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MgF₂ Crystal

POC-OC-122473-MgF₂ Crystal

  • Wide transparency range: 110 nm to 7.5 µm.
  • Excellent UV transmittance, ideal for ArF excimer laser applications.
  • Superior optical clarity with low absorption and scattering losses.
  • Durable and stable under extreme environmental conditions.
  • Customizable dimensions and coatings for specific optical requirements.

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

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MgF₂ Crystal Material General Description

Magnesium Fluoride (MgF₂) is a birefringent crystal with exceptional optical properties, making it an essential material in scientific and technological applications. Its broad transparency range (110 nm to 7.5 µm) ensures efficient performance across the ultraviolet (UV), visible, and infrared (IR) regions. MgF₂ is commonly utilized for its high transmittance, particularly at the 193 nm wavelength for ArF excimer laser applications. Additionally, its low refractive index, isotropy, and durability make it a preferred choice for lenses, windows, and prisms in demanding optical systems. With its excellent hardness and resistance to thermal and mechanical shock, MgF₂ is a versatile crystal for both industrial and high-precision scientific equipment.

MgF₂ Crystal General Applications and Examples

MgF₂ Crystals are widely used in the following applications:

  • Excimer Lasers: Due to their high transmittance at 193 nm, MgF₂ is highly suitable for ArF excimer laser windows in industrial and medical fields.
  • UV and IR Optics: Commonly employed in lenses, prisms, and windows for UV and IR optical systems.
  • Polarizing Elements: Effective as polarizing components in high-power UV optical instruments.
  • Vacuum Coating Systems: As a durable substrate for optical coatings in vacuum systems.
  • Scientific Instruments: Used in astronomical telescopes, high-energy physics detectors, and spectroscopic tools due to its transparency and mechanical stability.

Examples:

  1. Optical components for ArF excimer laser lithography.
  2. Precision windows in IR and UV spectroscopic applications.
  3. Polarizers and prisms for astronomical observation systems.

Chemical and Structural Properties

Property

Value

Density (g/cm³)

3.18

Melting Point (°C)

1255

Thermal Conductivity

0.3 W/m·K at 300 K

Thermal Expansion (°C⁻¹)

13.7 x 10⁻⁶ (c-axis), 8.9 x 10⁻⁶ (⊥ c-axis)

Knoop Hardness

415 (100g indenter)

Refractive Index (n₀, nₑ)

n₀ = 1.37608; nₑ = 1.38771 at 0.7 µm

Crystal Structure

Tetragonal

Cleavage Plane

(110)

Specific Heat Capacity

1003 J/Kg·K

Poisson Ratio

0.276

Optical, Laser and Nonlinear Optical Properties

Property

Value

Transparency Range

110 nm to 7.5 µm

Transmittance

>90% @ 0.193 – 6 µm

Reflection Loss

5.2% @ 0.6 µm (both surfaces)

dn/dT (°C⁻¹)

2.3 x 10⁻⁶ (c-axis); 1.7 x 10⁻⁶ (⊥ c-axis)

Absorption Coefficient

0.04 cm⁻¹ @ 2.7 µm

Standard Fabrication Specifications

Specification

Value

Maximum Diameter

170 mm

Clear Aperture

>85%

Surface Flatness

λ/4 @ 633 nm

Surface Quality

20/10

Wavefront Distortion

<λ/4 @ 633 nm

Chamfer

<0.25 mm x 45°

Length Tolerance

± 0.1 mm

Spectrum Transmission Curve:

The transmittance of MgF₂ exceeds 90% across a wide spectrum from UV (110 nm) to IR (7.5 µm). Below are the transmission curves for MgF₂ (3 mm thickness):

  • UV Region: High transmittance above 90% from 193 nm to 6 µm.
  • IR Region: Steady transmittance up to 7.5 µm.

Coating Specification:

 

MgF₂ crystals can be coated with anti-reflective coatings for enhanced transmittance and reflection reduction. Available coatings include:

  • AR Coating: Optimized for wavelengths from 0.193 µm to 6 µm.
  • Custom Coatings: Specific to application requirements.
  • 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) offers high-quality MgF₂ crystals tailored to demanding optical applications. Our expertise lies in:

  • Customizing crystal dimensions and coatings for specific needs.
  • Strict quality control for high durability and precision in optical performance.
  • Timely delivery and competitive pricing to meet industry standards.
  • Full OEM services, ensuring solutions for unique project requirements.

Standard Products

Dimensions

Length

Coating

Price (USD)

10 mm x 10 mm

5 mm

AR@193-6 µm

$120

20 mm x 20 mm

10 mm

AR@193-6 µm

$220

50 mm x 50 mm

15 mm

AR@193-6 µm

$550

Customization

As required

Custom Coating

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POC-OC-122473-MgF₂ Crystal

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