Page Comparison

...

Be warned, this is a ~1 hour process.  We are working on designing a more user-friendly repair process.  At no point in this process should the fiber be removed from its connector to the OSELOTS cage system (we'll pull the cage system itself out, but the fiber should stay connected)

Here are the steps (somewhat difficult to describe in text, so we've include an image here with some hopefully helpful arrows): 

1. Remove the rubber baffle around the cage system connecting slit to central column
   1. Unwraps by hand 
   2. Not shown in photo below
2. Use a small, imperial hex key to just loosen (DO NOT REMOVE ALL THE WAY) the small screws locking the cage into the central column 
   1. In the hex key set provided with the OSELOTS toolkit, the key you need is the small, red imperial key
3. Disconnect the slit holder from the support post, just to the right of the entrance hole
   1. We recommend unscrewing the small, horizontal, silver beam from the holder of the optical slit, keeping the larger poster pieces in place
   2. You should first loosen the screw locking this silver post in place, and then rotate it
4. Slide the cage posts holding the slit and fiber tip out the front hole of OSELOTS
   1. If all the screws have been appropriately loosened, the whole front of the cage system should cleanly slide out.
5. Connect a light source (like the HG-2 calibration lamp) to lens-end of the optical fiber
   1. See the section on taking wavelength calibration images, starting with "(OPTIONAL, BUT SHOULD DO IF POSSIBLE)", on the Nightly Observing Sequence page for guidance on how to do so
6. When the slit and fiber are well aligned, you should see bright light shining through the slit from the fiber
7. To adjust the alignment, you must gently move the slit around in it's holding tube
   1. (The slit, unfortunately, does not sit perfectly centered in the tube; it is held in place (imperfectly) with a ThorLabs 1" tube ring)
   2. Slide the slit holder off of the cage struts
   3. Loosen the ring holding the slit in place
      1. Can be done with a flathead screwdriver or the ThorLabs tube ring adjuster 
   4. Gently nudge the ring's position perpendicular to the long axis
      1. Best done with a soft, long object with a small tip, such as a toothpick or a cable tie
   5. tighten ring, gently
   6. slide slit holder back down cage struts until the fiber and slit are flush 
      1. Bring them into contact gently 
   7. Do you now see light from the fiber through the lens (as in the image above) when slit and fiber are flush? 
      1. If yes, then you're good
      2. If not, repeat steps c. through g., using the results from the previous adjustment to inform your next adjustment 
8. Once good alignment is retrieved, replace the cage struts and tighten system down
   1. i.e.  - reverse steps 2. through 4. 
9. Take an image with OSELOTS: 
   1. As su in the ~/Documents/OSELOTS/ directory, run: 

   2. bash doPixisImaging.bash -e 5 -o HG2 -p HG2_f23p0 -n 1 -h 0 -f 23.0

   3. (you might need to cool the camera and find focus home if this is the first image taken today): 

      1. bash doPixisImaging.bash -e 0 -o Cool -n 1 -h 1 

10. If the lines look good, the slit and fiber have been successfully realigned!
11. But the slit is likely slightly rotated out of position.  Are the lines perfectly vertical in the image, or is there a slight tilt?
    1. ds9's crosshair is helpful
    2. Here is an example (note in the left panel, how the crosshair traces the line, while in the right panel, the line drifts right off of the crosshair): 
    3. 
12. If the slit requires rotation correction: 
    1. Use a hex key to loosen the rotation stage for the slit 
    2. Rotate the slit slightly, making note of the direction
    3. Take another image and check the slit orientation 
    4. Repeat until good vertical slit orientation is achieved. 
13. The slit-fiber coupling error has now been fixed.