After the removal of polarization sensors for ITMX HWS an adjusting HWS STEER M10 to center onto ITMX HWS, as reported in alog25718 , we performed CO2 and RH tests on the ITMX HWS. The results show that the ITMX HWS beam is aligned and working as expected.

CO2 Test:

         We performed the CO2 test on March 1, turning up the CO2 laser deliver power to 4W between 1140906458 and 1140908050. The spherical power behaves as expected (see image CO2_ITMX_1Mar_SP.png )

                             - The spherical power increases up until tthe CO2 is turned off with the maximum change in spherical power of about 60 microdiopters

                              -After CO2 laser is turned off, the spherical power can be seen to decrease slowly before the ITMX HWS is stopped streaming

           The gradient plot also shows this change in spherical power:

                             -All arrows are pointing inward towards the location where the CO2 beam is positioned on the test mass (see image CO2_ITMX_Gradient_1Mar.png) , which has an offset towards the +ve y-direction and -ve x-direction from the centre of the HWS beam. 

                             Since the CO2 laser beam alignment is optimized for interferometer beam, an offset is acceptable.

RH Test:

              We performed the RH test on March 6 to check for the alignment of the ITMX HWS beam on the test mass. The HWS ran between 1141342135 and 1141351367. Both upper and lower RH's on ITMX is turned on to 1W for two hours between 1141342544 and and 1141349746. The recored spherical power also behaved as expected (see image RH_ITMX_5Mar_SP.png):

                               -The spherical power starts decreasing slowly as the RH is turned on.

                               - After  RH run,  the maximum decrease in spherical power is approximately 70 microdiopters before starting to increase back to 0 again. The time scale between after RH is off and increase in spherical power is about 30 minutes.

               The gradient plot shopws the evidence of this change in spherical power. All arrows grow outwards from the center and distributions of dx and dy change are more or less uniform around 0 (no apparent skewness) , which also imply that the ITMX HWS beam is correctly aligned on the center of ITMX. (see image  RH_ITMX_Gradient_6Mar.png ).