they weren’t using the special Fresnel-style lenses. There had been speculation about building this type of lens, but Fresnel was apparently unaware of them when he proposed his lens for ...

Fresnel, in 1821, managed to describe light ... resulted in a lens that corrected almost all aberrations. This type of lens is known as an Anastigmat, and the Protar was the first.

Fresnel lenses are all around us, but this vase puts the commonplace technology to work in an entirely new way. Borrowed From Old Lighthouses, A Method For Super-Powerful Solar Power With the help ...