Applications that use positrons to probe the nature of matter currently rely on large, expensive accelerator facilities. In the Oct. 23, 2000, issue of Applied Physics Letters, a research team from Max Planck Institute for Quantum Optics and LMU München, both of Garching, Germany, and Lund Institute of Technology, also in Germany, reported that tabletop femtosecond laser systems may be suitable sources of antielectrons. The researchers exposed jets of helium to 130-fs pulses of 790-nm light from the Atlas laser facility at the Max Planck Institute. The gas produced a beam of multimega-electronvolt electrons, which generated positrons when they collided with a 2-mm-thick lead disc. The team estimated the intensity of the antimatter source at 2 x 108 Bq and suggested that the process could be scaled up with higher-intensity lasers for applications in positron annihilation experiments and in Doppler-broadening and positronium spectroscopy.