Checking around in IMC whether there are any beam clipping. Still on the way.

• Ghost beam "MCF_GB7" in this document (or Ghost f in this document) can be seen without IMC lock when 30-50mW P-pol was input; in Fig.1, the left fainter beam spot was this, and this ghost was caught by the black shield. See also 15970, 15986, 16008. 1W would be enough to do full check.
• The beam height seemed slightly lowered (a few mm?) from the nominal 210 mm maybe during the IMC aligning work... probably. In 16410, we adjusted the beam height but it again seemed moved. Need further check. Fig. 2 is a photo of the output beam from MCo (the IMC resonation was blocked), Fig. 3 is between MCi and MCo, Fig. 4 is for the beam from MCe to MCi. Hmmm... need a laser level, otherwise a parallax will lead a wrong conclusion. It must be nice to set monitors for IMMT1T immediately.