Chien-ming, Yu-hang, and Aritomi

Today we found power fluctuation after we lock IRMC. Then we did lots of investigation. Especially we put power meter at some position to monitor laser power coming from the main laser. However, as we found before, we didn't see power fluctuation from it.

However, later we used photodetector directly monitor the part of the beam from the main laser. The signal from PD is shown in the attached figure. We could see a clear signal fluctuation.

Then we blocked the light going to SHG, and this power fluctuation disappears.

This proves that it is really necessary to install the second FI for the main laser.