Arago had a nose for young talent. He discovered Augustin Fresnel (1788-1827), a physicist who worked alone, and invited him to the Observatory. That was where Fresnel established his theory about the wave nature of light, subsequently accepted by all. Together with Arago, he showed its veracity via a number of experiments. Around 1820, the two scientists collaborated once again to perfect the lighthouse lenses invented by Fresnel, and which are still in use.

caption : Fresnel lens - credits : Observatoire de Paris

To know more : Fresnel at the Observatory