At its simplest, a point-defense laser grid is a system of hundreds of meshed, phased-array, variable-frequency, plasma laser elements (on its parent starship, these are the glossy black domes speckling the hull), capable of outputting an arbitrary number of variable-power beams, limited only by the capacity of the controlling computer, along an equally arbitrary number of bearings.
In its most benign civilian application, the laser grid protects the hull against incoming mass, by vaporizing small particles entirely, and by causing outgassing of the surface elements of larger ones in such a way as to produce thrust sufficient to redirect their course – acting, in effect, as a portable laser broom. A standard military laser grid fulfils this function on a larger scale, vaporizing and redirecting incoming kinetic slugs using the same essential principle, while penetrating and disabling AKVs. Such a grid is typically able, in full-autonomic mode, to keep the volume of space within a dodeciad miles of the parent starship clear of all material objects not explicitly tagged by IFF as friendly.
A military-grade grid, of course, has certain other applications. One, for example, is serving to propel various otherwise-unguided packages by use of the grid to heat inert ablative propellant attached to them, functioning as the power element of a laser thermal drive. Another, less advertised, is that of dealing with enemy starships that have been disabled, but which decline to surrender and which do not possess any unusual value to be recovered by an opposed boarding action: specifically, a disabled starship within effective range of a laser point-defense grid can be conveniently sliced and diced into effectively-inert fist-sized cubes.