Schematic of a standard Earth Fleet Grav Laser
A grav laser is a large and immensely powerful beam weapon for space combat. A Grav Laser is a large chemical laser which uses an artificial gravity field to focus the beam instead of a crystalline lens. This enables it to have beam energies and emitter diameters much higher than would be possible otherwise, by avoiding the problems of overheating associated with conventional designs. A grav laser can fire a beam so powerful that it would melt any physical lens in its path, no matter how optically perfect. For low-power shots for use in testing and such, retractable crystalline lenses are often fitted.
Behind the Scenes
The design for these weapons was partially inspired by the Grasers (Gamma Ray Lasers) seen in the Honor Harrington series by David Weber.