After the alignment of PR3 (see alog 9146), I aligned PR2 and PRM to get PRX flashing with the infrared light. The resultant alignment sliders are shown in the attached.
I could lock PRX quite smoothly, but it seems that some optics are oscillating in pitch by a non-negligible amount. Due to this, the intracavity field spatially wobbles by almost its beam size in pitch according to the CCD camera attached on BS's chamber. In this condition, the intracavity power observed by the POP_A QPD fluctuates more than 10%. We need to identify which optic is the culprit by using the oplevs and witness sensors. It seems to me that it is hopeless to try locking PRMI without improving this wobbliness.
An additional note:
The spatial beam motion was observed by introducing an intentional misalignment in ITMY and BS to let the ITMY reflection beam hit the BS baffle which is monitored by the BS CCD camera.