Calcium fluoride (CaF2), commonly known as optical crystals in many applications, is a significant material used primarily for its optical properties. It is naturally occurring as the mineral fluorite and is characterized by its low refractive index and high resistance to thermal shock, making it ideal for use in optical components under varying temperature conditions.
Properties and Uses:
Optical Transparency: Calcium fluoride is transparent across a wide range of wavelengths, from ultraviolet (UV) to infrared (IR). This makes it extremely useful in high-specification optical components such as windows, lenses, and prisms, especially for UV and IR applications.
Thermal Stability: It has a very low coefficient of thermal expansion, which ensures minimal dimensional changes in fluctuating thermal environments.
Hardness and Durability: Although it is less hard compared to other optical materials like fused silica, it is still durable and suitable for many optical applications.
Applications:
- Photolithography Equipment: Used in the semiconductor industry where deep ultraviolet light is needed for the photolithography process.
- Spectroscopy: Ideal for use in spectroscopic windows and lenses because of its broad band spectral transmission.
- Telescopes and Cameras: Employed in some telescope lens systems and camera lenses for its UV and IR transmission properties.
- High-Power Lasers: Components made from calcium fluoride are used in laser systems due to their ability to withstand high-energy laser beams without degrading.
The synthesis and processing of CaF2 for optical quality require careful control to ensure purity and clarity, which are crucial for its performance in high-precision optical systems.
Shape Optics is Able to Offer
- CaF2 IR viewport Windows for Infrared Thermography at 8m to 10m
- Various optics for IR & VUV application, using our CaF2 crystal materials
- Good quality CaF2 crystal blank materials
- OEM service for good quality CaF2 crystals
Capabilities
- Maximum Diameter 375mm
- Clear Aperture 85%
- Surface Flatness /4 @633nm
- Surface Quality 20/10
Wavelength (nm)
The Transmittance Curve of CaF2 Crystal (under 3mm thickness)
CaF2 Crystal Properties
Optical Properties
| Transmittsnce Range / m | 0.13～9 |
| Transmittance | > 94% @0.3~7m |
| Refractive Index | 1.39908 @5m |
| Reflection Loss | 5.4% @5m (both surfaces) |
| Absorption Coefficient / cm-1 | 0.03 @2.6 2.9m |
| dn/dT / ℃-1 | -10.6 x 10-6 |
Physical Properties
| Density / g.cm-3 | 3.18 |
| Melting Point / ℃ | 1360 |
| Thermal Conductivity / W.m-1K-1 | 9.71 @286K |
| Thermal Expansion / ℃-1 | 18.85 x 10-6 / ℃@273K |
| Knoop Hardness / kg.mm-2 | 158.3 with 100g indenter |
| Specific Heat Capacity / J.Kg-1K-1 | 854 |
| Dielectric Constant | 6.76 @1MHz |
| Youngs Modulus (E) / GPa | 75.80 |
| Shear Modulus (G) / GPa | 33.77 |
| Bulk Modulus (K) / GPa | 82.71 |
| Elastic Coefficient | C11=164; C12=53; C44=33.7 |
| Apparent Elastic Limit / MPa | 36.54 (3900 psi) |
| Poisson Ratio | 0.26 |
Chemical Properties
| Solubility / g | 0.0017 @ 20℃ |
| Molecular Weight | 78.08 |
| Crystal Structure | Cubic System |
| Cleavage Plane | (111) |
Calcium Fluoride crystal shows good optical and thermo-mechanical properties, can be used for optical windows, lenses, prisms within a wide range from 130nm to 9m. It has optical properties of isotropy, low absorption and low refractive index, which made CaF2 gain the unique advantages in the application of high power lasers.
Shapeoptics offers a comprehensive range of materials and advanced equipment for custom and OEM optical components, leveraging over 20 years of expertise in manufacturing lenses, prisms, windows, and more. We utilize high-quality materials like UV and IR grade fused silica, Germanium, and ZnSe, among others. Our state-of-the-art techniques and equipment minimize waste and optimize delivery times. Our in-house capabilities include standard and custom coatings across the UV-NIR spectrum, ensuring high quality and compliance with all industry standards. For precision and reliability in optics, contact Shapeoptics for your next project.
