Photonic field generator
From Memory Alpha, the free Star Trek reference.
A photonic field generator creates a massive, bubble-like environment where multiple holographic "individuals" may exist and interact with their environment, experiencing photonic life, as it were.
As opposed to holographic projectors, the photonic field generator allows unrestricted access to all areas within the coverage of the field. Such technology allowed for a homeworld to exist for Iden and other self-aware holograms on a class Y planet, uninhabitable by humanoid lifeforms. (VOY: "Flesh and Blood")
