Michael and Yuhang

Since we always have TAMA old PSDs broken and suspect AA noise coming from PR/BS oplev, we decide to buy new PSD/QPDs. Akutsu-san provided us two QPDs from KAGRA, we report the test of one of them in this elog.

The tested QPD is JGW-D1402411-v2.

We powered it with a DC voltage supply, the current consumpation is 0.069A for -15V while 0.084 for 15V.

We set this PD for BS oplev and compared with the measurement from TAMA PSD. Figure 1 shows this comparison. We could see that a better SNR can be achieved from KAGRA QPD. Besides, if we used a higher gain in KAGRA QPD, we gain even better SNR below ~50Hz. However, one strange thing is that the yaw spectrums show different peak structure for QPD or PSD.