richard.savage@LIGO.ORG - posted 08:01, Saturday 06 December 2014 - last comment - 17:38, Monday 15 December 2014(15479)
ETM high-resolution images with Green and IR light resonating
SudarshanK, TravisS, EvanH, AlexaS, RickS Using the Pcal beam localization cameras at both end stations, we took images of the ETM surfaces under three conditions: IR and Green resonating; IR only resonating, and Green only resonating. Attached below are two composite images composed of four separate images taken with the same camera settings: Upper Left: Xarm Green Lower Left: Xarm IR Upper Right: Yarm Green Lower Right: Yarm IR The images in the first composite were taken with the following camera settings: F8, ISO 200, 30 second exposure, WB-cloudy. For the second composite image the aperture was F29 (~13 times less light) The Yend camera was re-focused for the IR-only images, but the Xend camera was not re-focused.
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Thomas Abbott at LLO applied the Pcal beam localization analysis the the LHO ETMY image to calculate the position of the center of the optic in the image from last Friday. The image below contains lines that indicate the center of the optic using the Pcal image analysis.
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Attached is a picture of the original FirstContact (FC) sheet, circa ~Jan 2014, showing the "IAS window" which is a thinner film of FC in the central 3" of the larger sheet. To me, the shape of the FC window looks similar to the 3" ring showing up in green on the recent optic photo above. SYS is working with us to get our cleaning game plan together in order to remove the ring. As well, they are investigating other possible scenarios of where the ring came from if not the window. Note, there was a full FC sheet re-cleaning in March that apparently did not remove all of the ring that was left behind apon the removal of the first sheet. To be continued...
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I've attached an overlay of (a) the SolidWorks CAD view of ETMy along the PCal camera path and (b) the PCal camera image of H1 ETMy (scaled and rotated). Since SolidWorks does not diffract the image viewed through the ETM optic, I indicate the shift in the ETM Telescope Baffle aperture as well. Three of the 4 bright areas are along the ETM Telescope Input aperture/baffle edge (a coincidence?). (The upper one is red.) One of the 4 bright spots does not correspond to any feature in the CAD image and is likely a spot of residual First Contact. As subsequently shown by the zoomed in PCal image using the Green Lantern flashlight (green LED) after venting (see entry #15635), it is simply a coincidence that the two prominent bright areas appeared to be along the ETM Telescope baffle aperture edge.
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