Photon colliders: the first 25 years

Abstract

In this invited talk at the ``historical'' session of PHOTON2005, I was asked to recount the history and the development, from its earliest days to the present, of the idea of photon colliders based on conversion of high energy electrons to high-energy photons at a future high-energy linear e+e- collider. Described in this talk are the general features and schemes of a photon collider, the evolution in understanding of what the parameters of a realistic photon collider are, possible solutions of various technical problems, the physics motivation, and the present status of photon-collider development. For a more detailed description of the photon collider at the ILC and a discussion of the associated technical issues, please refer to my talks at PLC2005, the conference that immediately followed PHOTON2005 (to be published in Acta Physica Polonica B as well).