What Leonardo da Vinci machine was designed to grind concave mirrors?

Leonardo da Vinci’s mirror-grinding machine was designed to shape and polish concave mirrors. He studied the device as part of his wider interest in optics, reflected light, and the construction of scientific instruments.

Concave mirrors require a carefully controlled curved surface. Leonardo’s design used mechanical movement to keep grinding action consistent across the mirror, potentially making the process faster and more precise than hand work alone. His notes show attention to the relationship between curvature, reflection, and image formation.

The machine was not a telescope itself. A mirror-grinding apparatus makes an optical surface; it does not automatically create a complete observing instrument. Leonardo also investigated lenses, vision, shadows, and the geometry of light.

The surviving drawings are evidence of an engineering proposal rather than proof that a successful production machine operated in his workshop. They nevertheless show how Leonardo connected practical craftsmanship with mathematical optics.