NikoL, RickS

In response to comments that the 14 Hz harmonic of the Pcal injection at 7 Hz is larger (relatively) than it was in the past (it is still about -100 dBc), we adjusted the Optical Follower Servo (OFS) offset from the control room as follows:

1. Turn off the Pcal excitations
2. Open the OFS loop
3. Increase the OFS offset until the OFSPD value stops increasing or the loop breaks lock
4. Set the OFS offset (for example H1:CAL-PCALY_OPTICALFOLLOWEROFFSET) to half of the maximum OFSPD value
5. Re-enable excitations
6. Accept values in SDF

When we started, the loop offset was at 3.0, we had dropped it from 3.75 earlier in the day.  We left it at 2.95.  This is a ~20% decrease that might indicate that the laser output power is dropping, or that the AOM diffraction efficiency has decreased, or a combination of both.

We will measure the laser output power and begin to investigate further as soon as time and access allow.