[Cao, Ellie, Dave O, Aidan, Nutsinee, Kiwamu]

We scanned SR3 last night for 7:50:00 (LHO alog 25600). We use Aidan's MATLAB script from LLO alog 9368 to identify beam spots on the HWSY.  The three plots below are

1)HWSY_refl_map_early.jpeg  showing the averaged intensity early in the scan

2) HWSY_refl_map_lin.jpeg showing the averaged intensity after full scan with linear intensity colormap

3) HWSY_refl_map_log.jpeg showing the avegaed intensity after full scan with log intensity color map

The spots look very different from that recorded at LLO as expected due to the wrong optics install in vacuum. The images of full scan show four beam spots. We first checked the source of two upper bright spots by misaligning the ITMY. There were no change in the bright beam spot observed on the HWSY. Therefore, these must have come from the 2 surfaces of the compensation plate (CP). The beam correponding to the left bright spot is currently centered on the camera.

We then checked the bright spot immediately underneath the current position of pitch and yaw (which is at the center of the plot). By misaligning the ITMY, we saw the beam spot on the camera move. By further adjusting the pitch and yaw of ITMY, we could see the beam spot disappear. Therefore, this beam must have come from one of the surface of the ITMY.  The high intensity shown on SR3 scanning plot gives a strong indication that this beam comes from the HR surface of ITMY.

We will center this beam onto HWS this afternoon by walking the SR3 and periscope mirrors this afternoon. We are also planning to to run a definitive test tonight to confirm the source of this beam spot and see how far off we are from centering the beam by turning  the ring heater on with the HWS running.