Sizes and coatings are available upon your request. You could send us your specifications or drawings. We will be happy to return a quotation ASAP as the average response time is within 24 hours. Meanwhile our optical designers are always available to assist with your special needs, and our factories in China are ready to meet your quantity requirements. Calcium fluoride is often used in spectroscopic lenses due to its high transmission from 250nm to 7μm. Calcium fluoride is also commonly found in cryogenically cooled thermal imaging systems. Its low absorption and high damage threshold makes it a popular choice for laser optics. Calcium fluoride\'\'s low refractive index allows it to be used without an antireflective coating. Specifications: 1) Material: calcium fluoride single crystal 2) Diameter tolerance: ±0.0, -0.1mm 3) Thickness tolerance: ±0.2mm 4) Clear aperture: >80% 5) Parallelism: 1\'\' arc minute or as requested 6) Surface quality: 80 - 50 scratch and dig, or as requested 7 Flatness: λ/2 at 632.8mm 8) Bevel: