Since the CO2 Y laser is busted, we have been trying to lock for the past few days with 0.5 W of central heating on the X CP, and no heating on the Y CP. This has resulted in a noticeable 02/20 contrast defect in the AS port during a simple Michelson lock.

We reduced the X CP heating to 0.25 W, which (in combination with 0 W on the Y CP) basically puts us at the O1 configuration. After making this change, we are able to keep the interferometer stable and fully resonant (at 2 W of PSL power, anyway).