Laser media frequencies

Hello All,

Is there a book that has an exhaustive list of all materials that have been used for laser experiments and gives the primary frequency generated from said material (crystals, gases, everything)

IF so, is there any academic material on say why CO2 produces 10,000 nm and ND YAG produces 1,100 nm. Why are crystal lasers more powerful and could gas lasers be just as powerful with the proper cooling and gas circulation?

My specific project was a CO2 laser until I realized that CO2 will not produce the proper frequency I need at 10,000 nm. I need ~ 1,100 nm but the only laser I could find that will produce primarily in that frequency is a ND YAG laser which is a crystal laser. Does a gas laser exist that produces this frequency, I would think out of all the gasses known to man there would have to be a gas that produces ~ 1,100 nm

Also a geologist friend of mine just indicated that YAG is a synthetic crystal which means that someone deliberately created this stone for lasers ... how did they know they would need yttrium aluminum garnet and how did they know to dope it with Neodymium?

I typed a very elaborate response to your question assuming you had a legit use for alternative wavelengths. . I then read your post on the other forum and pulled my response based on your massive naivete and lack of Google-Fu.


I'm not interested in helping you foolishly try a really bad approach to shooting down drones.

Steve

So did the forum not let you completely delete the post?

Whew it sent me an email copy of your post before you deleted it. Thank you so much. I am going through abe books now.

It would still be cool to know the thought process of some one sitting there one day saying ... hey im going to create synethic yittrium aluminum garnet and dope it with neodymium.

Also why use diode lasers to pump it, why not use a CO2 laser to pump the ND YAG laser?

Perhaps once I have read through the material I will slowly develop the intuition to develop my own gas or crystal.

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Originally Posted by akmetal

So did the forum not let you completely delete the post?

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Do you really think if there was a high power gas laser with efficiency better then Co2 and not requiring Deuterium Fluoride or superheated Chlorine,Oxygen, Bromine and dense Iodine vapor moving while burning through a perfectly optically clear laminar flow at upwards of Mach 2.5, that it would not be in production?

If there were such a way to make a cheap beast like that my former employer would gladly license it.

f I found it he'd pay me enought to comfortably retire on the spot.

Steve

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Originally Posted by mixedgas

Do you really think if there was a high power gas laser with efficiency better then Co2 and not requiring Deuterium Fluoride or superheated Chlorine,Oxygen, Bromine and dense Iodine vapor moving while burning through a perfectly optically clear laminar flow at upwards of Mach 2.5, that it would not be in production?

If there were such a way to make a cheap beast like that my former employer would gladly license it.

f I found it he'd pay me enought to comfortably retire on the spot.

Steve

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That is a very good point. Yea i read about the bromine lasers and they seemed nasty and I dont have any desire to circulate nasty poisen through a cooling system.

Well it looks like I have some serious reading to do and if I do create said gas or even solid state/crystal I will try to post the performance youtube video here.

https://static.ffx.io/images/$zoom_1...45d7db9b174e9e

They were never told it was impossible - so they did it.

Overconfidence taken to an extreme, coupled with a desire to shoot at something he doesn't like and thinking that a laser would hide his identity while executing his fantasy. I'm guessing he also wants to make a "light sabre". Why not? All it takes is someone with enough confidence.

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Originally Posted by akmetal

Is there a book that has an exhaustive list of all materials that have been used for laser experiments and gives the primary frequency generated from said material (crystals, gases, everything)

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There are likely several books on the subject. Google is your friend. Here's a good starting point. A member here has also produced an app that had a pretty comprehensive list of lasing lines, but I can't find a link to it anymore. (Laser Line software - anyone remember this?)

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is there any academic material on say why CO2 produces 10,000 nm and ND YAG produces 1,100 nm.

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Short answer: Quantum Mechanics.

More in-depth answer: it's a result of the difference in energy between specific electron excitation states. Different molecules have different "allowed" energy states for their bound electrons. Find a substance that has a pair of meta-stable states corresponding to the wavelength you want and you're on the path. (Note: this is *hard*.)

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Why are crystal lasers more powerful and could gas lasers be just as powerful with the proper cooling and gas circulation?

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There is no hard and fast rule about which laser type is more powerful. *Some* crystal lasers are more powerful for a given application, while in other applications gas lasers are better. Some gas lasers are incredibly powerful. (Look into gas-dynamic lasers, deuterium-fluoride lasers, and chemical oxygen iodine lasers.) Likewise, there are massively powerful crystal lasers. (Shiva/Nova comes to mind.) For a given wavelength and operation mode (continuous vs pulsed) you can say that one technology is superior to the other. Change one of the variables, however, and you'll get a different "best" answer.

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I need ~ 1,100 nm but the only laser I could find that will produce primarily in that frequency is a ND YAG laser which is a crystal laser. Does a gas laser exist that produces this frequency, I would think out of all the gasses known to man there would have to be a gas that produces ~ 1,100 nm

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There may be several gases that can be made to lase at ~ 1100 nm, but other than the COIL technology mentioned above (hideously expensive, very complicated, and toxic to boot), I'm not aware of one off the top of my head.

More importantly though, this is something that has been researched to death already, and for that specific wavelength range the current "best solution" is YAG, unless you have the resources of a nation-state and want to experiment with the aforementioned chemical oxygen iodine laser. I should point out that this is a bit of a fools errand, however, as the US Government spent over $5 billion developing the COIL (and the modified 747 to carry and power it) before eventually deciding that the technology was a dead end. They are now focusing on YAG and direct diode solutions for output in this wavelength range.

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YAG is a synthetic crystal which means that someone deliberately created this stone for lasers ... how did they know they would need yttrium aluminum garnet and how did they know to dope it with Neodymium?

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See above answer about electron energy levels. And if you really want to get deep into it, you're looking at a *bunch* of 400-level (and up) college physics classes to understand the quantum mechanical math behind it. (For the record, I gave up long ago.) Suffice to say that in the early years of lasers (1960's-1980's) the research involved a lot of trial and error. But now with a ton of math (and computers to help), they're getting better about predicting materials that will work for a desired wavelength. And even so, they still struggle. (Look at how long it took to get direct-injection green diodes, for example.)

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Originally Posted by akmetal

It would still be cool to know the thought process of some one sitting there one day saying ... hey im going to create synethic yittrium aluminum garnet and dope it with neodymium.
Also why use diode lasers to pump it, why not use a CO2 laser to pump the ND YAG laser?

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Again, back to Quantum Mechanics and those electron energy levels. To pump (excite) the electrons to high energy levels you need to use a wavelength that is very close to the energy needed for the jump. Long wavelength = small jumps, short wavelength = larger jumps.

If you tried to pump YAG with the output of a CO2 laser you wouldn't be able to achieve a population inversion because you wouldn't be exciting the electrons to the metastable level from which they fall to emit 1064 nm light. At best you'd just heat up the YAG rod.

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Perhaps once I have read through the material I will slowly develop the intuition to develop my own gas or crystal.

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Perhaps.

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Originally Posted by mixedgas

Do you really think if there was a high power gas laser with efficiency better then Co2 and not requiring Deuterium Fluoride or superheated Chlorine,Oxygen, Bromine and dense Iodine vapor moving while burning through a perfectly optically clear laminar flow at upwards of Mach 2.5, that it would not be in production?

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HAHA! I had totally forgotten about the flow dynamics of the COIL laser, to say nothing of the H-F / D-F lasers. Excellent point Steve! You know, the more I read about the work on the YAL-1, the more in awe I am at the entire effort. You really have to give them credit for getting the damned thing to lase in the first place, let alone keeping it running inside a plane flying all over the place. Alignment alone had to be a cast-iron bitch! (Airplanes tend to be rather flexible, after all...)

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If there were such a way to make a cheap beast like that my former employer would gladly license it.

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Assuming the military didn't grab it first! They'd kill for something like that...

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Originally Posted by akmetal

That is a very good point. Yea i read about the bromine lasers and they seemed nasty and I dont have any desire to circulate nasty poisen through a cooling system.

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Copper Bromide lasers are child's play compared to the lasers Steve was talking about. Seriously, do some reading about the COIL-based YAL-1. If that doesn't give you pause, nothing will.

As for your final comment about the Wright Brothers, remember that the only ones who told them human flight was "impossible" were the uneducated. There were ample examples in nature (birds) that showed it was entirely possible, plus the world already had lighter-than-air vehicles. Most scientists knew it was only a matter of time before someone solved the heaver-than-air problem. The true challenge was *controlled* flight, and that is honestly their biggest innovation. Apart from that it was just some engineering and finding a lightweight engine that made enough power.

In this case, while the laws of physics don't explicitly prevent what you're looking for, a great number of people have spent a lot of time looking, and the consensus is that, for near IR wavelengths, gas lasers are inferior to YAG and direct diode technologies. But even with that caveat, it's still conceivable that they missed something. Still, the Wright Brothers had it easy by comparison.

Adam

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Originally Posted by akmetal

They were never told it was impossible - so they did it.

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Because what they were doing was NOT impossible. It's important to know the difference between impossible vs not impossible.

COIL was tough enough to solve that the AF Lab published a detailed, low cost, technical book on it in the 1980s, they were not worrying about it being too easy to solve. My local regional library had it in the 80s.

You can spend hours upon hours reading Marvin J. Weber's book on Gas Laser Wavelengths. Get an old one because the new editions are edited by someone who took a lot of detail out. All it does is give you a huge list of tables and then the references to go look up. Calibrated laser power meters did not exist in commercial form or were not common in the heyday of the laser researcher, so most books rank the estimated gain per meter on a unitless 1 to 5 scale. It was up to the researcher to make up that scale before publishing.

So yes, something might have slipped through the cracks, but without testing each system and optimizing six to ten variables each time, you'd have to get extremely lucky. If you start from the book, you are effectively playing "laser spin the bottle". Lasers that were easy to make and showed incredible promise on the first few runs are ultimately the ones that went into production, with a few devices that would be very useful in the lab slipping through the cracks. Anything that was really useful got noticed and patented by DOD or Commercial Researchers. You can spend all day at DTIC dot mil looking at research reports, some amazing, some stating where they hit a wall.


The thermodynamics just does not work out for most 3 level and 4 level gas laser systems. There are a few systems being looked at again, mostly behind the former Iron Curtain by people who made their lives dedicated to looking for a breakthrough in metal vapor lasers. One of those systems at 6.5 microns was suddenly found to be very medically useful, but not for reasons of raw power. Optically pumped metal vapor was finally made to work well with diode pumping a few years ago. The AF sponsored researcher went public with it, and the numbers are not spectacular. But it has really good uses for probing the atmosphere.

Diode pumped solid state mediums are just so much more efficient and easier to make, so they are the new world. Gas is not dead, and CO is really starting to prove useful.

I've been on the NKC-135A at Dayton and I got the impression that the folks riding in the cabin were my kind of Heroes.
While well built, it seemed primed for a disaster if some plumbing let go.

It really comes down to density and heat transfer for the high power stuff.

https://upload.wikimedia.org/wikiped...r_Lab_USAF.jpg

Steve

Steve,

Do you mind if I repost your post and maybe get it added as a sticky for others wanting to research this subject?

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Electronic destructive interference is just as complex as developing a new laser material due to the extremely high radio frequencies that drones and gps operate at. It would require complex mixing and digital signal processing in order to detect a drone signal halt the sensing antenna and then phase shift in the dsp and retransmit. Thus switching would have to be very rapid and would also have to simultaneously jam the gps signal

The power supply would be large as well

Also my obsession with lasers goes back 27 years.

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Originally Posted by kecked

Why not try a good old mortar the fires a net at the props. BTW there are many electronic ways to force it down.

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Originally Posted by akmetal

Electronic destructive interference is just as complex as developing a new laser material due to the extremely high radio frequencies that drones and gps operate at. It would require complex mixing and digital signal processing in order to detect a drone signal halt the sensing antenna and then phase shift in the dsp and retransmit. Thus switching would have to be very rapid and would also have to simultaneously jam the gps signal

The power supply would be large as well

Also my obsession with lasers goes back 27 years.

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Any form of RF jamming would likely be illegal anyway. Unless you're the military, in which case you already have those capabilities.

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Originally Posted by Diachi

Any form of RF jamming would likely be illegal anyway. Unless you're the military, in which case you already have those capabilities.

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We are becoming more and more of a police state where everything is illegal. I can’t even keep track. The more esoteric the law the harder (or almost impossible) it is to enforce.

If you turned on a passive jammer (only turned on when a signal came on) it would take considerable resources to trace.

But discussing legalities does not really absolve one of deep intellectual thought on a sub forum for deep intellectual topics.

You don’t just get to say - oh it’s illegal so I don’t have to think now lol

I don’t even know that it truely is illegal or not, passive signal destructive interference of specific frequencies or a range of frequencies is much different that flooding the air with noise.

There has to be a branch of chemistry for crystals, “crystal chemistry” on how to make synthetic crystals?

https://www.youtube.com/watch?v=XbBc4ByimY8

Using the Czochralski technique new crystal types can be made in the same way silicon wafers are made

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Originally Posted by kecked

Why not try a good old mortar that fires a net at the props.

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Because a directed energy weapon can act at far greater distances, probably. But yeah, for close-in work a physical intercept is pretty lethal and a lot cheaper.

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BTW there are many electronic ways to force it down.

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Agreed. Although to be fair the military is currently investigating directed-energy weapons for anti-drone work. But yes, interfering with the flight electronics directly (difficult, but very effective if you succeed) or the RC control link / GPS signal (easier to accomplish, assuming the drone isn't flying autonomously) also works.

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Originally Posted by akmetal

Electronic destructive interference is just as complex as developing a new laser material due to the extremely high radio frequencies that drones and gps operate at.

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Ah, no. Just - no. Electronic jamming has been around for 6 to 7 decades. It's a very mature technology. Developing a new laser gain medium is *far* more difficult.

And you've got your physics backwards. It's *easier* to interfere with, overpower, or outright block the shorter wavelength radio waves. It's the long wavelength stuff that is hard to block. (This is why missile submarines use VLF and ELF radio for launch orders; short of a nearby supernova detonation you're not going to stop that signal from reaching the receiver.)

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It would require complex mixing and digital signal processing in order to detect a drone signal halt the sensing antenna and then phase shift in the dsp and retransmit.

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Ahem. Your understanding of jamming is woefully incomplete. Yes, sampling the control signal in real time, modifying the phase and/or pulse widths, and then re-broadcasting a phantom duplicate signal is *one* means of jamming. (And one that was implemented as early as the Vietnam War to combat early radar-homing anti-air missiles.) There are far more sophisticated methods available today.

More to the point, however: if your goal is merely to stop the drone, all you need is a stupidly-powerful transmitter that splatters across the entire control band plus a directional antenna. This is something most hobbyist electronics geeks could build in their garage. (Though admittedly such a construction *would* violate several FCC regulations.)

Also: just for the record, the DSP chip needed to accomplish the signal processing described in your example (even against commercial-grade, high-frequency, agile, spread-spectrum control schemes) can be purchased for about $200 from Digikey. (And that's for the 8-core TMS320C6678, clocked at 1.25 Ghz, which is overkill.) Like I said, the technology has advanced a great deal.

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Thus switching would have to be very rapid and would also have to simultaneously jam the gps signal

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GPS jamming is even easier (although it's equally illegal). GPS signals have no means to detect or avoid jamming. Thus, simply overpowering the signals from space with a local transmitter is a trivial task. Now, if you want to SPOOF the GPS signals so that the drone *thinks* it is on course when it really isn't, then yes, that is more involved, but even so this is essentially a programming challenge, not a technological limit. The math itself isn't that hard to calculate. (Once again, the DSP chip above is more than capable.)

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The power supply would be large as well

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Given that you are protecting something located on the ground, the size of the power supply (on the ground) seems irrelevant. The limits are all on the drone, which has to be able to fly...

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Originally Posted by akmetal

If you turned on a passive jammer (only turned on when a signal came on) it would take considerable resources to trace.

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That is not a passive jammer. A passive jammer does not generate or amplify a signal. It channels and re-directs an incoming signal and often modifies the modulation by stretching or compressing the pulse train. Basically it's a fancy antenna.

What you are describing is an active jammer with instant-on capability. (Note that as far as the FCC is concerned, both are illegal.)

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I don’t even know that it truely is illegal or not

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Everything we're discussing - passive interference of radio control signals, active interference of radio control signals or GPS signals, and the use of a directed energy weapon to disable a drone... *ALL* of these things are illegal in the USA. Yes, the military is researching the subject and developing new systems. But you and I are not the military. It is most definitely a *federal* crime!

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passive signal destructive interference of specific frequencies or a range of frequencies is much different that flooding the air with noise.

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Let's ignore for a moment that "flooding the airwaves with noise" is *already* quite illegal all by itself. The FCC has specifically ruled on the subject of passive devices that intentionally create harmful interference with incident radio signals. The actual ruling is rather lengthy and dry, but here is the relevant text: "...operation of an intentional, unintentional, or incidental radiator is subject to the condition that it may not cause harmful interference."

Adam

https://transition.fcc.gov/Daily_Rel...C-97-404A1.pdf
https://www.fcc.gov/general/jammer-enforcement

... and not to forget - EMP-"canons" :cool:

AFAIK the police owns "handsome" portable EMP generators which can stop a car in a distance of some Kilometers by overpowering/wrecking all the internal electronics with a single directed/focussed microwave-flash ...

Viktor

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Originally Posted by buffo

Because a directed energy weapon can act at far greater distances, probably. But yeah, for close-in work a physical intercept is pretty lethal and a lot cheaper.



Agreed. Although to be fair the military is currently investigating directed-energy weapons for anti-drone work. But yes, interfering with the flight electronics directly (difficult, but very effective if you succeed) or the RC control link / GPS signal (easier to accomplish, assuming the drone isn't flying autonomously) also works.



Ah, no. Just - no. Electronic jamming has been around for 6 to 7 decades. It's a very mature technology. Developing a new laser gain medium is *far* more difficult.

And you've got your physics backwards. It's *easier* to interfere with, overpower, or outright block the shorter wavelength radio waves. It's the long wavelength stuff that is hard to block. (This is why missile submarines use VLF and ELF radio for launch orders; short of a nearby supernova detonation you're not going to stop that signal from reaching the receiver.)



Ahem. Your understanding of jamming is woefully incomplete. Yes, sampling the control signal in real time, modifying the phase and/or pulse widths, and then re-broadcasting a phantom duplicate signal is *one* means of jamming. (And one that was implemented as early as the Vietnam War to combat early radar-homing anti-air missiles.) There are far more sophisticated methods available today.

More to the point, however: if your goal is merely to stop the drone, all you need is a stupidly-powerful transmitter that splatters across the entire control band plus a directional antenna. This is something most hobbyist electronics geeks could build in their garage. (Though admittedly such a construction *would* violate several FCC regulations.)

Also: just for the record, the DSP chip needed to accomplish the signal processing described in your example (even against commercial-grade, high-frequency, agile, spread-spectrum control schemes) can be purchased for about $200 from Digikey. (And that's for the 8-core TMS320C6678, clocked at 1.25 Ghz, which is overkill.) Like I said, the technology has advanced a great deal.



GPS jamming is even easier (although it's equally illegal). GPS signals have no means to detect or avoid jamming. Thus, simply overpowering the signals from space with a local transmitter is a trivial task. Now, if you want to SPOOF the GPS signals so that the drone *thinks* it is on course when it really isn't, then yes, that is more involved, but even so this is essentially a programming challenge, not a technological limit. The math itself isn't that hard to calculate. (Once again, the DSP chip above is more than capable.)



Given that you are protecting something located on the ground, the size of the power supply (on the ground) seems irrelevant. The limits are all on the drone, which has to be able to fly...



That is not a passive jammer. A passive jammer does not generate or amplify a signal. It channels and re-directs an incoming signal and often modifies the modulation by stretching or compressing the pulse train. Basically it's a fancy antenna.

What you are describing is an active jammer with instant-on capability. (Note that as far as the FCC is concerned, both are illegal.)



Everything we're discussing - passive interference of radio control signals, active interference of radio control signals or GPS signals, and the use of a directed energy weapon to disable a drone... *ALL* of these things are illegal in the USA. Yes, the military is researching the subject and developing new systems. But you and I are not the military. It is most definitely a *federal* crime!



Let's ignore for a moment that "flooding the airwaves with noise" is *already* quite illegal all by itself. The FCC has specifically ruled on the subject of passive devices that intentionally create harmful interference with incident radio signals. The actual ruling is rather lengthy and dry, but here is the relevant text: "...operation of an intentional, unintentional, or incidental radiator is subject to the condition that it may not cause harmful interference."

Adam

https://transition.fcc.gov/Daily_Rel...C-97-404A1.pdf
https://www.fcc.gov/general/jammer-enforcement

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In the case of passive jamming my thoughts were towards protecting aircraft with occupants (where its impossible or impractical to install a laser) and the power supply is somewhat limited on small aircraft so a targeted jam with destructive interference is far preferable to flood the air with noise since power is restricted and you want as big a bubble as possible around your plane. I have had numerous friends almost have drone strikes in the last couple of years.

Just because drones are suppose to stay below tree top level does not mean that they do. And I have seen numerous drones operating near airports with no communication. Its just a matter of time before there is an incident.

The challenge I was having with jamming was dsp design that would take directly high frequency inputs without complex mixing. Ideally a fully analog circuit is the best but I have not figured out how to phase shift in full analog AND allow for antenna switching so that the 2 antenna were not competing against each other. I would love to talk to you further about this and learn how they build these new DSP circuits that allow for direct input of say 1-6 ghz radio frequency.

Out here in no mans land no one cares what you do so long as you are not committing sexual assault or domestic violence. I could build a particle accelerator and start producing plutonium and no one would care. Of course what do you produce the mile long linear proton accelerator out of that wont break the bank (recycled booze bottles lol).

Anyways it would be cool to get to know you and learn more about advance circuits, I have the basics down as well as the advanced math (partial differentials, etc) but dont have any real design work. I will send you a PM.

It would be cool to get to know steve too but I feel like he is really upset. I feel like I have found my people.

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Originally Posted by VDX

... and not to forget - EMP-"canons" :cool:

AFAIK the police owns "handsome" portable EMP generators which can stop a car in a distance of some Kilometers by overpowering/wrecking all the internal electronics with a single directed/focussed microwave-flash ...

Viktor

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You could install your circitry in a farday cage and be fine, of course the entire engine compartment would have to be protected as the emp could travel through any exiting wires. EMP's are cool but a real emp requires explosives and a massive AC power supply and I don't like messing with explosives.

I dont know what the police use but if its not a coil wound explosive device then its effectiveness is marginal and even a basic faraday cage would stop it.

These also dont work on older vehicals. I also will never understand why newer cars dont use the same systems as airplanes for fuel injection systems. My plane uses a gear driven pump off the main crank shaft and the injection lines are hydraulicly ballanced and the mixture is controlled by the pilot. There are no chips or computers. In fact the only thing electrical is the mags which are built like a brick shit house and the starter which is the biggest head ach lol.

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Originally Posted by kecked

Shotgun works well. My real question is what are YOU trying to hide and from WHOM. You could always fly a second drone into the first. Train a faulken use a bright spot light to blind the camera. Use a laser to destroy the camera

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Discharging a shot gun near airports, neighborhoods, city limits, etc is SUPER illegal and because of the noise and relativly short distance (camera on drone can capture you) its super easy to get busted. Range of a shot gun is extremely paltry and you could end up hurting someone else with the shot.

We live in a police state so anyone acting like a free person has something to fear from our nanny police state. Our police state is so massive that it is rare when the people can stand up against it (remember FAA, FCC, DEA beurocrats are not elected officials - they create laws and "regulations" that congress rarely votes on, they do it from some back office like little dictators or monarchs). Once in a blue moon someone will go through the personal pain and sacrafice (remember there is no pain or sacrafice for the bearucrat writing police) to bring the regulation to the supreme court but its rare and the beaurcrat has little to fear.

There are things in the work with Trump administration to make these people MUCH easier to fire and to SUE - such as if the FAA creates some onerous policy for me to use my own property I can sue that guy personally and attach his entire net worth, take his kids 529 plan etc. I hope this becomes law because you will see alot of policy recalled and alot of firings.

For instance the FAA has made it virtually cost prohibitive for any serious recreational piloting through forced annual inspections by a "qualified person" (and of course getting that qualified persons status requires writing LARGE checks to the FAA designated persons), forced medicals, outrageously expensive examination fees and on and on. All so I can fly my own personal property.

Anyways I digress, I dont really want to get on here to talk about law because until we get enough congressmen in and a stronger president that will start disolving woodrow willsons little fiefdom then there is not much to do on the average citizens end. But I will tell you I wont table my academic endevors because of a bearucrat, especially in a state where its extremely difficult for the feds to operate.

https://www.youtube.com/watch?v=ZwmUH5AGydQ

Could a proton beam be used to pump a crystal laser instead of diodes or flash lamps?

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Originally Posted by akmetal

Could a proton beam be used to pump a crystal laser instead of diodes or flash lamps?

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Why, do you happen to have a linear accelerator lying around doing nothing?

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Originally Posted by akmetal

In the case of passive jamming my thoughts were towards protecting aircraft with occupants (where its impossible or impractical to install a laser) and the power supply is somewhat limited on small aircraft so a targeted jam with destructive interference is far preferable to flood the air with noise since power is restricted and you want as big a bubble as possible around your plane. I have had numerous friends almost have drone strikes in the last couple of years.

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OK - A mobile airborne anti-drone system is quite a bit more complex that the ground-based station I was discussing. For one, you now have a much higher intercept velocity because of the movement of the plane (which is likely to be much faster than the drone). Also, you don't want to interfere with any of the plane's on-board systems, so denying GPS information to the drone is likely not an option, and even interrupting the control signal (depending on the band) might also interfere with navigational beacons. (VOR operates on an even multiple of the 6 meter ham band, which can be used for RC, for example.) In this case I can see the merits of actually trying to interrupt or spoof the control signal. However, this is also an edge-case scenario (protecting a light aircraft), and the method you're discussing is patently illegal.

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Just because drones are suppose to stay below tree top level does not mean that they do. And I have seen numerous drones operating near airports with no communication. Its just a matter of time before there is an incident.

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Incidents have already happened. Most have involved light private aircraft, but there has been at least one incident in Canada where a passenger airliner was involved in a drone strike.

The good news is that in all cases the damage was not nearly enough to bring down the planes. Even a 4-passenger prop plane that took a hit dead-on the leading edge of the wing was still able to fly normally and land. (That strike was from a DJi Phantom, and most of the damage was likely due to the heavy battery it carries.) While I agree that drones are a growing problem, I don't think there's any need for a jamming system at airports. And I definitely would not suggest building one yourself. The penalties for doing so are going to be severe. (Like I mentioned above, these are federal crimes.)

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The challenge I was having with jamming was dsp design that would take directly high frequency inputs without complex mixing.

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OK, I'll pretend I didn't just read that! :o Seriously though, if we're having a theoretical discussion that's one thing. But if you're actually trying to build this, then we need to stop talking. What you're proposing is all kinds of illegal, and I don't want to be involved in any way, shape, or form. While you may believe that living in a scarcely populated area will keep you safe, I can tell you that all it takes is one concerned individual to contact the FCC about "strange interference" to get Uncle Sam looking into things. Then too, Ham radio operators are everywhere, and they notice things that are out of place.

If you or a pilot friend are worried about a drone strike, spend a few hundred bucks on sheet metal to reinforce the leading edge of the wing of the plane. That's much easier than building a jammer. It's also cheaper and is more likely to yield a positive outcome in the unlikely event of a strike. Plus it doesn't have the potential to land you in federal prison...

Actually, since you live in a remote area, maybe your best option is to reach out to the done enthusiasts in your area and discuss the problem with them. I seriously doubt that any of them are intent on causing harm. Some signage at the local airstrip warning of the danger might be another good idea to consider.

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Ideally a fully analog circuit is the best but I have not figured out how to phase shift in full analog AND allow for antenna switching so that the 2 antenna were not competing against each other.

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Um... Phase-shifting is pretty trivial. How hard have you worked on this? And preventing the outgoing signal from blocking the incoming one is a simple matter of antenna design and placement. Do you have any formal training in radio?

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I would love to talk to you further about this and learn how they build these new DSP circuits that allow for direct input of say 1-6 ghz radio frequency.

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The DSP chip I mentioned above has a development environment for Windows and for Linux. With an evaluation board (about $300) you should be able to make it dance the jitterbug if you wanted. Alas, I'm not a code monkey.

To be honest, I'm actually feeling rather uncomfortable right now with the way this thread is progressing. Let me say this again, very clearly: Unless you are a government contractor working for the military on an approved project that explicitly gives you permission, then it is a federal crime to build a device that radiates radio waves that interfere with authorized radio communications. One could argue that developing the code for the DSP chip (even absent having the RF antenna and I/O connected) might be a crime in itself. I know *I* wouldn't want to touch it...

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Out here in no mans land no one cares what you do so long as you are not committing sexual assault or domestic violence.

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That may be true for your local Sheriff's office, but the Feds have other ideas.

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I could build a particle accelerator and start producing plutonium and no one would care.

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Now this *does* land in my wheelhouse. I'm a former Navy Nuc (submariner), and I was an ELT to boot. I realize your statement was meant as hyperbole, but honestly you couldn't have picked a worse example. So I'm going to indulge myself for a moment:

First, you don't use a particle accelerator to make plutonium, you use an operating fission reactor. (You need to add a neutron to an atom of Uranium-238 to make Uranium-239, which then goes through two inverse-beta decay cycles to become Plutonium-239. Kinda hard to accelerate a neutron with a particle accelerator, given that neutrons have no charge!) And second, long before you ever obtained any fissile material to fuel your reactor you'd be overrun by federal agents. Seriously - fissionable material is just about the most closely monitored commodity on the planet...

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Anyways it would be cool to get to know you and learn more about advance circuits, I have the basics down as well as the advanced math (partial differentials, etc) but dont have any real design work.

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There are several electrical engineers here who are very good at circuit design. Likewise, the fourier tranformation math is not something I'm really good at, but we've got plenty of programmers here with experience. It's just that I think very few people are going to help you with this once they realize the end goal is to building something that is highly illegal. We already struggle with people going against the CDRH rules for lasers. How likely do you think people will be to go against the FCC? (Or worse, the FAA, if your jammer accidentally interferes with other aviation radio systems...)

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It would be cool to get to know steve too but I feel like he is really upset. I feel like I have found my people.

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In fairness to Steve, we have had a lot of problems with trolls lately. They take the form of new folks who appear to be very interested in lasers but clearly haven't done any research on the subject at all. OK, that's fine, not everyone is adept at using Google, and we're here to share knowledge, right? But when senior members offer advice to these new folks and then see that advice rejected immediately, well, that tends to upset people. A related issue is when a new member claims to be an "expert" at something laser-related, only to make a gross conceptual error just a few posts further down. Steve has been on the receiving end of more than a few of these sorts of people lately, and it's made him a bit more cynical. I can't honestly blame him though, as I've had similar thoughts myself. But we still do our best to give every new member the benefit of the doubt.

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Originally Posted by akmetal

You could install your circitry in a farday cage and be fine, of course the entire engine compartment would have to be protected as the emp could travel through any exiting wires.

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And this is why it's difficult to harden a drone against an EMP. So long as you plan to have RF remote control of it (or even have it fly autonomously using GPS for navigation), you'll have to have an antenna sticking through the Faraday cage, and that is a potential entry point. (That's why military flight hardware includes an inertial navigation system that is isolated from the outside; if they lose remote control *and* GPS, they can continue the mission using dead reckoning.)

Re: EMP

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I dont know what the police use but if its not a coil wound explosive device then its effectiveness is marginal and even a basic faraday cage would stop it.

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My understanding is that most of the police units are basically magnetrons. And yeah, a Faraday cage would defeat it. It's just that the typical driver who will run from the cops isn't likely to think about hardening the car's ignition control module first.

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I also will never understand why newer cars dont use the same systems as airplanes for fuel injection systems.

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In an aviation environment, reliability wins over efficiency. Also remember that fuel economy for private aircraft is unregulated. Not so for cars. (CAFE)

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Originally Posted by akmetal

Discharging a shot gun near airports, neighborhoods, city limits, etc is SUPER illegal

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It's interesting that you agree with the law here, but you don't appear to agree with the law preventing the construction or use of a jammer. Typically when people in a society are allowed to choose which laws they follow (and which ones they don't), the end result is not pretty.

And I think that's where I'll stop, as we're drifting well away from the original topic. :)

Adam

Older (I do MEAN OLDER) editions of the CRC Laser Handbook from Abebooks will provide you wavelength tables and a reference to a journal article to go to a university science library and look up. They will rarely provide you with accurate estimates of laser power.

CO2 Systems lase in a band 9.6 microns to somewhat past 10.6 microns depending on gas mixture and additives. While the majority of the power is at 10.6 there are other bands. Often you just need a grating tuning addition to the Co2 cavity.

Koechner's textbooks on Solid State Lasers usually have that wavelength table for crystalline hosts.

And Marvin J. Weber has two books that are relevant tables for gas lasers and solid state lasers. You will again have to pull the scientific journal referenced in the table if Google is not your friend.

When you get into non-standard laser wavelengths, you will find its easier to bend your experiment to the wavelength or buy a tunable laser (Plug here for Altos Photonics, Spectra Physics, or Coherent Tunable OPO based Systems) rather then spend tens of thousands on constructing non standard lasers from an age where everyone was trying to find new wavelengths but often did not own accurate means of measuring the performance of the laser they discovered.

The hows and whys of what lases when and where and how to design it as a system are are best learned from Silfvast's text "Laser Fundamentals", and Koechner's Solid State Lasers book and you want the second edition or later, the first can be a little sparse.

Amon Yariv's book on Laser Quantum Mechanics or A.E. Siegman's Text "Lasers" are good at the graduate level.

Answering your other questions would take me too much time, so I suggest you start reading up on why Population Inversion occurs and where in a given host.

Steve

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Originally Posted by NobleGas

Why, do you happen to have a linear accelerator lying around doing nothing?

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Unfortunatly no, I have the real estate to run one through the woods but what would I make it out of that would be cheap enough? I dont have enough booze bottles to melt down into glass pipe lol. Wood? Maybe, its an insulator and I dont see why it could not hold a vacuum, with small glass sections where the magnets would be housed ....

Never the less that is not practical to run a laser but would be highly useful for other things like converting elements.

http://www.scientificmaterials.com/index.php

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Originally Posted by akmetal

http://www.scientificmaterials.com/index.php

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Okay? Is there some reason for sharing this or...?

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Originally Posted by Diachi

Okay? Is there some reason for sharing this or...?

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Yea, FLIR now builds laser rod crystals, a whole assortment. I thought it was a great reference.

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Originally Posted by akmetal

Yea, FLIR now builds laser rod crystals, a whole assortment. I thought it was a great reference.

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Now builds? They acquired Scientific Materials Corp. in 2005, which itself was incorporated in 1989.

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Originally Posted by Diachi

Now builds? They acquired Scientific Materials Corp. in 2005, which itself was incorporated in 1989.

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Well it’s new to me I can delete it if it upsets people

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Originally Posted by Diachi

Now builds? They acquired Scientific Materials Corp. in 2005, which itself was incorporated in 1989.

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Who' principals had made some really nice rods even 15 years before that at another company. As in some of the first commercial rods.

Steve

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Originally Posted by mixedgas

Who' principals had made some really nice rods even 15 years before that at another company. As in some of the first commercial rods.

Steve

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Yay there’s Steve.

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Originally Posted by akmetal

Yay there’s Steve.

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Considering a modest sized bare ND:YAG rod (max 120 watts of IR output when lamp pumped, 2014 quote, pre buyout pricing ) with polished and coated ends from them starts at ~ 800$, What are you trying to do?

Steve

Quote:

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Originally Posted by mixedgas

Considering a modest sized bare ND:YAG rod (max 120 watts of IR output when lamp pumped, 2014 quote, pre buyout pricing ) with polished and coated ends from them starts at ~ 800$, What are you trying to do?

Steve

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What ever I do it won’t be spending $800. I am trying to get educated to redue my entire design.

I am looking up how the diodes work with a mind as to how I could custom machine parts, for the crystal I will probably buy one, I saw one on eBay for like $150.

I am simultaneously working with a friend to upgrade my cnc machine so I can custom make as much stuff as possible from bulk materials.

Once I develop an idea I build it out in solid works. The total project will probably cost a lot but I enjoy it so if I die before I complete it that’s ok.

My work situation is ideal time and job satisfaction wise but income wise not so good. I used to be an oil and gas process engineer but our contracts got cut and our family is not excited about moving to Timbucktu and my wife makes good money so we are fine I just can’t drip thousands on equipment tools and parts anymore.

Quote:

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Originally Posted by akmetal

What ever I do it won’t be spending $800. I am trying to get educated to redue my entire design.

I am looking up how the diodes work with a mind as to how I could custom machine parts, for the crystal I will probably buy one, I saw one on eBay for like $150.

I am simultaneously working with a friend to upgrade my cnc machine so I can custom make as much stuff as possible from bulk materials.

Once I develop an idea I build it out in solid works. The total project will probably cost a lot but I enjoy it so if I die before I complete it that’s ok.

My work situation is ideal time and job satisfaction wise but income wise not so good. I used to be an oil and gas process engineer but our contracts got cut and our family is not excited about moving to Timbucktu and my wife makes good money so we are fine I just can’t drip thousands on equipment tools and parts anymore.

---

So, scaling back from your original plans of 10-40kW CW?

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Originally Posted by Diachi

So, scaling back from your original plans of 10-40kW CW?

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Since I’m completely switching designs I don’t know what is achievable but the over all goal of the laser is the same, it has to have significant reach otherwise this endeavor is a failure. Whether that means 10kw 5kw etc I don’t know.

Assuming a generous 0.1 mRad divergence, at 40 kilowatts, your only an eye hazard to well over 45,000 meters, or about 28 miles. You'd have to notify DOD and FAA just to fire the laser. DOD notifies the recon sat project offices, who will want to say yes/no in a very serious and real time way. The Notice to Airman and Laser Safety Paperwork is time consuming, trust me, I've done it for 7 Watts very close to three Class Bravos a few tens of miles apart.

We once had one fellow on the forum with two up-collimated 45 watt Copper Vapor Lasers with similar divergence, and it was hinted that he got to talk to the powers that be in a very serious way every time he did a outdoor show. Basically you'll be lucky if you can get a land based test window as a civilian at all, given the amount of orbital objects "up there" these days. Might not want to promise your investors anything before you have that worked out.

Plan on installing a minimum of two dedicated manned "hotlines" at your test site, if you can FIND a test site. Civilian radars for laser safety in airspace are a no-no, I was once in a position where I needed to ask if that was OK. The request went out as a simple email. The "NO" came back in writing. While you can listen to transponders legally, not everything you have to worry about is squawking. When the NOHD extends past the distance that human spotters can see, you will get some repercussions.

Without a few letters of no objection, any high power testing in airspace these days will likely land you a serious Federal felony. All they have to prove is that one un-observed aircraft had a flight path near your test. Near is "undefined" under the new law.


You may want to take a look at FAA Advisory Circular AC70-1 in its updated form. That is just the beginning of the paperwork,



Steve

Quote:

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Originally Posted by mixedgas

Assuming a generous 0.1 mRad divergence, at 40 kilowatts, your only an eye hazard to well over 45,000 meters, or about 28 miles. You'd have to notify DOD and FAA just to fire the laser. DOD notifies the recon sat project offices, who will want to say yes/no in a very serious and real time way. The Notice to Airman and Laser Safety Paperwork is time consuming, trust me, I've done it for 7 Watts very close to three Class Bravos a few tens of miles apart.

We once had one fellow on the forum with two up-collimated 45 watt Copper Vapor Lasers with similar divergence, and it was hinted that he got to talk to the powers that be in a very serious way every time he did a outdoor show. Basically you'll be lucky if you can get a land based test window as a civilian at all, given the amount of orbital objects "up there" these days. Might not want to promise your investors anything before you have that worked out.

Plan on installing a minimum of two dedicated manned "hotlines" at your test site, if you can FIND a test site. Civilian radars for laser safety in airspace are a no-no, I was once in a position where I needed to ask if that was OK. The request went out as a simple email. The "NO" came back in writing. While you can listen to transponders legally, not everything you have to worry about is squawking. When the NOHD extends past the distance that human spotters can see, you will get some repercussions.

Without a few letters of no objection, any high power testing in airspace these days will likely land you a serious Federal felony. All they have to prove is that one un-observed aircraft had a flight path near your test. Near is "undefined" under the new law.


You may want to take a look at FAA Advisory Circular AC70-1 in its updated form. That is just the beginning of the paperwork,



Steve

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I know places to go that are the middle of nowhere and no one cares, trust me, no one cares. Maybe this stuff applies if your in southern Cali or something.

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Originally Posted by akmetal

I know places to go that are the middle of nowhere and no one cares, trust me, no one cares. Maybe this stuff applies if your in southern Cali or something.

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Where is this magical place that planes never fly over? Because I truly live in the middle of nowhere and we still get planes flying over all the time, most of them aren't bound for here.

Why is it that on a technical forum (and this seems to be a systemic issue across many forums) that a large number of people are hyper focused on bureaucratic regulations rather than the technical details?

It is excruciatingly painful to try to have an intellectual deep technical discussion without someone interjecting "you cant do that" or "its impossible". I mean are these forums filled with feds trying to gain control of the public to slowly pick away at the freedom we enjoy in the USA (enjoyed?) or is it just that people don't really know the technical side as much, but if its the later wouldn't people want to learn .... since we are on a photonics technical discussion board?

I mean when I was getting my pilots license the FAR's were something you had to force yourself to read because a bureaucrat was forcing you to know it for the exam not because it was fun to read or that I needed to know it to land and control the aircraft (thats all stick and rudder skills). Granted the FAA produces some super good quality material but some of it is just bureaucratic and costs pilots and owners BIG money to comply with which is legally / constitutionally suspect (such as forcing someone to do business with another private entity in order to use your own personal property). It would be like saying I can only hire federally designated contractors to wire up a new switch in my house ... oh and they cost 80-100 hr because we only designate a very tiny number of people and if you do it yourself we will kick in your door and beat the s**t out of you and throw you in jail. Just let that sink in. Yes I get it, major commercial operations with huge jets flying hundreds of people of the public is a different situation but the FAA applies the same rules to a small aircraft in sparsely populated areas.

As far as my OP for this thread, I think that I have more than enough to chew on with the text references from Steve, I got them all lined up in my cart and found them CHEAP. But I think this over arching issue of people being hyper focused on bureaucracy is a major issue and impediment to intellectual / technical discourse, it seems to permeate every on line forum I see, even ones I just lurk on, there is always multiple people that never fail to bring up some obscure buried regulation and its super irritating as they bring it up BEFORE the technical discussion.

I don't know maybe people living in so cal packed in like sardines have to worry about every time you sneeze breaking a regulation but where I am no one cares. I can see having a nice robust technical discussion and then at the very end in a foot note indicate that our overlords frown on free people doing free things, maybe one or two lines and done.

Oh Boy, You have no idea how much the Scheduled Airlines and FAA/ DOD hate lasers in airspace.

I've been there, done that, and have the T-Shirt for an outdoors New Years Eve show.

There are the negotiated procedures per the book for a reason.

You won't get a day in court, the "Notice of Apparent Liability" just shows up telling you to pay a Fine to a Federal account at Mellon bank in Pittsburgh. Well, they will give you 30 days to reply with endorsement. It is a procedural Civil matter.


Then there is Endangering a Crew, and a Lasers in Airspace Felony...



Steve

... scan through the forums with tags like "pointer-kiddies" :cool:

Viktor

When someone goes to the trouble of explaining all the things you don't know that you don't know - the smart thing to do is read them and try to accommodate the new (to you) information. What you're doing is (at best) trying to assimilate the information. Assimilation is where you try to cram the information into your poorly equiped preconceptions. You might want to read up on Cognitive Dissonance and the Dunning-Kruger effect.

Quote:

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Originally Posted by akmetal

I know places to go that are the middle of nowhere and no one cares, trust me, no one cares. Maybe this stuff applies if your in southern Cali or something.

---

Scan even further back and look at "Lasers in Vegas". We lost profitable outdoor shows nationwide for years, and when we got them back, the rules were draconian, and having to give 30 days notice killed the business for the pros.
All because of one Idiot in Vegas that ignored a cease and desist and illuminated traffic coming into McCarren for weeks with an automated high power, laser system on a casino. They have lightened up a bit, but I do scientific lasing now, and not big outdoor shows, for a reason.

I have a 60 Watt outdoor system setting on a trailer in the driveway. Pre-Vegas, It would have sold for 20,000 to 30,000$. Post Vegas, I'm lucky if I can get 500$ for it. No it is not for sale right now, unless you have a variance. If you'd like, I can show you a video of a guy with one in his apartment. He's lighting a cigarette from the beam, with no safety glasses, and a toddler is in a high chair about two yards away. The room is glowing bright green from no beam stop. Idiots spoil it for the rest of us.

The folks on the other laser forum are hyper focused on "getting away with it", but even they say don't aim at aircraft, you'll spoil it for us. They generally do not reach our power levels and investment that we have on PL.

We get to do what we love within reason. We know what has happened in other countries, we talk. Try doing a laser show in France, Outdoors. Maybe if the Prime Minister/Premier wants it to happen.
Try importing a small laser to Australia. See if it makes it past customs without docs, if it is in a cylindrical package and over 5 milliwatts. Some of us here know the 20 year history of lasers in Airspace. Which went from have fun, once a year reporting. to good luck getting a decent beam power for your show.


Steve

Quote:

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Originally Posted by akmetal

Why is it that on a technical forum (and this seems to be a systemic issue across many forums) that a large number of people are hyper focused on bureaucratic regulations rather than the technical details?

It is excruciatingly painful to try to have an intellectual deep technical discussion without someone interjecting "you cant do that" or "its impossible".

---

"If everywhere you go it smells like shit, maybe it's time to check your own shoes."

Maybe don't ask for the impossible if you don't want people telling you "it's impossible". ;) Not that building a 10-40kW CW laser is necessarily impossible, but when you throw in some sort of limitation like a lack of infinite funds/time/resources it becomes impossible. :rolleyes:

Quote:

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Originally Posted by mixedgas

No it is not for sale right now, unless you have a variance.

Steve

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What if I live somewhere that doesn't require a variance? *retardo J/k, that much power is too scary for me. *warn

What if I live somewhere that doesn't require a variance? *retardo J/k, that much power is too scary for me. *warn[/QUOTE]

Diachi, I'd gladly sell you the "Cobra". You've been around enough to know it needs respect. Long, but beautiful, drive with trailer or truck to get it there.
Cobra's are 800 series made in a compliant package, with a touring PSU.

Steve

Quote:

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Originally Posted by Diachi

"If everywhere you go it smells like shit, maybe it's time to check your own shoes."

Maybe don't ask for the impossible if you don't want people telling you "it's impossible". ;) Not that building a 10-40kW CW laser is necessarily impossible, but when you throw in some sort of limitation like a lack of infinite funds/time/resources it becomes impossible. :rolleyes:



What if I live somewhere that doesn't require a variance? *retardo J/k, that much power is too scary for me. *warn

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I would not say I have infinite time but like I said before if I run out of time and its not done then thats life. I would rather pursue what interest me rather than put together a lack luster project and have a glorified laser pointer at the end and get all excited that it lit a match, sorry, just like I could not get excited over a cessna 150 other than to rent for initial training, RENT. OR have something that is truly cool, like where you wave a 1/4" steel rod across the beam and the other end of the rod falls to the ground, I fantasize about that from time to time.

there is no poo on my shoe, just an S2B in a hangar and a solo in my log book with less than 140 hrs total time, do you know how many people told me I was crazy that I needed a zillion hours to fly a pitts and that "air line captians" have wrecked pitts etc etc etc. Well here we go with a laser :)

I figured out how to make money before and I will do it again I am just in a less that ideal situation right now. But times like these are perfect to read up and educate myself, maybe take an Edx class. i am hoping that edx releases their electrical masters program for cheap so I can start that soon.

Quote:

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Originally Posted by mixedgas

What if I live somewhere that doesn't require a variance? *retardo J/k, that much power is too scary for me. *warn

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Diachi, I'd gladly sell you the "Cobra". You've been around enough to know it needs respect. Long, but beautiful, drive with trailer or truck to get it there.
Cobra's are 800 series made in a compliant package, with a touring PSU.

Steve[/QUOTE]

I could do with a vacation during these cold dark winter months...

Maybe I'll take my truck down that way one of these days, would be a fun road trip and I'm in dire need of a good LEM photon fix, been a while.

Remember seeing pictures of Pat B's (or one of them at least?), nice looking machines. Bet it still takes a couple guys to move one if it's anything like the last converted system I was around.:rolleyes:

Quote:

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Originally Posted by akmetal

But times like these are perfect to read up and educate myself

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That's never a bad thing.

So I am able to get 6 CRC laser handbooks (1-5 plus Crc Handbook of Lasers, With Selected Data on Optical Technology) and the Koechner book for $131

Is this a pretty good deal?
Solid-State Laser Engineering by Walter KoechnerSolid-State Laser Engineering by Walter KoechnerSolid-State Laser Engineering by Walter KoechnerSolid-State Laser Engineering by Walter Koechner