Thorlabs LA1540-B Plano Convex Lens

What It Is / Key Specs

• Part: Thorlabs LA1540-B

• Type: Plano-convex spherical lens

• Material: N-BK7 glass

• Diameter: ½″ = 12.7 mm

• Focal Length: ~15 mm (design value ~14.9 mm ±1%)

• Anti-Reflection (AR) Coating: Broadband coating for 650–1050 nm

• Center / Edge Thickness: Center ~5.1 mm, edge ~1.8 mm

• Radius of Curvature (convex side): ~7.7 mm

• Back Focal Length (BFL): ~11.6 mm

• Surface Quality: 40–20 scratch-dig

• Centration: < 3 arcmin

• Clear Aperture: > 90% of the diameter

• Design Wavelength: 587.6 nm (for lens curvature design)

Applications / Where It’s Useful

This lens is useful in a variety of optical setups, especially when:

• You need to focus or collimate light in the visible to near-infrared (650-1050 nm) range.

• You want a short focal-length, small-diameter lens for compact beam-shaping.

• You’re building optical experiments, microscope systems, or laser alignment setups.

Because it’s plano-convex, it’s best used such that the curved side faces the incoming (collimated) beam when focusing, to minimize spherical aberration.