Illuminating Disjoint Line Segments in the Plane

It is shown that a set of $n$ disjoint line segments in the plane can always be illuminated by $\lfloor (n+1)/2\rfloor$ light sources, improving an earlier bound of $\lfloor 2n/3\rfloor$ due to Czyzowicz et al. It is also shown that $\lfloor 4(n+1)/5 \rfloor$ light sources are always sufficient and sometimes necessary to illuminate the free space and both sides of $n$ disjoint line segments for every $n\geq 2$.