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reduce frame deflection variation - Part 21 #175

Open BrianClement opened 7 years ago

BrianClement commented 7 years ago

DB0094 [Created: 2017-02-01]

Both the Y-arm and frame are supported along only one edge. This leads to deflection ('droop') that takes the sample surface out of the nominal imaging plane and may well influence results.

 
There are a number of things that might reduce deflection, e.g.:
  1. support the free end of the Y-arm
  2. counter weight the frame to reduce Y-arm torsion (at the expense of increasing flexure)
  3. torsionally stiffen the frame member that attaches to the Y-arm
  4. add diagonal bracing (possibly active) to allow frame droop to be counteracted
While reducing the absolute level of deflection is desirable, it is more important to minimise its variation both within and between scans, including between scans of actual samples and the daily calibration cassette. Supporting the free end of the Y-arm is likely to yield the biggest reduction in deflection variation.
 
Evaluate options for supporting the Y-arm and test.