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Entry  Mon Nov 12 21:33:41 2007, Stefan, Laser, PSL, ISS servo work 
    Reply  Tue Nov 13 19:06:18 2007, rana, Laser, PSL, ISS servo work 
Message ID: 9     Entry time: Mon Nov 12 21:33:41 2007     Reply to this: 10
Author: Stefan 
Type: Laser 
Category: PSL 
Subject: ISS servo work 
I fixed a few things on the ISS board:
- Fixed the input THS4131 on the ISS board
- Fixed all monitoring point cables for the inner loop part.

With that I was able to lock the ISS with up to 400kHz UGF (limited by variable gain at max).

The sensing noise is about 60nV/rtHz at 100Hz without light, but there is some additional noise pick-up when the VCO driver is connected.

The In-loop noise, with 6V DC (~8mWatt on the diode) and a UGF of 400kHz is
100Hz: 170nV/rtHz (2.8e-8/rtHz)
200Hz: 60nV/rtHz (1.0e-8/rtHz)
500Hz: 50nV/rtHz (8.3e-9/rtHz)

The out-of loop noise is still a lot worse ( a few e-7/rtHz at 100Hz), but that's not surprising:
The table is quite noisy and not much care went into choosing good mounts.
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