MgF2 exhibits excellent broadband transmission from 120 nm to 8 μm , from the deep UV to the mid infrared. This makes them a good choice for UV radiation sources and receivers as well as for use at the Hydrogen Lyman-alpha line. They are often used as UV viewpoints, and are a good option for UV polarizers and excimer laser applications. It has a high transmittance between 120 nm and 8 µm, and between 0.4-5.0 µm transmits over 90%.
MgF2 has a melting point of 1255 degrees Celsius. It has a density of 3.177 g/cm3, and a tetragonal crystal type. Our optical windows are typically oriented with the round surfaces perpendicular to the c-axis of the MgF2 crystal to minimize birefringence. Custom random cut MgF2 windows can be manufactured on request.
MgF2 is the only optical material which combines a wide spectral transmission band with birefringence. This birefringence means that the refractive index depends on the polarization and propagation direction of light. Because of birefringence, a MgF2 window can exhibit double refraction, so that a ray of light will be split by polarization into two rays with different paths.
The ray component for which the optical window has a higher effective refractive index is called the slow ray, while the one with the lower effective refractive index is referred to as the fast ray. If a beam enters the MgF2 window from air, the slow ray will be refracted more towards normal.
|Material||Magnesium Fluoride MgF2|
|Diameter Tolerance||+/- 0.02mm|
|Thickness Tolerance||+/- 0.02mm|
|Parallelism||30 arc sec|
|Wavefront Distortion||l/4 per 25mm|