Today Daniel, Sheila, Dana, and myself went to EX to look further into the ALS system to hopefully fix the locking trouble that we've had (summary in alog74323). We hooked up a spectrum analyzer before the phase frequency discriminator and verified that we saw the 40MHz signal that should be there. We then checked on table to make sure that there was no clipping on the beatnote path (table layout - D1800270). The two beams looked decently co-aligned after ALS-BS3, and while it wasn't perfect it was deemed good enough. The beam on the ALS-M3 mirror was on the very far edge of the optic, but seemed to be fully making it to the BBPD ALS-PD7.

While we were looking at the beam on the table, Daniel tried tuning the temperature and current of the laser and ended up back at the settings we started with (June 30th alog70976).

There was no obvious reason for any of the locking troubles we've seen recently, and now the beatnote power (H1:ALS-X_FIBR_A_DEMOD_RFMON) seems to be back up to where it has been even though we didn't make any changes. I guess we'll revisit this in 6 months when it happens again...