Few weeks ago we started to receive some alerts from the DMS warning us that the reflection of the slave was decreasing (to be noted that the reflection is actually the beam seeding the neovan).It might be coming from a slight misalignment inside the cavity.
We took a better look at the trend of this power since the installation of this SL (beginning of 2023), the plot is attached. There was a first period till december 2023 in which it did a vary a lot and eventually decreased. It seems that it stopped and became stable when we sapped the PID controller of the temperature of the crystal 2.
So, recently it started to decrease again. Nothing worrying for now (plot 2) but we keep an eye on it. It is not critical since we do have some margin with the power we send towards the ITF but if it would ever become a problem it may require an intervention to realign the beam inside the cavity.
We will keep on monitoring the situation. .
Monitoring the evolution of the dc power on PSL/INJ of the last few weeks, we noticed that the PMC transmission slightly decreases as well as the SL_REFL_PD1_DC and AMP_DC and (fig.1, bottom right, normalized).
Looking at the relative evolutions of the three powers (fig. 1 top left and right, bottom righ), it seems that both SL and AMP are (very slightly) loosing power indipendently, causing the PMC_tra to decrease for both effects. One reason could be a small misalignment of the beam on the Laser Bench.
We will continue to monitor the situation during the next weeks.
We keep on monitorning the evolution of the laser power on PSL/INJ. An update can be seen on fig. 1.
As we can observe, approximately one week ago, the SL laser changed behavior and stabilized its power. This seems to correlate quite well with a sudden change in temperature of the EEROOM (see fig. 2), where part of the SL electronics & pumping diodes is. Moreover, it seems even more evident the effect of the day/night variation of the temperature on the SL power.
Beside, it is worth to notice that the temperature of the AMP head is continuing to increase over time. For the time being, we are far from reaching a critical temperature, but we will continue to monitor the situation.
