Lithium fluoride (LiF) is a highly useful optical crystal, especially recognized for its wide transmission range, spanning from the deep ultraviolet (UV) to the mid-infrared (IR) regions of the light spectrum. This makes it particularly valuable in various high-tech optical applications.

Properties of Lithium Fluoride:

1. Broad Spectral Transmission: LiF is one of the few materials that offer high transparency in both the deep UV and the mid-IR spectrums, which is rare among common optical materials.
2. Low Refractive Index: It has one of the lowest refractive indices among common infrared materials, which minimizes optical distortions.
3. High UV Radiation Resistance: LiF can withstand intense UV radiation, making it suitable for environments exposed to high-energy photons.
4. Thermally Stable: It has a relatively high melting point and excellent thermal stability, which is advantageous for applications involving high temperatures.
5. Low Solubility: LiF is less hygroscopic (prone to absorbing moisture) compared to other alkali halides, which enhances its durability in humid conditions.

Applications:

1. UV Optics and Lithography: LiF’s ability to transmit UV light efficiently makes it an excellent choice for photolithography equipment used in semiconductor manufacturing, where precise patterning is crucial.
2. Infrared Spectroscopy: Due to its IR transparency, LiF is used for windows, lenses, and prisms in infrared spectroscopy applications.
3. Cryogenics: Its properties remain stable at very low temperatures, making it suitable for use in cryogenic environments, such as in space exploration sensors and instrumentation.
4. Nuclear Radiation Windows: LiF is often used in windows for nuclear reactors and other radiation-intensive applications because it resists radiation damage.

The synthesis and fabrication of LiF crystals require careful handling to maintain optical clarity and structural integrity, as the material is relatively soft and can be cleaved easily. This precision contributes to its effectiveness in specialized optical components where high performance under extreme conditions is essential.

Shapeoptics is Able to Offer

• Optical element for X-ray diffraction devices
• Various optics for IR & VUV application
• Good quality LiF crystal blank materials
• OEM service for good quality LiF crystals

Capabilities

• Maximum Diameter 170mm
• Clear Aperture 85%
• Surface Flatness /4 @633nm
• Surface Quality 20/10

Wavelength (nm)

The Transmittance Curve of LiF Crystal (under 3mm thickness)

Transmittance (%)

LiF Crystal Properties

Optical Properties

Transmittance Range / m	0.105 ～ 6
Transmittance	> 90%@0.3 ～ 4.5m
Refractive Index	1.3733 @2.5m; 1.6240 @121nm
Reflection Loss	4.4% @4m (both surfaces)

Physical Properties

Density / g.cm-3	2.64
Melting Point / ℃	845
Thermal Conductivity / W.m-1K-1	11.3 @ 314K
Thermal Expansion / ℃-1	37 x 10-6
Mohs Hardness / Kg.mm-2	113 with 600g indenter
Specific Heat Capacity / J.kg-1k-1	1562
Dielectric Constant	9.0 @100 Hz
Youngs Modulus (E) / GPa	64.79
Shear Modulus (G) / GPa	55.14
Bulk Modulus (K) / GPa	62.03
Rupture Modulus / MPa	10.8
Elastic Coefficient	C11=112; C12=45.6; C44=63.2

Chemical Properties

Solubility / g	0.27 @18℃
Molecular Weight	25.94
Crystal Structure	Cubic System
Cleavage Plane	(100)

Lithium Fluoride crystal is used as windows, lens for the 105nm to 6m. It also works as the optical elements in X-ray diffraction devices.

Shapeoptics offers a comprehensive range of materials and advanced equipment for custom and OEM optical components, leveraging over 20 years of expertise in manufacturing lenses, prisms, windows, and more. We utilize high-quality materials like UV and IR grade fused silica, Germanium, and ZnSe, among others. Our state-of-the-art techniques and equipment minimize waste and optimize delivery times. Our in-house capabilities include standard and custom coatings across the UV-NIR spectrum, ensuring high quality and compliance with all industry standards. For precision and reliability in optics, contact Shapeoptics for your next project.