Reports until 17:28, Thursday 21 February 2013
H1 ISC
sheila.dwyer@LIGO.ORG - posted 17:28, Thursday 21 February 2013 - last comment - 13:29, Tuesday 12 March 2013(5555)
ALS SHG Temperature controller 
The ALS SHG oven is assembled without the crystal and the temperature controlled.  

I added washers between the 5 axis stage and the aluminum base for the ALS SHG, now with the vertical adjustment screws all the way in the crystal is just at four inches.  I think if Bram adds 3 mm to the aluminum base plate for the rest of the units they should have the crystal at 4 inches when the screws are in the center of the adjustment, without any extra washers.  

The temperature controller is working.  The TEC is mounted for this unit in a way that seems upside down when you look at it, the larger face is on top, this requires crossing the wires that drive the TEC.  I did that because the data sheet says that the less wide face of the TEC should be the cool face.  

One last warning about assembling it, I thought I was using a very small amount of thermal paste, but I wish I had used even less.  The thermal paste in the hole for the thermistor was not a problem, but when I lightly tightened the bolt that holds the copper holder in place, the small amount of paste I had on the TEC came oozing out.  I was glad that I did this without the crystal installed.  

The TwinCAT library is called TECController.  Daniel Set up the corner 5 chassis for the third interferometer in end X (really the MSR for now) and there is a PLC called TEST on it.  We configured this system manager to control the TEC, and it is in the SVN at C:SlowControlsTwinCATTargetH1ECATX1H1ECATX1.tsm revision 684

So far none of the variables are in EPICS, but I had a look at the step response using a trend in the TwinCAT visualization.  1 Volt sent towards the TEC raises the temperature by about 18.3 C, and the time constant is roughly 50 seconds.  

The library has a servo, the filter has a pole at zero, a zero at 0.02Hz, and you can adjust the UGF with the user interface.  It seems to work for ugf settings up to 9 Hz, you can push the UGF up to 15 Hz if it is already locked and you aren't changing the temperature, but I don't think that's necessary.  

I will try to post some step responses once we have the channels in EPICS.  

Sheila
Comments related to this report
sheila.dwyer@LIGO.ORG - 13:29, Tuesday 12 March 2013 (5762)
Link 

Here are some pictures of the SHG temperature controller, with the TEC mounted with the wider side up.  The fig file has some step responses recorded using strip tool, zoomed in on one that is a 1 degree step with the UGF at 5Hz.  The overshoot is around 20% when the ugf is at 5 Hz, and as you can see once things have partially settleded the in loop sensor see fluctuations of less than 0.05 C peak.  
  
The step resposes settings were:
Set Temp   UGF
27         5Hz  (tuning servo on)
29         5Hz
26         5 Hz
28         10 Hz
27         10 Hz
28         7 Hz
27         3Hz
28         3Hz
27         5Hz
28         5Hz
Images attached to this comment
Non-image files attached to this comment