  High energy photon colliders based on laser backscattering are a very natural
extension of a e+e- linear colliders and open new possibilities to study of the
matter. This option has been included in the pre-conceptual designs of linear
colliders and work on Technical Design Reports is in progress. The physics
motivation for photon colliders is quite clear though more studies are needed.
The proof of its technical feasibility and the search for the best solutions is
of first priority now. In this talk we discuss: physics motivation, laser
problems and new possible solutions, and generation of low emittance beams
needed for obtaining very high luminosities.
