M. Todd, S. Muusse, C. Compton, S. Dwyer
I wanted to get another measurement of what the HWS think the coupling factor is for thermal lens from ring heater power.
The HWS were not on, so after filling out a work permit Camilla and I went out and turned on the HWS SLEDs. Then we restarted the HWS codes in the individual computers. We also asked Jim to take ITMY ISI to fully isolated.
After waiting about 25 minutes for the HWS to get a baseline reading we turned up both ITMY and ITMX ring heaters by 4W (2W/segment). The HWS will track the defocus and I will compare with my models tomorrow morning. I wanted to do both ITM ring heaters to get a self-consistent measurement.
We also plan on doing single bounce OMC scans tomorrow morning with the ITMs being sufficiently thermalized after the RH turn on. This should give us another lens (punny pun here) to look at the thermalization business.
Here is a screenshot of this test. For ITMX this shows -78 uD of spherical power for 4W of total ring heater power. This means -9.75uD/W of defocus of the substrate lens.
For ITMY this is -82uD of spherical power for 4W, which is -10.25uD/W of defocus. This agrees reasonably well with the -9.9uD/W that is used in finesse.