What instrument did Leonardo da Vinci design for grinding and polishing optical lenses?

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

His notebooks include mechanical studies connected with the production of lenses, including devices intended to rotate and work a lens surface. Precise curvature and smooth polishing were essential because optical defects could distort an image. Leonardo’s interest in lenses was linked to his investigations of vision, light, perspective, and the anatomy of the eye.

This machine should not be called a telescope. Leonardo made observations relevant to optics, but there is no firm evidence that he built a working telescope. A lens-grinding machine is a manufacturing device, whereas a telescope combines lenses to magnify distant objects.

The designs illustrate Leonardo’s habit of joining scientific observation with workshop engineering. He treated optical instruments as mechanical problems involving controlled motion, accurate surfaces, and repeatable craftsmanship.