From: "Michael D. Bathrick" <bathrick@berkshire.net>
To: "'North American Fruit Explorers'" <nafex@lists.ibiblio.org>
Subject: RE: [NAFEX] soil solarizaton
Date: Wed, 24 Mar 2004 15:54:58 -0500
Actually, a fresnel lens is much more complicated than that - this just
happens to be a flat fresnel lens. Pretty fascinating item, if you're
into optics.
Mike
-----Original Message-----
From: nafex-bounces@lists.ibiblio.org
[mailto:nafex-bounces@lists.ibiblio.org] On Behalf Of Mark Lee
Sent: Wednesday, March 24, 2004 10:19 AM
To: 'North American Fruit Explorers'
Subject: RE: [NAFEX] soil solarizaton
Del,
A fresnel lens is a flat lens. I bought a 11"x11" one from Edmund
Scientific. It is only 1/16" thick. Here is a link http://scientificsonline.com/product.asp_Q_pn_E_3052833
It concentrates the sunlight hitting the 11" square surface down to a
pinpoint. As I said yesterday, this concentrated spot of sunlight is
hot enough to melt a small chunk of lead. I don't think it would be
practical for controlling weeds in a large area, but I'm thinking of
using it to keep grass and weeds from growing in the cracks of my
driveway. -Mark Lee, Seattle
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