Calcium Fluoride (CaF2) sheets are widely utilized as precision optical substrates and protective components in ultraviolet (UV), visible, and infrared (IR) systems. Known for their exceptional transparency, low refractive index, and mechanical stability, CaF2 sheets serve as foundational materials in high-performance optical and laser technologies, especially where resistance to radiation and temperature fluctuations is critical.
Material Overview
CaF2 crystallizes in a face-centered cubic fluorite lattice (space group Fm̅3m), providing isotropic optical and mechanical behavior. The material exhibits a refractive index of approximately 1.43 at 589 nm and maintains high transmittance (above 90%) from 130 nm in the UV to 9 µm in the IR range. Its mechanical properties include a hardness of 158 kg·mm−2, a Young’s modulus of around 75 GPa, and excellent resistance to thermal shock. According to Su et al. (2005), temperature-gradient–grown CaF2 crystals show exceptional homogeneity, making them ideal for optical sheet fabrication. In thin or sheet form, CaF2 exhibits minimal birefringence and maintains optical flatness under variable humidity and thermal cycling conditions. Furthermore, Muniz et al. (2021) observed that CaF2-based glass–ceramic systems retain structural stability and consistent optical transmission, even under continuous high-intensity laser exposure. These characteristics make CaF2 a preferred substrate for precision optical assemblies, photonics, and spectroscopy.
Applications and Advantages
CaF2 sheets are widely used in laser windows, spectrometer optics, infrared camera lenses, and lithography components. Their high UV transparency and low dispersion make them particularly suitable for excimer laser optics and UV lithography in semiconductor processing. Hahn (2014) reported that CaF2 is the leading material for deep-UV projection lenses due to its low birefringence and high resistance to radiation-induced color centers. Additionally, the combination of low refractive index and superior chemical inertness allows CaF2 sheets to function as protective optical covers in chemically aggressive or high-radiation environments. In high-vacuum systems, they serve as infrared windows for spectroscopy and emission monitoring, while in cryogenic optics, their low thermal expansion ensures dimensional precision across wide temperature gradients.
Goodfellow Availability
Goodfellow supplies premium Calcium Fluoride (CaF2) sheets in research-grade purity and optical quality. Sheet thicknesses, surface finishes, and dimensional tolerances can be customized to suit optical, photonic, or analytical instrumentation needs.
Explore Calcium Fluoride CaF2 – Sheet – Material Information and other advanced materials in Goodfellow’s online catalogue: Goodfellow product finder.
References
- Su, L., Dong, Y., Yang, W., Sun, T., Wang, Q., Xu, J., & Zhao, G. (2005). Growth, characterization and optical quality of CaF2 single crystals grown by the temperature gradient technique. Materials Research Bulletin, 40(5), 761–767. https://doi.org/10.1016/j.materresbull.2005.01.006
- Muniz, R. F., Soares, V. O., Montagnini, G. H., Medina, A. N., & Baesso, M. L. (2021). Thermal, optical and structural properties of sodium calcium silicate glass and glass-ceramic containing CaF2. Ceramics International, 47(17), 24821–24831. https://doi.org/10.1016/j.ceramint.2021.05.224
- Hahn, D. (2014). Calcium fluoride and barium fluoride crystals in optics. Optik & Photonik, 9(4), 38–41. https://doi.org/10.1002/OPPH.201400066