Overview of MgF2 Windows
MgF2 windows are precision optical components made from crystalline magnesium fluoride. Due to the material properties, these windows are known for their exceptional durability and resilience, making them ideal for use in harsh environments, resisting chemical etching, mechanical stress, and thermal shock.
Optical Properties of MgF2 Windows
MgF2 windows have excellent optical transmission capabilities covering a wide range, from 120 nm in the deep ultraviolet (UV) range to 8 μm in the mid-IR range. This broad transmission range makes them particularly suitable for use as UV radiation sources and receivers, including applications targeting the hydrogen Lyman-alpha line.
Material Properties of MgF2
MgF2 has a melting point of 1255 °C and a density of 3.177 g/cm³, and is a tetragonal crystal type. To minimize birefringence effects, our optical windows are typically oriented with the rounded surfaces perpendicular to the c-axis of the MgF2 crystal. Customized random cut windows are also available upon request to meet specific application requirements.
Birefringence of MgF2
One of the unique properties of MgF2 is its birefringence, meaning that the material’s refractive index changes depending on the polarization and direction of travel of the light. This property results in birefringence, where an incident ray of light splits into two different rays, each taking a different path due to the different effective refractive indices.
The ray with the higher effective refractive index is called the “slow ray”, while the ray with the lower effective refractive index is called the “fast ray”.
When light enters the MgF2 window from air, the slow ray is refracted more toward the normal, creating different optical paths for the two components.
Handling and Caring for MgF2
While MgF2 is softer than fused silica, it is the hardest of the optical fluorides. Therefore, care must be taken during handling to avoid scratching or damaging it. With its exceptional combination of optical clarity and physical robustness, MgF2 remains the preferred choice for high-performance optical applications.
Conclusion
MgF2 optical windows offer versatile solutions for a range of applications, particularly in the UV and mid-IR regions. Their unique properties make them essential components in fields such as laser technology, spectroscopy and other advanced optical systems. For tailor-made solutions, custom manufacturing options are available to meet the specific needs of your project.
We Mok Optics offers many types of optical components. If you have any questions about these products, please feel free to contact us.
Email: info@mokoptics.com