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Home / All / BK7 vs K9 Optical Glass: Which is Best for Optical Domes?

BK7 vs K9 Optical Glass: Which is Best for Optical Domes?

Apr 7,2026
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.
James Fu, Sales Director of FELIX OPTICAL GLASS, and a poster displaying contact information for an optical glass deep-processing factory.James Fu, Sales Director of FELIX OPTICAL GLASS, and a poster displaying contact information for an optical glass deep-processing factory. 2
Learn more from our FAQ
What is the minimum order quantity for custom precision optical glass components?

FELIX OPTICAL GLASS offers highly flexible MOQs to support customer projects, including prototype testing, small-batch trial orders, and high-volume production. All products can be fully customized to your drawings, tolerances, and application standards. Please send us your specifications, and we will reply within 1-5 hours and provide an accurate quotation after careful evaluation within 1-2 days.

Can I get free glass samples for testing before bulk order?

Yes, our FELIX GLASS factory supports sample testing for a wide range of precision optical glass components and assemblies. The lead time for sample production is 3 to 7 working days. Please contact us today to arrange samples and obtain a customized solution that meets your needs.

What is the production lead time for custom optical glass components?

A: The production cycle for standard samples is 3-10 working days, while mass production requires 15-35 working days, depending on the complexity of the product and the order quantity. We provide reliable precision optical glass components and fast delivery services for orders from industries such as defense, industrial equipment, medical devices, shipbuilding, robotics, automotive, and aerospace. Please submit your project details so we can provide you with an accurate delivery schedule.

Are your optical glass products ISO, CE and RoHS certified?

All precision optical glass components from FELIX OPTICAL GLASS comply with ISO quality system standards as well as CE and RoHS requirements. We provide comprehensive test reports, spectral graphs, material certificates, and inspection documents for customer review. Please feel free to request complete certification details and a formal quotation at any time.

Do you offer one-stop custom optical glass processing services?

Yes. We offer a full range of precision optical glass component processing services, including CNC machining, precision grinding, optical polishing, chemical/physical tempering, vacuum coating (AR anti-reflective coating, AF anti-fingerprint coating, AG anti-glare coating, IR infrared coating), and screen printing. From raw materials to finished products, every step is completed in our own factory. Please tell us your needs, and we will provide you with the most cost-effective solution.

CONTACT US NOW FOR A QUOTE
We will respond promptly within 1 to 5 hours and provide an optimal, formal quotation within 1 to 2 days. Partnering with us is the smartest choice—start a mutually beneficial partnership today!
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With 19 years of experience as a precision optical glass expert, we provide comprehensive and satisfactory customized solutions.

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