Marc, Pierre (remote)

Since the replacement of the EOM, we had difficulties to achieve automatic lock of IRMC.

This is mainly due to the fact that we're using 78MHz sidebands instead of 88MHz and had to change the PD in reflection of the IRMC for a non-resonant one.

First, the reflection signal of a scan of IRMC is different than before.

The base is at 1.38V and the TEM00 dip at 692mW while in the past the dip was negative.

This meant that we had to modify the pin P4 strap from pin 2-3 to pin 1-2.

Also, the threshold value was tweaked looking at this signal.

Then, the error signal was about 83mVpk while it was about 10 times more in the past.

Despite putting the servo gain to max I could not achieve lock (even though it was detected from the blinking LED).

I used the CCFC amplifier (32dB) and got an error signal about 2.2Vpk.

As the error signal slope and triangle scan slope are identical, the lock can be achieved with the switch INV.

I put a gain of 0.5 and could lock reliably the IRMC.