| Topic: |
Science > Physics |
| User: |
"Michael Lodman" |
| Date: |
10 Apr 2006 12:36:59 PM |
| Object: |
diode laser |
When I look at the output of a diode laser, it doesn't look like a solid
color spot, but scintillates (sparkles).
Why is that?
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| User: "doug" |
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| Title: Re: diode laser |
10 Apr 2006 02:27:43 PM |
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"Michael Lodman" <jlodman@baja-montana.com> wrote in message
news:Xns97A16C0326A31jlodmanbajamontana@70.169.32.36...
When I look at the output of a diode laser, it doesn't look like a solid
color spot, but scintillates (sparkles).
Why is that?
Do not look into laser with remaining good eye
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| User: "Michael Lodman" |
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| Title: Re: diode laser |
10 Apr 2006 02:41:59 PM |
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"doug" <nospam@nospam.com> wrote in news:443ab19f$0$16388$892e7fe2
@authen.yellow.readfreenews.net:
"Michael Lodman" <jlodman@baja-montana.com> wrote in message
news:Xns97A16C0326A31jlodmanbajamontana@70.169.32.36...
When I look at the output of a diode laser, it doesn't look like a solid
color spot, but scintillates (sparkles).
Why is that?
Do not look into laser with remaining good eye
I'm looking at the spot on white paper....
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| User: "Gregory L. Hansen" |
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| Title: Re: diode laser |
10 Apr 2006 08:28:32 PM |
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In article <Xns97A16C0326A31jlodmanbajamontana@70.169.32.36>,
Michael Lodman <jlodman@baja-montana.com> wrote:
When I look at the output of a diode laser, it doesn't look like a solid
color spot, but scintillates (sparkles).
Why is that?
Have you noticed that the speckles are still unless you move your head, or
that they're the same size no matter how far away the spot is? The
speckling isn't happening on the paper, it's happening in your eyeball.
--
"Work hard, be curious and persistent, and you will prevail." -- Howard
Schilit, "Financial Shenanigans" 2nd ed.
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| User: "Andy Resnick" |
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| Title: Re: diode laser |
11 Apr 2006 08:05:34 AM |
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Gregory L. Hansen wrote:
In article <Xns97A16C0326A31jlodmanbajamontana@70.169.32.36>,
Michael Lodman <jlodman@baja-montana.com> wrote:
When I look at the output of a diode laser, it doesn't look like a solid
color spot, but scintillates (sparkles).
Why is that?
Have you noticed that the speckles are still unless you move your head, or
that they're the same size no matter how far away the spot is? The
speckling isn't happening on the paper, it's happening in your eyeball.
That is true- also, if you have glasses and remove them, the speckle
remains in focus.
--
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
Case Western Reserve University
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| User: "Sam Wormley" |
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| Title: Re: diode laser |
10 Apr 2006 12:58:01 PM |
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Michael Lodman wrote:
When I look at the output of a diode laser, it doesn't look like a solid
color spot, but scintillates (sparkles).
Why is that?
See: http://en.wikipedia.org/wiki/Speckle
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| User: "John Bailey" |
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| Title: Re: diode laser |
11 Apr 2006 07:05:08 AM |
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On Mon, 10 Apr 2006 17:58:01 GMT, Sam Wormley <swormley1@mchsi.com>
wrote:
Michael Lodman wrote:
When I look at the output of a diode laser, it doesn't look like a solid
color spot, but scintillates (sparkles).
Why is that?
See: http://en.wikipedia.org/wiki/Speckle
Thanks Sam, I always appreciate your findings.
I now realize that wikipedia is all about knowing the right word for
something.
In my case--the word is the star or halo like visual effect around
nearly point sources at night. There is a viral infection of the eye
called Thygeson's disease which causes me to see halo's. When I use
cortisone eyedrops for a week the halo's go away and become
star-like.
What's the word, Sam? For the visual artifact not Thygeson's
Superficial Punctate Keratopathy.
John
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| User: "Michael Lodman" |
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| Title: Re: diode laser |
11 Apr 2006 12:22:13 PM |
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John Bailey <john_bailey@rochester.rr.com> wrote in
news:286n3213s52f01ka3ef7lc8v54tahavjhv@4ax.com:
On Mon, 10 Apr 2006 17:58:01 GMT, Sam Wormley <swormley1@mchsi.com>
wrote:
Michael Lodman wrote:
When I look at the output of a diode laser, it doesn't look like a
solid color spot, but scintillates (sparkles).
Why is that?
See: http://en.wikipedia.org/wiki/Speckle
Thanks Sam, I always appreciate your findings.
I now realize that wikipedia is all about knowing the right word for
something.
Me too. I tried doing a search but I didn't have the right word.
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| User: "Dave Lister" |
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| Title: Re: diode laser |
10 Apr 2006 01:56:28 PM |
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Sam Wormley <swormley1@mchsi.com> wrote in
news:J0x_f.91538$oL.24235@attbi_s71:
Michael Lodman wrote:
When I look at the output of a diode laser, it doesn't look like a
solid color spot, but scintillates (sparkles).
Why is that?
See: http://en.wikipedia.org/wiki/Speckle
Is this true of all lasers or just diode lasers? Does this interfere with
the creation of holograms?
--
Elect a Crook - Vote Republican
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| User: "Andy Resnick" |
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| Title: Re: diode laser |
11 Apr 2006 08:03:28 AM |
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Dave Lister wrote:
Sam Wormley <swormley1@mchsi.com> wrote in
news:J0x_f.91538$oL.24235@attbi_s71:
Michael Lodman wrote:
When I look at the output of a diode laser, it doesn't look like a
solid color spot, but scintillates (sparkles).
Why is that?
See: http://en.wikipedia.org/wiki/Speckle
Is this true of all lasers or just diode lasers? Does this interfere with
the creation of holograms?
It's due to the transverse coherence length, and is present in all light
sources. The ransverse coherence length is set by the size f the
source, while the longitudinal coherence length is set by the spectral
width of the source. With suitable filtering, one can observe speckle
from sunlight, which has a transverse coherence length of about 0.5 mm,
IIRC. For holography, the light is spatially filtered to increase the
transverse coherence length so that speckle is not present.
--
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
Case Western Reserve University
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| User: "Richard Herring" |
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| Title: Re: diode laser |
11 Apr 2006 08:27:35 AM |
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In message <Xns97A1797DBEDD1retsildivad33hotmail@70.169.32.36>, Dave
Lister <retsildivad33@hotmail.com> writes
Sam Wormley <swormley1@mchsi.com> wrote in
news:J0x_f.91538$oL.24235@attbi_s71:
Michael Lodman wrote:
When I look at the output of a diode laser, it doesn't look like a
solid color spot, but scintillates (sparkles).
Why is that?
See: http://en.wikipedia.org/wiki/Speckle
Is this true of all lasers or just diode lasers?
All of them.
Does this interfere with
the creation of holograms?
On the contrary. It's evidence for the coherence that's required to
create them.
--
Richard Herring
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