Custom Magnesium Fluoride

Sapphire windows for Energy, Utilities and Renewables Magnesium Fluoride (MgF₂) is a colourless and durable crystalline material grown by vacuum Stockbarger technique. Whilst magnesium fluoride does transmit into the MWIR region, its transmission is inferior compared to calcium fluoride and barium fluoride, therefore its main applications fall into the VUV and UV regions.

It exhibits many beneficial properties including:

Naturally birefringent	Resistant to mechanical shock
Low absorption	Chemically stable
Resistant to water	Resistant to thermal shock

Below is a brief summary of magnesium fluoride’s optical properties, a full data sheet is available here.

Transmission range	0.12 to 7µm
Refractive Index	1.413 @ 0.22µm
Density	3.18 g/cm³
Melting Point	1255°C
Hardness	Knoop 415

Knight Optical supplies high quality magnesium fluoride components, including windows, lenses and prisms, made to your custom specification. We can offer uncoated and coated optics, including broadband antireflective (BBAR) coatings. Our typical manufacturing specifications are listed below however we are always expanding our capabilities so if your requirements are not mentioned below, please contact our technical sales team who will guide you through your enquiry.

Diameter	< 5mm to 50mm +
Form error (@633nm)	< 0.25 waves
Centration /parallelism	< 1 arc minute
Scratch/dig	< 40/20
Typical coatings	BBAR @ 1-7µm DLC @ 1-7µm

Contact our multilingual technical sales team and discover how Knight Optical’s high quality Magnesium Fluoride optical components and service can improve your instrumentation and supply chain experience.

Uncoated, 1mm thick

MgF2 window capabilities
MgF2 spherical lens capabilities
MgF2 prism capabilities
MgF2 ground blank capabilities

IR material magnesium fluoride

Magnesium Fluoride Windows

Additional Information

Magnesium fluoride is the hardest of the fluoride materials used in optical components, and so is often used where durability is desired., especially when used in harsh conditions.
It can be cut in different orientations to produce either minimal or maximum birefringence, dependent on the application it is intended for.

Typical Applications

Rochon Polariser

Magnesium fluoride exhibits slight birefringence and therefore is often the substrate used in Rochon polarisers, which is made from two birefringent prisms. Other substrates such as calcite or crystalline quartz are also used.

Retarder plates

Due to magnesium fluorides birefringence it is also used as the substrate for retarder plates, such as quarter-wave plates.

Excimer Lasers

Magnesium fluoride transmits into the vacuum ultraviolet (VUV), it is durable and creates minimal aberrations. For excimer applications, magnesium fluoride would be cut in such a way to produce minimal birefringence. It is often the substrate used for excimer laser mirrors along with calcium fluoride.

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