What type of machine did Leonardo da Vinci design to manufacture mirrors with a curved surface?

Leonardo da Vinci designed a concave-mirror grinding machine for shaping curved reflective surfaces.

The machine used coordinated mechanical movement to grind and polish a mirror into a concave form. Leonardo was interested in optics, especially the behavior of light, image formation, and the possibility of concentrating sunlight. A precisely shaped concave mirror could reflect incoming rays toward a focal point.

This design is often connected with Leonardo’s studies of burning mirrors and optical instruments. It was not a telescope: a telescope is an assembled instrument for observing distant objects, while Leonardo’s machine was a workshop device for manufacturing a curved mirror.

The concept also shows why Leonardo’s inventions crossed disciplinary boundaries. Mechanical engineering supported his optical investigations, while his experiments with materials and geometry informed the machine’s construction. The sketch is evidence of a proposed manufacturing process, not a documented mass-production system.