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How to Glue a Secondary Telescope Mirror

A secondary mirror is used on Newtonian reflector telescopes to redirect the light collected by the primary mirror into the ocular (eyepiece). The ocular is where you view and focus the image being magnified by the telescope. The secondary telescope mirror is supported by a mirror spider composed of up to four metal supports and is centered within the telescope tube. The mirror must be securely held in place and at the proper angle to ensure maximum performance of the optical array.

Things You'll Need

Lens cleaner
Lint-free lens cloth
Flexible silicone glue

Instructions

- 1
  Clean the secondary mirror support plate. Remove any old adhesive and check for damage. If the support plate is damaged, replace it.
- 2
  Clean the secondary mirror with lens cleaner and a lens cloth. Carefully handle it by holding it around the outside edge so your fingers do not touch the surface. Place a small amount of flexible silicon glue onto the secondary mirror support plate.
- 3
  Smear the flexible silicon glue around the mirror support plate so it covers all exposed parts. Carefully place the secondary mirror in the center of the support plate and press it firmly into the silicon glue.
- 4
  Return the secondary mirror (and any support) to its proper position within the telescope tube (if you removed it). Look into the draw tube and adjust the secondary mirror so it is centered on the primary mirror. Allow the glue to dry.

Astronomy