We alighed first-loop PDs (PD_A and PD_B) and we connected cables.
We were able to get PD signal via DGS.
The figure shows power spectrum of output from PD_A, PD_B and AOM driver.
The legends shows below
1. K1:PSL-ISS_AOM_MON_CON_IN -> AOM offset signal
2. K1:PSL-ISS_PDA_MON_CON_IN -> PDA DC output
3. K1:PSL-ISS_PDB_MON_CON_IN -> PDB DC output
4. K1:PSL-ISS_AOM_MON_CON_IN(REF0) -> AOM offset signal (same as 1.)
5. K1:PSL-ISS_PDA_MON_CON_IN(REF1) -> PDA electrical noise
6. K1:PSL-ISS_PDB_MON_CON_IN(REF2) -> PDB electrical noise
In this figure, it seems that power spectrum in high frequency region limitted by ADC noise, so we have to incert whitning filter.
Furuhata kun, what is the unit for the y axis?
If it is in uncalibrated digital counts, the signals you are sending to the ADCs seem super small beucase they use something like a few counts only, according to the spectra. Do you have a way to increase the scalar gain somewhere?
The unit for the y axis is uncalibrated digital counts.
The output from PD is about -0.25V (-800counts).
Now, detected beam power P is very low,
P = 0.25[V] / 1000[ohm] / 0.78[A/W] = 0.32mW,
where 1000[ohm] is transimpedace R and 0.78[A/W] is responsivity of PD.
In the experiment in Toyama, PD detected 10mW beam, so we will increase the detected power in the future.
K1:PSL-ISS_PDA_MON_CON_IN conected PDA DC output, although it has to be conect PDA Filter output in ordinary case.
Power spectrum [counts/Hz^(1/2)] of filtered output(input beam is 7mW) is shown in the figuer.
Anyway whitening filter is need,becase higher power is low shot noise.
