BK7 Optical Glass

BK7 is the most widely used optical glass for visible and near-infrared applications. A borosilicate crown glass, BK7 offers excellent optical clarity, good homogeneity, and reasonable cost — making it the default choice for many general-purpose optical components.

• Excellent visible transmission (>92% per surface uncoated)
• High material homogeneity and consistency
• Good chemical resistance and stability
• Cost-effective — widely available in stock sizes
• Suitable for most visible and NIR applications

• Not suitable for UV below 350nm
• Higher thermal expansion than fused silica
• Lower LIDT than fused silica for high-power lasers
• Hygroscopic under extreme humidity conditions
• Limited IR transmission beyond 2μm

Imaging lenses and objectives

Beam splitters and prisms

General-purpose windows

Spectrometer optics

Machine vision systems