Laser Focusing & Spot Size Simulator
Visualize Gaussian beam focusing in real time. Adjust Focal Length, Input Beam Diameter, and M² Beam Quality to calculate focused spot size, depth of focus, and peak intensity instantly.
Interactive optics labLaser Focusing & Spot Size
Start here
1Choose a focusing example.
2Adjust beam diameter or lens focal length.
3Point at the beam to inspect it.
Move or tap to measure beam diameter and intensity
Focused spot diameter—
Peak intensity—
Depth of focus—
Rayleigh range—
Logarithmic peak-intensity scale
—
Start with an example beam
Educational starting points—not product specifications1 · Input beam
A larger beam at the lens produces a smaller diffraction-limited spot.
1 mm10 mm
Ideal 1.0Poor 5.0
2 · Focusing lens
Shorter focal length gives a smaller spot but also a shorter depth of focus.
5 mm300 mm
70%100%
3 · Power & view
Power changes intensity, while the axial range changes only the view.
0.1 W20 W
±1 zR±10 zR
f-number—
Beam parameter product—
Power after lens—
What this means: Adjust a parameter to explore focusing.
Continuous-wave Gaussian model · ideal thin lens · no clipping or aberrations·
w₀ = 2M²λf/(πD)·I₀ = 2Pout/(πw₀²)