High resistance to thermal and mechanical shock
High transmittance from 120 nm to 8 µm
<30 arc-second parallelism
Resistant to chemical attack
Low surface reflectance even uncoated
Newport\'s Magnesium Fluoride Optical Windows are transparent over a very wide 120 nm to 8 µm spectral range. Magnesium Fluoride is durable, resistant to both thermal and mechanical shock, and has a high laser damage threshold.
As Magnesium Fluoride has the lowest refractive index of all optical glasses, AR coatings are not required to have low surface reflectance. Therefore the windows are not limited to the spectral band of a broadband AR coating, permitting use at any wavelength from Deep UV to IR (120nm - 8µm). This is ideal for applications requiring transparency across multiple wavelengths simultaneously, such as spectroscopy or fluorescence imaging of samples under vacuum. The windows may also be used in excimer laser applications due to transparency in the deep UV.
Magnesium fluoride is extremely durable comparing to other materials which are transparent from the UV to IR spectrum, making it an excellent choice for many biological and military imaging applications.
| Material | Magnesium Fluoride |
| Thickness | See Window Information Table |
| Size tolerance | +0.0/-0.1 mm |
| Refractive Index | ne=1.39 and no=1.38 @ 560 nm |
| Surface Quality | 40-20 scratch-dig |
| Surface Flatness | λ/2 @632.8 nm |
| Parallelism | < 1 arc minute |
| Clear Aperture | 90% of central diameter |
| Hardness (Knoop) | 415 kg mm-2 |
| Young\'s modulus | 1.39 x 1011 N m-2 |
| Thermal Limit | 14-15 W m-1 K-1 @ 300 K |
| Thermal expansion coefficient | Parallel: 14 x 10-6 K-1 @ 310 K ; Perpendicular: 8.9 x 10-6 K-1 @ 310 K |