The following is a calculator that helps you calculate the Divergence angle $\theta$, by inputting the Beam waist, Beam quality factor and Central wavelength.

www.simtrum.com

${\theta}= 2M^2 (\frac{λ}{\pi w_0})$

Input
Beam Waist, $w_0$:
mm
Beam Quality Factor, $M^2$:

Central wavelength, λ
nm


Output
Divergence angle, $\theta$ :
mrad