China optical glass bk7 price manufacturers

When sourcing BK7 (known as K9 in China), you must prioritize Refractive Index (1.5168) and Abbe Number (64.17) consistency. Ensure the supplier provides data on optical homogeneity (Grade H1 to H4) and stress birefringence, which should ideally be ≤ 5nm/cm for precision applications. Additionally, verify the bubble class (e.g., B0 or B1) to ensure minimal inclusions for laser or imaging tasks.

Buyers must ensure the glass is RoHS and REACH compliant, meaning it is free from hazardous substances like lead and arsenic. For high-precision industries, look for suppliers following ISO 10110 for optical drawing standards and MIL-PRF-13830B for surface quality (e.g., 60/40 or 40/20 Scratch-Dig). Requesting a Material Test Report (MTR) is essential to verify these parameters.

The price is primarily driven by dimensional tolerances (e.g., ±0.01mm vs ±0.1mm) and surface flatness (measured in fractions of a wavelength, like λ/4 or λ/10). Coating requirements (AR, BBAR, or reflective coatings) can significantly increase the unit cost. Furthermore, volume-based pricing is standard; ordering in bulk can reduce costs by 20-40% compared to small prototype batches.

BK7 is a versatile crown glass used for lenses, prisms, and windows in the visible and near-infrared spectrum. If your application involves high-power lasers, you must specify a higher damage threshold. For industrial sensors or medical devices, prioritize chemical resistance and mechanical hardness to ensure long-term stability in harsh environments.

Optical glass is extremely fragile and sensitive to environmental changes. Insist on vacuum-sealed anti-static packaging and the use of pearl cotton or custom foam inserts. For bulk shipments, use wooden crates with shock-absorption indicators. Ensure the Incoterms are clearly defined; CIF or CIP are often preferred for high-value optics to include insurance coverage.

Focus on long-term yield rates rather than just the initial unit price. Ask for a Golden Sample before mass production. Negotiate a staged payment plan (e.g., 30% deposit, 70% after third-party inspection) to ensure quality leverage. Mentioning your intent to source via Made-in-China.com can also provide access to verified suppliers with established export track records.

Utilize third-party inspection services (like SGS or Intertek) to perform a pre-shipment inspection (PSI) focusing on surface accuracy and coating adhesion. Always use secure payment methods and verify the supplier's ISO 9001 certification to ensure they have a robust Quality Management System in place.