From: c.knight_at_juno.com
Date: 10/02/02
Date: Wed, 2 Oct 2002 23:17:16 -0500 Subject: Re: Omega Garden - High-density gardening for small spaces/urban farming Message-ID: <20021002.231717.1104.4.c.knight@juno.com> From: c.knight_at_juno.com
> > Light pipes are relatively easy to design.
>
> That is an awesome idea... and it brings to mind other things, like
> a
> network of light tubes, that you can plug a new unit into when you
> get
A while back someone designed a sulfur based light bulb that
worked inside a microwave cavity -- supposed to be super efficient,
but it put out SO much light that it would have been used only for
commercial installations. They would put a tiny bulb at the end of
a light pipe (made from 3M material -- a photomicrograph shows
that it looks like a bunch of prisms, and it allows emission only out
the "out" side of the tube) and then run a single pipe to the other
end of the parking garage.
Much like a fiber, the source of the light is irrelevant -- it matters
only that it is coupled to the system, and then distributed.
> I know very little about light tubes (other than
> small scale fibre optics, of which I know a bit more). Is this kind
> of thing feasible for these kind of scales?
Fiber is the same basic principle as a light pipe. Ever seen a
Sola-Tube? It's a type of skylight sold here in the States, with an
output that looks very much like a circular light fixture on the ceiling.
Internal reflections keep the light bouncing around inside the system
until it reaches an "exit," and hopefully one that was purposefully
designed.
As to these "scales," let's look at the Omega garden's claims. On
their main site, it lists a 400W HID bulb as the light source for the
standard unit. It then lists lumens per square foot at various
distances,
illustrating the law of squares.
Even on a cloudy day, in the shade, the sun is still a LOT brighter
than that. On the off chance that we need more light, we could just
use an optical concentrator -- think of it like a big magnifying glass,
or satellite dish.
After we get the requisite amount of light "funneled" into the system,
it's just a matter of distribution. There are MANY ways to do this,
which could include light pipes, but could also use nothing more than
an outdoor heliostat directing light onto a diffuser or reflector located
at the center of the drum.
LOTS of choices. Engineering can be so much fun!
> What about combining the natural light tube with supplemental
> artificial light?
Why? Plants require darkness as much as they do light...they have
different biological processes that happen at night. Other than just
using it to balance out day and night into ~12 hour periods, I can't
imagine requiring more light than is naturally available, especially
with the easy availability of optical concentrators.
-- Chuck Knight
________________________________________________________________
GET INTERNET ACCESS FROM JUNO!
Juno offers FREE or PREMIUM Internet access for less!
Join Juno today! For your FREE software, visit:
http://dl.www.juno.com/get/web/.