Fig. 4From: Do Leonardo da Vinci’s drawings, room acoustics and radio astronomy have anything in common?Caustic formed by rays incident on a hemispherical reflector. R radius of the reflector, dS, dSc ring on the reflector and on the caustic, x(θ),y(θ) Cartesian coordinates of the caustic (Eq. (3), dlc: the element of the section of the caustic [13]Back to article page