BK7 vs K9 Optical Glass: Which is Best for Optical Domes?
- Share
- publisher
- FELIX GLASS
- Issue Time
- Apr 7,2026
Summary
Compare BK7 vs K9 optical glass for custom domes: refractive index, durability, and cost explained by Felix Glass. Find which material fits your industrial, aerospace, or CCTV needs.
Felix Glass breaks down the key differences between BK7 and K9 optical glass for custom optical domes. Both are high-quality materials, but they serve distinct use cases based on optical performance, durability, and budget.
BK7 Optical Glass
With a refractive index of ~1.51 and excellent transmittance across the visible spectrum, BK7 is a cost-effective, easy-to-process choice. It’s ideal for standard applications including CCTV camera domes, underwater housings, and general optical components. If you need reliable performance without premium pricing, BK7 is a practical solution.
K9 Optical Glass
K9 glass offers a slightly higher refractive index (~1.52) and superior optical clarity, making it preferred for high-precision projects. It performs better under temperature fluctuations and delivers sharper imaging, perfect for aerospace domes, medical imaging lenses, and high-end security systems.
Quick Selection Guide
- Choose BK7 for cost-effective, standard optical domes
- Choose K9 for higher precision, demanding applications, and enhanced clarity
At Felix Glass, we offer custom sizing, AR/AF/AG coating, and full OEM/ODM support for both BK7 and K9 optical domes. Whether you need standard or custom specifications, our team can deliver the right solution for your project. Contact us today for a free quote.