Magnesium Fluoride

Magnesium fluoride is a colorless, crystalline compound whose low refractive index (n=1.38) makes it effective as a lens antireflection coating when deposited by thermal evaporation in a near vacuum. This process develops a coating that is robust and stable, though only a few molecules thick. Magnesium fluoride is used as a prism and window for wavelengths from the vacuum ultraviolet region of 115.0mm to the infrared region of 9.5. It is most suitable material as window for ArF Eximer Laser, because it has the wide band-gap. It is also effective as a polarizing element in the ultraviolet region. Also, the crystal fine grain is appropriate as a vacuum evaporation material.

Magnesium fluoride is used for optical elements in the infrared where extreme ruggedness and durability is required. Its useful transmission range is 0.11μm - 7.5μm. Red Optronics can supply single crystal mosaic free UVU grade MgF2 material. This material can reach transmission greater than 50% at 121.6nm and it can be used for excimer & Nd:YAG laser optics. MgF2 is relatively soft and somewhat hygroscopic so polishing, coating and handling are more critical than for Fused Silica windows. The quality of a UV window can be extremely critical, it should be of high purity and polish in order not to affect the optical system. Irradiation does not lead to color centers. Magnesium fluoride is a rugged, hard material which is resistant to thermal and mechanical shock. Considerable mechanical shock is needed to cause cleavage which is near perfect when it occurs. The natural form of MgF2 is known as Sellaite. Magnesium fluoride is a positive birefringent crystal grown normally to 135mm diameter by vacuum Stockbarger technique, seeding along the C-axis. Magnesium fluoride (MgF2) is commonly used for UV windows, lenses and polarisers. It is also usful in its transmission range for some IR spectroscopy applications. Magnesium fluoride is the most widely used thin, film material for optical coatings. Its performance is not outstanding but represents significant improvement compared to an uncoated surface. Because of the wide transmission range, magnesium fluoride is an excellent coating material in UV wavelength.

Chemical Formula: MgF2
Molecular Weghter: 62.31
CAS Number: 7783-40-6
Description: Colorless quadratic crystal,tasteless.Dissolved in nitric acid,slightly dissolved in dilute acid,insoiuble in wter and alcohol.