The photon structure function measurements from LEP

One of the most powerful tools to investigate the internal structure of quasi real photons is the measurement of photon structure functions in deep inelastic electron photon scattering at ee colliders. These measurements have by now a tradition of sixteen years since the first F γ 2 was obtained by PLUTO [1]. The LEP accelerator is a unique place for the measurements of photon structure functions until a high energy linear collider is realised. It is unique because of the large coverage in Q owing to the various beam energies covered within the LEP programme, and due to the high luminosities delivered to the experiments. Structure function measurements are performed by all four LEP experiments, however concentrating on different aspects of the photon structure. The main idea is that by measuring the differential cross section