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AdV-PSL (Laser Bench setup)
cleva, coulon, derossi, pillant - 17:04 Tuesday 29 January 2019 (44601) Print this report
Slave & PMC check, PZT TF

This mornig some checks on the Slave laser.

Slave PDH check

PMC PDH check

Slave piezo TF

--> no flaw found there, more data will come later

 

we found that the way the "pertub" channel is used to act as a safety actuator wrt the EIB ("hijack" of the original purpose) introduces an offset on the PMC lock and induces various coupling Freq-to-RIN

this has to be cured asasp

Comments to this report:
cleva - 15:15 Friday 08 February 2019 (44798) Print this report

Slave piezo channel investigation

# plot 1 gives the TF of the Slow pzt.

PZT fast removed, gain 1/f, Pertub on 'analog in' channel. TF = Injection error signal / Vpzt (voltage on the pzt, not pztmonit)

# plot 2 gives the TF of the Fast pzt

PZT fast disconnected, gain 1/f, Gain reduced as much as possible to avoid that slow the Slow pzt eats the perturb sent on the Fast pzt. Perturb on PZT_fast input. TF = Injection error signal / Vpzt

# Plot 3 gives the extrapolated TF of PZT_fast and PZT_slow channels from M11 AmpOp input to the Error signal. M11 Amp Op input receives the voltage which is then split into Fast and slow PZT channels (factor x90 between the gain of both channels in the rampauto).

we see that there is a mismatch between both slow and fast channel. 10 dB gain are missing on the fast channel to be as efficient as the slw channel.

# Plot 4 gives the Error signal and superimposed te TF of the slw pzt

we see that the above 10k strctures are due to the Slow piezo.

Those structure should be eaten by the fast piezo which seems to have only a very weak correction.

--> it seems there is an un-balance between fast and slow pzt channels. Altough it has been already checked ( 44340 )

--> the perf are anway compliant

# Plot 5 is te OLTF of the injection loop.

with ATT_RF = 20 dB, PDH = 1,8 Vpp

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cleva - 15:48 Friday 08 February 2019 (44800) Print this report

Follow-up of PDH: see plot (the signal SL_PZT_LF (PZTmonit on rampauto) has been multiplied by 100 for plot convenience)

- Rampauto is ELEC-9801-01

- locking range is 2,8 MHz

- PZT_Monit is 889 MHz/V

- offset is neglgible

the PDH has decreased from 4,2 to 3,1 V (*) since 10/12/19 and the locking range has decreased from 3,0  to 2,8 MHz since 10/12/19 (43966)

we did not try to optimize the ML to Slave alignment to avoid any possible misalignment wrt the neoVAN amplifier (long to revover)

(*) assuming ATT_RF = 14 dB

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Cleva, Coulon - 22:34 Monday 18 February 2019 (44919) Print this report

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cleva - 15:13 Tuesday 19 February 2019 (44925) Print this report

From plot there is only 3,5 dB between the pzt channels (instead of the 10 dB mentionned)

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