[Furuhata, Sakamoto, Kitazawa, Kokeyama]

We changed laser power of PSL by rotating HWP. The laser power was increced to maximum power to get enough power for ISS. At this time, pickoffed beam for FSS (No.3) and PSL output (No.8) were dumped. Power at several points before and after changing are below.

After increacing beam power, we tried to lock ISS. As a result, ISS was locked! The stability of laser intensity are shown in attached figures. We measred power spectrum of free run, controlled and controlled (boost mode) beam detected by in-loop PD and out-of-loop PD. The data in first figure were measured in usual circumstances (light on, fan is running). The data in second figure were measured in dark circumstances (fan is still running). Seeing these figure, in-loop was able to be stabilized, while out-of-loop was able to be stabilized. Additionally data in dark circumstances are totally more stable. I suppose stability of out of loop will be better if we use PD box (for sheltering light and wind).