# Fabry Perot interferometer used as a filter

1. Oct 10, 2011

### DiracRules

Hi all!!!

I'm studying Fabry Perot optical interferometer (with monochromatic light without taking time into account so far) and as its first application we studied it can be used as a filter, letting pass only certain frequencies
$\nu= \frac{mc}{2n_fd\cos(\theta_t)},\,\,m\in\mathcal{N}$ where c is speed of light, $n_f$ is the refractive index of the dielectric, d is its width and $\theta_t$ is the transmission angle.

That said, I was wondering: since the plot of $(\nu,T_tot)$ - Ttot being the total transmittance - reminds me the frequency spectrum of the sampling of a sinusoidal wave, can the interferometer be thought as a sampling device operating on the light wave?

I mean, since Fourier's transformation of the sampling of a sinusoidal wave is the repetition of Fourier's transformation of the wave, I thought that we can think backward: since we see the repetition of peaks, it can be the spectrum of the sampling (in time's domain) of the sinusoidal light wave.

I am wondering if it is craziness or if there is something not so foolish in my observation.
DR