Fwd: light sources

Sadaf Khan sadafpbs at yahoo.com
Fri Jul 16 16:40:09 EST 2004

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From: "Ian Cummings" <Ian.Cummings at utas.edu.au>
To: <sadafpbs at yahoo.com>
Subject: light sources
Date: Fri, 16 Jul 2004 09:52:22 +1000
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Sadaf, your message was passed on to me for reply by Dr Elliot who subscibes
to the arabadopsis group, some info on our red far red and blue leds is
You may also want to contact Malcolm Pratt at the Uni of Leicester,  our
design is based on theirs and they have since improved their design. I
believe it is difficult to get leds from Shinkoh now, they got their last
lot from Applied Opotech, don't have any other contact details.

LED's are an expensive option as you need a lot to cover a small area.
Intensity with these (unlike normal lights) is more to do with degree of
overlap as each LED is a point source, so the closer they are together, the
brighter the light you construct will be; but to cover a large area you need
a real lot. We compromised and constructed the LEDs into 40 cm strips that
we can place close together or seperate according to the intensity required
and area to cover. Our strips have the LEDs 10mm apart in 3 rows mounted on
velo board. This seemed to give us the most efficient result. There are 120
LEDs per strip. I can send more detail, drawings etc if you wish. We mounted
these strips in polycarbonate tubes for protection (expensive, but
transmission is clear and perspex will craze). You need the appropriate
resistors in the line, that sort of info comes with the LEDs. They plug into
240 - 12 v transformers; we can dial down the power output on these for
lower intensities.
The intensities we get depend on the type of LED and the configoration of
our tubes. The far reds are by far the brightest, we can easily get 50
micromoles over a square metre using 4 tubes at 50 cm; with the reds its
about 20 micromoles, and the blues only about 10. You can get higher
intensities closer, but the area is reduced. Very close (5cm) we read about
90 micromoles for blue and 270 micromoles for far red! LEDs have very little
heat output so one option is to use fewer leds very close. Anyway, some
contact details below.
KL450-660GDDH for red; peaks are at 730 and 660 respectively and are very
clean- ie a narrow spike, no other wavelength contamination. Also Shin was
VERY helpful and very patient with us as we sorted out what we needed.

October 2000 prices JPY200.00-/pcs at 1,000pcs/lot=JPY200,000- (about $2.70
Australian each)
Shin Kinoshita
International Sales Dept./
skinoshita at shinkoh-elecs.co.jp

Blues (peak 460nm, again very clean) Nichia NSPB510S WF3 Super Blue
  US$1.70 per piece delivered
Nichia Corporation
>Tel:  +65-324 8218
>Fax:+65-324 5756
>e-mail: sales at nichia.com.sg
You may also want to look at Quantum Devices snaplights which use the same
LEDs closer together in a ready made light so the intensities they get are
higher; but the lights are very small and very expensive, probably around
$10 000 US to start up. Have a look at their website- www.quantumdev.com

Ian Cummings
School of Plant Science
University of Tasmania
Private Bag 55,
Hobart, Tasmania, 7001
Ph 03 62262648
Fax 03 62262698
Email Ian.Cummings at utas.edu.au

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