Diffraction rings are useful for collimating a reflector.

RobVG — 3/1/2022 5:35:59 AM (archived)

Just throw a star out of focus and adjust the primary until they're concentric.

Edit: the adjustment is made with the secondary mirror on a Schmidt-Cassegrain.

The whole thread (12 posts)

Weird diffraction spikes on the JWST imagery - ER - 2/28/2022 4:14:05 AM
- Can I post elsewhere as I know somebody will be interested ? - Pebble - 2/28/2022 5:45:47 PM
  - No problem. - ER - 3/1/2022 12:12:37 AM
    - Diffraction rings are useful for collimating a reflector. - RobVG - 3/1/2022 5:35:59 AM
  - Link to this post: - podrock - 2/28/2022 6:22:27 PM
    - The HZ Space Board is available to all for reading - podrock - 2/28/2022 6:29:11 PM
      - Thanks - Pebble - 2/28/2022 7:11:01 PM
- Technical question for RL... - ER - 2/28/2022 4:37:31 AM
  - Had to look it up... - RL - 3/2/2022 6:33:37 PM
    - What is "R=100"? - ER - 3/3/2022 4:39:16 AM
      - I believe it has to do with the spectrometer - RL - 3/9/2022 12:19:27 AM
        
        That seems reasonable. Thanks. - ER - 3/9/2022 1:03:05 AM

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