Mirrors aren't perfectly reflective, even if they deflect the majority of the energy for a fraction of a second, they will absorb some of it, scorching and beco

Mirrors aren't perfectly reflective, even if they deflect the majority of the energy for a fraction of a second, they will absorb some of it, scorching and becoming less shiny. You can use mirrors in laser optics because the beam is relatively diffuse at that end. I believe the best defence against a laser is likely to be a matter of having a material with a high vaporisation energy for its mass and to spin your projectile very fast so that the laser has difficulty maintaining a single point of contact. Or, you know, just fire your weapons in mass and hope to saturate their point defence systems. These things must cost like a million bucks each or something - mortar rounds must be pretty cheap. And war is, when you get down to it, an extension of logistics and thus to an extent of whether your system is cost effective.