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Entry  Fri Aug 10 11:29:39 2018, aaron, Configuration, Upgrade, Parts list for BHD 
    Reply  Fri Aug 10 16:43:50 2018, gautam, Configuration, Upgrade, Parts list for BHD 
       Reply  Sun Aug 12 10:59:34 2018, aaron, Configuration, Upgrade, Parts list for BHD 
          Reply  Mon Aug 13 17:20:07 2018, aaron, Configuration, Upgrade, Parts list for BHD BHD_layout.pdf
Message ID: 14158     Entry time: Mon Aug 13 17:20:07 2018     In reply to: 14155
Author: aaron 
Type: Configuration 
Category: Upgrade 
Subject: Parts list for BHD 

I've attached the diagram of what I mean.

There are a couple caveats and changes that would have to be made that are not included in this diagram, because they would be made on different tables.

  1. I moved MMT2, which means the other MMT optics would have to be adjusted to accomodate this. I checked out the configuration on the BS table and this seems doable with a small rotation of MMT1 and maybe PJ2.
  2. I don't know the best way to get the OMC REFL beam out... thoughts?
  3. This diagram is kind of crappy after my edits, someone should tell me how to avoid collapsing all layers when I open these layout diagrams in inkscape, because I ended up editing the layout in Acrobat instead, where the lack of object grouping caused a bunch of the optics to lose one or two lines along the way.
  4. I didn't include all beam paths explicitly but can if this looks like a good configuration.
  5. The optic that picks off the transmission through MMT2 will need to move a bit, but there was a clamp in the way; this should be a minor change.
  6. The optic just before the OMC needs to be moved up a bit.
  7. The optic after the signal OMMT should be changed to a PBS and translated a bit; this is where the LO and signal beams will combine

Gautam also had some questions about the BHD/OMC timeline and plan. I feel somewhat on shaky ground with the answers, but figured I'd post them so I can be corrected once and for all.

  1. Is the plan really to use the current OMC setup to make a homodyne measurement? 
    1. I'm not sure where on the timeline the new OMC and BHD switchover are relative to each other. I have been imagining doing the swap to BHD before having a new OMC.
  2. I thought the current OMC resurrection plan was to do DC readout and not homodyne?
    1. I think the OMC resurrection plan is leading to DC readout, but when we switch over to BHD we'll be able to operate at the dark fringe. Is that right?
  3. Is it really possible to use our single OMC to clean both the LO and dark port beams? Isn't this the whole raging debate for A+?
    1. My understanding is yes, with the LO and DP in orthogonal polarizations. It's not clear to me why we expect to be able to do this while there is a debate for A+, perhaps our requirements are weaker. It is something I should calculate, I'll talk to Koji.
  4. A layout diagram would be really useful.
    1. Attached now.
  5. Where in the priority list does this come in?
    1. I am a leaf in the wind. I think this comes well after we have the OMC resurrected, we just want to get a sense for what parts we need so we can order them before the fiscal year closes.
Quote:

That seems fine, I wasn't thinking of that beam. in that case could we just have a PBS directly behind MMT2 and send both beams to the same OMMT?

Alternatively we can move OM5 and the beam path OMPO-OMMTSM towards -y, then put the LO-OMMT parallel to the existing OMMT but displaced in +x... we'd have to move the existing OMC and BHD towards +x as well. 

Quote:

Can we use the leakage beam from MMT2 on the OMC table as the LO beam? I can't find the spec for this optic, but the leakage beam was clearly visible on an IR card even with the IMC locked with 100 mW input power so presumably there's enough light there, and this is a cavity transmission beam which presumably has some HOM content filtered out.

 

Attachment 1: BHD_layout.pdf  137 kB  Uploaded Mon Aug 13 18:43:14 2018  | Hide | Hide all
BHD_layout.pdf
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