Primary mirror for dobsonian telescope

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SUMMARY

Using a concave aluminum mirror as the objective mirror for a Dobsonian telescope is feasible, but it presents significant challenges. The high thermal expansion of aluminum means the mirror will only maintain its shape at a specific temperature, complicating the polishing process. Without a diamond turning machine, achieving the desired shape during polishing is difficult. Additionally, the aluminum surface requires either aluminization or a method to remove the oxidized layer for optimal performance.

PREREQUISITES
  • Understanding of thermal expansion properties of materials
  • Knowledge of telescope optics and mirror fabrication
  • Experience with polishing techniques for reflective surfaces
  • Familiarity with aluminization processes for mirrors
NEXT STEPS
  • Research diamond turning machines for precision mirror fabrication
  • Learn about the effects of thermal expansion on optical components
  • Explore techniques for polishing aluminum mirrors effectively
  • Investigate methods for removing aluminum oxidation from mirror surfaces
USEFUL FOR

Astronomy enthusiasts, telescope builders, and optical engineers interested in custom mirror fabrication and performance optimization for Dobsonian telescopes.

josue2503
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can i use a concave aluminum mirror as an objective mirror of a dobsonian telescope??
 
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Yes - but
It has a high thermal expansion so it will only be correct at one temperature, this also makes it difficult to polish since the heat from the polishing changes the shape while you are polishing it - unless you have access to a diamond turning machine.
You will still have to either aluminise it or find a way of removing a thin top layer of the aluminium as it oxidises
 

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