manufactured in accordance with your exact requirements. We can provide both coated and uncoated optical options, including Broadband Translucency Augmentation (BBAR) coatings. The table below lists our typical manufacturing requirements. If your needs are not covered by the aforementioned list, get in touch with our technical sales team. We can help you since we have a lot of experience in this area.
LiF Windows
| Diameter Range | 5 mm ~ 60 mm |
| Diameter Tolerance | ± 0.1 mm |
| Centre Thickness | up to 30 mm |
| Centre Thickness Tolerance | ± 0.05 mm |
| Clear Aperture | 90% |
| Centration Tolerance | 1 arc minute |
| Form Error | better than λ/4 (633nm) over aperture |
| Surface Radius Tolerance | 1 fringe over aperture |
| Linear Dimension | up to 60 mm |
| Linear Tolerance | ± 0.1 mm |
| Angular Tolerance | 5 arc minutes |
| Edge Finish | ground |
| Chamfer | 0.3x0.3@45° |
| Surface Quality | 20-10 scratch/ dig |
LiF Prisms
| Length of Hypotenuse | up-to 60 ± 0.1 mm |
| Length of Sides | up-to 60 ± 0.1 mm |
| Thickness | 30 ± 0.05 mm |
| Angle Tolerance | better than 1 arc minute |
| Edge Finish | ground, blacked |
| Clear Aperture | 90% of entrance dimensions |
| Chamfer | 0.3x0.3@45° |
| Form Error | 0.2 fringe from test flat |
| Surface Quality | 20-10 scratch/dig |
LiF Ground Blanks
| Diameter Range | less than 5 mm to 60 mm |
| Diameter Tolerance | better than ± 0.5 mm |
| Centre Thickness | up to 30 mm |
| Centre Thickness Tolerance | better than ± 0.5 mm |
| Clear Aperture | 90% |
| Linear Dimension | up to 60 mm |
| Linear Tolerance | better than ± 0.5 mm |
| Angular Tolerance | better than 10 arc minutes |
| Edge Finish | fine ground N6 |
| Chamfer | 0.3x0.3@45° |
Applications:
- X-ray Monochromator Plates: Due to a certain lattice gap, the LiF crystal structure reflects X-rays at a particular wavelength and incidence angle. This process is called Bragg diffraction. Monochromatic X-ray beams can be chosen using LiF plates.
- Transmission Windows: LiF windows are frequently employed in VUV and excimer lasers due to their excellent VUV transmission.
LiF's Optical Properties
LiF is frequently used to create windows, prisms, and lenses in the vacuum UV, ultraviolet, visible, and infrared spectrums due to its high transmittance. Out of the frequently used infrared materials, LiF has the lowest refractive index. Additionally, at 121 nm, it transmits above the hydrogen Lyman-alpha line, giving it the highest UV transmittance of any IR material.
LiF can be utilized up to 600°C in dry conditions even though it is highly insoluble in water and is destroyed by ambient moisture at about 400°C. LiF is susceptible to thermal shocks brought on by abrupt temperature fluctuations, which can cause the material to break.
Fig 1. Color online Structure of a LiF crystal. (Buth C, et al. 2005)
Below is a quick description of LiF's optical characteristics. For more information on the properties of LiF materials please click here.
| Transmission Range | 0.12 to 6 µm |
| Refractive Index | 1.392@0.6 µm |
| Melting Point | 848 °C |
| Density | 2.639 g/cm3 |
| Hardness | Knoop 102 with 600g indenter |
If you need technical advice, please contact our technical team to learn more about our high-quality services.
Reference
- Buth C, et al. (2005). "Ab Initio Green's Function Formalism for Band Structures." Physical Review. B, Condensed Matter. 72(19):195107.