camilla.compton@LIGO.ORG - posted 10:23, Friday 11 November 2022 - last comment - 12:33, Friday 11 November 2022(65729)
Turned ITM HWS SLEDs off via medm for this power up
As Dan found that we are getting IR coupling into the CCD camera, we turned ITMX and ITMY HWS SLEDs off via medm for this power up to measure how much IR we are seeing.
Comments related to this report
daniel.brown@LIGO.ORG - 12:24, Friday 11 November 2022 (65734)
For reference attached are the HWS images at the ITMs. There doesn't appear to be any on ITMY, there is a small amount of light on Y still around (480,350) could be from an LED or some other scattered light. The ITMX spots will be from 1um BS AR reflection I expect.
Images attached to this comment
aidan.brooks@LIGO.ORG - 12:33, Friday 11 November 2022 (65735)
For reference attached are the HWS images at the ITMs. There doesn't appear to be any on ITMY, there is a small amount of light on Y still around (480,350) could be from an LED or some other scattered light. The ITMX spots will be from 1um BS AR reflection I expect.
This is partly AR reflection and partly orthogonal polarization from the BS AR surface.
Seems like the filters that strip this off have been removed.