Re: [time-nuts] More HP5065 experiments

[Attila Kinali]

On Tue, 29 Sep 2015 09:05:18 +0200
Attila Kinali  wrote:

> BTW: for those who are looking for Vanier, don't try to get
> a print version. They are unobtanium. And even if you find one, they
> are horribly expensive. CRC offers the pdf's for 750USD, which is
> wy overpriced for what they did (quite a cheap scan of the books,
> without even doing OCR). The pdf's are floating around on some websites
> though.

That said... if anyone has a printed copy and is willing to sell it
for a reasonable price. I'd be a buyer :-)

Attila Kinali

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Re: [time-nuts] More HP5065 experiments

[Attila Kinali]

On Mon, 28 Sep 2015 22:59:27 +0200
Magnus Danielson  wrote:

> > There should be somewhere a mention how much the frequency shift
> > of an Rb vapor cell due to light intensity change is, but i couldn't
> > find a good number in a couple of minutes. If you need one, please let
> > me know and I look a bit more carefull.
> 
> You really should check J. Vanier and C. Audoin "The Quantum Physics of 
> Atomic Frequency Standards, Volume 2" Chapter 7 Rubidium Frequency 
> Standards.

Oh.. right. I totally forgot about that book!

> Now, it is interesting to note that the temperature of the filter cell, 
> the temperature of the lamp cell and the intensity of lamp plasma 
> interacts here. For a optimum filter cell temperature, you can cancel 
> the lamp intensity.

Yes. There is a myriad of processes that shift the frequency.
I sometimes wonder how they are able to build primary standards
at all. Yes, modern techniques like using lasers get rid of a couple
of the processes, but still there are many that change the measurement
ever so slightly.

> Anyway, those plots give strong indication that measuring the light 
> intensity from the detector and then servo the intensity can be a good 
> strategy.

If possible, I'd also check the spectrum of the lamp before and after
the filter, depending on different lamp voltages, temperatures and
filter temperatures. But that depends on having an optical spectrometer.

PHK: if you want, you can borrow one of mine Ocean Optics HR2000.
 
> W.J. Riley "Rubidium Frequency Standard Primer" is a good read, but 
> Vanier is much more fundamental.

Oh.. I didn't know about Riley's book. Thanks for the hint.

BTW: for those who are looking for Vanier, don't try to get
a print version. They are unobtanium. And even if you find one, they
are horribly expensive. CRC offers the pdf's for 750USD, which is
wy overpriced for what they did (quite a cheap scan of the books,
without even doing OCR). The pdf's are floating around on some websites
though.

Alternatively you can buy the updated version by Vanier and Tomescu which
has been released last month. But I cannot say anything about its content
as I haven't had the time to buy it, yet.

Also an alternative is Fritz Riehle's "Frequency Standards: Basics and
Applications". Eventhough this has been also out of print, the pdf's
have a more reasonable priced (150EUR), or are available using your
favorite university library for "free"
( http://onlinelibrary.wiley.com/book/10.1002/3527605991 ).
Riehle mentioned a couple of years ago that he is planing to update
and republish his book, but apparently this has not happend yet.

Attila Kinali

-- 
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Re: [time-nuts] More HP5065 experiments

[Tom Van Baak]

> That said... if anyone has a printed copy and is willing to sell it
> for a reasonable price. I'd be a buyer :-)

Attila,

There's a bunch of copies at http://www.abebooks.com/ in the $300 to $400 range.

/tvb

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Re: [time-nuts] More HP5065 experiments

[paul swed]

I did go out to look for the "The Quantum Physics of Atomic Frequency
Standards. Did see numerous pay for sites and then others that were very
questionable.
There were two possible sites. One appera to be an Italian Amateur and the
other a Chinese site. Anyone have a semi trusted link please.
Regards
Paul
WB8TSL

On Tue, Sep 29, 2015 at 4:02 AM, Tom Van Baak  wrote:

> > That said... if anyone has a printed copy and is willing to sell it
> > for a reasonable price. I'd be a buyer :-)
>
> Attila,
>
> There's a bunch of copies at http://www.abebooks.com/ in the $300 to $400
> range.
>
> /tvb
>
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Re: [time-nuts] More HP5065 experiments

[Magnus Danielson]

Attila,

On 09/29/2015 09:05 AM, Attila Kinali wrote:

On Mon, 28 Sep 2015 22:59:27 +0200
Magnus Danielson  wrote:


There should be somewhere a mention how much the frequency shift
of an Rb vapor cell due to light intensity change is, but i couldn't
find a good number in a couple of minutes. If you need one, please let
me know and I look a bit more carefull.


You really should check J. Vanier and C. Audoin "The Quantum Physics of
Atomic Frequency Standards, Volume 2" Chapter 7 Rubidium Frequency
Standards.


Oh.. right. I totally forgot about that book!


It's a really good write-up.


Now, it is interesting to note that the temperature of the filter cell,
the temperature of the lamp cell and the intensity of lamp plasma
interacts here. For a optimum filter cell temperature, you can cancel
the lamp intensity.


Yes. There is a myriad of processes that shift the frequency.
I sometimes wonder how they are able to build primary standards
at all. Yes, modern techniques like using lasers get rid of a couple
of the processes, but still there are many that change the measurement
ever so slightly.


... and add some new. Polarization error can cause a shift, so a quarter 
wave window is mandator for that reason. However, if you play your 
locking tricks right it helps. However, with lasers you have a 
difficulty to steer intensity independent on wavelength as you have the 
same steering properties, but then there is a patent for that too.



Anyway, those plots give strong indication that measuring the light
intensity from the detector and then servo the intensity can be a good
strategy.


If possible, I'd also check the spectrum of the lamp before and after
the filter, depending on different lamp voltages, temperatures and
filter temperatures. But that depends on having an optical spectrometer.


The anti-pump line can be bothersome. This is where I like Corby's approach.


PHK: if you want, you can borrow one of mine Ocean Optics HR2000.


W.J. Riley "Rubidium Frequency Standard Primer" is a good read, but
Vanier is much more fundamental.


Oh.. I didn't know about Riley's book. Thanks for the hint.


It's not the definitive reference, but I think most hobbyist will find 
it useful as it touches on the subject with a focus on telecom rubidiums 
rather than scientific instruments view. For those that need the intro, 
read that first to get the overall plot and then do the Vanier and 
Andoin for more in depth. After that, a bunch of modern articles on CPT 
can be a nice reading.



BTW: for those who are looking for Vanier, don't try to get
a print version. They are unobtanium. And even if you find one, they
are horribly expensive. CRC offers the pdf's for 750USD, which is
wy overpriced for what they did (quite a cheap scan of the books,
without even doing OCR). The pdf's are floating around on some websites
though.


I did manage to get my set.


Alternatively you can buy the updated version by Vanier and Tomescu which
has been released last month. But I cannot say anything about its content
as I haven't had the time to buy it, yet.

Also an alternative is Fritz Riehle's "Frequency Standards: Basics and
Applications". Eventhough this has been also out of print, the pdf's
have a more reasonable priced (150EUR), or are available using your
favorite university library for "free"
( http://onlinelibrary.wiley.com/book/10.1002/3527605991 ).
Riehle mentioned a couple of years ago that he is planing to update
and republish his book, but apparently this has not happend yet.

Attila Kinali



Thanks for those hints.

Cheers,
Magnus
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Re: [time-nuts] More HP5065 experiments

[Attila Kinali]

On Tue, 29 Sep 2015 10:32:44 -0400
paul swed  wrote:

> I did go out to look for the "The Quantum Physics of Atomic Frequency
> Standards. Did see numerous pay for sites and then others that were very
> questionable.
> There were two possible sites. One appera to be an Italian Amateur and the
> other a Chinese site. Anyone have a semi trusted link please.

Well, if you want to have the book legaly, the crc books website is
where you want to go. If you want to get it not so legaly, then all
sites are questionable. There are a couple of sites that offer a
collection of "books for free". If you google for "free books" or
"free college books", you can find many of those. You might
also want to have a look at http://imgur.com/gallery/chIa5ok

Attila Kinali

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Re: [time-nuts] More HP5065 experiments

[Poul-Henning Kamp]

In message <560ac40b.1040...@rubidium.dyndns.org>, Magnus Danielson writes:

>> If possible, I'd also check the spectrum of the lamp before and after
>> the filter, depending on different lamp voltages, temperatures and
>> filter temperatures. But that depends on having an optical spectrometer.
>
>The anti-pump line can be bothersome. This is where I like Corby's approach.

I must admit that at least in the first iteration, I only plan to
try to improve the electronics.

Physics, including Corbys filter idea will be second iteration.

My measurement of the lamp supply sensitivity was mainly intended
to provide data on the required level of power supply stability.


-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
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Re: [time-nuts] More HP5065 experiments

[Poul-Henning Kamp]

In message <560b0e63.1060...@rubidium.dyndns.org>, Magnus Danielson writes:

>For instance, the lamp oscillator is 
>open-loop, so supply voltage and temperature effects will factor in 
>undamped. Servo up the intensity seems to be the remedy there.

It might also be an interesting experiment to injection-lock the
lamp-exciter oscillator, just to see if there is any RF leakage or
light intensity effects related to that...

>What about the C-field, can we servo up that by looking at the side-band 
>Rabi/Ramsey pedistals? Yes, it should be there, but I haven't had the 
>time to measure it. Doing that would require hacking into the 
>synthesizer side and jump around on the 5,3 MHz signal much as you would 
>do to the 12 MHz signal for Cesiums.

Doing a DSS based synth is a pretty obvious experiment, and along
with an ADC on the optical signal and a processor, a lot of servo-loop
algorithms become viable.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
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Re: [time-nuts] More HP5065 experiments

[Magnus Danielson]

Poul-Henning,

On 09/29/2015 10:01 PM, Poul-Henning Kamp wrote:


In message <560ac40b.1040...@rubidium.dyndns.org>, Magnus Danielson writes:


If possible, I'd also check the spectrum of the lamp before and after
the filter, depending on different lamp voltages, temperatures and
filter temperatures. But that depends on having an optical spectrometer.


The anti-pump line can be bothersome. This is where I like Corby's approach.


I must admit that at least in the first iteration, I only plan to
try to improve the electronics.

Physics, including Corbys filter idea will be second iteration.

My measurement of the lamp supply sensitivity was mainly intended
to provide data on the required level of power supply stability.


I see that there is room for both approaches. The filter helps a lot, 
and clears the table with that aspect, so we can focus on intensity 
variations.


What I like about your approach is that you look at other stuff and try 
to see what is also un-attended to. For instance, the lamp oscillator is 
open-loop, so supply voltage and temperature effects will factor in 
undamped. Servo up the intensity seems to be the remedy there.


What about the C-field, can we servo up that by looking at the side-band 
Rabi/Ramsey pedistals? Yes, it should be there, but I haven't had the 
time to measure it. Doing that would require hacking into the 
synthesizer side and jump around on the 5,3 MHz signal much as you would 
do to the 12 MHz signal for Cesiums.


Servo or stabilize, it's interesting to see what stuff we can play 
around with on these large rubidiums, which seems to offer the 
possibility for improvements over what their original designs allowed for.


Cheers,
Magnus
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Re: [time-nuts] More HP5065 experiments

[Attila Kinali]

On Sun, 27 Sep 2015 07:46:26 +
Poul-Henning Kamp  wrote:

> Discovery of the day:  The voltage supplied to the Rb87 lamp changes
> the frequency on the order of 1.5e-11 per volt.
> 
> I have no idea why...
> 
> http://phk.freebsd.dk/hacks/HP5065A/index.html

My first guess would be "light shift" (aka "AC Stark effect").
Does the intensity of the lamp change as well?

Also, it could be that the other spectral components of the lamp
(due to Xe/Ne gas filling) get stronger modulation than the Rb D1 line.

The only paper I know about that deals with the spectral modes of the
Rb lamp is [1], but as it is quite current, it does not deal with much
of the basics, but it might provide you with some references.

There should be somewhere a mention how much the frequency shift
of an Rb vapor cell due to light intensity change is, but i couldn't
find a good number in a couple of minutes. If you need one, please let
me know and I look a bit more carefull.

Attila Kinali

[1] "rf-power and the ring-mode to red-mode transition in an inductively
coupled plasma", by Coffer and Camparo, 2012
http://dx.doi.org/10.1063/1.4705469

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Re: [time-nuts] More HP5065 experiments

[Poul-Henning Kamp]

In message <56080c0a.20...@gmail.com>, EB4APL writes:

>According to your linked info I understand that you don't have 
>schematics and more info about the 105 OCXO.

The info I was referring to is the background typically found in
a HP Journal article, which says something about design choices etc.


-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
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Re: [time-nuts] More HP5065 experiments

[Magnus Danielson]

Hej,

On 09/28/2015 04:17 PM, Attila Kinali wrote:

On Sun, 27 Sep 2015 07:46:26 +
Poul-Henning Kamp  wrote:


Discovery of the day:  The voltage supplied to the Rb87 lamp changes
the frequency on the order of 1.5e-11 per volt.

I have no idea why...

 http://phk.freebsd.dk/hacks/HP5065A/index.html


My first guess would be "light shift" (aka "AC Stark effect").
Does the intensity of the lamp change as well?

Also, it could be that the other spectral components of the lamp
(due to Xe/Ne gas filling) get stronger modulation than the Rb D1 line.

The only paper I know about that deals with the spectral modes of the
Rb lamp is [1], but as it is quite current, it does not deal with much
of the basics, but it might provide you with some references.

There should be somewhere a mention how much the frequency shift
of an Rb vapor cell due to light intensity change is, but i couldn't
find a good number in a couple of minutes. If you need one, please let
me know and I look a bit more carefull.


You really should check J. Vanier and C. Audoin "The Quantum Physics of 
Atomic Frequency Standards, Volume 2" Chapter 7 Rubidium Frequency 
Standards.


You will find that "Figure 7.3.6 Cell resonance frequency as a function 
of light intensity as measured by means of the current id at the photo 
detector" is an interesting plot showing linear slopes of different 
rates depending on which temperature the filter cell has.


Now, it is interesting to note that the temperature of the filter cell, 
the temperature of the lamp cell and the intensity of lamp plasma 
interacts here. For a optimum filter cell temperature, you can cancel 
the lamp intensity.


You will also find that "Figure 7.3.7 Cell resonance frequency as a 
function of the filter cell temperature" on the next page shows a 
parabolic shape.


Anyway, those plots give strong indication that measuring the light 
intensity from the detector and then servo the intensity can be a good 
strategy.


W.J. Riley "Rubidium Frequency Standard Primer" is a good read, but 
Vanier is much more fundamental.


Cheers,
Magnus
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Re: [time-nuts] More HP5065 experiments

[Magnus Danielson]

Poul-Henning,

On 09/27/2015 09:46 AM, Poul-Henning Kamp wrote:

Discovery of the day:  The voltage supplied to the Rb87 lamp changes
the frequency on the order of 1.5e-11 per volt.

I have no idea why...

 http://phk.freebsd.dk/hacks/HP5065A/index.html



I can think of two mechanisms in play:

1) The obvious one is the light-shift as such, which comes from the 
intensity of the lamp. This is due to the Stark DC shift mechanism.
If you dig in literature, stabilizing the intensity of pump-lamp/laser 
is important in reducing the effect. The same goes for the RF-field 
strength.


2) A little less obvious is the fact that the intensity and hence heat 
shift the spectrum slightly, such that the filter-cell does not do as 
good job in filtering the D-line. If one has replaced the filter-cell 
with a modern filter, this effect can still be seen. The miss-match 
between the filter cell and the lamp will cause leakage of the other 
D-line and that will counter-act the pumping and well, reduces S/N and 
such. An even more subtle shift is that you drift away between the pump 
lamp and the rubidium in the reference cell, but most of that is 
compensated by the fact that the lamp is so wideband sources that you 
hardly notice.


Expect not only the feed but also temperature to shift intensity and 
frequency of the pump oscillator.


You should be able to servo the intensity using the DC intensity level 
detected by the photodetector.


Cheers,
Magnus
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Re: [time-nuts] More HP5065 experiments

[Poul-Henning Kamp]

In message <5607d3b0.80...@rubidium.dyndns.org>, Magnus Danielson writes:

>You should be able to servo the intensity using the DC intensity level 
>detected by the photodetector.

That would require a way to steer the intensity.

I can try to measure that at some point.

-- 
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Re: [time-nuts] More HP5065 experiments

[EB4APL]

Hi Poul-Henning,

According to your linked info I understand that you don't have 
schematics and more info about the 105 OCXO.
The HP 105 and HP 5065A don't include any information, treating it as a 
module that is not field reparable, but the HP 5061A Cesium Frequency 
Standard manual, while stating  the same, does include this info both in 
theory of operation and schematics.

If you don't have this manual at hand I can send you these info from mine.

Regards,
Ignacio EB4APL


El 27/09/2015 a las 9:46, Poul-Henning Kamp escribió:

Discovery of the day:  The voltage supplied to the Rb87 lamp changes
the frequency on the order of 1.5e-11 per volt.

I have no idea why...

 http://phk.freebsd.dk/hacks/HP5065A/index.html



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