Comments on: Flat parabolic mirror is not an oxymoron!

By: Black Dense

Black Dense — Wed, 10 Aug 2011 10:17:32 +0000

Hi. And where can one buy fresnel lenses in Kenya? I mean good enough for solar cooking.

By: Things I Liked (05.28.10)

Things I Liked (05.28.10) — Fri, 28 May 2010 21:45:41 +0000

[...] of life and death. This isn’t capacitive touchscreens, or 1000fps cameras, its car batteries, broken mirrors, and old bikes, each of which is having profound impacts on peoples [...]

By: Fundstücke: Afrigadget, Webmontag, Basteldisco | untergeek

Fundstücke: Afrigadget, Webmontag, Basteldisco | untergeek — Tue, 18 May 2010 13:56:49 +0000

[...] die Afrigadget aufgetan hat, sind einen Blick wert: beispielsweise der anaerobe Gärtank, der flache Parabolspiegel (übrigens: Fresnellinse, Jungs!) oder der Verdunstungskühler für somalische Kamelmilch. Bei [...]

By: izzy

izzy — Fri, 26 Feb 2010 22:57:34 +0000

The cheapest I have seen Fresnel lenses is – they are sold in the US in drugstores, at the pharmacy counter, for old people who can’t see/read. They usually have them in various sizes, including credit-card size, and are only a couple dollars at the counter (Not 6.99 – that is pricey) Of course wholesale would be cheaper.
Or if there is a round clear glass vase – as close to a sphere as possible – you can fill it with water and it will act like a magnifying glass. (Here people’s things catch on fire when they put a fishbowl in the sun!)
In the old days they would put clear spheres with water in front of a candle at night, to magnify the light.
Probably you know all this…

By: paula

paula — Mon, 11 Jan 2010 06:48:52 +0000

Interesting discussion…I’m not an engineer but hope that Dominic can respond to all of these comments sometime soon! Wikipedia has something on Fresnel lenses used in solar power plants here http://en.wikipedia.org/wiki/Concentrating_solar_power which looks similar to what Dominic is trying to do.

By: Patrick

Patrick — Fri, 08 Jan 2010 19:06:15 +0000

Simon,
Since you are in Berlin you should go visit the roof of the Reichstag where they have implemented a very large-scale version of what you propose. There are smaller versions such as the solar skylight(at http://store.sundancesolar.com/18nalituskki.html). So others have at least started implementing similar solutions although not exactly the same as what you wanted. Good luck and maybe you will find something that would work for you.

By: Simon

Simon — Fri, 08 Jan 2010 14:15:17 +0000

Hi,

I am not an engineer, but some time ago I realized the following problems in big cities in developed countries (NY, Paris, or Berlin where I am from):

If you live in a rent apartment there, you don´t get much light, because the houses are built in certain ways (too closed, narrow, etc.).
So my roommate and I contemplated about installing mirrors on the opposite side, the neighbours’ side, which will redirect the light into your window. Additionally the partnering neighbour may get also some electricity from it. Some quick research revealed that these parabolic mirrors are very expensive here in Germany.

So as I am not an engineer, my question to the community here, is the following:

- Is the proposed solution feasible and cheap? Is redirecting possible?

Would love to hear from you, and might work on a business model (if technology is possible).

Kindly Regards,

Simon

By: sleeplesskenya.wordpress.com

sleeplesskenya.wordpress.com — Fri, 08 Jan 2010 04:58:57 +0000

I am very impressed by your work blogger; I am a Kenyan student studying in the states who recently entered the blogosphere. This site is defintely an inspiration as I try to write original articles about Kenya with a focus on “Things North Kenya”. Please check out my site and give me some tips

By: Woody

Woody — Fri, 08 Jan 2010 03:58:11 +0000

Edmund Scientific has been selling fresnel lenses since forever. Check them at scientificsonline.com. They have an 11″ square fresnel for $6.95. They also have other cool science/education stuff too.

By: James

James — Thu, 07 Jan 2010 19:08:08 +0000

There are flat magnifiers sold in office product stores which are fresnel lenses. The large ones are 8.5×11 inches. Probably not as good quality as those in projection televisions, but they are good enough to do some things.