# Wavelength bandwidth converter

## About this calculator

This calculator converts a spectral bandwidth expressed in wavelength $\Delta\lambda$ at a certain central wavelength $\lambda_0$ to frequency domain. This calculator does not use the common linear approximation but computes the start and stop frequencies directly as follows:

$\nu_{start} = \dfrac{c}{\lambda_0 + \lambda / 2}$

$\nu_{stop} = \dfrac{c}{\lambda_0 - \lambda / 2}$

and the frequency bandwidth is then directly

$\Delta\nu = \nu_{stop} - \nu_{start}$

The center frequency is calculated from the center wavelength as

$\nu_{0} = \dfrac{c}{\lambda_0}$