1. LIGO-G9900XX-00-M LIGO R&D1 ITM Cooldown Spot Size Measurements at LLO, Jan. 2007 Valera Frolov Doug Lormand Antonio Luchianetti Sam Waldman Phil Willems

2. LIGO-G9900XX-00-M LIGO R&D2 Goals of Measurement Cooldown measurements at LLO in Nov. 2006 yielded inconclusive results Want to repeat & refine measurement »Use AS camera for both ITMX and ITMY »Reduce scatter in spot size measurement if possible »Better understand systematics

3. LIGO-G9900XX-00-M LIGO R&D3 TCS Cooldown Calibration ITMX horizontal (100 mW) ITMX vertical ITMY horizontal (300 mW) ITMY vertical Note: TCS power settings are not well calibrated

4. LIGO-G9900XX-00-M LIGO R&D4 Spot Drifts During TCS Calibration Are Relatively Small ITMX horizontal ITMX vertical ITMY horizontal ITMY vertical

5. LIGO-G9900XX-00-M LIGO R&D5 Faraday Lens Measurement (4W forward + 4W back, spot off ITMX) Faraday horizontal spot size Faraday vertical spot size Faraday horizontal drift Faraday vertical drift

6. LIGO-G9900XX-00-M LIGO R&D6 IFO Cooldown Curves Don’t Look Much Like TCS Cooldown Curves ITMX horizontal ITMX vertical ITMY horizontal ITMY vertical

7. LIGO-G9900XX-00-M LIGO R&D7 Spot Sizes Vs. MMT1 Steering ITMX MMT1 pitch ITMX MMT1 yaw ITMY MMT1 pitch ITMy MMT1 yaw camera vertical camera horizontal

8. LIGO-G9900XX-00-M LIGO R&D8 Try Stabilizing Spot Location During Cooldown ITMX: not stabilized stabilized

9. LIGO-G9900XX-00-M LIGO R&D9 More Stuff to Do Correct IFO cooldown data using MMT1 steering measurements (in progress) Check actual TCSY power with 300 mW requested Measure Faraday thermal lens and drift with 8W forward & 0W return power Actively stabilize AS spot location using variant of BS servo Find and characterize better spot on AS camera w.r.t. drifts and operate there