Fig. 1
From: Do Leonardo da Vinci’s drawings, room acoustics and radio astronomy have anything in common?
a Drawing of caustic from Leonardo da Vinci’s notebook. The note below the picture in Fig. 1a, made in Leonardo’s famous reverse script, says that in concave mirrors of equal diameter, the one that has the shallower curve will concentrate the largest number of reflected rays onto a focal point, and “as a consequence, it will kindle a fire with greater rapidity and force” [9] © British Library Board, Source: Arundel MS 263. b Details of Leonardo’s drawing, (c, d) 3D views of the caustics created by spherical and cylindrical concave mirrors [10]