aidan.brooks@LIGO.ORG - posted 13:31, Thursday 30 October 2014 - last comment - 11:10, Friday 31 October 2014(14742)
Required central heating to correct ITMX static lens: 201mW
Based on the TCSX central heating calibration (62.3 micro-diopters single-pass per Watt) and the calculated static lens of -80213m, we require:
+201mW of central heating on ITMX to correct this static lens.
Edited 31-Oct-2014: this isn't correct because of an error in the laser power calibration
The calibration of defocus vs delivered power is incorrect as the delivered power channel, H1:TCS-ITMX_CO2_LSRPWR_MTR_OUTPUT, was not calibrated correctly.
I went back and reviewed the delivered power for this measurement:
Before thermal lens: H1:TCS-ITMX_CO2_LSRPWR_MTR_INMON = 172.7 counts
During thermal lens H1:TCS-ITMX_CO2_LSRPWR_MTR_INMON = 2113.4 counts
The new gain through the filter banks is 7.2087E-4 Watts per count.
This means 1.399 Watts was applied to ITMX during the thermal lens measurement.
Further analysis of the HWS measurements of the thermal lens show:
Therefore, the single-passed ITMX steady-state thermal lens coefficient is 28.1 micro-diopters per Watt
Based on the TCSX central heating calibration and the calculated static lens of -80213m, we require:
+444mW of central heating on ITMX to correct this static lens.