How to align the calibration unit

Information on the original alignment can be found here.

This is not a routine maintenance procedure.
The procedure should only be done if no alternative are available.
The person executing this procedure must be very familiar with the calibration unit system - mechanics, operation!!

Currently the procedure is not tested and might fail even if followed properly!

As long parts of the swing arm and calibration unit have not be changed or touched we do not expect, that the calibration unit has to be re-aligned!

However, in 2020 we experiences on SX some misalignment in rotation, which required re-adjustment to close day time the loop for the LGS system with the calibration unit.
Therefore, we describe here how to algin the calibration unit in rotation in more detail.

Tools needed

  • Allen keys:
    • For cover screws: M3
    • For cover amr block screws: M4
    • For clamp set screw: M2.5

How to align the calibration unit in rotation

The rotation angle can be determined before the calibration unit cover is removed.
Remove the calibration unit cover with the telescope at Horizon
  • Remove the M3 screws indicated in the image below. There are loose washers underneath as spacers.
  • Remove the cover.
  • Put the screws and washers back so you don't loose them.
Cal1 annotated.jpg

  • Loosen the M4 screws holding the cover arm block, tow on each side (see image below).
  • Slide down the block to release tension on the roller arm.
  • Tighten screws.

IMG_1688 annotated.jpeg IMG_1687 annotated.jpeg
Get the amount of rotation
  • Setup the system for daytime closed loop operation
  • Set calibration source off entrance window
    • take snapshot
    • calculate from snapshot the mismatch

Entrance window position on patrol cameras:
patrol cam x0 y0
yellow 166 142
red 179 124
blue 165.5 120

Entrance window position difference between patrol cameras:
delta position delta X delta Y
yellow - red -13 18
yellow - blue 0.5 22
red - blue 13.5 4
Formula to calculate the rotation angle:

This formula has still to be tested!! Data to do testing is urgently needed!!!
Rotate the calibration unit
  • Move swing arm to park position.
  • Climb up to the platform where you can access the calibration source.
  • Loose the small screw in the cone. Take care! Don't remove the screw because it holds a clamp, which can fall away.

  • Check the scale

  • Turn the unit of the needed amount.
  • Check the position on patrol cameras (see previous paragraph)
  • Re-do until alignment is perfect
  • Fix all screws
  • Go back to horizon and attach the cap
  • Visual/functional inspection if in all orientations cap, switches, swing arm, etc. works properly

-- WolfgangGaessler - 24 Aug 2020
I Attachment Action Size Date Who Comment
Cal1 annotated.jpgjpg Cal1 annotated.jpg manage 678 K 20 May 2021 - 01:08 GustavoRahmer  
IMG_1687 annotated.jpegjpeg IMG_1687 annotated.jpeg manage 2 MB 20 May 2021 - 01:23 GustavoRahmer  
IMG_1688 annotated.jpegjpeg IMG_1688 annotated.jpeg manage 2 MB 20 May 2021 - 01:19 GustavoRahmer  
argos_cal_3.jpgjpg argos_cal_3.jpg manage 656 K 25 Aug 2020 - 15:07 WolfgangGaessler screw to loosen the calibration unit for rotation
argos_cal_3mod.jpgjpg argos_cal_3mod.jpg manage 712 K 13 May 2021 - 21:09 GustavoRahmer  
argos_cal_5.jpgjpg argos_cal_5.jpg manage 613 K 25 Aug 2020 - 15:08 WolfgangGaessler  
argos_cal_6.jpgjpg argos_cal_6.jpg manage 527 K 25 Aug 2020 - 15:05 WolfgangGaessler scale to rotate calibration unit
argos_formula_cal_rot.jpgjpg argos_formula_cal_rot.jpg manage 18 K 26 Aug 2020 - 11:02 WolfgangGaessler  
Topic revision: r10 - 20 May 2021, GustavoRahmer
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