Exceptional Spectral Range
Useful transmission from approximately 0.13 to 10 µm, depending on optical grade, thickness, surface finish, and coating.
Optical Fluoride Crystal
Calcium Fluoride (CaF₂)
Broadband Optical Performance from Deep UV through the Infrared.
A low-index cubic crystal offering excellent ultraviolet, visible, and infrared transmission, low dispersion, and low stress birefringence for demanding laser, spectroscopy, imaging, and analytical optical systems.
Why Calcium Fluoride
A Versatile Fluoride Crystal for UV, Visible, and IR Optics
Calcium fluoride combines a wide transmission range with low refractive index, high Abbe number, and good environmental stability. It is widely selected for UV and excimer laser optics, spectroscopy, infrared windows, imaging systems, and analytical instrumentation.
Low Refractive Index
Low index reduces uncoated Fresnel reflection and supports high transmission across broad wavelength bands.
Low Dispersion
A high Abbe number supports low chromatic dispersion in precision imaging and broadband optical systems.
Low Stress Birefringence
Cubic crystal symmetry makes CaF₂ isotropic, supporting polarization-sensitive and precision laser applications.
Engineering Properties
Optical, Mechanical, and Thermal Characteristics
Representative values for optical-grade calcium fluoride. Final values vary by crystal grade, wavelength, orientation, thickness, supplier specification, and test method.
Physical & Mechanical Properties
| Chemical Formula | CaF₂ |
|---|---|
| Crystal Structure | Cubic fluorite structure |
| Density | Approximately 3.18 g/cm³ |
| Knoop Hardness | Approximately 158 |
| Young’s Modulus | Approximately 75.8 GPa |
| Poisson’s Ratio | Approximately 0.26 |
| Thermal Expansion | Approximately 18.85 × 10⁻⁶/K |
| Melting Point | Approximately 1360°C |
Optical Properties
| Transmission Range | Approximately 0.13–10 µm, grade and thickness dependent |
|---|---|
| Refractive Index nd | Approximately 1.434 |
| Abbe Number Vd | Approximately 95 |
| Birefringence | Isotropic cubic crystal; low stress birefringence when properly processed |
| Reflection Loss | Low relative to many optical materials due to low refractive index |
| Coating Compatibility | UV, VIS, NIR, MWIR AR, beamsplitter, and custom coatings |
| Available Grades | VUV, UV, laser, spectroscopy, and infrared grades |
Optical Transmission
Broad Transmission from Deep UV to Mid-Infrared
CaF₂ is one of the most versatile broadband optical materials. Actual performance depends on crystal grade, thickness, surface condition, absorption bands, and coating design.
Representative only. Final transmission depends on grade, thickness, surface finish, absorption bands, and coating.
Material Comparison
When Calcium Fluoride Is the Best Fit
| Property | Sapphire | BK7 | Fused Silica | CaF₂ |
|---|---|---|---|---|
| Deep-UV Performance | Very Good | Limited | Excellent | Excellent |
| Infrared Reach | Good | Limited | Limited | Excellent |
| Chromatic Dispersion | Moderate | Low | Low | Very Low |
| Scratch Resistance | Excellent | Moderate | Good | Low |
| Thermal Expansion | Low | Moderate | Very Low | Higher |
Manufacturing Capabilities
From CaF₂ Crystal Blank to Finished Optical Component
COE Sapphire supports prototype, low-volume, and repeat production of precision calcium fluoride optics with controlled fabrication, coating, and inspection.
Precision Machining
Controlled cutting, edging, beveling, drilling, and custom geometry fabrication for a relatively soft and cleavage-sensitive crystal.
Optical Polishing
Precision flat, spherical, and custom polishing with process control to minimize subsurface damage and edge defects.
Optical Coating
UV, visible, NIR, MWIR AR, beamsplitter, and application-specific multilayer coatings.
Quality Assurance
Dimensional inspection, interferometry, surface inspection, transmission verification, and documentation.
Design Guide
Specify the Right Calcium Fluoride Optical Component
Provide optical grade, operating wavelength, dimensions, tolerances, surface quality, flatness or power, wedge or parallelism, clear aperture, edge treatment, coating, quantity, and environmental requirements.
Discuss Your SpecificationMaterial GradeVUV, UV, laser, spectroscopy, or IR grade
Surface QualityCommercial through precision optical grades
Flatness / PowerApplication-specific interferometric control
Wedge / ParallelismPrecision parallel, wedged, or custom geometry
Edge TreatmentProtective bevel or chamfer recommended for fragile edges
CoatingsUV, VIS, NIR, MWIR, beamsplitter, and custom coatings
Related Optical Components
Calcium Fluoride Components Manufactured to Your Specification
Frequently Asked Questions
Calcium Fluoride FAQ
What is calcium fluoride commonly used for?
CaF₂ is widely used for UV and excimer laser optics, spectroscopy windows and lenses, infrared systems, analytical instruments, fluorescence microscopy, and broadband imaging.
What wavelength range can CaF₂ transmit?
High-quality calcium fluoride can provide useful transmission from the deep ultraviolet into the infrared, commonly cited at approximately 0.13–10 µm depending on grade and thickness.
How does calcium fluoride compare with fused silica?
Both materials provide strong UV performance. CaF₂ extends farther into the infrared and has lower dispersion, while fused silica is generally tougher, has far lower thermal expansion, and is easier to process.
Is calcium fluoride birefringent?
CaF₂ has a cubic crystal structure and is intrinsically isotropic. Residual stress from processing or mounting can still introduce stress birefringence.
Does calcium fluoride require special handling?
Yes. CaF₂ is softer and more cleavage-sensitive than fused silica or sapphire, so protective edge design, clean handling, careful mounting, and controlled cleaning are recommended.
Can calcium fluoride be optically coated?
Yes. CaF₂ is compatible with UV, visible, near-infrared, mid-infrared, beamsplitter, and custom multilayer coatings when coating design and process conditions are matched to the substrate.
Can COE Sapphire manufacture custom CaF₂ shapes and tolerances?
Yes. COE Sapphire can manufacture custom windows, lenses, prisms, wedges, apertures, holes, edge treatments, and application-specific tolerances.
What information is needed for a CaF₂ quotation?
Please provide material grade, wavelength range, dimensions, tolerances, surface quality, flatness or power, wedge or parallelism, clear aperture, coating, quantity, and inspection requirements.
Custom Calcium Fluoride Optical Components
Request a QuoteReady to Discuss Your CaF₂ Project?
Send us your drawing, specification, or application requirements.