[time-nuts] [OT] Ikea Lamp

[Robert Atkinson]

Hi Steve,They do use them in the USA.The advantages are,1 High efficiency2 Better visibility in rain and fog. As there is only one main colour you do not get diffraction rainbows.3 Kind to astronomers. A simple narrow stop band optical filter allows astronomers to remove the light pollution. In some areas around observatories they are mandated by local planning regulations.
These are considered to outweigh the disadvantage of no colour rendition.
Robert G8RPI.  

--- On Sun, 31/1/10, Steve Rooke <sar10538 at gmail.com> wrote:

From: Steve Rooke <sar10538 at gmail.com>
Subject: Re: [time-nuts] [OT] Ikea Lamp
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
Date: Sunday, 31 January, 2010, 9:19

Not wishing to push this O/T thread more O/T but coming from England,
and now in New Zealand, we have these sodium streetlights which I
think are a pain in the neck. They have only two narrow spectra of
yellow light and although they produce light it makes it hard, if not
impossible, to make out colours. I wonder if they are being used in
other members countries?

Steve

2010/1/31 Dave Martindale <dave.martindale at gmail.com>:
> If you care about accurate colour rendering, stick with incandescent,
> preferably halogen.  "White" LEDs are actually blue LEDs coated with a
> phosphor that absorbs some of the blue light and emits approximately yellow
> instead.  If you look at the spectrum, you'll see a broad yellow peak and a
> narrower blue peak.  Your eyes see it as approximately white, but it's
> deficient in red and green compared to a black body emitter like hot
> tungsten.  On the other hand, it's not as spiky as the output of
> fluorescents.

-- 
Steve Rooke - ZL3TUV & G8KVD
A man with one clock knows what time it is;
A man with two clocks is never quite sure.

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