NAOJ GW Elog Logbook 3.2
[Marc, Michael, Shalika, Yuhang]
First we changed the DDS1 DAC0 and 1 frequency from 88 to 88.3 MHz (resonant freq of the EOM).
Then, we installed a powermeter in transmission of the SHG (as in elog 3091).
We scanned the SHG and tuned its alignment. In the end, we achieved about 91% mode-matching.
Then, we locked the SHG on TEM00 and monitored the reflected green power after the FI as a function of SHG temperature (see fig2).
The optimal temperature is now 3.16 kOhm which gives us about 280mW of green power.
We did same power budget as in elog 3091 :
Incident IR (measured before dichroic): 685 mW
Reflected green (measured before FI): 288 mW
Reflected IR (measured before ND2 on photodetector): 144 mW.
This gives us a slightly better SHG efficiency at around 40.2%.
It seems that we recovered the usual situation.
Last step for SHG is to install a PD in transmission to have the automatic lock of the servo working.