A prospect and retrospect - the Japanese case.

The early through recent history of synchrotron radiation research in Japan, since the initial efforts in 1962, is reviewed. Following a period of parasitic use of an electron synchrotron, Japanese users attempted to build a storage ring as a dedicated soft X-ray source, which was completed in 1974. It opened up a new era of second-generation synchrotron radiation research. The Photon Factory, a dedicated X-ray source commissioned in 1982, provided a much wider research area as well as a number of technical innovations, among which insertion devices brought the further prospect of significant improvements in the properties of sources. As a consequence, the new concept of a light source oriented towards full exploitation of insertion devices, or the idea of a third-generation source, was created. The motivations and developments which led to Spring-8, a third-generation Japanese X-ray source that is currently being commissioned, will be reviewed briefly.