  Linear colliders offer unique opportunities to study gamma-gamma (gg),
gamma-electron (ge) interactions. Using the laser backscattering method one can
obtain gg, ge colliding beams with an energy and luminosity comparable to that
in e+e- collisions. This work is a part of the Conceptual Design of TESLA/SBLC
linear colliders describing a second interaction region for gg, ge collisions.
We consider here possible physics in high energy gg, ge collisions, e -> g
conversion, requirements to lasers, collision schemes, attainable luminosities,
backgrounds, possible lasers, optics at the interaction region and other
associated problems.
