Sheila, Camilla, Begum, Ryan Short

Summary: Beam is aligned to filter cavity, and through SFI1 + SFI2, with only a couple of % loss.  We are clipping on B:L2 apperture, which we plan to remove tomorow.  

This morning Camilla and I worked on the alignment from the VIP to the filter cavity.  We started by looking at the centering on the A:L2 aperture, which Begum and Camilla adjusted yesterday using a power meter downstream (90528).  To me the beam looked a bit high on this aperture, but we have seen in the past that looking at the aperture isn't a good way to judge the centering and it is best to rely on the power meter, so we've left A:M1 and A:M2 as they were we plan to leave them this way. 

We adjusted A:M3 to center the beam on FC1, then walked ZM3 sliders to get the beam retro reflected in return off ZM1.  Camilla moved ZM3 off in pitch so we could better judge yaw, then off in yaw so we could better judge pitch.  This gave us a beam in transmission of SFI1, we adjusted  B:M1 to clear the aperture attached to B:L2, and to bring us close to centered on the SFI2 aperture.  The beam looks good in pitch on the B:L2 aperture but slightly to the -X side of the aperture, not enough to be concerned about clipping.  We also adjusted B:M2 and B:M4 to get the beam transmitted through SFI2 and the ZM4 iris, but it is clipping on the B:L2 aperture.  (Labeled cartoon)  We can see that the beam makes it through the SQZT7 iris and to the SQZT7 IR PD, but it is quite low on the first iris.   This afternoon we reset the positions of the irises in front of ZM3 and ZM1 to center on this new alignment which we believe is correctly retro-reflecting off the filter cavity, screenshot of these slider positions is attached.  

We made an attempt to use a non-magnetic allen key to remove the retaining ring for the apperture on B:L2, but ring is too tight for us to remove it from the akward angle.  We think that we will have to pull it out of the chamber so we have space to use the correct tool for the retaining ring.  

This afternoon, Ryan Short, Begum and I went back and tried to make some beam profile measurements of the beam returning off FC1 by inserting a beam splitter.  We ultimately weren't able to find a spot to place the beam splitter and phasics camera where the beam was the right size without blocking either the OPO reflected beam or the path to FC1.  

We did take 6 measurements with the phasics camera of the beam reflected off ZM1 towards the filter cavity, with the translation stage lens in 3 different positions at two different camera locations.