Any hobbyist OPM magnetometers yet? picotesla, like a SQUID

[stackexchange] I want to use an unmanned aerial vehicle to tow an airborne gradiometer...

Flying a raster pattern with a detector over the landscape; I bet the real money is in undiscovered pallasites, not ancient submerged anchors or cannon. And, go get a shovel, no need for rental marine salvage ships. How many multi-ton nickel- iron meteorites are sitting out there in wilderness, a couple meters deep?

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Everyone [search "OPM," latest cool magnetometer,][1] like a  
SQUID but no cryo required, nor heavy shielding.  Laser plus  
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Reply to
Bill Beaty
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Optically pumped magnetometers have been around for years, I think it was Bell and Bloom who made one that flew out to the planets... (late 60's/ 70's) I have an article somewhere....

You might be able to hack a Rb atomic clock and make it a magnetometer. Diode lasers are nice, keeping one tuned to the right freq will be the challenge. The nice thing about an Rb lamp is that it always puts out the right frequency of light.

(just my random thoughts) George H.

Reply to
George Herold

It would be cool to make a local mag field (or e-field) map. But a flux gate would be plenty good enough. Minute pointing errors will make a background noise level in the microT range, especially if you hang the sensor on a wire below a drone copter.

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John Larkin         Highland Technology, Inc 

lunatic fringe electronics
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Reply to
John Larkin

The tens of amperes in the electric quadcopter motors might call for a fairly long tether. For the same reason you probably can't have the processing electronics very close. As you say orientation error is a major noise source.

Not clear whether OP wants a magnetometer or a gradiometer.

--sp

Reply to
speff

It's been a while since I thought about this, but I think the Rb magnetometer measures the magnitude of the field. (There may be some directions where the signal goes away.)

"Principles of Operation of the Rubidium Vapor Magnetometer" by A.L. Bloom is the article I recall, but I can only find it behind a pay wall.

George H.

Reply to
George Herold

Useful for ELF Earth magnetic field change sensing/recoding? No more extra-long expensive inductors?

Reply to
Robert Baer

Go down to the local library and do an ILL loan..

Reply to
Robert Baer

TI makes a cheap fluxgate chip. Noise is 1.5 nT/rtHz, bandwidth 47 KHz. The eval board is only $22.

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John Larkin         Highland Technology, Inc 

lunatic fringe electronics
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Reply to
John Larkin

Oh I assume there are a lot of other good articles about the technique. I just don't know the literature that well. (I always kinda wanted to turn our optical pumping apparatus into a magnetometer.. As seems to always be the case, I need a faster photodiode electron precision frequency is something near 1 MHz in the Earths field.)

George h.

Reply to
George Herold

Courtesy of the lovely and talented Ms. Elbakyan:

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(1 MB)

-- john, KE5FX

Reply to
John Miles, KE5FX

Thanks John. Who is Ms. Elbakyan?

I could'nt f George, sorry to hijack the thread, but you were looking for "Principles of Operation of the Rubidium Vapor Magnetometer" by A.L. Bloom

I found it at

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You can find many paywalled articles at Sci-Hub:

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More info at

"Subscription Journals Are Doomed Because of Sci-Hub's Big Cache of Pirated Papers, Suggests Data Analyst"

Posted by BeauHD on Thursday July 27, 2017 @07:20PM from the beginning-of- the-end dept.

An anonymous reader quotes a report from Science Magazine: There is no doubt that Sci-Hub, the infamous -- and, according to a U.S. court, illegal

-- online repository of pirated research papers, is enormously popular. But just how enormous is its repository? That is the question biodata scientist Daniel Himmelstein at the University of Pennsylvania and colleagues recently set out to answer, after an assist from Sci-Hub. Their findings, published in a preprint on the PeerJ journal site on July 20, indicate that Sci-Hub can instantly provide access to more than two-thirds of all scholarly articles, an amount that Himmelstein says is "even higher" than he anticipated. For research papers protected by a paywall, the study found Sci-Hub's reach is greater still, with instant access to 85% of all papers published in subscription journals. For some major publishers, such as Elsevier, more than 97% of their catalog of journal articles is being stored on Sci-Hub's servers -- meaning they can be accessed there for free. In a chat with ScienceInsider, Himmelstein concludes that the results of his study could mark "the beginning of the end" for paywalled research.

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Reply to
Steve Wilson

Awesome, thanks! Saved in my optical pumping folder. I did the configuration shown in figure 3. I'll have to read it again.

George H.

Reply to
George Herold

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(but I think you knew that.)

George H.

Reply to
George Herold

No, I never went to wikipedia. But it is good news to bypass the outrageous charges on Elsevier. Papers probably cost a few millicents to store and download. Demanding $25 or $50 is simply criminal.

Reply to
Steve Wilson

I'm conflicted about sci-hub. It's illegal, but I also think all old (say 20-30 years) research papers funded by our government, should be free. (liberal thinking?) If it came to trial, I'd have to fall on the 'it's illegal' side.

George H.

Reply to
George Herold

Who made it illegal, and how did it get that way? How did copyright get extended to 70 years after the author's death, or 120 years after creation?

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I could see paying $0.50 or so for an article and would be happy to do so. But not $50. Gouging, usury, and many other financial sins are illegal. Why is extreme overcharging also not criminal.

Serves them right. Hopefully, Sci-hub will redress the wrongs.

Reply to
Steve Wilson

When a question comes up in 1962, you just whip up a quick simulation ...on your analog computer.

Also, I see lots of cheap $100 Rb stuff on eBay.

Also, purists making their own Rb oven could do like

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a speck of Rb metal under neon at crude vacuum.

Also, it's a DIY hobbyist Rabi-oscillations demo.

Reply to
Bill Beaty

Recent articles were about opm *sensors,* like this:

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Few-grams, no opto bench. So, I speculate about meteorite-search hobby, using drones. Earlier: dinosaur bone search hobby on BLM land using jeep-towed scintillators. But supposedly that's now illegal (since a hoard of greedy creeps started doing it.)

Reply to
Bill Beaty

Ahhhhh.... If I only had a brain....

Reply to
boB

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