Even today, 19 years after Hubble's launch, it's not all that uncommon to hear a newscaster refer to "Hubble's lens". I once heard it used by an announcer on a science show produced by the Space Telescope Science Institute, the agency that runs Hubble!
The thing is, Hubble doesn't use a lens. It has a mirror.
Galileo used a telescope with a lens, as did everyone up until Isaac Newton. He was the genius who figured out that a properly shaped mirror could focus light as well, and has advantages over a lens: mirrors need only be ground on one side (lenses have two), and mirrors can be made larger than lenses because they can be supported all across their back side, while lenses must be supported around their circumference, where the glass is thinnest and most vulnerable.
Over a certain size, lenses are simply impractical, so mirrors are used. Hubble's primary mirror is 2.4 meters across, about 8 feet. Although it's the biggest mirror for astronomy ever lofted into space, it's considered small by ground-based standards; many telescopes today have mirrors...
