Laser propagation characteristics in laser-based alignment experiment at the KEKB injector linac

A new laser-based alignment system is under development at the KEKB injector linac. Towards the Super-KEKB project, the new system is strongly required for increasing the operation stability and enhancing the quality of electron and positron beams. The new laser optics for the generation of so-called Airy beam has been developed for the laser-based alignment system. The new system comprises a flat mirror with two apertures of different diameter and spherical mirror. By using this system, the 100-m-long laser propagating is tested, and its profile is measured. It is confirmed that the measured profile has a good agreement with the simulation result. We report the overview of the new alignment system, the preliminary test result, and the simulation result in detail. (author)