Lens Calculator

Describe your beam and where you need it — the tool recommends the right lens.

Input Beam Diameter⌀1Output Beam Diameter⌀2Distance from LensdFocal Lengthfλ = 632.8 nmPlano-Convex
Your Beam
What You Need
Lens Parameters
Best for collimated-to-focus. Orient curved side toward collimated beam.
Recommended Lens
100 mm FL · 1/2" ⌀ · f/7.9 · N-BK7 · Plano-Convex
Calculated Results
Minimum Lens Diameter
85% clear aperture → next standard size: 1/2" (12.7 mm)
2.4mm
Radius of Curvature
51.5mm
f-number
f/50.00
Focused Spot Diameter (1/e²)
40.29µm
Spherical Aberration (est.)
Within diffraction limit
0.000λ
Airy Disk Diameter
First zero of diffraction pattern (2.44 λ f/#)
77.20µm
Depth of Focus (2× Rayleigh range)
4.03mm
Back Focal Length (est.)
Based on ~2.0 mm estimated center thickness
99.3mm
Refractive Index — N-BK7
At λ = 632.8 nm (Sellmeier equation)
1.51509
Abridged Optics — Lens Calculator v1.0Gaussian beam calculations assume TEM₀₀ mode

All information, equations, and calculations have been compiled and verified to the best of our ability. For mission-critical applications, we recommend independent verification of all values. If you find an error, please let us know.