homebrew maser
Same general idea, but an image intensifier plate would probably not work well. They are usually thinner and are cut at a bias so the electrons ricochet along its length. You might be able to mount one so that it cancels the bias angle.
They are made by stretching a bundle of hollow glass tubes that have been filled with solid glass rods of a different composition. The original bundle can be very large (like over a meter) and is shrunk down to like 100 fibers per millimeter. It is then sliced and polished. Often the slices (or the pulled bundles) are joined into a bigger plate. Then the inner solid glass is dissolved out with a strong alkali. The hollow tubes are coated with a photoelectric material.
The image from the tube is inverted using a "twister"... a coherent fiber optic rod that has a 180 degree twist.
Do you know if the collimator is made from an uncoated microchannel plate?
If so, an old, broken Gen II image intensifier might be a viable source.
PTFE wall storage bulb wall coatings haven't been used for some decades,
FEP (or the Russian fluoropolymer ) is better in that a smoother coat is
achievable see:
http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA509340
http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA509340
A sual hexapole state selector is probably a little more effective than
the cruder method used in the Russian masers.
Bruce
Mark Sims wrote:
Same general idea, but an image intensifier plate would probably not work well. They are usually thinner and are cut at a bias so the electrons ricochet along its length. You might be able to mount one so that it cancels the bias angle.
They are made by stretching a bundle of hollow glass tubes that have been filled with solid glass rods of a different composition. The original bundle can be very large (like over a meter) and is shrunk down to like 100 fibers per millimeter. It is then sliced and polished. Often the slices (or the pulled bundles) are joined into a bigger plate. Then the inner solid glass is dissolved out with a strong alkali. The hollow tubes are coated with a photoelectric material.
The image from the tube is inverted using a "twister"... a coherent fiber optic rod that has a 180 degree twist.
Do you know if the collimator is made from an uncoated microchannel plate?
If so, an old, broken Gen II image intensifier might be a viable source.
time-nuts mailing list -- time-nuts@febo.com
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and follow the instructions there.
That's a great article. It almost makes the job seem doable.
It is going to be expensive, though. If someone can build a working maser
for less than $10K in materials and bespoke fabrication services alone, I'll
be impressed. An obvious question is, what's the so-called "minimum viable
product" that can actually produce a population inversion in a cavity and
demonstrate maser action? Do you need any magnetic shielding at all, beyond
a couple of Helmholtz coils? Maybe not. Do you need to coat the bulb at
all if you don't care about line width? Maybe not. How exotic does the
collimator need to be if you don't care much about service life? Probably
not very. You definitely don't need a multilayer vacuum system. What
corners can be cut to get a rough prototype running?
Control electronics is trivial, and not even worth thinking about until the
physical details are nailed down.
Once you start talking about cutting corners just to get a maser up and
running, though, there's another obvious question worth considering: what
about starting with an ammonia maser? This was the first molecular
oscillator. Experience optimizing the (numerous) operating parameters in an
NH3 maser would no doubt be helpful in later work with an H maser.
Ammonia molecules have a dipole moment and can be state-selected
electrostatically. There is no need for either a dissociator or a storage
bulb, just a basic electrostatic lens and cavity in a vacuum. Townes's
original 1954 paper makes no mention of magnetic shielding. But at 24 GHz a
high-Q cavity is small and manageable, so if you do have to enclose it in
mu-metal it's not going to cost a fortune.
Further, with stabilities in the 1E-12 range, a 5065A-class rubidium
standard or a well-optimized GPS clock can be used as a reference for
tweaking and debugging an NH3 maser. If you do manage to build a hydrogen
maser, OTOH, you are going to need to build at least two of them to get any
idea where your performance floor is.
Just one possible thought...
-- john, KE5FX
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com]On
Behalf Of Bruce Griffiths
Sent: Tuesday, August 31, 2010 1:23 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] homebrew maser
PTFE wall storage bulb wall coatings haven't been used for some decades,
FEP (or the Russian fluoropolymer ) is better in that a smoother coat is
achievable see:
http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&
AD=ADA509340
<http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf
&AD=ADA509340>
A sual hexapole state selector is probably a little more effective than
the cruder method used in the Russian masers.
Bruce
Mark Sims wrote:
Same general idea, but an image intensifier plate would
probably not work well. They are usually thinner and are cut at
a bias so the electrons ricochet along its length. You might be
able to mount one so that it cancels the bias angle.
They are made by stretching a bundle of hollow glass tubes that
have been filled with solid glass rods of a different
composition. The original bundle can be very large (like over a
meter) and is shrunk down to like 100 fibers per millimeter. It
is then sliced and polished. Often the slices (or the pulled
bundles) are joined into a bigger plate. Then the inner solid
glass is dissolved out with a strong alkali. The hollow tubes are
coated with a photoelectric material.
The image from the tube is inverted using a "twister"... a
coherent fiber optic rod that has a 180 degree twist.
Do you know if the collimator is made from an uncoated
microchannel plate?
If so, an old, broken Gen II image intensifier might be a viable source.
time-nuts mailing list -- time-nuts@febo.com
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and follow the instructions there.
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To unsubscribe, go to
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and follow the instructions there.
Microwave test gear and plumbing is very significantly harder to get at 24
GHz than at 1.4 GHz.
At a guess I've seen easily 100 times more stuff available at 1.4 GHz.
FWIW,
-John
============
That's a great article. It almost makes the job seem doable.
It is going to be expensive, though. If someone can build a working maser
for less than $10K in materials and bespoke fabrication services alone,
I'll
be impressed. An obvious question is, what's the so-called "minimum
viable
product" that can actually produce a population inversion in a cavity and
demonstrate maser action? Do you need any magnetic shielding at all,
beyond
a couple of Helmholtz coils? Maybe not. Do you need to coat the bulb at
all if you don't care about line width? Maybe not. How exotic does the
collimator need to be if you don't care much about service life? Probably
not very. You definitely don't need a multilayer vacuum system. What
corners can be cut to get a rough prototype running?
Control electronics is trivial, and not even worth thinking about until
the
physical details are nailed down.
Once you start talking about cutting corners just to get a maser up and
running, though, there's another obvious question worth considering: what
about starting with an ammonia maser? This was the first molecular
oscillator. Experience optimizing the (numerous) operating parameters in
an
NH3 maser would no doubt be helpful in later work with an H maser.
Ammonia molecules have a dipole moment and can be state-selected
electrostatically. There is no need for either a dissociator or a storage
bulb, just a basic electrostatic lens and cavity in a vacuum. Townes's
original 1954 paper makes no mention of magnetic shielding. But at 24 GHz
a
high-Q cavity is small and manageable, so if you do have to enclose it in
mu-metal it's not going to cost a fortune.
Further, with stabilities in the 1E-12 range, a 5065A-class rubidium
standard or a well-optimized GPS clock can be used as a reference for
tweaking and debugging an NH3 maser. If you do manage to build a hydrogen
maser, OTOH, you are going to need to build at least two of them to get
any
idea where your performance floor is.
Just one possible thought...
-- john, KE5FX
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com]On
Behalf Of Bruce Griffiths
Sent: Tuesday, August 31, 2010 1:23 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] homebrew maser
PTFE wall storage bulb wall coatings haven't been used for some decades,
FEP (or the Russian fluoropolymer ) is better in that a smoother coat is
achievable see:
http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&
AD=ADA509340
<http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf
&AD=ADA509340>
A sual hexapole state selector is probably a little more effective than
the cruder method used in the Russian masers.
Bruce
Mark Sims wrote:
Same general idea, but an image intensifier plate would
probably not work well. They are usually thinner and are cut at
a bias so the electrons ricochet along its length. You might be
able to mount one so that it cancels the bias angle.
They are made by stretching a bundle of hollow glass tubes that
have been filled with solid glass rods of a different
composition. The original bundle can be very large (like over a
meter) and is shrunk down to like 100 fibers per millimeter. It
is then sliced and polished. Often the slices (or the pulled
bundles) are joined into a bigger plate. Then the inner solid
glass is dissolved out with a strong alkali. The hollow tubes are
coated with a photoelectric material.
The image from the tube is inverted using a "twister"... a
coherent fiber optic rod that has a 180 degree twist.
Do you know if the collimator is made from an uncoated
microchannel plate?
If so, an old, broken Gen II image intensifier might be a viable
source.
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Microwave test gear and plumbing is very significantly harder to get at 24
GHz than at 1.4 GHz.
At a guess I've seen easily 100 times more stuff available at 1.4 GHz.
That is so far down the list of "101 Things That Are Hard About Building a
Hydrogen Maser" I'm not even sure it makes the top 101. :)
There is a ton of prior art in the Amateur Radio microwave community on 24
GHz microwave activity and construction. At 1.420 GHz, not so much.
-- john, KE5FX
How about a "Laser-Cooled Mercury Ion Frequency Standard"?
http://tf.nist.gov/general/pdf/1225.pdf
Here's another approach:
"A diode-laser optical frequency standard based on laser-cooled Ca
atoms:Sub-kilohertz spectroscopy by optical shelving detection"
http://www.nist.gov/customcf/get_pdf.cfm?pub_id=105042
----- Original Message -----
From: "John Miles" jmiles@pop.net
To: jfor@quik.com; "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Tuesday, August 31, 2010 8:02 PM
Subject: Re: [time-nuts] homebrew maser
Microwave test gear and plumbing is very significantly harder to get at
24
GHz than at 1.4 GHz.
At a guess I've seen easily 100 times more stuff available at 1.4 GHz.
That is so far down the list of "101 Things That Are Hard About Building a
Hydrogen Maser" I'm not even sure it makes the top 101. :)
There is a ton of prior art in the Amateur Radio microwave community on 24
GHz microwave activity and construction. At 1.420 GHz, not so much.
-- john, KE5FX
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Either of those are a lot harder than a H MASER.
-John
=============
How about a "Laser-Cooled Mercury Ion Frequency Standard"?
http://tf.nist.gov/general/pdf/1225.pdf
Here's another approach:
"A diode-laser optical frequency standard based on laser-cooled Ca
atoms:Sub-kilohertz spectroscopy by optical shelving detection"
http://www.nist.gov/customcf/get_pdf.cfm?pub_id=105042
----- Original Message -----
From: "John Miles" jmiles@pop.net
To: jfor@quik.com; "Discussion of precise time and frequency
measurement"
time-nuts@febo.com
Sent: Tuesday, August 31, 2010 8:02 PM
Subject: Re: [time-nuts] homebrew maser
Microwave test gear and plumbing is very significantly harder to get at
24
GHz than at 1.4 GHz.
At a guess I've seen easily 100 times more stuff available at 1.4 GHz.
That is so far down the list of "101 Things That Are Hard About Building
a
Hydrogen Maser" I'm not even sure it makes the top 101. :)
There is a ton of prior art in the Amateur Radio microwave community on
24
GHz microwave activity and construction. At 1.420 GHz, not so much.
-- john, KE5FX
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
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and follow the instructions there.
On Tue, 31 Aug 2010 17:02:16 -0700
"John Miles" jmiles@pop.net wrote:
Microwave test gear and plumbing is very significantly harder to get at 24
GHz than at 1.4 GHz.
At a guess I've seen easily 100 times more stuff available at 1.4 GHz.
That is so far down the list of "101 Things That Are Hard About Building a
Hydrogen Maser" I'm not even sure it makes the top 101. :)
There is a ton of prior art in the Amateur Radio microwave community on 24
GHz microwave activity and construction. At 1.420 GHz, not so much.
I agree here with the other John, 1.4GHz is a lot easier to handle
than 24GHz. While the physics of a H maser are not trivial, handling
frequencies over 5GHz gets difficult. Going over 20GHz, finding electronics
that work reliably there, having a low noise floor etc is something
that even companies specialized in that stuff have difficulties with.
Ie it would lead to the situation where it becomes near impossible
to test whether the electronics is working correctly or whether the
physics package has some problems. Considering this, i'd rather stick
with electronics that can be done with off the shelf components and that
is easy to test and verify.
If the size of the cavity is a problem with the H maser, it would be quite
easy to load the cavity with some high \epsilon material and thus shrinking
it (as it is done with all modern H masers i've read about)
IMHO, the "right" way to build a maser would be first to build the cavity
and the electronics. Verify that the cavity is resonant at the right
frequency, can be tuned in a wide enough range and can be stabilized well
enough that changes in cavity resonance will only have a minor effect on
the maser itself.
Then build and verify the vacuum system.
Then build the beam source, collimator and state selector and verify that
they are working as they are supposed to do.
And last, put everything together, and hope that it magically works ;-)
Attila Kinali
--
If you want to walk fast, walk alone.
If you want to walk far, walk together.
-- African proverb
Hi
Both seem to require a lot more work than a maser, not to mention a steady
flow of liquid nitrogen.
Bob
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Heathkid
Sent: Tuesday, August 31, 2010 10:11 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] homebrew maser
How about a "Laser-Cooled Mercury Ion Frequency Standard"?
http://tf.nist.gov/general/pdf/1225.pdf
Here's another approach:
"A diode-laser optical frequency standard based on laser-cooled Ca
atoms:Sub-kilohertz spectroscopy by optical shelving detection"
http://www.nist.gov/customcf/get_pdf.cfm?pub_id=105042
----- Original Message -----
From: "John Miles" jmiles@pop.net
To: jfor@quik.com; "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Tuesday, August 31, 2010 8:02 PM
Subject: Re: [time-nuts] homebrew maser
Microwave test gear and plumbing is very significantly harder to get at
24
GHz than at 1.4 GHz.
At a guess I've seen easily 100 times more stuff available at 1.4 GHz.
That is so far down the list of "101 Things That Are Hard About Building a
Hydrogen Maser" I'm not even sure it makes the top 101. :)
There is a ton of prior art in the Amateur Radio microwave community on 24
GHz microwave activity and construction. At 1.420 GHz, not so much.
-- john, KE5FX
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
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and follow the instructions there.
On 09/01/2010 04:11 AM, Heathkid wrote:
How about a "Laser-Cooled Mercury Ion Frequency Standard"?
http://tf.nist.gov/general/pdf/1225.pdf
I have way too little liquid helium dewar flasks at all... but sure, it
would be fun. I would certainly see a bunch of challenges in mixing down
from about 40,5 GHz.
Here's another approach:
"A diode-laser optical frequency standard based on laser-cooled Ca
atoms:Sub-kilohertz spectroscopy by optical shelving detection"
http://www.nist.gov/customcf/get_pdf.cfm?pub_id=105042
Yet more challenges. Getting the visible light lasers frequency-related
to something like 10 MHz or 100 MHz is a whole bunch of optical
lab-bench and lockings later. Few labs have dared to achieve it as far
as I know. Who else but PTB?
Thank you for making a homebrew H-maser look simple! :)
Cheers,
Magnus