Before, the locking scheme was to produce an error signal with the PDH box, send its output to the electronic amplifier box and then to the laser EOM for the fast loop and to the Laselock input. The drawback was changing one loop gain, changes also the other loop gain.

Now, the locking scheme is the error signal coming from the PDH box is directly sent to the Laselock input and in a same time to the electronic amplifier box which is only connected to the laser EOM for the fast loop. then, one has the fast loop gain which can be changed with the electronic amplifier box, one has the slow loop gain which can be changed on the Laselock and if one needs to change global gain of both loops, one can move the PDH diffuser.

This scheme is currently used and locked the setup.