[en] The radiation from bend magnets, wiggler magnets, and, most recently, undulator magnets, has spawned a new era on photon research at wavelengths beyond the visible part of the spectrum, extending to 100 keV and beyond. These devices routinely generate photon beams with cw powers in excess of a kilowatt, collimated into angles of a few arcsec, and originating from source areas much less than a square millimeter. The subsequent generations of storage rings will drive these performances even further, resulting in qualitatively new scientific opportunities. (author). 53 refs.; 7 figs.; 1 tab