Laser Beam Divergence Calculator

Calculate how much your laser beam spreads over distance.

Laser Parameters

Solve For

Wavelength (λ)

Beam Waist Radius (w₀)

Divergence Results

Enter parameters to calculate divergence

Quick Reference

λWavelength

w₀Beam waist radius

θDivergence angle (half)

π3.14159...

Overview

Laser beam divergence describes how fast a laser beam expands as it travels. For a Gaussian beam, it is fundamentally limited by diffraction. This calculator supports both the theoretical Gaussian model and the practical measurement method using two points.

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Pro Tips

Smaller beam waists result in larger divergence angles due to diffraction.
For deep space communications, very low divergence (microradians) is required.
Beam expanders are often used to decrease divergence by increasing the initial beam diameter.

Fun Facts

"The laser beams used to measure the distance to the Moon expand to about 6.5 kilometers (4 miles) by the time they reach the lunar surface."
"Ideally, a perfectly collimated beam would have zero divergence, but diffraction makes this physically impossible."
"Green lasers (532nm) often appear to have tighter beams than red ones because our eyes are more sensitive to green light."

Formula: θ = λ / (π * w₀)

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