TTFSS is not working properly yet. The signal from Fast out is distorted, but it still can lock the laser. All three actuators are being tested over night. Fine tuning has yet to be done. Once the temperature is settled, I'll measure the beat signal.

       I tried to lock the laser with the new TTFSS. There are three actuators, SLOW (thermal control), FAST (acts on PZT), and PC ( acts onEOM).  First, I locked the laser with FAST actuator only. PD input and LO input were removed from the old FSS card and connected to the TTFSS servo box.Then, I scanned the laser by modulating the laser frequency via laser's FAST input to check the error signal. The signal measured at mixer out, FAST MON, RAMP IN OUT2 (see fig 0, for where the outputs are) were good, see fig1 and fig2, but the signal from FAST OUT(tnc) is distorted, see fig3.

      Another problem was about the lemo output, it appeared that

     1)when I measured the signal from FAST OUT(lemo), I did not see any signal at all, and

     2)when I observed the distorted signal from FAST OUT(tnc) and plugged in a lemo connector to lemo FAST OUT, the signal from tnc also disappeared. The connector on the cable is the one we used for FSS, it should be working properly, but I will double check it. There might be shorted/ bad connections in the cable. It probably is the problem from the lemo connector on the board. When I did the test on the box 6 months ago, I used only FAST OUT(tnc).

fig0: a part of the schematic from TTFSS servo. FAST OUT has two output, tnc and lemo connectors. The full schematic can be found here.

I measured the signal from FASTM, RAMP IN OUT2, FAST OUT (tnc), and FAST OUT(lemo)

 fig1: signal from mixer mon

fig2 signal from fast out2 (similar to that from fast out mon (different in amplitude), so I post only this picture)

fig3: signal from fast out (which is fed to the laser)