| Topic: |
Science > Physics |
| User: |
"son of sound" |
| Date: |
26 Jan 2005 02:46:39 PM |
| Object: |
wavelenght transformation |
Is there a way of transforming the wavelenght
of a laser?
for example, turning a 532nm beam into a 473nm beam?
there most be some kind of optical mecanism, has anyone
work on this at all?
thanks
raymond
sonofsound.com
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| User: "The Ghost In The Machine" |
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| Title: Re: wavelenght transformation |
27 Jan 2005 01:01:41 AM |
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In sci.physics, son of sound
<bat@birdband.net>
wrote
on 26 Jan 2005 12:46:39 -0800
<1106772399.672372.312840@f14g2000cwb.googlegroups.com>:
Is there a way of transforming the wavelenght
of a laser?
for example, turning a 532nm beam into a 473nm beam?
there most be some kind of optical mecanism, has anyone
work on this at all?
I can only approach it from a highly empirical standpoint,
mostly because I know just enough QM to get me into trouble.
However, there is a question I have: if one is transforming
a 532nm to a 473nm beam, is one trying to have:
[1] the same power output?
[2] the same number of photons?
If [1], one has the minor problem of trying to figure out
which photons get zapped and which don't. If [2], one
has to input energy into the converter as more power
is coming out (E = N*h*c / lambda) than going in.
The simplest method I can think of is using a rotating
crystal, which wouldn't work all that well as it would
"warble" or chop up the beam, since crystal faces prefer to
be flat. (The reason it must rotate is so that the face
bouncing the beam can be de-energized, and then something
else can re-energize it on the other side, say. There is
the possibility of rotating the crystal perpendicular to
a face, a bit like a disc, but the atoms of a crystal
face will still be in a regular pattern, and one would
probably get warbling again, although maybe not as much
as when rotating it like a drum.)
The only other method I can think of that might have even
a remote chance of working is moving the laser beam into
an appropriately-moving rocket, and harnessing a variant
of the Doppler effect.
thanks
raymond
sonofsound.com
--
#191,
It's still legal to go .sigless.
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| User: "Timo Nieminen" |
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| Title: Re: wavelenght transformation |
28 Jan 2005 05:15:36 AM |
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On Thu, 27 Jan 2005, The Ghost In The Machine wrote:
son of sound <bat@birdband.net> wrote:
Is there a way of transforming the wavelenght
of a laser?
for example, turning a 532nm beam into a 473nm beam?
there most be some kind of optical mecanism, has anyone
work on this at all?
The simplest method I can think of is using a rotating
crystal, which wouldn't work all that well as it would
"warble" or chop up the beam, since crystal faces prefer to
be flat.
[cut]
There is
the possibility of rotating the crystal perpendicular to
a face, a bit like a disc, but the atoms of a crystal
face will still be in a regular pattern, and one would
probably get warbling again, although maybe not as much
as when rotating it like a drum.)
The only other method I can think of that might have even
a remote chance of working is moving the laser beam into
an appropriately-moving rocket, and harnessing a variant
of the Doppler effect.
Essentially, a combination of your suggestions actually works.
Take a 1/2 wave plate, and shine a circularly polarised beam through. Out
comes a circularly polarised beam of the opposite handedness. Then, spin
the waveplate, and the frequency of the transmitted beam is shifted by 2
times the rotation frequency of the waveplate. This effect is usually
called rotational frequency shift or rotational Doppler shift. The
direction of the shift depends on the direction of rotation compared to
the handedness of the incident beam.
This has been suggested as a practical method for obtaining small,
well-controllable frequency shifts. In principle, you can obtain large
shifts by having two sets of overlapping waveplates on two axles spinning
in opposite directions, so that the beam goes through a waveplate spinning
each way in sequence. I think that this particular scheme has been
published. Most of the literature the topic is new, but there are a few
older papers, too, with a thorough treatment back in 1935 or so.
However, I think it will be hard to get a frequency shift of 100 kHz in
practice, and that's not much of a shift in wavelength at all.
--
Timo
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| User: "Raymond Yohros" |
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| Title: Re: wavelenght transformation |
31 Jan 2005 04:40:37 PM |
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Take a 1/2 wave plate, and shine a circularly polarised beam through.
Out
comes a circularly polarised beam of the opposite handedness. Then,
spin
the waveplate, and the frequency of the transmitted beam is shifted
by 2
times the rotation frequency of the waveplate. This effect is usually
called rotational frequency shift or rotational Doppler shift. The
direction of the shift depends on the direction of rotation compared
to
the handedness of the incident beam.
This has been suggested as a practical method for obtaining small,
well-controllable frequency shifts. In principle, you can obtain
large
shifts by having two sets of overlapping waveplates on two axles
spinning
in opposite directions, so that the beam goes through a waveplate
spinning
each way in sequence. I think that this particular scheme has been
published. Most of the literature the topic is new, but there are a
few
older papers, too, with a thorough treatment back in 1935 or so.
However, I think it will be hard to get a frequency shift of 100 kHz
in
practice, and that's not much of a shift in wavelength at all.
--
Timo
wow, it looks like a significant wavelenght transformation is
not jet even near within our grasp and from what you're saying, it
looks like an extremly complex and dificult task.
if funny how easy it is to do this in the audio ranges and
why it becomes so hard at higher ranges
regards
http://www.sonofsound.com
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| User: "Timo Nieminen" |
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| Title: Re: wavelenght transformation |
31 Jan 2005 04:58:44 PM |
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On Tue, 31 Jan 2005, Raymond Yohros wrote:
wow, it looks like a significant wavelenght transformation is
not jet even near within our grasp and from what you're saying, it
looks like an extremly complex and dificult task.
if funny how easy it is to do this in the audio ranges and
why it becomes so hard at higher ranges
regards
Well, at somewhat lower frequencies (eg RF) there's no great problem in
doing the transformation electronically. Very, very, distinct physically
from changing the wavelength of a beam, since you receive the beam, and
re-encode it's envelope or signal or whatever on a different carrier. Not
so much a transformation of a beam, but a destruction of it and the
reconstruction of a similar beam.
Well, you could even do it optically, as well. Use a photodetector to
monitor the incoming beam, and use it to control the output of a laser at
a different wavelength. Then you have a black box that behaves like a
wavelength transformer.
And there's mixing in non-linear media, too, which generate sum and
difference frequencies. But that's also not a matter of simply altering
the wavelength of a single beam as it passes through a "magic beam
transformer".
Flourescence, perhaps, could be considered wavelength conversion too, but
the output isn't much of a beam.
--
Timo
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| User: "Raymond Yohros" |
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| Title: Re: wavelenght transformation |
31 Jan 2005 06:56:04 PM |
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But that's also not a matter of simply altering
the wavelength of a single beam as it passes through a "magic beam
transformer".
I understand. the problem that laser display proyectors
have today is that argon-krypton lasers are too fragile and
also the greens are not as bright as the greens on dpss lasers.
but dpss proyectors need 3 lasers and therefore 3
powersupplys in order to be full color. that increases the
cost alot but the frequencies are the best ones for display:
(635nm 532nm and 473nm.)
so i was thinking, what could be the simplest way to
produce this wavelenghts with solid state tecnology but
i guess there's no way arround it
regards
raymond
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| User: "Timo Nieminen" |
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| Title: Re: wavelenght transformation |
31 Jan 2005 07:45:01 PM |
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On Tue, 31 Jan 2005, Raymond Yohros wrote:
But that's also not a matter of simply altering
the wavelength of a single beam as it passes through a "magic beam
transformer".
I understand. the problem that laser display proyectors
have today is that argon-krypton lasers are too fragile and
also the greens are not as bright as the greens on dpss lasers.
but dpss proyectors need 3 lasers and therefore 3
powersupplys in order to be full color. that increases the
cost alot but the frequencies are the best ones for display:
(635nm 532nm and 473nm.)
so i was thinking, what could be the simplest way to
produce this wavelenghts with solid state tecnology but
i guess there's no way arround it
What you want is three cheap, sufficiently high power solid state lasers.
There's been a lot of improvement recently - now you can get affordable
green laser pointers [1] (although they go through batteries quickly),
420nm and other blue diode lasers have been around for a while (don't
know about affordability). One problem with trying to do it all with one
laser is that the simplest wavelength transformation to do is halving (ie
frequency-doubling, standard for converting NdYAG 1064nm to 532nm).
Perhaps it might be possible to get frequency-doubled and
frequency-tripled beams out of the same source, but they won't match the
wavelengths that you want.
Best bet is three diodes. Price and power will get better.
[1] The one's that I've seen are actually frequency-doubled; that must be
the cheap way to do it.
--
Timo Nieminen - Home page: http://www.physics.uq.edu.au/people/nieminen/
Shrine to Spirits: http://www.users.bigpond.com/timo_nieminen/spirits.html
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| User: "Raymond Yohros" |
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| Title: Re: wavelenght transformation |
01 Feb 2005 10:01:19 AM |
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420nm and other blue diode lasers have been around for a while
but that wavelenght is too dim to be seen
473 nm it's the pretties blue but is very expensive.
also the beam quality of dpss (diode pumped solid state)
it's alot better than simple diodes but there's no dpss for 635nm.
only for 670nm and that it's also too dim to be seen.
so now the display industry it's using dpss for 473nm
and 532nm and simple diodes for 635nm or 650nm.
(a combination of dpss and simple dioes)
regards
raymond
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| User: "Raymond Yohros" |
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| Title: Re: wavelenght transformation |
01 Feb 2005 11:04:36 AM |
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420nm and other blue diode lasers have been around for a while
but that wavelenght is too dim to be seen
473 nm it's the pretties blue but is very expensive.
also the beam quality of dpss (diode pumped solid state)
it's alot better than simple diodes but there's no dpss for 635nm.
only for 670nm and that it's also too dim to be seen.
so now the display industry it's using dpss for 473nm
and 532nm and simple diodes for 635nm or 650nm.
(a combination of dpss and simple dioes)
regards
raymond
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| User: "son of sound" |
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| Title: Re: wavelenght transformation |
27 Jan 2005 02:30:57 PM |
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The Ghost In The Machine wrote:
In sci.physics, son of sound
<bat@birdband.net>
wrote
on 26 Jan 2005 12:46:39 -0800
<1106772399.672372.312840@f14g2000cwb.googlegroups.com>:
Is there a way of transforming the wavelenght
of a laser?
for example, turning a 532nm beam into a 473nm beam?
there most be some kind of optical mecanism, has anyone
work on this at all?
I can only approach it from a highly empirical standpoint,
mostly because I know just enough QM to get me into trouble.
However, there is a question I have: if one is transforming
a 532nm to a 473nm beam, is one trying to have:
[1] the same power output?
[2] the same number of photons?
If [1], one has the minor problem of trying to figure out
which photons get zapped and which don't. If [2], one
has to input energy into the converter as more power
is coming out (E = N*h*c / lambda) than going in.
The simplest method I can think of is using a rotating
crystal, which wouldn't work all that well as it would
"warble" or chop up the beam, since crystal faces prefer to
be flat. (The reason it must rotate is so that the face
bouncing the beam can be de-energized, and then something
else can re-energize it on the other side, say. There is
the possibility of rotating the crystal perpendicular to
a face, a bit like a disc, but the atoms of a crystal
face will still be in a regular pattern, and one would
probably get warbling again, although maybe not as much
as when rotating it like a drum.)
this doesn't sound like an elegant solution.
maybe using the aproach on microchips but with
an optical device? could this be posible?
raymond
sonofsound.com
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| User: "Uncle Al" |
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| Title: Re: wavelenght transformation |
26 Jan 2005 03:56:51 PM |
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son of sound wrote:
Is there a way of transforming the wavelenght
of a laser?
for example, turning a 532nm beam into a 473nm beam?
there most be some kind of optical mecanism, has anyone
work on this at all?
Sum and difference non-linear optical mixing; harmonic generation;
start with a multi-line laser (argon) or a tunable laser; or an
optical parametric amplifier; or blast the thing through a capillary
filed with hydrogen - though an elongated optical crystal will be less
lossy.
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
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| User: "son of sound" |
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| Title: Re: wavelenght transformation |
26 Jan 2005 05:33:29 PM |
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Uncle Al wrote:
son of sound wrote:
Is there a way of transforming the wavelenght
of a laser?
for example, turning a 532nm beam into a 473nm beam?
there most be some kind of optical mecanism, has anyone
work on this at all?
Sum and difference non-linear optical mixing; harmonic generation;
start with a multi-line laser (argon) or a tunable laser; or an
optical parametric amplifier; or blast the thing through a capillary
filed with hydrogen - though an elongated optical crystal will be
less
lossy.
sorry for not being clear on the source,
i don't want to use an argon or argon/krypton MIXGAS ION laser
and use a pcaom cristal to filter the witelight.
what i want to use is a D.P.S.S laser as the source
of only one wavelenght and transform it into another.
can an elongated optical crystal make this transformation?
regards
raymond
sonofsound.com
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| User: "tj Frazir" |
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| Title: Re: wavelenght transformation |
26 Jan 2005 11:14:45 PM |
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Refracting it threw a crystal might wreck the beam in a few yards.
Try a liquid filter.
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| User: "tj Frazir" |
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| Title: Re: wavelenght transformation |
26 Jan 2005 11:08:36 PM |
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Use a filter.
Shades for a laser.
Red ,,red filter.
Blue ,,a blue filter.
red over blue.
yellow over green.
shortwave over xray.
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| User: "Sam Wormley" |
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| Title: Re: wavelenght transformation |
26 Jan 2005 04:29:03 PM |
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son of sound wrote:
Is there a way of transforming the wavelenght
of a laser?
for example, turning a 532nm beam into a 473nm beam?
Green lasers start in the UV range
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| User: "relay61:13:214:23" |
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| Title: Re: wavelenght transformation |
26 Jan 2005 03:05:28 PM |
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tunable dye lasers - google it
or multiply it
"son of sound" <bat@birdband.net> wrote in message
news:1106772399.672372.312840@f14g2000cwb.googlegroups.com...
Is there a way of transforming the wavelenght
of a laser?
for example, turning a 532nm beam into a 473nm beam?
there most be some kind of optical mecanism, has anyone
work on this at all?
thanks
raymond
sonofsound.com
.
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