What optical machine did Leonardo da Vinci design for making mirrors?

Leonardo da Vinci designed a mirror-grinding machine for shaping and polishing optical mirrors.

The machine was intended to mechanize the laborious process of grinding a curved surface. Leonardo’s design used coordinated mechanical motion to keep an abrasive tool moving across the mirror, helping produce a more regular surface than hand work alone could provide.

This invention is sometimes confused with a telescope. A mirror-grinding machine makes an optical component; it is not itself an observing instrument. Leonardo was interested in mirrors because polished and curved surfaces could improve the study of light, vision, reflection, and image formation.

The design belongs to Leonardo’s wider investigations into optics and workshop technology. His notebooks contain many proposals that were never manufactured at full scale, so the machine is best described as a design rather than a proven working product. Its significance lies in applying mechanical precision to optical craftsmanship.