# Laser aperture transmission calculator

## About this calculator

This calculator computes the fraction and absolute power of a Gaussian laser beam that passes through a circular aperture. The transmitted fraction is given by

$\frac{P}{P_0} = 1-e^{-\frac{2a^2}{w^2}}$

where $a$ is the radius of the aperture and $w$ is the $1/e^2$ beam radius at the aperture. The total transmitted power can also be computed if the incident power $P_0$ is known.