Magnesium Fluoride (MgF₂) Optical Windows
Chenyu Optics manufactures Magnesium Fluoride optical windows for demanding ultraviolet, vacuum ultraviolet and infrared applications. MgF₂ combines broad transmission, low refractive index, higher hardness than CaF₂, and good environmental durability for laser systems, spectroscopy instruments, high-vacuum chambers and research optical assemblies.
Magnesium Fluoride Optical Windows Overview
Magnesium Fluoride (MgF₂) optical windows are crystalline optical components used where deep ultraviolet transmission, low reflection and environmental durability are required. MgF₂ transmits from the vacuum ultraviolet region to the mid-wave infrared, making it useful for VUV spectroscopy, excimer laser systems, UV instruments and selected infrared optical assemblies.
MgF₂ has a low refractive index, so uncoated windows can provide relatively high transmission compared with higher-index infrared materials. It is also harder and more mechanically durable than Calcium Fluoride, which makes it a preferred fluoride crystal for exposed optical windows, high-vacuum viewports and applications requiring better resistance to handling or environmental stress.
Because MgF₂ is birefringent, crystallographic orientation should be considered for imaging, laser and polarization-sensitive systems. Chenyu Optics can support oriented MgF₂ windows, custom dimensions, precision polishing, edge finishing, UV AR coating, broadband AR coating and infrared AR coating according to customer drawings.
Key Advantages of Magnesium Fluoride Optical Windows
VUV, UV Laser & Spectroscopy Use
MgF₂ windows are commonly used in VUV spectroscopy, excimer laser systems, high-vacuum optical viewports, UV analytical instruments and research equipment requiring stable ultraviolet transmission.
Typical Specifications of Magnesium Fluoride Optical Windows
| Material | Magnesium Fluoride / MgF₂ |
|---|---|
| Material Grade | Standard Optical Grade MgF₂ / VUV Grade MgF₂ / Oriented MgF₂ |
| Transmission Range | Approx. 120 nm – 7 μm, depending on grade, thickness and coating |
| Refractive Index | Approx. 1.38 @ 1 μm |
| Crystal Structure | Tetragonal, birefringent crystal |
| Density | Approx. 3.18 g/cm³ |
| Knoop Hardness | Approx. 415 kg/mm² |
| Surface Quality | 60-40, 40-20, 20-10 or 10-5 scratch-dig |
| Surface Flatness | λ/10, λ/4, λ/2 or custom @ 632.8 nm |
| Parallelism | ≤ 10 arcsec, ≤ 1 arcmin, ≤ 3 arcmin or custom |
| Clear Aperture | ≥85%, ≥90%, ≥95% or drawing-based |
| Optical Orientation | Random orientation or c-axis cut available |
| Diameter / Size | Custom round, square, rectangular or special-shaped windows |
| Coating Options | Uncoated, UV AR, VUV coating, VIS-NIR BBAR, MWIR AR, custom coatings |
Optical Transmission Characteristics of Magnesium Fluoride Optical Windows
Typical MgF₂ Transmission Curve
Magnesium Fluoride provides useful transmission from the vacuum ultraviolet region to the mid-wave infrared. Its low refractive index helps reduce surface reflection, while VUV-grade crystal material is selected for 157 nm, 193 nm and other deep ultraviolet applications.
Why Choose Chenyu Optics for Magnesium Fluoride Optical Windows
MgF₂ is more durable than many fluoride crystals, but its birefringent crystal structure requires attention to orientation and polishing control. Chenyu Optics supports drawing-based MgF₂ window production for UV, VUV, high-vacuum, laser and industrial optical applications.
Manufacturing Capability for Magnesium Fluoride Optical Windows
Precision Polishing
Controlled polishing for MgF₂ surfaces to achieve required flatness, surface quality and low scatter.
Optical Coating
UV AR, VUV, VIS-NIR BBAR and MWIR coating support based on wavelength and application conditions.
Inspection & Packaging
Dimensional inspection, surface quality review, transmission verification and clean protective packaging.
Custom Manufacturing Options for Magnesium Fluoride Optical Windows
Dimensions & Geometry
Round, square, rectangular, wedge and special-shaped MgF₂ windows can be manufactured according to customer drawings, including custom diameter, thickness and clear aperture.
Orientation & Surface Quality
C-axis cut MgF₂, surface quality, flatness, parallelism and chamfer specifications can be selected based on imaging, laser or polarization requirements.
Coating & Wavelength Design
Uncoated, UV AR, VUV, VIS-NIR broadband AR and MWIR AR coatings can be designed for spectroscopy, excimer laser and infrared systems.
Magnesium Fluoride Optical Windows Material Comparison
| Material | Magnesium Fluoride (MgF₂) | Calcium Fluoride (CaF₂) | UV Fused Silica | Barium Fluoride (BaF₂) | Sapphire |
|---|---|---|---|---|---|
| Transmission | Approx. 120 nm – 7 μm | Approx. 130 nm – 10 μm | Approx. 185 nm – 2.1 μm | Approx. 200 nm – 12 μm | UV to approx. 5 μm |
| Main Advantage | VUV transmission and good fluoride-crystal durability | Broader IR transmission and low dispersion | Excellent UV performance and high thermal stability | Extended IR transmission compared with MgF₂ | Very high hardness and environmental durability |
| Mechanical Behavior | Harder than CaF₂ and BaF₂, birefringent | Soft crystal, sensitive to thermal shock | Harder and more thermally stable | Very soft and more moisture sensitive | Very hard and durable |
| Typical Use | VUV windows, excimer lasers, high-vacuum optics | UV spectroscopy, broadband windows, IR instruments | UV lasers, optical flats, machine vision windows | IR spectroscopy and broadband IR instruments | Protective windows and harsh environment optics |
Applications of Magnesium Fluoride Optical Windows
VUV Spectroscopy
Vacuum ultraviolet spectrometers, gas analysis cells and fluorescence detection instruments.
Excimer Lasers
Optical windows for 157 nm, 193 nm, 248 nm and other UV laser systems.
High-Vacuum Viewports
Durable MgF₂ windows for vacuum chambers, plasma systems and research equipment.
UV Optical Instruments
UV analytical systems, optical sensors and laboratory measurement instruments.
MWIR Systems
Selected infrared assemblies where transmission up to the MWIR region is required.
Aerospace Research
Space simulation, synchrotron beamlines and plasma diagnostic optical systems.
Magnesium Fluoride Optical Windows FAQ
What wavelength range can Magnesium Fluoride optical windows transmit?
MgF₂ can transmit from approximately 120 nm to 7 μm, depending on material grade, crystal quality, thickness and coating design. VUV-grade MgF₂ is required for the shortest ultraviolet wavelengths.
Why is crystal orientation important for MgF₂ windows?
Magnesium Fluoride is birefringent. For imaging, laser and polarization-sensitive systems, c-axis orientation helps reduce unwanted polarization effects and wavefront distortion at normal incidence.
How does MgF₂ compare with CaF₂?
MgF₂ is harder and more durable than CaF₂, making it better for exposed optical windows and high-vacuum environments. CaF₂ has broader infrared transmission and lower dispersion, so material selection depends on wavelength and system requirements.
Can MgF₂ windows be used for excimer laser systems?
Yes. VUV-grade MgF₂ is commonly selected for excimer laser wavelengths such as 157 nm, 193 nm and 248 nm, provided the crystal grade, orientation, polishing quality and coating are specified correctly.
Can Magnesium Fluoride windows be AR coated?
Yes. MgF₂ windows can be supplied uncoated or with UV AR, VUV, VIS-NIR broadband AR, MWIR AR or custom coatings depending on the wavelength range and laser fluence requirements.
What information should I provide for quotation?
Please provide wavelength range, material grade, orientation requirement, size, thickness, surface quality, flatness, parallelism, clear aperture, coating requirements, quantity and drawing if available.
Where can I learn more about Magnesium Fluoride optical materials?
Additional Magnesium Fluoride material information can be found from Edmund Optics.
Related Products for Magnesium Fluoride Optical Windows
Need Custom Magnesium Fluoride Optical Windows?
Send us your MgF₂ wavelength range, orientation requirement, size, thickness, coating requirements, quantity and drawing. Chenyu Optics will review the optical and mechanical requirements and provide a suitable manufacturing suggestion.