10.28.09

Here's a crappy video of the total, tilt removed phase as its corrected by the PI controller.


Quite amazing considering the crap I was getting before. Most of the bias error is concentrated in the focus mode, and its important that note only is the phase largely corrected, but the actuators don't saturate at all.

Of course adding tilt screws things up. Even though the DM clearly attempts to correct those errors, some of the actuators quickly saturate. Manually removing it is difficult since the large distances in my setup make it extremely sensitive to even someone touching a mirror. There are three options for dealing with this:

1. Ignore tilt completely. My preference, and not entirely unrealistic since it is often handled by a separate tracking loop anyway.

2. Add a steering mirror. Probably tougher than it sounds, would require another beamsplitter and probably a month of playing around.

3. Use the disturbance DM. The disturbances are largely free of tilt and probably don't saturate the mirror on their own, thus the tilt modes on the disturbance mirror could be used to correct for some of the overall tracking error of the system.

For now #1 is the only option. Word on the grapevine is that another package is on its way, so hopefully it contains my second mirror. In the mean time, here's what I want done tomorrow:

- Finish implementing an RLS adaptive equalizer example in Simulink
- Test out/modify the existing Simulink files to run the PI loop
- Work on my prospectus
- Look into committee possibilities.