[Kiwamu, Elli, Nutsinee, Cao]

We attempted to align the SLED beam onto the Y-arm HWS today. We scanned the SR3 in both pitch and yaw and identify three beam spots. Two spots could be obseved while scanning in yaw and in pitch. One of them was a common spot. The two spots were separated by 800 micro-radians.

           PITCH: To identify two spots in PITCH, use wedge angle of ITMY: vertical wedge with angle of .07 degrees.    Thus ITMy causes beams to separate in vertical direction

                  Increasing pitch of ITMY leads to moving both vertically separtated spots move upward, which implies that the beam reflected off the HR surface is vertically below the beam reflected off the R surface.

                  This was re-confirmed by scanning the SR3. We noticed that the beam identified as the HR beam occurs consistently at 800 mico-radians below the AR beam.

           YAW: To identify  two spots in YAW, we turned the CO2 lasr on and apply 4W power to observe change in spherical power measured by the HWS. The spherical power only changes for the beam spot at lower SR3 yaw value. The only issue theat occurs was that when compared to simulation, the changes is in the opposite sign.  But we are sure that this the right beam spot, which is surpringly the beam spot at the beginning

We then walk the SR3 to nominal value and performed fine adjustment of the picometer to centre the beam spot on the y-arm HWS.

We then check the X-arm HWS, this is where new problem arises. After scaning the SR3 both in pitch and yaw, we optimise to centre the X SLED beam on the HWS. Despite this, the image streamed from the X-HWS shows a beam with lower intensity, as compared to Y arm HWS beam. The Gaussian beam profile is also not clearly visible. We performed a CO2 laser test again and observed spherical power measured by the X-HWS. The results shows that the spherical power value is very noisy and doesn't have an apparent trend hat it is supposed to have as the CO2 laser is on.