Making a flat parabolic mirror

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By Matt Mets
Posted 2010/01/07 @ 9:59 am
Category Science

Regular parabolic mirrors are great for concentrating sunlight for solar heating, however they are bulky and can be difficult to repair. That’s where Dominic Wanjihias’ flat parabolic mirror comes into play. He replaced the traditional curved mirror with a series of thin strips of mirror, making what appears to be a Fresnel reflector. It’s a pretty simple concept, but has a bunch of practical advantages:

It is very cheap,

It can be quickly dismantled or moved,

It is easily transportable as it can be carried flat or in a tube,

It is easily repaired if broken as the individual mirror pieces can be replaced (rather than having to fix or replace an entire parabolic mirror).

It’s not mentioned in the article, but I assume that the individual pieces have to be bent into a curve shape to be able to focus light to a point. Anyone know for sure? [via afrigadget]

In the Maker Shed

7 Responses to Making a flat parabolic mirror

Shelby Davis on January 7th, 2010 at 10:36 am said:

This is more like the parabolic troughs you see in the Mojave desert, so it still concentrates solar energy, but on a line instead of a point.

I bet it’s great for toasting baguettes!

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- Matt Mets on January 7th, 2010 at 10:37 am said:
  
  Ha, awesome! Now I like the idea even more!
  
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steve on January 7th, 2010 at 10:45 am said:

No need to make the strips curved. When they lock onto the sun, they’ll reflect around a 1″ band of light. As long as all the mirrors converge, it should work.

but yeah, it’s a pretty long 1″ band of light…

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- jeff-o on January 7th, 2010 at 10:51 am said:
  
  That’s exactly what you want, if you’re trying to heat water (or something else) flowing through a long pipe.
  
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  steve on January 7th, 2010 at 12:43 pm said:
  
  Ah! Good point!
  
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Curmudgeon on January 7th, 2010 at 5:23 pm said:

If you want cheap, simply take one of the satellite dishes from any house — the one that have been made obsolete, of course, by the installation of new ones. Ask the Dish Network guy for them, he’ll be glad to get rid of them. Then use a viscous silver paint — viola!

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mrmeval on January 9th, 2010 at 11:49 am said:

http://www.google.com/search?q=Compact+Linear+Fresnel+Reflector

Flat mirrors work fine and they will focus on a line so pipes work as stated above. There is a company that makes large versions. http://www.ausra.com/technology/

By rotating each individual mirror they stay focused on the collector.

I wonder if an array of simple round mirrors with motors controlled by an arduino mega would be of use?.

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