[kTanaka, Hirose] PRXARM lock trial Day 5. Continued from klog30134.
First, we did again FINE TUNING work. However, at this point, the offset was still on the RFPD of RFFL. However, when PRX was locked, somehow the offset dropped and the flash range crossed zero in RF45 signal. In this situation, PRXARM was successfully locked manually. However, the cause of the offset on the RF45 signal is unknown.
Detail
- First, to clarify the RFAM, IMC was locked down and the offset of the RF13 PD(IMCRFPD) was checked. However, there is only -0.006 V (10 cts) when dark. Also, there is very little offset of RF13 after locking PMC.(FIG1) Looking only at this result, it seems unlikely that RFAM is caused by EOM, but it is difficult to determine whether it is caused by EOM.
- We then performed the FINE TUNING work of IMCLSC in PRM's reflection. In the previous work, we eliminated only the peaks in the RF45I signal.This time, we eliminated the peaks in REFL RFPDs by adjusted the offset of IMC_CMS and the frequency of the Seed function generator.(FIG2: From above, PD1RF45, RF56, RF17, PD3RF45) However, there is still an offset on the RFPDs of REFL at this time.
(FIG3 is the offset of the RFPD when dark. I'll post the figure of the offset on later.) - We did initial alignment, turned the HWP and locked PRX. Then somehow the RF45 signal crossed to 0. (FIG4: PDH signal). In this state, we succeeded in the handover.(FIG5) It kept for a maximum of 12 seconds.
- Handover was performed as follows.
- First, slowly increase the IR gain from -4dB to 6dB. If ALSX is on, lockdown at 10 dB.
- Turn off IN2.
- At this time, REFLPD:8mW, phase sifter:1.440.
Future Plan
- We need to optimise the offset and the gain of CARMCMS. (We tried to access the Moku:Lab in the control room today but could not, so it is possible that the Moku:Lab is not connected in the mine.)
- Also, the peak height when finding IR resonance is unstable. We were changing the threshold each time.
- To investigate whether RFAM is caused by the EOM, we would also like to explore the relation with the temperature in the PSL room.
- We also want to discuss the installation of the RFAM monitors in the PSL room.
