Creating a D.I.Y Rubidium Atomic Clock
There are some pretty resourceful people out there. The glassware might be considered an uphill battle, but it's not impossible.
It would be fair to suggest using pieces off of eBay as a starting point and make the whole system work and then go back and solve those problems.
Diode laser pumping might drastically simplify things.
From: Bob Stewart via time-nuts time-nuts@lists.febo.com
Sent: Wednesday, June 7, 2023 1:35:05 PM
To: Richard Karlquist via time-nuts time-nuts@lists.febo.com
Cc: Bob Stewart bob@evoria.net
Subject: [time-nuts] Re: Creating a D.I.Y Rubidium Atomic Clock
Speaking of existing commercial "physics packages", various iterations of the FE-5680 are available on ebay. I got one years ago and was disappointed. I can't imagine them having made so many if they thought it was a failure, so I guess my expectations were higher. Could someone(s) comment on the FE-5680 and how it could be made better? Is it just a matter of temperature control, or is their physics package just not up to time-nuts standards?
Bob
On Wednesday, June 7, 2023 at 04:50:28 AM CDT, Richard Karlquist via time-nuts <time-nuts@lists.febo.com> wrote:
In a former life, I was on the design team of a mini rubidium standard
at Hewlett-Packard. We built some working prototypes before it was
cancelled. It was going to have the model number 10816. I was the RF
person, but I worked very closely with the other team members.
Remembering what we had to go through to make "glassware", it is
inconceivable that you could do that as a "home brew" project. And this
was the same HP facility that already made the 5065 rubidium standard.
The best you could hope to do is to start with a commercial "physics
package" as we called it, and make your own electronics for it. Reading
books about how rubidium standards work, etc is fine, but again, you
can't home brew the glassware.
Rick Karlquist
N6RK
On 2023-06-06 15:39, Tom Van Baak via time-nuts wrote:
Hi Leo,
That sounds like a fun project. Here are some extremely informative resources:
"Introduction to the Rubidium Frequency Standard"
by Michael Parker, 358 pages
http://www.leapsecond.com/u/parker/ParkerIntroRFS-PPCP.pdf
"Rubidium Frequency Standard Primer"
by Bill Riley, 163 pages
http://www.wriley.com/Rubidium%20Frequency%20Standard%20Primer%20102211.pdf
"Selection Criteria for Rubidium Frequency Standards"
by Bill Riley, 51 pages
http://www.wriley.com/Selection%20Criteria%20for%20Rubidium%20Frequency%20Standards.pdf
Also read service manuals for commercial Rb products. Didier's site has a nice collection. Search by product number (e.g., 5065a) or by title (e.g., rubidium):
http://www.ko4bb.com/getsimple/index.php?id=manuals
/tvb
On 6/6/2023 12:25 PM, Leo Ahluwalia via time-nuts wrote:
Hello, my name is Leo, and I was wondering about the feasibility of
creating a simple rubidium atomic clock at home, and good places to source
parts for this sort of project. I was also wondering what instruments and
specialized knowledge would be required depending on how pre-built the
parts are, for example, the prerequisite knowledge for creating PLL(s) for
both frequency division to provide an output and also to modulate the input
of the microwave oscillator. Any good resources or PDFs would be greatly
appreciated, as I am very new to frequency analysis and phase manipulation
in general. I was also hoping to keep the cost of the project soft-line
below 500$, though that would be assuming a decent level of precision and
already possessing basic equipment (oscilloscope, multimeter, etc...). Safety
is also a major concern, as I know while the intensity of the EM waves
involved is low, the power source may or may not be. This is all of course
assuming a basic design, where my assumption is that it will involve the
microwaves being shot at a rubidium vapor cell which is directed towards a
photodetector. This would then be connected up to the PLL and circuitry to
both provide a stable standard while also modulating the microwave
oscillator to offset any external environmental factors. I don't have a
clear vision of what would truly be the best design for both simplicity and
cost, though this is what I've found to be a common design in what I've
looked at online.
Thanks, Leo
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Hi Rick,
Yes. The D1 and D2 lines of Rb87 and Rb85 align up so you can use Rb85
as filter for the Rb87 to get a more efficient optical pumping of the
Rb87 gas cell. It is mainly this property that enabled rubidium to be
the primary gas cell atom & isotope, that enabled a much cheaper
physical package. Today you could potentially replace the Rb85 filter
cell with modern optical filters. The Rb85 filter is really just part of
the lamp, but in practice many have a mix of Rb85 and Rb87 in the
reference cell.
Then again, replace the filter with a laser diode for 780 nm that is
steered up to the right wavelength, and you avoid the filtering
altogether. That has a few issues of itself naturally, but they can be
solved and is so for modern setups. Then you can use some completely
different spieces, and look at them CSACs doing this with cesium instead.
It is interesting how very specific details steer what type of clocks is
built. There where rubidium and thallium beams too, but they became less
meaningful as cesium was selected. But then again, rubidium became
popular for the folded beam-tube called fountain. Thallium could have
been our reference, but it was harder to ionize and it was harder to
produce the 24 GHz frequency for, so it was not very easy to replicate,
but those drawbacks is gone with todays RF and laser technologies.
One thing which our normal rubidiums does not handle well is the
amplitude of optical pumping field as well as RF field will cause AC
Stark frequency shift, those providing a mechanism for low frequency
drift. Stabilizing these with servo loop could be among the things one
can have a look at if one fool around.
Cheers,
Magnus
On 2023-06-07 23:45, Richard Karlquist via time-nuts wrote:
My understanding is that the Rb85 and Rb87 isotopes happen to
accidentally be correct to make the optical filter cell work correctly.
I don't believe you can do this with any other atom. It's different
from primary atomic standards that just excite the hyperfine quantum
transition. In that case, you can debate about which atom or ion to
use.
Rick Karlquist
N6RK
On 2023-06-07 13:37, Marek Doršic via time-nuts wrote:
On 7 Jun 2023, at 20:37, djl via time-nuts time-nuts@lists.febo.com wrote:
Certainly interesting topic. Rb provides a safe approach. However, I am curious to know if anyone has explored the possibility of using other elements, specifically Indium?.md
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Hi Leo,
So, the setup is very straight forward. You put the Rb-lamp, the filter,
the Rb resonance cell all lined up in a straight path and at the far end
of that you have a photo-detector. The resonance cell you want to keep
magnetically shielded, which is typically done by one or more (I have
clocks with 3) layers of mu-metal. You have a coil, called C-field coil,
through which a DC current creates a magnetic field that separates the 5
Rb resonances so that only the (1,0)->(2,0) absorption occurs, which is
detected by a thad lower intensity of the pump light.
Look at Tom's email and I strongly suggest you get "Rubidium Frequency
Standard Primer" of William J. Riley which has a lot of info in it
covering a lot of the things that goes into it. This includes a lot of
photo of the actual inner parts of the rubidium clocks. There is more
material to gather, but already that book will answer a lot of things
for you and summarizes a lot of stuff in a very condensed and straight
forward way.
Cheers,
Magnus
On 2023-06-08 00:38, Leo Ahluwalia via time-nuts wrote:
I appreciate all of the help so far, and assuming the procurement of a
rubidium vapour cell and rubidium lamp (and of course all the other
components), I was wondering how exactly the optical pumping setup should
be achieved (to make sure all the components are "hooked up" so to speak),
and whether there was already a standard way of achieving it along with the
installation of the magnetic shielding?
- Leo
On Wed, Jun 7, 2023 at 6:27 PM Bruce Griffiths via time-nuts <
time-nuts@lists.febo.com> wrote:
That just leaves the Rubidium lamp.
An ECDL (external cavity diode laser) locked to the appropriate Rubidium
transition is much easier to build. There are several ECDL designs in the
literature. Mostly these are Littrow designs. A Cateye resonator design is
another option. All the components required are readily availble.
VCSEL's should be avoided as those without polarisation mode stabilisation
gratings on the output face randomly mode hop between a pair or
orthogonally polarised modes.
A well designed but relatively simple ECDL can have a much narrower line
width than a typical DFB laser.Bruce
On 08/06/2023 06:37 NZST djl via time-nuts time-nuts@lists.febo.com
wrote:The Rb capsules are available on ebay, eg: 124012486501
the classblowing part is done?On 2023-06-07 07:50, Richard (Rick) Karlquist via time-nuts wrote:
On 6/7/2023 5:03 AM, Stephen C. Menasian via time-nuts wrote:
- some pure Rb87
- a glass blowing setup (and some skill)
- A selection of inert gasses (at least including Ar)
- Light source (Rb discharge was used then with a circular polarizer;
At HP we had really skilled glass blowers, with specific experience in
making Rb glassware. We had to use an exotic grade of glass that was
only one step removed from fused quartz. It had a part number that I
don't remember. Very difficult to work with.The Rb lamp (one of three pieces of glassware) is very tricky to work
with. We used a resonant coil driven at 95 MHz at several watts.
The trick is to "strike" the plasma and make the lamp light up;
you can at least see visible light when that happens. I spent a
lot of time fooling with it. We never got it to work as
well as the 5065 lamp.BTW, one of the Rb isotopes is slightly radioactive. Might be
hard to get as a hobbyist due to regulations. The physicist I
sat next to had a tank of it illegally stored in his cubicle.Rick
N6RK
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"It's always something."
Roseanne Rosannadanna
----------------------"
Dr. Don Latham AJ7LL
PO Box 404, Frenchtown, MT, 59834
VOX: 406-626-4304
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On 6/7/23 7:22 AM, Bob Camp via time-nuts wrote:
Hi
Back when I was with EG&G, they spent a lot of effort on the “glassware” side
of things. It was a major undertaking for a facility that already made vacuum
tubes.
Was what they did overkill? In the end that was a bit unclear. Their whole “accurate
dose” gas fill was still being debated years later. That said, you still need some
way to get a very precise mix into each and every cell.
Bob
On Jun 6, 2023, at 8:26 PM, Richard Karlquist via time-nuts time-nuts@lists.febo.com wrote:
In a former life, I was on the design team of a mini rubidium standard
at Hewlett-Packard. We built some working prototypes before it was
cancelled. It was going to have the model number 10816. I was the RF
person, but I worked very closely with the other team members.
Remembering what we had to go through to make "glassware", it is
inconceivable that you could do that as a "home brew" project. And this
was the same HP facility that already made the 5065 rubidium standard.
The best you could hope to do is to start with a commercial "physics
package" as we called it, and make your own electronics for it. Reading
books about how rubidium standards work, etc is fine, but again, you
can't home brew the glassware.
Rick Karlquist
N6RK
I know a bunch of people on the Cold Atom Lab project, which is making
Bose Einstein Condensates on ISS - they run both K and Rb (I don't know
if it's in the same cavity). But if you need contacts on how they made
theirs, I can probably find some people to talk to.
That project was described as "take a lab bench full of equipment and
three post docs and turn it into a box you can take to the space
station, push a button, and make BECs" It was, as these things are, an
adventure.
Hi
The obscure footnote to much of this is that each cell is not always “pure”
this or that. There are a range of issues that come up. You add buffer gas
of this or that type to correct for these issues. Just what’s on that list …. it’s
been to many decades since I was into this ….
Bob
On Jun 7, 2023, at 6:37 PM, Ed Marciniak via time-nuts time-nuts@lists.febo.com wrote:
At least one implementation of rubidium clocks I've seen use a lamp, filter and resonance cell.
The filter had rubidium 85, the lamp and resonance cell had rubidium 87 or possibly a natural isotopic mix, likely with the lamp being natural rubidium isotopic abundance.
I suspect the higher quality ones had resonance cells with isotopically enriched rubidium 87.
Increased signal to noise ratio would allow lower lamp power, and potentially both lower light shift, and longer lifetimes on components.
From: Stephen C. Menasian via time-nuts time-nuts@lists.febo.com
Sent: Wednesday, June 7, 2023 4:03:24 PM
To: Discussion of precise time and frequency measurement time-nuts@lists.febo.com
Cc: Stephen C. Menasian menasian@ptd.net
Subject: [time-nuts] Re: Creating a D.I.Y Rubidium Atomic Clock
I would suspect that indium is not suitable. The easiest elements to pump
optically are the alkali metals, due to their strong D lines which allow
the ground state atoms to absorb the appropriate radiation strongly,
thus, enabling the optical pumping effect.
On Wed, 7 Jun 2023 22:37:42
+0200 Marek Doršic via time-nuts time-nuts@lists.febo.com wrote:
Certainly interesting topic. Rb provides a safe approach. However, I am
curious to know if anyone has explored the possibility of using other
elements, specifically Indium?
.md
On 7 Jun 2023, at 20:37, djl via time-nuts time-nuts@lists.febo.com
wrote:
The Rb capsules are available on ebay, eg: 124012486501
the classblowing part is done?
On 2023-06-07 07:50, Richard (Rick) Karlquist via time-nuts wrote:
On 6/7/2023 5:03 AM, Stephen C. Menasian via time-nuts wrote:
- some pure Rb87
- a glass blowing setup (and some skill)
- A selection of inert gasses (at least including Ar)
- Light source (Rb discharge was used then with a circular
polarizer;
At HP we had really skilled glass blowers, with specific experience
in making Rb glassware. We had to use an exotic grade of glass that
was only one step removed from fused quartz. It had a part number
that I don't remember. Very difficult to work with.
The Rb lamp (one of three pieces of glassware) is very tricky to work
with. We used a resonant coil driven at 95 MHz at several watts.
The trick is to "strike" the plasma and make the lamp light up;
you can at least see visible light when that happens. I spent a
lot of time fooling with it. We never got it to work as
well as the 5065 lamp.
BTW, one of the Rb isotopes is slightly radioactive. Might be
hard to get as a hobbyist due to regulations. The physicist I
sat next to had a tank of it illegally stored in his cubicle.
Rick
N6RK
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"It's always something."
Roseanne Rosannadanna
----------------------"
Dr. Don Latham AJ7LL
PO Box 404, Frenchtown, MT, 59834
VOX: 406-626-4304
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There are 795nm laser diodes. It would be pretty easy to lock one of these
to 795.5nm. I bet they are expensive.
https://www.photodigm.com/products/795-nm-laser-diode
Colin Kaminski
On Wed, Jun 7, 2023 at 6:32 PM Bob Camp via time-nuts <
time-nuts@lists.febo.com> wrote:
Hi
The obscure footnote to much of this is that each cell is not always “pure”
this or that. There are a range of issues that come up. You add buffer gas
of this or that type to correct for these issues. Just what’s on that list
…. it’s
been to many decades since I was into this ….
Bob
On Jun 7, 2023, at 6:37 PM, Ed Marciniak via time-nuts <
time-nuts@lists.febo.com> wrote:
At least one implementation of rubidium clocks I've seen use a lamp,
filter and resonance cell.
The filter had rubidium 85, the lamp and resonance cell had rubidium 87
or possibly a natural isotopic mix, likely with the lamp being natural
rubidium isotopic abundance.
I suspect the higher quality ones had resonance cells with isotopically
enriched rubidium 87.
Increased signal to noise ratio would allow lower lamp power, and
potentially both lower light shift, and longer lifetimes on components.
From: Stephen C. Menasian via time-nuts time-nuts@lists.febo.com
Sent: Wednesday, June 7, 2023 4:03:24 PM
To: Discussion of precise time and frequency measurement <
Cc: Stephen C. Menasian menasian@ptd.net
Subject: [time-nuts] Re: Creating a D.I.Y Rubidium Atomic Clock
I would suspect that indium is not suitable. The easiest elements to pump
optically are the alkali metals, due to their strong D lines which allow
the ground state atoms to absorb the appropriate radiation strongly,
thus, enabling the optical pumping effect.
On Wed, 7 Jun 2023 22:37:42
+0200 Marek Doršic via time-nuts time-nuts@lists.febo.com wrote:
Certainly interesting topic. Rb provides a safe approach. However, I am
curious to know if anyone has explored the possibility of using other
elements, specifically Indium?
.md
On 7 Jun 2023, at 20:37, djl via time-nuts time-nuts@lists.febo.com
wrote:
The Rb capsules are available on ebay, eg: 124012486501
the classblowing part is done?
On 2023-06-07 07:50, Richard (Rick) Karlquist via time-nuts wrote:
On 6/7/2023 5:03 AM, Stephen C. Menasian via time-nuts wrote:
- some pure Rb87
- a glass blowing setup (and some skill)
- A selection of inert gasses (at least including Ar)
- Light source (Rb discharge was used then with a circular
polarizer;
At HP we had really skilled glass blowers, with specific experience
in making Rb glassware. We had to use an exotic grade of glass that
was only one step removed from fused quartz. It had a part number
that I don't remember. Very difficult to work with.
The Rb lamp (one of three pieces of glassware) is very tricky to work
with. We used a resonant coil driven at 95 MHz at several watts.
The trick is to "strike" the plasma and make the lamp light up;
you can at least see visible light when that happens. I spent a
lot of time fooling with it. We never got it to work as
well as the 5065 lamp.
BTW, one of the Rb isotopes is slightly radioactive. Might be
hard to get as a hobbyist due to regulations. The physicist I
sat next to had a tank of it illegally stored in his cubicle.
Rick
N6RK
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
"It's always something."
Roseanne Rosannadanna
----------------------"
Dr. Don Latham AJ7LL
PO Box 404, Frenchtown, MT, 59834
VOX: 406-626-4304
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
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I had a consulting assignment to design a 6.8 GHz synthesizer for a Cold
Atom Rb around 2019. It was kind of just like Jim said including the
three post docs, although AFAIK, it was just a frequency source to use
for whatever; they never mentioned it going to space. IIRC, it was
optically pumped by lasers, and there was no absorption cell. Much
greater degree of difficulty than the traditional Rb gas cell standard.
However, a whole lot more stable/accurate. The synthesizer I designed,
I would say, was the "easy" part. However, the OCXO cost something like
$5,000.
Rick Karlquist
N6RK
On 2023-06-07 16:56, Lux, Jim via time-nuts wrote:
I know a bunch of people on the Cold Atom Lab project, which is making Bose Einstein Condensates on ISS - they run both K and Rb (I don't know if it's in the same cavity). But if you need contacts on how they made theirs, I can probably find some people to talk to.
That project was described as "take a lab bench full of equipment and three post docs and turn it into a box you can take to the space station, push a button, and make BECs" It was, as these things are, an adventure.
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at 8:26 PM, Richard Karlquist via time-nuts time-nuts@lists.febo.com wrote:
In a former life, I was on the design team of a mini rubidium standard
at Hewlett-Packard. We built some working prototypes before it was
cancelled. It was going to have the model number 10816. I was the RF
person, but I worked very closely with the other team members.
Remembering what we had to go through to make "glassware", it is
inconceivable that you could do that as a "home brew" project. And this
was the same HP facility that already made the 5065 rubidium standard.
The best you could hope to do is to start with a commercial "physics
package" as we called it, and make your own electronics for it. Reading
books about how rubidium standards work, etc is fine, but again, you
can't home brew the glassware.
Rick Karlquist
N6RK
Hi Stephen, I appreciate the advice, and while glass-blowing isn't
something I've had much experience with, making the glass package
definitely sounds like a fun challenge.
Thanks, Leo
On Wed, Jun 7, 2023 at 8:23 AM Stephen C. Menasian via time-nuts <
time-nuts@lists.febo.com> wrote:
Leo,
This is a complex, but interesting, project. The electronics/microwave
part of the project is fairly straightforward and is best left for later
phases of the project. The interesting part of the project is the
"physics" package, which I refer to as "optical pumping". My experience
in this area is a bit dated (5-6 decades ago), when my undergraduate and
PhD work was centered on optical pumping of Rb, Na and Cs atoms as well as
H2+ and Hg+ ions. A lot has changed since then; in particular, many
refinements have been made to create practical miniaturized Rb based
systems suitable for commercial time standards; I am not current on these
changes.
Your first task would be to establish and demonstrate optical pumping of
Rb87 atoms. For this, you would need, at a miniumum:
- some pure Rb87
- a glass blowing setup (and some skill)
- A selection of inert gasses (at least including Ar)
- Light source (Rb discharge was used then with a circular polarizer;
intensity pumping via Rb89 (I believe) is often used now.
Infrared lasers look very interesting to me. - A low noise light detector (I used photomultipliers - many more modern
solid state possibilities exist now. - a uniform magnetic field (Helmholtz coils or solenoid) and magnetic
shielding. - A means of controlling cell temperature (Rb vapor pressure)
- A bit of electronics, including RF power for the lamp. Note that a
noisy lamp discharge will mask the desired signal.
You should start with the Zeeman transitions, which are much easier to
observe and don't require microwave hardware. If you can't see a Zeeman
transition, there is no hope for the hyperfine transition. Getting
collisional disorientation down to a low enough level might involve
experimentation with various buffer gas formulations and pressures and
cell wall coatings (we used a very thin teflon film).
If you get to the point where you can see the Zeeman transitions, you
will have accomplished and learned a lot. With a little more effort, you
should be able to see the hyperfine transition.
Good Luck!!!
Stephen
On Tue, 6 Jun 2023 15:25:47 -0400
Leo Ahluwalia via time-nuts time-nuts@lists.febo.com wrote:
Hello, my name is Leo, and I was wondering about the feasibility of
creating a simple rubidium atomic clock at home, and good places to
source parts for this sort of project. I was also wondering what
instruments and specialized knowledge would be required depending on
how pre-built the parts are, for example, the prerequisite knowledge
for creating PLL(s) for both frequency division to provide an output
and also to modulate the input of the microwave oscillator. Any good
resources or PDFs would be greatly appreciated, as I am very new to
frequency analysis and phase manipulation in general. I was also hoping
to keep the cost of the project soft-line below 500$, though that would
be assuming a decent level of precision and already possessing basic
equipment (oscilloscope, multimeter, etc…). Safety is also a major
concern, as I know while the intensity of the EM waves involved is low,
the power source may or may not be. This is all of course assuming a
basic design, where my assumption is that it will involve the
microwaves being shot at a rubidium vapor cell which is directed
towards a photodetector. This would then be connected up to the PLL and
circuitry to both provide a stable standard while also modulating the
microwave oscillator to offset any external environmental factors. I
don't have a clear vision of what would truly be the best design for
both simplicity and cost, though this is what I've found to be a common
design in what I've looked at online.
Thanks, Leo
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Hi Magnus, I'll definitely have to take a look at the resources Tom, zfe,
and Andy sent my way. To my theoretical knowledge, the attenuation of the
photo-detector is a possibility - to avoid having to dim out the room where
the apparatus is contained - and I was wondering if you or anyone else had
experience working with something of that nature. I appreciate the advice
on the setup, it definitely cleared up some things for me.
- Leo
On Wed, Jun 7, 2023 at 9:27 PM Magnus Danielson via time-nuts <
time-nuts@lists.febo.com> wrote:
Hi Leo,
So, the setup is very straight forward. You put the Rb-lamp, the filter,
the Rb resonance cell all lined up in a straight path and at the far end
of that you have a photo-detector. The resonance cell you want to keep
magnetically shielded, which is typically done by one or more (I have
clocks with 3) layers of mu-metal. You have a coil, called C-field coil,
through which a DC current creates a magnetic field that separates the 5
Rb resonances so that only the (1,0)->(2,0) absorption occurs, which is
detected by a thad lower intensity of the pump light.
Look at Tom's email and I strongly suggest you get "Rubidium Frequency
Standard Primer" of William J. Riley which has a lot of info in it
covering a lot of the things that goes into it. This includes a lot of
photo of the actual inner parts of the rubidium clocks. There is more
material to gather, but already that book will answer a lot of things
for you and summarizes a lot of stuff in a very condensed and straight
forward way.
Cheers,
Magnus
On 2023-06-08 00:38, Leo Ahluwalia via time-nuts wrote:
I appreciate all of the help so far, and assuming the procurement of a
rubidium vapour cell and rubidium lamp (and of course all the other
components), I was wondering how exactly the optical pumping setup should
be achieved (to make sure all the components are "hooked up" so to
speak),
and whether there was already a standard way of achieving it along with
the
installation of the magnetic shielding?
- Leo
On Wed, Jun 7, 2023 at 6:27 PM Bruce Griffiths via time-nuts <
time-nuts@lists.febo.com> wrote:
That just leaves the Rubidium lamp.
An ECDL (external cavity diode laser) locked to the appropriate Rubidium
transition is much easier to build. There are several ECDL designs in
the
literature. Mostly these are Littrow designs. A Cateye resonator design
is
another option. All the components required are readily availble.
VCSEL's should be avoided as those without polarisation mode
stabilisation
gratings on the output face randomly mode hop between a pair or
orthogonally polarised modes.
A well designed but relatively simple ECDL can have a much narrower line
width than a typical DFB laser.
Bruce
On 08/06/2023 06:37 NZST djl via time-nuts time-nuts@lists.febo.com
wrote:
The Rb capsules are available on ebay, eg: 124012486501
the classblowing part is done?
On 2023-06-07 07:50, Richard (Rick) Karlquist via time-nuts wrote:
On 6/7/2023 5:03 AM, Stephen C. Menasian via time-nuts wrote:
- some pure Rb87
- a glass blowing setup (and some skill)
- A selection of inert gasses (at least including Ar)
- Light source (Rb discharge was used then with a circular
polarizer;
At HP we had really skilled glass blowers, with specific experience in
making Rb glassware. We had to use an exotic grade of glass that was
only one step removed from fused quartz. It had a part number that I
don't remember. Very difficult to work with.
The Rb lamp (one of three pieces of glassware) is very tricky to work
with. We used a resonant coil driven at 95 MHz at several watts.
The trick is to "strike" the plasma and make the lamp light up;
you can at least see visible light when that happens. I spent a
lot of time fooling with it. We never got it to work as
well as the 5065 lamp.
BTW, one of the Rb isotopes is slightly radioactive. Might be
hard to get as a hobbyist due to regulations. The physicist I
sat next to had a tank of it illegally stored in his cubicle.
Rick
N6RK
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Hello Lux, I appreciate the offer, and while I haven't done much research
regarding the Cold Atom Lab project, it's to my understanding that it
utilizes an atom chip for a lot of its procedures regarding the containment
of the Rb and potassium. While I'd love to work on something of that scale
one day, it's definitely above my paygrade both in terms of knowledge and
equipment as of right now.
Thanks, Leo
On Wed, Jun 7, 2023 at 9:31 PM Lux, Jim via time-nuts <
time-nuts@lists.febo.com> wrote:
On 6/7/23 7:22 AM, Bob Camp via time-nuts wrote:
Hi
Back when I was with EG&G, they spent a lot of effort on the
“glassware” side
of things. It was a major undertaking for a facility that already made
vacuum
tubes.
Was what they did overkill? In the end that was a bit unclear. Their
whole “accurate
dose” gas fill was still being debated years later. That said, you still
need some
way to get a very precise mix into each and every cell.
Bob
On Jun 6, 2023, at 8:26 PM, Richard Karlquist via time-nuts <
time-nuts@lists.febo.com> wrote:
In a former life, I was on the design team of a mini rubidium standard
at Hewlett-Packard. We built some working prototypes before it was
cancelled. It was going to have the model number 10816. I was the RF
person, but I worked very closely with the other team members.
Remembering what we had to go through to make "glassware", it is
inconceivable that you could do that as a "home brew" project. And this
was the same HP facility that already made the 5065 rubidium standard.
The best you could hope to do is to start with a commercial "physics
package" as we called it, and make your own electronics for it. Reading
books about how rubidium standards work, etc is fine, but again, you
can't home brew the glassware.
Rick Karlquist
N6RK
I know a bunch of people on the Cold Atom Lab project, which is making
Bose Einstein Condensates on ISS - they run both K and Rb (I don't know
if it's in the same cavity). But if you need contacts on how they made
theirs, I can probably find some people to talk to.
That project was described as "take a lab bench full of equipment and
three post docs and turn it into a box you can take to the space
station, push a button, and make BECs" It was, as these things are, an
adventure.
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