A laser in which the beam passes through the lasant only once; mirrors are not required for the operation of such a laser, as they are with more conventional lasers which are sometimes called "cavity lasers" to distinguish them from superradiant lasers. Free electron lasers may also be superradiant; the laser beam of a superradiant free electron laser would pass once through the electric or magnetic field (instead of a lasant) in the presence of an electron beam.