Re: new streetlight - comply w/ Dark Dky Initiatives

Ο "Martin Brown" <|||newspam|||@nezumi.demon.co.uk> έγραψε στο μήνυμα
news:deheit$e72$1@xxxxxxxxxxxxxxxxxxxxxxx
>
> Ioannis wrote:
[snip]
> > There are already monochromatic green and blue lamps out. Both by OSRAM
and
> > Radium. The green one contains Thalium, which gives just one line.
>
> That is a bit too much on the nasty toxic heavy metal side. They are
> already trying to phase out mercury for toxicity reasons.

A little "too little, too late".

[snip]

> Sodium D lines are fairly
> close to the human eye dark adapted peak of sensitivity. Few light
> sources can approach the efficacy of LPS in lumens per watt.

Few *already existent* light sources can approach the efficiency of LPS.
Lighting engineers certainly haven't tried all possible elements (much less
all possible element combinations) and elements from group 2/period 2 and up
to group 3, like Li, K, Ca, Rb, Sr, Cs and Ba, have ionization energies
comparable to that of Na, so it is not inconceivable that some optimum
operating pressure can be found with some of these elements exceeding the
efficiency of Na at low pressure (180-200 lm/W).

Not to mention molecular light sources, for which there is very little
reserach done. (In the 1940's, for example, a CO2 high pressure lamp was
developed that had excellent color rendering capabilities and it produced
almost white light).

[snip]

> Mercury unfortunately has too many emission lines including some that
> get in the way of spectroscopic astrophysics observations. That is one
> situation where continuum light would be preferable.

And what were the astrophysicists doing during the 60's, 70's and early
80's, when the world nightlite color was mercury dominated?

The mercury lines are certainly easier to filter out than the broadband
emissions from high pressure Sodium, which contain lines as well as
continuum, spread over a huge spectral area.

> Regards,
> Martin Brown
--
I. N. Galidakis
http://users.forthnet.gr/ath/jgal/
Eventually, _everything_ is understandable

.

Relevant Pages

  • Re: New newsgroup?
    ... Right, yeah, sensible. ... mercury use at all). ... either the only jim or ask you which one. ...
    (uk.comp.sys.mac)
  • Re: Correction of a yet another set of lies from Rob Candlish
    ... It was vetted by their libel lawyer before publication and ... "The Hertfordshire Mercury" reported matters very responsibly by ... before publication by a lawyer specialising in defamation cases the ...
    (uk.rec.naturist)
  • Re: OT: Audiobook..
    ... The silicon pads really do a fantastic job of keeping the pressure off. ... Unfortunately the Lindberg web site has to be the biggest pile of poo ... No nose dents at all. ...
    (uk.rec.motorcycles)
  • Re: More attention problems (was re: treats.....)
    ... Teaching her to drop her head from the slightest pressure on her poll ... You first teach the exercise when she is calm. ...
    (rec.equestrian)
  • Re: Martyrs for the cause
    ... > | SNIP ... > apply pressure, we exert force. ... Lorentz didn't know the laws of Newton... ... We don't apply pressure, we exert force. ...
    (sci.physics.relativity)