What machine did Leonardo da Vinci design to grind lenses more precisely?

Leonardo da Vinci designed lens-grinding machines to shape optical lenses more precisely.

Grinding a lens requires removing material in a controlled way and producing a carefully curved surface. Leonardo’s mechanical studies explored rotating tools, abrasive material, and adjustable supports that could make the process more consistent than purely hand-shaped work.

These designs belong to his broader investigations of optics and precision machinery. Leonardo studied how light enters the eye and how images are formed, but his lens-making machines should not be treated as completed modern optical factories. The surviving drawings are engineering proposals and studies.

A lens-grinding machine is not itself a microscope or telescope. Those instruments use lenses to magnify or form images; the grinding machine is a manufacturing device used to produce the curved glass components they require.