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Entry  Thu Aug 9 11:13:19 2018, aaron, Things to Buy, Cryo Q, GeNS v2 
    Reply  Wed Aug 15 14:50:08 2018, aaron, Things to Buy, Cryo Q, GeNS v2 
Message ID: 2132     Entry time: Wed Aug 15 14:50:08 2018     In reply to: 2125
Author: aaron 
Type: Things to Buy 
Category: Cryo Q 
Subject: GeNS v2 

After discussion with Rahul, I've made the following additional changes to the GeNS system:

Platform

  • The opening for the periscope is now wide enough that the holder post hangs over the opening at its attachment to the platform. While this problably won't have any effect because there's a bit of clearance to the periscope, I've increased the radius of the circular pattern and changed the angular spacing a bit for those holes so there is no more overhang on either the periscope opening or the side of the platform.
  • Gave the opening in the platform through which the getter may travel an extra 0.05'' clearance (so rather than a 1'' opening, there is a 1.1'' diameter opening)

Sphere Base

  • The holes for the posts connecting the platform to the substrate holder were changed on the platform, so I made the corresponding change on the through holes of the sphere base, allowing the posts holding the substrate holder to the platform to still travel through the sphere base
  • Reduced the height of the sphere base by 0.05'', which also required me to change the spacing of the holes that will attach the ESD holder. I don't think these holes will now accomodate four total attachment points for the ESD, but anyway it will be fully constrained so we can just use two screws at a time.

Substrate Holder

  • I changed the spacing of the holes connecting the substrate holder to the platform due again to the periscope opening.

Base Posts

  • Reduced the height of the base posts to 2'', from 2.1''. We can't go much shorter than this without cutting off the top of the periscope mount that we plan to install, which is 1.95'' tall. If we went with a periscope that was directly mounted onto the bottom heat shield (rather than in a mount) we could probably reduce this height further.

Holder Posts

  • Reduced the height of the holder posts by the height reduction of the base posts (0.15''), keeping the substrate holder at the same level relative to top of the the sphere base.

0.5'' Lens Mount

  • Reduced height by 0.1''

Hemisphere Mount and clamp

  • Reduced heigth of each by 0.1''

ESD Holder

  • Shortened by 0.1'' to match the shorter lens mount

The total height reduction I found was only 0.25'' total, which is quite small. Because I have considered the top of the periscope mount a constraint on the location of the bottom of the sphere base, and because the lens mount does need some height to function properly, I don't think I can squeeze much more from this stone--perhaps the sphere base could be a bit thinner, perhaps we could use a different periscope mirror that requires less vertical room, if we never used the 0.5'' lens mount and only used the hemisphere clamp it would save a bit, and finally we could reduce the height of the schwarzschild though not by much. The cost of this 0.25'' is the need to machine a new hemisphere mount and clamp, holder posts, and base posts.

See it on the DCC:

https://dcc.ligo.org/D1700187

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