Rays of light trapped by conics

In a previous note [2], some geometric constructions were shown which can be interpreted as a ray of light trapped in a polygon by successive reflections on the sides. The same question is addressed here, replacing polygons by conics or pairs of conics. In some cases, the light is concentrated towards a specific segment. The tools used for the computations are elementary geometry, calculus and, in some cases, Commutative Algebra Software.