Niko, Tvo, Georgia
A couple of weeks ago (alog-44087) TVo and I posted a comparison of HWS contours for the ring heater, IFO beam, and CO2 beam positions on the HWS. Niko has since added a feature to the HWS contour code to calculate the centroid of the contours, which I am still tweaking up. This will help work out spot (mis-)centering on the ITMs using the Hartmann
Attached screenshot is the same contours as those from TVo's log with the centroids added (see blue spots, and position info in the plot titles). The full IFO and CO2 positions relative to the ring heater centroids is tabulated below:
| ITMX (x, y) | ITMY (x, y) | |
|
IFO beam centroid relative to RH centroid [mm, HWS] September 12 September 13 |
(+22, -0.5) (+24, 6) |
(+16, +6) (+22, +7) |
| CO2 beam centroid relative to RH centroid [mm, HWS] | (+2.1, -0.9) | (+5.9, +5.6) |
I don't think the 5mm shift in the IFO beam x position between September 12 and 13 is real but rather an indication of the uncertainty. It's interesting that we seem to generally be better aligned in x (yaw), and worst in y (pitch) given the snowman mode we see at the AS camera with the CO2 lasers on.
Currently the centroid calculation only uses the highest 1/3 of the wavefront contours, as using the full data biased the data away from the beam center. It also currently only works for cool-down data.
The headings in the figure are the wrong way around: ITMY is on the left and ITMX is on the right. The ring heater, ifo, and co2 labels are all correct though.