While inspecting the HR surface during (and just) after the FirstContact pull on the ETMX HR Surface yesterday, Travis and I saw a few points within the central 6" of the optic. Pictures are attached. One feature looks more like a small sleek or scratch rather than a dot. Upon review of the "map" we made roughly a year ago when the optic was in the bonding lab (also attached), we see that many of these were there during that inspection. In conference with GariLynn this morning, she confirmed my decision to move to chamber closeout and the door has just been installed on the chamber. We will digest these pictures and compare to previously obtained coating maps and metrology data.
Note, keep in mind that it is very difficult to say much about the optic surface quality based on these photos. It is difficult to state whether such observed features will be a problem, whether they are in the coating or on top of the coating, etc. TBC...
The scratch is found in the original polishing defect report at C1205029 Scatter measured with an integrating sphere shows several high points in the center 50 mm diameter, measured scatter is 7.7 ppm at E1500336 Thanks for the great pics!
Further analysis at https://dcc.ligo.org/T1800255 No new conclusions.