Used 1W into JAC.
9 (26.8dBm into EOM), 45 (27dBm) and 118MHz (10.76dBm) -> Used a single bounce beam from ITMX and scanned OMC. Successful for 9 and 45, nothing visible for 118. Detailed will be posted later.
24MHz (IMC, 14.2dBm) -> Scanned IMC length and tried to find something in IMC transmission. Nothing visible.
43MHz (JAC, 12.2dBm) -> Scanned JAC, saw nothing in JAC transmission. Boosted RF power with an amp to 29.67dBm -> m=0.092. Without the amp modulation index would be 0.012.
| 9MHz | 26.5/26.8dBm (readback/requested) | 0.26 |
| 45 | 27/26.7 (readback/requested) |
0.31 |
| 118 | 10.76 | Not measured yet |
| 24 (IMC) | 14.2 | Not measured yet |
| 43MHz (JAC) | 12.2 (temporarily boosted to 29.67 for measurement) | 0.012 (w/o boosting the RF level) |
Mode scans saved as /ligo/home/jennifer.wright/git/2026/JAC/20260202_OMC_scan.xml
43MHz details.
We temporarily boosted RF level into EOM in the PSL room to 29.67dBm, scanned JAC and measured the transmission.
43MHz 00 transmission = 0.0057.
C00 transmission (closest to 43MHz 00 mode )= 2.72.
m(29.67dBm) ~ 2*sqrt(0.0057/2.72) = 0.092.
Non-boost RF power = 12.2dBm
m(12.2dBm) = m(29.67dBm) * 10^((-29.67+12.2)/20) = 0.012.
JAC PZT whitening cable and JAC TRANS PD whitening are cross-wired.
We were scratching our collective head that changing whitening gain and filter for JAC TRANS PD didn't do anything. Daniel checked the cabling and it was good. After a while it was found that maxing out the TRANS PD whitening gain changes the PZT voltage readback by about 30mV. Turns out that the PZT whitening and the TRANS PD whitening are cross-wired.
As an example, attached shows what you should do to set the whitening gain of the JAC TRANS PD to +3dB with one whitening filter ON. (Note that the digital filter is not cross-wired.)
This morning Masayuki and Keita turned the 9 and 45 MHz RF supplies in the PSL rack up to 26.5dBm and 26.8dBm, respectively.
We took another mode scan with the IMC using the template at userapps/omc/h1/templates/OMC_scan_single_bounce_slower.xml.
We can now measure the 9 and 45 MHz sidebands.
Pink is Friday's measaurement with the RF power for 9 and 45 turned down, yellow is today.
The cursors are at the carrier and 9 MHz peaks in this image and the carrier and 45 peaks in this image.
This makes m_45 = 0.31 and m_9 = 0.26, for the modulation index of 45 MHz and 9MHz sidebands respectively.
The 118 Hz peak was buried in the noise, looking back at this measurement from Elenna in alog #62730, the 118 MHz only shows up as a peak below 0.002 mA, so it would be hard to see with our current power, maybe possible if we went up to 10 W (factor of ~ in amplitude).