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How to Repair a Telescope Mirror

Telescopes allow us to see distant planets and stars by collecting the light that they emit and magnifying the focused image for our eyes. Originally, telescopes used lenses to collect the light emitted by the object, but Isaac Newton introduced the use of mirrors in 1668. Mirrors provide better images than lenses, so most modern telescopes use mirrors to gather light. However, there are a variety of issues that can cause your mirrors to give subpar images. Often, you can fix these problems yourself, but some require a professional.

Things You'll Need

Compressed air cleaner or camel-hair brush
Liquid lens cleaner
Sterilized surgical cotton pad
Waterproof tape
Large sink
Distilled water

Instructions

- 1
  Ensure that your mirrors are properly aligned (or collated) on the same optical axis. A misaligned mirror can render a distorted image.
- 2
  Spray off any loose particles of dust with compressed air or delicately brush the dust off of the mirror with a camel-hair brush. Never rub the mirror with a rag, as dust particles will scratch the surface and ruin it.
- 3
  Wash the mirror with liquid lens cleaner, wiping it with sterilized surgical cotton. For mirrors that cannot be removed from the telescope, cover the parts of the telescope surrounding the mirror with waterproof tape (not duct tape). Fill a deep sink with tepid water and a few drops of mild, unscented liquid dishwashing soap. Submerge the mirror in the water and gently wipe the mirror with surgical cotton. Rinse the mirror with distilled water.
- 4
  Set the mirror upright to air dry. Remove any tape, if used. Ensure that the telescope dries fully, as moisture can severely damage your telescope.
- 5
  Recoat your mirror if the image is still not optimal. Since recoating a mirror requires advanced equipment, hazardous materials and optical expertise, you will probably need to send the mirror to a professional. Coatings can be made of beral, standard aluminum or enhanced aluminum. Beral is the cheapest and lasts for about three years; enhanced aluminum is more expensive, but it lasts much longer and provides better reflectivity. Depending on the model of your telescope and the damage to the mirror, it may be cheaper to buy a new mirror or a whole new telescope.

Astronomy