[Aritomi, Eleonora P&C, Yuhang]
This is work on July 2nd.
First we increased green power to 60mW. OPO temperature and p pol PLL are as follows
| green power (mW) | OPO temperature (kOhm) | P pol PLL (MHz) |
| 60 | 7.19 | 150 |
Then we scanned AOM frequency and measured green and IR transmission with diaggui. Note that this data is slow channel and sampled at 16Hz. Setting of AOM is shown in Pic 1. FM is 2 mHz and deviation is 1 MHz (peak to peak: 2MHz). During this measurement, we scanned green phase with 2kHz, 700mVpp. We also took a movie of green and IR camera to characterize higher order modes. Starting time is 19-07-02-07-08-57 UTC. Pic 2 shows transmission of green and IR. Higher order mode is as follows.
| time (s) | mode |
| 22.75 | TEM00 |
| 46.81 | pitch HOM |
| 72.5 | HG10,01 |
| 97.94 | HOM |
| 147.4 | TEM00 |
| 197.1 | HG10,01 |
| 248.6 | HG11,02 |
| 347.8 | HG10,01 |
| 423.2 | TEM00 |
| 472.8 | HG10,01 |
Note that speed of scan is 2 MHz / 250 s = 8 kHz/s and measured FSR is 147.4 - 22.75 = 124.65 s which means FSR is 0.9972 MHz in AOM.
As you can see, green transmission is also scanned by AOM since AOM scan changes alignment of green injected into filter cavity. But this shouldn't be a problem as long as alignment of filter cavity is fixed. When you look at TEM00 closely (Pic 3), sampling rate seems not enough. We'll try with oscilloscope today.
