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Entry  Thu Jul 26 10:58:02 2012, Sarah, DailyProgress, ISS, ISS Box Transfer Function 8x
    Reply  Mon Jul 30 20:26:39 2012, Sarah, DailyProgress, ISS, ISS Box Transfer Function 13x
       Reply  Mon Aug 6 18:28:08 2012, Sarah, DailyProgress, ISS, ISS Box Transfer Function 7x
          Reply  Tue Aug 7 03:00:31 2012, rana, DailyProgress, ISS, ISS Box Transfer Function 
          Reply  Wed Aug 8 20:57:15 2012, Sarah, DailyProgress, ISS, ISS Box Transfer Function 
          Reply  Wed Aug 8 23:03:52 2012, Sarah, DailyProgress, ISS, ISS Box Transfer Function 7x
Message ID: 1031     Entry time: Mon Jul 30 20:26:39 2012     In reply to: 1030     Reply to this: 1033
Author: Sarah 
Type: DailyProgress 
Category: ISS 
Subject: ISS Box Transfer Function 

 Today the TCS ISS box was modified, the resulting transfer function was measured, and we began to set up the box in the experiment.

Setup:

I used LISO to design two additional op amp stages and soldered in the necessary components. I attached the updated pdf for the schematic.

TF Measurements:

The transfer function for the four total op amp stages is shown below:

tf_overall.png

The transfer functions for the two individually added stages are shown below:

 tf_stage_2.pngtf_stage_3.png

Thankfully all of the measured transfer functions seem to match up nicely with those generated with LISO.

The transfer function for the entire box (not just filter stages) is:

 tf_box.png

So, there isn't really much else contributing to the transfer function than the four filter stages.

Implementation of ISS Box:

We then proceeded to hook up the box to suppress RCAV RIN. The eaom was used as the actuator, and we used to pd's as in loop and out of loop sensors. We found out that the input signal to the ISS box needs to be AC coupled, which the pd signal is not. As a quick fix, we used an SR560 set to AC coupling between the pd signal measuring intensity noise and the servo. A more carefully constructed component will have to added in order to fix this, so ill have to think about this. 

The following plot shows the results for the free intensity noise vs the suppressed intensity noise:

RIN_free_sup.png

The suppression was just a quick check. There might be an issue with using the SR560.

The gain for the whole loop is plotted below against the calculated open loop gain [(free noise / suppressed noise) -1]:

OLG_calc_meas.png

 

Attachment 2: tf_overall.fig  297 kB
Attachment 5: tf_stage_3.fig  286 kB
Attachment 6: tf_stage_2.fig  293 kB
Attachment 8: tf_box.fig  11 kB
Attachment 10: RIN_free_sup.fig  50 kB
Attachment 11: D080351_REV_A3.pdf  1.457 MB  | Hide | Hide all
D080351_REV_A3.pdf D080351_REV_A3.pdf D080351_REV_A3.pdf
Attachment 13: OLG_calc_meas.fig  30 kB
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