Calcium Fluoride (CaF₂) is a high-purity optical crystal extensively used in UV, visible, and infrared optical systems. Although it occurs naturally as fluorite, optical-grade CaF₂ is synthetically grown and precisely processed to achieve exceptional optical clarity, low absorption, and excellent thermo-mechanical stability.
With a broad transmission range from 130 nm to 9 μm, a low refractive index, and optical isotropy (no birefringence), CaF₂ is a preferred material for high-precision optical windows, lenses, and prisms in photolithography, spectroscopy, thermal imaging, astronomy, and high-power laser systems.
Optical Properties
- Transmission Range: 0.13 – 9 μm (UV to IR)
- High Transmittance: >94% @ 0.3 – 7 μm
- Low Absorption: Suitable for high-energy and precision optics
- Optical Isotropy: No birefringence
- Refractive Index: 1.39908 @ 5 μm
- Reflection Loss: ~5.4% @ 5 μm (both surfaces, uncoated)
- Absorption Coefficient: 0.03 cm⁻¹ @ 2.6–2.9 μm
- dn/dT: −10.6 × 10⁻⁶ /°C
Physical Properties
- Density: 3.18 g/cm³
- Melting Point: 1360 °C
- Crystal Structure: Cubic system
- Cleavage Plane: (111)
- Molecular Weight: 78.08
Mechanical Properties
- Knoop Hardness: 158.3 kg/mm² (100 g indenter)
- Young’s Modulus (E): 75.80 GPa
- Shear Modulus (G): 33.77 GPa
- Bulk Modulus (K): 82.71 GPa
- Poisson’s Ratio: 0.26
- Apparent Elastic Limit: 36.54 MPa (3900 psi)
Thermal Properties
- Thermal Conductivity: 9.71 W·m⁻¹·K⁻¹ @ 286 K
- Thermal Expansion Coefficient: 18.85 × 10⁻⁶ /°C @ 273 K
- Specific Heat Capacity: 854 J·kg⁻¹·K⁻¹
Electrical Properties
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Dielectric Constant: 6.76 @ 1 MHz
Chemical Stability
- Low solubility in water (0.0017 g @ 20 °C)
- Stable in most operating environments
- Suitable for vacuum and laser optics
- Care recommended for prolonged exposure to humid conditions
Typical Applications of CaF₂ Optics
- Photolithography & semiconductor equipment (deep-UV optics and high-purity projection systems)
- Spectroscopy & analytical instrumentation (UV–IR windows, lenses, and research optics)
- Infrared & thermal imaging systems (8–10 μm IR viewport windows, thermal cameras, sensors)
- High-power laser systems (low-absorption laser windows and lenses)
- Astronomical & precision imaging systems (telescope optics and UV/IR camera lenses)
Shape Optics CaF₂ Capabilities
Shape Optics Technologies supplies high-quality CaF₂ crystal materials and finished optical components for UV, VUV, and IR applications, backed by over 20 years of optical manufacturing expertise.
Product & Service Offering
- CaF₂ IR viewport windows for infrared thermography (8–10 μm)
- Optical windows, lenses, and prisms for UV–IR systems
- High-purity CaF₂ crystal blanks
- OEM and custom optical component manufacturing
Manufacturing Capabilities
- Maximum Diameter: Ø375 mm
- Clear Aperture: ≥85%
- Surface Flatness: λ/4 @ 633 nm
- Surface Quality: 20/10 scratch-dig
Why Choose Calcium Fluoride (CaF₂)?
Calcium Fluoride uniquely combines broadband transmission, optical isotropy, low absorption, and excellent thermal stability, making it ideal for:
- High-power laser optics
- Deep-UV photolithography
- Infrared thermal imaging
- Precision scientific and astronomical instrumentation
Its low refractive index and resistance to thermal shock provide critical advantages in high-precision and high-energy optical systems.