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LiF Crystal

POC-OC-122474-LiF Crystal

  • Exceptional optical transmittance over a wide spectral range (105 nm to 6 μm).
  • Smallest refractive index among infrared materials.
  • High radiation resistance suitable for harsh environments.
  • Ideal for thermal imaging, aerospace optics, and excimer laser optics.
  • Custom dimensions, orientations, and coatings available on request.

Customizable Components Available for This Material to Meet Your Specific Needs!

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LiF Crystal Material General Description

Lithium Fluoride (LiF) crystal is known for its remarkable optical properties, including high transmittance in the ultraviolet (UV), visible, and near-infrared regions, spanning wavelengths from 105 nm to 6 μm. It possesses the lowest refractive index among commonly used infrared materials, making it indispensable for applications that demand minimal optical distortion. LiF crystals are highly resistant to radiation damage, which enhances their reliability in extreme environments such as aerospace and thermal imaging applications. They also feature excellent thermal and chemical stability, contributing to their usability in high-energy optics. Additionally, LiF is employed as optical elements in X-ray diffraction devices due to its unique crystal lattice properties.

 General Applications and Examples

LiF crystals find extensive applications across various fields:

  1. Thermal Imaging Systems: With their exceptional optical transmission and low refractive index, LiF are perfect for use in thermal imaging systems, offering clear and precise image capturing in harsh environments.
  2. Aerospace and Military Applications: LiF’s high radiation resistance and lightweight properties make it an ideal choice for optical components in aerospace and defense technologies.
  3. Excimer Laser Windows: The superior UV transmittance of LiF crystals ensures their efficiency as windows for excimer laser systems operating at 193 nm and other UV wavelengths.
  4. X-Ray Diffraction Devices: Thanks to its crystalline structure, LiF serves as an essential component in X-ray spectrometers and diffraction applications.
  5. High-Resolution Optics: LiF crystals are used in lenses and prisms for optical instruments requiring high transmittance and low distortion, especially in the visible and UV ranges.

These properties make LiF crystals a versatile material for cutting-edge technological advancements.

Chemical and Structural Properties

Property

Value

Density (g/cm³)

2.64

Melting Point (°C)

845

Thermal Conductivity (W·m⁻¹·K⁻¹)

11.3 @ 314 K

Thermal Expansion (°C⁻¹)

37 × 10⁻⁶

Hardness (Mohs)

4

Dielectric Constant

9.0 @ 100 Hz

Elastic Coefficient

C₁₁=112; C₁₂=45.6; C₄₄=63.2

Crystal Structure

Cubic System

Cleavage Plane

(100)

Solubility (g @ 18°C)

0.27

Refractive Index

1.3733 @ 2.5 μm

Optical, Laser and Nonlinear Optical Properties

Property

Value

Transmittance Range (μm)

0.105–6

Transmittance (%)

>90% @ 0.3–4.5 μm

Refractive Index

nₒ=1.3733 @ 2.5 μm; nₑ=1.6240 @ 121 nm

Reflection Loss (%)

4.4% @ 4 μm (both surfaces)

Standard Fabrication Specifications

Parameter

Specification

Dimension Tolerance

±0.1 mm

Surface Flatness

λ/4 @ 633 nm

Parallelism

<3 arcmin

Surface Quality

20/10 (Scratch/Dig)

Clear Aperture

>90%

Chamfer

<0.25 × 45°

Spectrum Transmission Curve:

The transmission curve demonstrates LiF’s superior transmittance across wavelengths ranging from 105 nm to 6 μm. This property highlights its efficiency for UV to IR optical systems. (Refer to the included graphs for visual representation.)

Coating Specification:

 

LiF crystals can be customized with the following coatings to enhance their performance:

  • Anti-Reflective (AR) Coating: Available for UV, visible, and IR wavelengths.
  • Custom coatings for specific wavelength ranges.
  • Adhesion Test Compliant with MIL-C-675C military standards, an adhesion test involved applying a tape that meets LT-90 specifications onto the lens film layer. The tape was affixed fully and then removed vertically. This procedure was performed three times, resulting in no blistering or peeling.
  • Temperature Test In line with MIL-C-675C specifications, test pieces were subjected to temperatures of -62±1℃ and 71±1℃. After maintaining them at room temperature (16℃~32℃) for two hours, the adhesion test was repeated, confirming no film detachment.
  • Abrasion Resistance Test Conforming to MIL-C-675C and CCC-C-440 standards, the abrasion resistance test involved a gauze tester applying a minimum force of 1.0 lbs (0.45 kg) to the film. This was repeated 25 times with gauze widths of 1/4 inch (6.4mm) and 3/8 inch (9.5mm), ensuring no damage occurred to the film surface.
  • Humidity Test Under MIL-C-675C criteria, the test piece was placed in a controlled temperature and humidity chamber set to 49 ±2℃ and 95%~100% humidity for 24 hours. The film remained intact, with no peeling, scratches, or other defects.
  • Solvent and Cleaning Testing Following MIL-C-675C specifications, test pieces were exposed to room temperature conditions (16℃~32℃) and tested with acetone and alcohol for at least 10 minutes each. After air drying and subsequent cleaning with a cotton cloth soaked in alcohol, the film surface showed no signs of peeling or scratches.
  • Salt Spray Test After 100 hours in a 35°C environment with a 5% saltwater concentration, the film showed no signs of damage.

POC Strength and Capabilities

 

Photonics On Crystals (POC) excels in providing high-quality optical materials for advanced applications. POC’s expertise in precision manufacturing and customizable options ensures optimal solutions tailored to customer requirements. Key strengths include:

  • A dedicated R&D team ensuring cutting-edge innovation.
  • Strict quality control procedures for flawless crystal performance.
  • OEM capabilities to meet diverse industry standards.

Standard Products

Dimension (mm)

Coating

SKU

Price (USD)

20 × 20 × 5

Uncoated

7301

150

30 × 30 × 5

AR Coating @ 0.3–4.5 μm

7302

180

40 × 40 × 10

AR Coating @ UV

7303

220

50 × 50 × 10

Custom

7304

250

POC-OC-122474-LiF Crystal

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