Large Precision N-BK7 Biconvex Lens – 95 mm Diameter

This is a high-quality surplus N-BK7 biconvex (double-convex) singlet lens in pristine condition – an excellent opportunity to acquire a large-aperture precision optic at a fraction of new retail cost. S

Key Specifications

• Diameter: 95 mm (full clear aperture)

• Effective Focal Length (EFL): Approximately 140 mm (~f/1.5 – relatively fast for a singlet)

• Material: N-BK7 optical glass

• Center Thickness: ~18 mm

• Edge Thickness: ~2 mm (symmetric biconvex design)

• Surfaces: Uncoated (typical bright neutral reflections, ~4% loss per surface)

• Condition: Pristine – lab surplus, optically perfect

This lens is ground and polished to precision standards, making it suitable for demanding optical setups where large beam diameters are needed.

Applications & Uses

This versatile biconvex lens is ideal for a wide range of optical projects:

• Laser Optics: Excellent for focusing or collimating medium to large laser beams (e.g., CO2, HeNe, diode systems). The fast ~ f/1.5 ratio provides strong convergence for beam conditioning or expansion setups.

• Imaging & Projection: Use as a simple objective in DIY telescopes, enlargers, projectors, or magnifiers. Pairs well in relay systems or with other elements to correct aberrations.

• Beam Expansion: Combine with a shorter-FL negative lens for Galilean or Keplerian beam expanders.

• Experimental & Educational: Perfect for optical bench demonstrations, schlieren photography, interferometry setups, or teaching lens principles (focusing, image formation, chromatic aberration).

• Condenser Systems: Large aperture makes it great for illumination condensers in microscopes, projectors, or lighting optics.

• Hobbyist & Maker Projects: Telescope building, custom cameras, art installations, or solar concentrators (with appropriate safety precautions).

While uncoated (optimal for specific wavelengths where AR isn’t needed), it performs beautifully in visible light with high transmission. For higher efficiency, professional AR coating can be added later.