[rika, aaron]
At Seiji and Gautam's suggestion, we added an additional RF photodiode (NewFocus 1611) to the system so we can calibrate our transfer functions. The configuration is now laser -> BS --> lenses -> QPD and BS --> lenses -> RFPD. We added lenses to get the beams focused on the RFPD and QPD heads, and are again set up for TF measurement.
We took the following data. These parameters were consistent across all measurements:
- 1kHz IF BW
- log sweep with 801 points
- 32 averages
- auto attenuation
- -10 dBm excitation amplitude
- 19.2 mA DC current to the laser
- The DC level of the reference PD is -, and with the beam blocked (dark current) it is
| Measurement |
file |
parameters |
| WFS2_SEG1 / RFPD |
TFAG4395A_12-09-2019_155901.txt
|
100 MHz - 500 MHz |
| WFS2_SEG1 / RFPD |
TFAG4395A_12-09-2019_160811.txt |
10 MHz - 100 MHz |
| WFS2_SEG1 / RFPD |
TFAG4395A_12-09-2019_170234.txt
|
100 kHz - 10 MHz |
| WFS2_SEG2 / RFPD |
AG4395A_12-09-2019_183125.txt |
100 MHz - 500 MHz |
| WFS2_SEG2 / RFPD |
TFAG4395A_12-09-2019_183614.txt |
10 MHz - 100 MHz |
| WFS2_SEG2 / RFPD |
TFAG4395A_12-09-2019_183930.txt |
100 kHz - 10 MHz |
| WFS2_SEG3 / RFPD |
TFAG4395A_12-09-2019_225243.txt |
100 MHz - 500 MHz |
| WFS2_SEG3 / RFPD |
TFAG4395A_12-09-2019_225601.txt |
10 MHz - 100 MHz |
| WFS2_SEG3 / RFPD |
TFAG4395A_12-09-2019_225922.txt |
100 kHz - 10 MHz |
| WFS2_SEG4 / RFPD |
TFAG4395A_12-09-2019_230758.txt
|
100 MHz - 500 MHz |
| WFS2_SEG4 / RFPD |
TFAG4395A_12-09-2019_232058.txt |
10 MHz - 100 MHz |
| WFS2_SEG4 / RFPD |
TFAG4395A_12-09-2019_234447.txt |
100 kHz - 10 MHz |
After taking the data for segment 1, I moved the beam to segment 2. The beam didn't fit on segment 2 without partially illuminating segment 1 (tested by maximizing the signal on segment 2, then blocking the beam. If the beam is entirely on one segment, only that segment should be effected; in this case, we found that segment 1's DC signal also changed when the beam was blocked). We readjusted the telescoping lenses to get the beam a bit smaller, and now the beam fits on segment 2. We know it is entirely on segment 2 because small beam movements do not change the signal on segment 2.
We are trying to take the remaining data, but AGmeasure keeps hanging while sending the data (after taking the measurement, over 10 min). We tried restarting the network analyzer to no avail. I was able to grab the data by cancelling the measurement and running
AGmeasure --getdata -i vanna
I've uploaded the spectrum for segment 1 in the meantime. Zero model is on the way.
When I finished up the measurements on WFS2, I removed the cables from the AP table and closed the cover.
EDIT: I forgot to switch the LEMO connector to measure the other segments, so we measured the RF signal from segment 1 even when the beam was on segments 2-4. We'll have to try again tomorrow. |