Steps taken to commission the ITMY ring heater pair:
- Updated to the recently committed Beckhoff code that Joe B and Adam M worked on yesterday.
- Added the calibration values that Aidan B had recommended for running the ring heaters.
- Opened up a strip tool to monitor the vacuum pressure with the closest gauge (HVE-LY:Y1_120BTORR)
- Turned the ring heaters on to low power (~.01 Watts) to make sure that the channels were working properly
- Increased the power to 1 Watt for a 4 hour period starting at 12:00PM Pacific Time, keeping an eye on the pressure gauge previously mentioned.


Upper:
Requested Power = 1.00 Watts
Measured Voltage = 5.94 Volts
Measured Current = 0.17 Amps 
Calculated Power = .99 Watts
Calculated Resistance = 34.94 Ohms

Lower:
Requested Power = 1.00 Watts
Measured Voltage = 5.92 Volts
Measured Current = 0.16 Amps 
Calculated Power = .98 Watts
Calculated Resistance = 37.0 Ohms

A four hour trend of the pressure gauge and ring heater settings is attached.

A quick, back-of-the-envelope calculations shows that the ring heaters are working properly. The next step for measuring the thermal lensing would be to measure the beam diameter of a single reflection off of the back of ITMX independently and then changing the radius of curvature of ITMY using the ring heater to match. This requires looking at the REFL beam either in the HAM1 chamber or on the ISCT1 table, depending on how much power we are able to get out of REFL.  The Thorlabs beam profile we have on site requires a minimum of ~1e-5 Watts of incident beam power to function.