Participaint: Aritomi, Eleonora and Yuhang
Today we finally recovered the PLL. The problem we had during this recovery is listed as following.
1. We didn't record the current value and temperature value of main laser and auxiliary laser. The situation now is listed as following.
| Current(A) | Temperature(deg) | |
|---|---|---|
| main laser | 1.410 | 24.17 |
| AUX1 | 1.210 | 34.77 |
| AUX2 | 1.308 | 34.98 |
2. The spectrum analyzer is broken so that we have only bandwidth of 130MHz. This is too small range and brings diffculty to find the beat note. We found a new one and now it is placed in the place of former spectrum analyzer.
3. The transformer cannot be replaced by DCclock of minicircuit. Fortunatly, Matteo and Eleonora made quite a lot of new transformers. We guess the DCblock doesn't block enough low-frequency signal.
4. The set up of PLL board still needs to investigated. Up to now, the lock of beat note 20MHz seems fine. However, we need to know how to change set-up if we want to lock it on a different beatnote frequency.
The measurement of birefringence effect is like this. We send both bright alignment beam(s-pol) and p-pol beam inside OPO. We set up temperature of OPO from 7.2kohm to 7.8kohm. At each temperature we change the temperature of p-pol laser so that to make s-pol and p-pol overlap on the oscilloscope. However, this measurement is also not very precise. Because it is very diffcult to know the exact frequency in which two polarization overlap. What we did is just to make the overlap peak as high as possible.
