Calcium Fluoride (CaF₂) is a crystalline optical material with an extraordinarily broad transmission range spanning from the deep ultraviolet through the mid-infrared. Its extremely low dispersion makes it invaluable for UV optics, spectroscopy, and ultrafast laser systems.
Deep UV spectroscopy
Ultrafast laser systems (low dispersion)
Excimer laser optics
FTIR and IR spectroscopy
Lithography and UV imaging
| Property | Value |
|---|---|
| Coefficient of Thermal Expansion (CTE) | 18.9 × 10⁻⁶ /K |
| Thermal Conductivity | 9.71 W/m·K |
| dn/dT (Thermo-optic Coefficient) | -10.4 × 10⁻⁶ /K at 633 nm |
| Maximum Operating Temperature | ~600°C |
CaF₂ has a negative dn/dT, meaning its refractive index decreases with temperature. High thermal conductivity helps dissipate heat in laser applications.
Standard coating types available for this material. Custom coating designs available on request.
Soft material, relatively easy to machine but prone to cleavage along crystal planes. Handle with care during fabrication.
Requires care to avoid subsurface damage. Can achieve excellent optical surfaces with proper technique.
Slightly hygroscopic — store in dry conditions. Prolonged exposure to moisture may degrade surface quality.
Moderate to high cost. Size limited by crystal growth process. Larger blanks command premium pricing.
No single optical material is perfect for every application. Here are situations where Calcium Fluoride (CaF₂) may not be the best fit, and what to consider instead.
→ Consider: Sapphire or Fused Silica
CaF₂ is relatively soft (Mohs ~3) and sensitive to mechanical stress. For rugged or high-vibration environments, sapphire or fused silica will last longer.
→ Consider: Fused Silica or BK7
CaF₂ has moderate thermal conductivity and can crack under rapid temperature changes. Fused silica has near-zero thermal expansion for better thermal shock resistance.
→ Consider: BK7
CaF₂ is expensive to grow and fabricate. For visible-only work where its special UV/IR properties aren't needed, BK7 is far more cost-effective.
→ Consider: Fused Silica or BK7
Growing large CaF₂ boules without defects is difficult. For windows larger than 150mm diameter, fused silica or BK7 may be more practical.
Browse our catalog of precision optical components available in Calcium Fluoride (CaF₂)
Consider fused silica for visible/NIR applications where cost matters. CaF₂ is preferred for UV-to-IR broadband transmission, but it is softer and more fragile than most optical glasses. Handle with care during mounting.
Send us your specifications. Our engineering team will review and respond with material and coating recommendations within 24 hours.
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