A vuv and soft x‐ray light source based on spontaneous anti‐Stokes scattering from atomic population stored in a metastable level is proposed. It is shown that the source has a maximum brightness equal to that of a blackbody at a Boltzman temperature characteristic of the population of the metastable level. This maximum brightness is attained as the media approaches two‐photon opacity. The source should have high resolution, may be of picosecond time scale, and on a pulsed basis should be brighter than other laboratory‐scale vuv light sources.