Evan, Paul

Yesterday we took beam size measurements on ISCT of the beam directly reflected from ITMY. I didn't get around to processing the data until later, hence the late post.

The results were: ITMY direct reflected beam size = 2329um (x-axis), 2398um (y-axis)

As expected, the ITMY direct relfected beam size is smaller than the ITMX direct reflected beam size, but only by 6% or so. I will check against my model to see if the difference in sizes makes sense quantitatively, though the unknown non-thermal lens in ITMY may make it difficult to draw a strong conclusion from this.

I attach again plots of the ASD of the beam spot centroid position and radius throughout the first 60 seconds of logging.