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Entry   correct parameters for locking the FP-cavity, posted by Ronic Chiche at ThomX igloo about software good_parameters.png
    Reply   correct parameters for locking the FP-cavity, posted by Ronic Chiche at ThomX igloo about software 
       Reply   correct parameters for locking the FP-cavity, posted by Ronic Chiche at ThomX igloo about software Correct_lock_parameters.png
Message ID: 328     Entry time: Mon Mar 4 09:32:06 2024     In reply to: 327     Reply to this: 331
 Author: Ronic Chiche 
 Status: Fixed 
 Type: info 
 Category: software 
 Location: ThomX igloo 
 Title: correct parameters for locking the FP-cavity 

this morning I solved the problem of the 33MHz frequency beating which should be ~12kHz between the generator (at the new frequency 33.3378MHz) and the laser cavity frequency (still at the old frequency which is 33.35MHz)...
the generator providing the 33MHz frequency has 2 channels, and only one was set at the proper frequency !

so, I set both channels at  33.3378MHz and now I measure properly ~12kHz of frequency beating.

now, we can move the laser cavity and the FP cavity in confidence.

Ronic Chiche wrote:

Today, we restarted the FP-cavity locking, after 3 weeks without using it.
those 3 weeks have been used to set the machine ring at the new (better) frequency : 500.067MHz (corresponding to a change of -183kHz)
or 33.3378MHz in fondamental frequency (corresponding to a change of -12.2kHz)

the power supply of FP-cavity photodiodes was OFF maybe due to some electrons losses.
we had to switch it OFF and ON to restart it.

the computer was restarted and we had to restart the applications and set their parameters.
in attachement, the parameters of the Kangoo software.
we had several "warnings" from the laser amplifier software => the amplifier stopped
but maybe it's because of the electrons not sent in the dump which pertubate the monitoring signal levels of the amplifier => to be confirmed

we had to do some alignment.
with 33% of  amplifier ratio, we had 49kW inside the FP-cavity.
we tried to move a bit the L-shape mirror but without any significant effect to improve the intra-cavity power.

we didn't start the laser and FP cavities length increase procedure.

surprinsingly, the beating frequency between laser cavity and 33.3378MHz is only 140Hz and not 12kHz as expected.... to be investigated
 

 

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