I tried the PZT dither today:
- The green arm transmitted signal is now available in the ASC system
  (ADC card 3, channel 24-27 [25-28], are connected to output 1-4 form the the ALS PD concentrator 3) 
- I used the demodulated green arm transmitted signal for all the loops I tried today.
- Dithering PZT2 provided a nice error signal for TMS pointing.
- Dithering PZT1 gave an error signal that I couldn't zero out - not sure why yet. (TMS position offset?)
- Dithering ITM at 1.7 Hz provided a good loop for aligning ITMY.
- The loop did a good job aligning the cavity, but mode-hopping was still hampering the effort.


Still to do:
- Try higher frequency ITM dither (lower stage drive?)
- Investigate PZT1 dither error signal offset - Try Green QPD pointing offset?
- Do yaw loops.