At several locations of the beam delivery system (BDS) of a future linear collider (FLC), beam spot sizes ranging from several hundreds to a few micrometers have to be measured. The large demagnification of the beam in the BDS and the high beam power puts extreme conditions on any measuring device. With conventional techniques at their operational limit in FLC scenarios, new methods for the detection of the transverse beam size have to be developed. Laser based techniques are capable of measuring high power beams with sizes in the micrometer range. General aspects and critical issues of a generic device based on Compton scattering are outlined and specific solutions proposed.