A lasgun (pronounced lāz-gŭn) is a fictional directed-energy weapon in the Dune universe created by Frank Herbert. In Terminology of the Imperium, the glossary of the 1965 novel Dune, Herbert provides the following definition:
LASGUN: continuous-wave laser projector. Its use as a weapon is limited in a field-generator-shield culture because of the explosive pyrotechnics (technically, subatomic fusion) created when its beam intersects a shield.
The interaction of a lasgun beam and a Holtzman field results in subatomic fusion and a nuclear explosion. The magnitude of this blast is unpredictable; sometimes it destroys only the shielded target and gunner, sometimes the explosion is more powerful than atomics. Using lasguns in a shielded environment can result in military and environmental catastrophe, though at one point in Dune Duncan Idaho deliberately allows shield-lasgun contact as a discouragement to his enemies. In God Emperor of Dune (1981), lasgun fire is described as "blue arcs"; a lasgun is noted to be "heavy" in Chapterhouse: Dune (1985). A cutteray is described in Dune as a "Short-range version of a lasgun used mostly as a cutting tool and surgeon's scalpel."
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