From: Don Klipstein on
In article <eq7s9v$fkd$1(a)theodyn.ncf.ca>, Michael Black wrote:

>But, the point of lasers is that they are a very small beam. They
>wouldn't be useful if they weren't. SO the fact that you get a nice
>read dot on the wall down the hall that's brighter than a flashlight
>would give at the distance isn't important. Because you can't do
>much in the way of lighting with that little red dot, while you can
>do things with the flashlight. (Of course, there are things you
>can do with the laser, but it doesn't include lighting.)

A laser beam can easily be spread out with optics or blurred with a
diffuser. The main problems are cost effectiveness, regulations, speckle
and the fact that visible lasers are not as efficient as currently
available better LEDs. Not even visible lasers costing thousands of
dollars.

- Don Klipstein (don(a)misty.com)
From: Ron Peterson on
On Jan 31, 11:50 pm, d...(a)manx.misty.com (Don Klipstein) wrote:
> In article <1170306957.709652.325...(a)a75g2000cwd.googlegroups.com>, Ron
>
> Peterson wrote:

> >That's true for white LEDs which use flourescent material, but
> >monochrome LEDs can be more efficient on a lumens per watt basis for
> >applications like stop lights.

> What? By who? Where and how to get? I don't believe it. For that
> matter, best lumens out per watt in is more for white than for any
> spectral color for announced laboratory prototypes also as far as I have
> heard.

I forgot that lumens per watt depends on eye sensitivity to the color.
I was thinking about power efficiency instead.

> The big efficiency advantage of LEDs in traffic signals is over the
> really lousy efficiency of superlonglife vibration resistant incandescents
> that have some, mainly most, of their light blocked by colored filters.

Yes, if monochrome light is desired, LEDs are the way to go.

I was reading an article in IEEE Spectrum where it was explained that
LEDs have a big advantage in tail lights because they can turn on a
few milliseconds faster giving a following car more time to brake.

Seeing that you have some good web pages on LEDs, perhaps you have an
idea when RGB arrays of LEDs will become practical for LCD displays
giving a better color gamut.

--
Ron



From: Don K on
"Don Klipstein" <don(a)manx.misty.com> wrote in message news:slrnesevjg.i0q.don(a)manx.misty.com...
> In article <eq7s9v$fkd$1(a)theodyn.ncf.ca>, Michael Black wrote:
>
>>But, the point of lasers is that they are a very small beam. They
>>wouldn't be useful if they weren't. SO the fact that you get a nice
>>read dot on the wall down the hall that's brighter than a flashlight
>>would give at the distance isn't important. Because you can't do
>>much in the way of lighting with that little red dot, while you can
>>do things with the flashlight. (Of course, there are things you
>>can do with the laser, but it doesn't include lighting.)
>
> A laser beam can easily be spread out with optics or blurred with a
> diffuser. The main problems are cost effectiveness, regulations, speckle
> and the fact that visible lasers are not as efficient as currently
> available better LEDs. Not even visible lasers costing thousands of
> dollars.
>
> - Don Klipstein (don(a)misty.com)

Just to expand a little about the reference to "regulations":

The laser diodes I use for optical links at 1310nm put out around
4 to 10 milliWatts of optical power into a pinpoint when biased at 35 to 45 mA.

If you wanted to use a laser with a diffuser to replace a 100W lightbulb,
you are going to be playing with devices that probably could be modified
into deathrays.

Don


From: Anthony Matonak on
Don K wrote:
....
> If you wanted to use a laser with a diffuser to replace a 100W lightbulb,
> you are going to be playing with devices that probably could be modified
> into deathrays.

You say that like it's a bad thing. :)

Anthony
From: Rick on
Jeff wrote:
>
> SMS wrote:
>
> > fluffy bunny wrote:
> >
> >> CF's have clearly overcome that hurdle, while recognizing much of
> >> their current popularity upsurge is the result of various economic
> >> subsidizations. So i'd say that finally, the fluorescent tube is
> >> replacing the filament lamp for home use.
> >
> >
> > Pretty much, though they have their drawbacks. They take a while to
> > reach full brightness,
>
> That is certainly true for the smaller lamps
>
> and they're not good for high-intensity lamps.
> > For women, putting on make-up in a bathroom lit by fluorescents doesn't
> > work well.
>
> That appears to be changing. My Photo Club just replaced the color
> balanced high intensity hot lamps (lifetime of just a few hours and $7
> each) with some color balanced High Intensity CF's for our Print
> Competitions. Aside from the much longer lifespan the color of the new
> CFs is much better, and that being judged by some color critical people.
> Incidentally, it's the B&W prints that really benefit from the new lamps
> (much much less metamirism).
> >
> > I was especially pleased to see all the fluorescent bulbs for recessed
> > lighting. I have a lot of recessed lighting in my house, about 40
> > recessed fixtures, and they are almost all fluorescent now. I spaced
> > them a little closer together than I would have if I had been using
> > incandescent.
> >
> > LED lamps are great for low intensity applications, but the higher
> > intensity LEDs (5W Luxeon) generate a lot of heat that is difficult to
> > manage.
>
> BTW, just ran across this:
>
> <URL: http://www.theinquirer.net/default.aspx?article=29472 />
>
> Nichia claims to have an LED with 113 lumens/watt and there's another
> lab model at 130 lumens. That takes us close to replacing household CF's
> with LEDs within the decade.
>
> Jeff

If they can get the color right. How many "white" LED flash lights have
you seen that aren't really white? More like a bluish white. Wanna see
the dear wife put makeup on with those? 8-)

Rick