What type of machine did Leonardo da Vinci design to grind optical lenses?

Leonardo da Vinci designed a lens-grinding machine for shaping optical lenses.

His notebooks contain mechanical studies related to grinding and polishing curved surfaces. A machine of this kind could use controlled motion to shape glass more consistently than hand work alone, an important goal for making lenses and studying optics.

Leonardo’s interest in lenses was connected to his investigations of vision, light, reflection, and the anatomy of the eye. His designs show how he linked scientific observation with mechanical engineering.

The drawings should not be mistaken for evidence that Leonardo invented the telescope. Telescopes appeared later, and Leonardo’s lens studies were part of a broader optical program rather than a completed telescope project. His machine concepts nevertheless anticipated the need for precision lens manufacture.