CaF2 (Calcium Fluoride) plano-concave lenses are high-performance negative optical elements manufactured from high-purity calcium fluoride single crystals. Featuring one flat surface and one concave surface, these lenses provide a negative focal length used for beam divergence, projection systems, and optical path expansion, boasting exceptionally wide transmission from the ultraviolet (UV) through the visible and into the infrared (IR) spectrum with minimal wavefront distortion.
Technical Applications & Industrial Use Cases
Due to their broad transmission window, extremely low refractive index change with temperature, and high resistance to laser-induced damage, CaF2 plano-concave lenses are vital across precision industries:
- Laser Beam Expansion & Divergence: Utilized as divergence elements in beam expanders and spatial filtering assemblies across UV, visible, and infrared laser systems[cite: 10].
- Thermal Imaging & Multi-Spectral Optics: Deployed in thermal cameras, FLIR systems, and infrared detectors operating in the 3 to 5 micrometer spectral band[cite: 10].
- Scientific & UV Instrumentation: Perfect for excimer laser optics, spectrophotometers, and astronomical observation equipment requiring broad broadband transparency.
Key Specifications & Performance Advantages
- Material: High-purity Calcium Fluoride (CaF2) single crystal optimized for wide-band transmission.
- Design Wavelength: Calibrated for precision performance with strict focal length tolerance.
- Surface Quality: High-precision 60-40 scratch-dig with tight centration tolerance (< 3 arcmin) and protective chamfers.
- Coating Options: Available uncoated or featuring specialized low-absorption infrared anti-reflective (IR1) coatings (average reflectance < 1.5% across 3 to 5 micrometers) to maximize throughput.
