Shortest wavelength laser from harmonic generation

Records for the shortest wavelength at which coherent radiation has been achieved in the search for an x‐ray laser system are falling with remarkable speed:

▸ It was only in June that Henry Hutchinson, C. C. Ling and Daniel Bradley (Imperial College, London) reported at the Amsterdam Quantum Electronics Conference that they had extended the range of generation of coherent radiation into the extreme ultraviolet at 570 Å.

▸ After a preliminary paper in August, at the International Conference on the Physics of X‐ray Spectra, John Reintjes, Robert Eckardt, Nicholas Karangelen, Raymond Elton and Ronald Andrews of the Naval Research Laboratory (Washington, DC) and Chiao‐Yao She of Colorado State University report in a current Letter that they pushed the record down to 532 Å.

▸ Now, at the Tucson meeting of the Optical Society in October, the NRL group reported preliminary results indicating they had reached 380 Å.