DIY Optical Active Camouflage

18:21, 23/06/2024, Sunday

I feel like I already talked about this somewhere, but I don't really remember when/were...

I'm actually quite interested on starting a Hackaday project on making my own active camouflage, but I'm literally broke and I since I literally didn't even start making anything with my Mech/Exosuit project, I think I should just post the idea and let someone smarter (and more competent) than me to do the work.

Not a super advanced technology:

DEPENDING on what you want with the final product, it really doesn't require a super advanced technology.

If you want something more akin to the Predator's or the Elites in Halo, then yes, it is impossible with our current technology.
Of course, there isn't a precise explanation for what they do, but it seems that they bend light around their body perfectly, being useful in any perspective and any distance.

And yes, point of view/perspective of the observer is a huge factor with these active camouflages:
If you look at a transparent camouflage like in the examples from the front with a wall in the back, they are perfect, but if simply walk around, you will see the distortions in background objects.

What we can do:

Attach a bunch of cameras or colour sensors around a suit and a non-light display along it to either make a camouflage combining with the ambient or a straight up image of the surroundings.

A few examples: Octocamo from Metal Gear 4 and the Thermoptic Camouflage from Ghost In the Shell.

It uses colour sensors and flexible displays to blend in the background, and it can do it with multiple objects at the same time.

It also seems to use flexible peltier plates to change the heat in the surface to fool infrared cameras.

I don't know exactly how it works in ghost in the shell, but by the name, it is probably the same thing, but way more advanced.

Real life technologies that could be used:

In the real world there also are those leticular lenses plastic panels that are normally used on holographic plates/tazos.

There are also electrochromic displays and electrowetting displays.

Posy made a really good video explaining the first:

This method doesn't need backlight and neither transmits light like LED pixels, which would be essential, or else you would be just a giant firefly in the night and a dim colour during the day.

Now, to me, electrowetting is the most promising type of display for this type of optical active camouflage, it basically uses a similar methode to the e-paper, but using individual liquid pixels instead of a super complex paint with two polarities.

In simple terms, you have two electrodes separated by a dielectric material (insulator) where one of the electrodes is a droplet of liquid and the other electrode is just a conductive material (graphite, metal etc). When you add a charge to one of the electrodes, the droplet expands itself over the surface of the dielectric material, making a coloured pixel.

You can use these two examples as a possible way of making the pixels, you "just" need to add more layers with different colours and change the intensity of the charge and the quantity of pixels being activated to change colours.

There are entire displays out there that uses this technology, and since they don't emit light, but reflect it, they use a really small amount of energy.

But I do think you would need the back of all the pixels to be a frosted mirror, because these kinds of mirrors reflect the ambient light instead of a full on mirror.

I couldn't re-find the exact picture I had in mind, but a close thing is those diffusers for photography and movies:

In either way, electrowetting is not limited to ink pixels, but for some very specific applications, like microfluidic systems.

You could literally move droplets, and maybe, you could make a movable ink background for every colour.

However, if you can make a LED/light emitting...

Magnetohydrodynamic Generators

Well, hello.

I'm making this page because, for some reason, I feel like talking about Magnetohydrodynamic Generators (MHD generators for short), but I don't have any kind of project log to talk about it.

I would want to make a new project on this subject, but let's be honest, I'm broke and not a professional in any useful area, so it is most likely I would left the project to rot and unnecessarily fill up Hackaday's memory.

But being honest², I do feel tempted in making such project because I have a faint hope that someone more qualified than me would see and try it.

In any case:

Magnetohydrodynamic generators:

These kinds of generators are just like alternators, but with no moving part and using plasma instead.

What do I mean: alternators have electromagnets on both the rotor and the stator, once you rotate it, the disturbance in the electromagnetic field will generate energy.
A MHD generator maintains electromagnetic fields that maintain a conductive medium (normally plasma), once a disturbance in this equilibrium appears, it is turned into energy.

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The problems:

The first issue that one notices when researching about the subject is the lack of information and the lack of large scale applications of such generators (with the exception of being used on rocket engines).

I can barely find any information on the subject and it always substantially changes depending on the article/news paper you are reading.

Some websites say that the MHD generators aren't viable because they achieve plasma by superheating gases until they turn into plasma, others say it is because they need a "seeding material", which is normally a radioactive isotope of some random material that will "seed" ions on the gases, turning them into plasma.
And finally, others say it is because it only produces enough energy if they use blasts that travel through tunnels, which need to be as strong as conventional explosions. Which is dangerous and damages materials.

It is probably all the three and more, but the issue repeats itself: there isn't enough information on the subject.

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The ideas:

Not knowing enough about the subject and not having enough money even to test the most basic of MHD's didn't stop me from imagining how I would do it (even though it is the most incorrect and unpractical idea).

The first thing it comes to mind are toroidal plasma fusion reactors, or Tokamaks:

Of course I'm not saying "Imma turn MHD's into fusion reactors 'cause it is easy", I'm saying that tokamaks are possibly a good blueprint for different MHD generators.

But this put into question: "if they were so good as you say, then why there aren't any MHD with such shape?"

And to be honest, I don't know and I'm probably wrong.

In either way, I do think that fusion reactors will eventually become some type of magnetohydrodynamic generators, because it is way simpler to extract energy like this.

Today's proposals focuses on using the heat generated that hits the walls to turn water into steam.

Which, needless to say, seems quite... Unpractical.

I'm not saying that I know better than the physicists that are creating these marvel of technologies, but I always question myself on how they are going to do it when the fusion they create literally and absolutely destroys the reactor itself from inside.

If I had the capacity/knowledge/competency/budget to do so, I would try to research how to make walls of plasma.Imagine it like this: 

Every layer in this plasma donut is a different gas being ionized, and each gas ionized helps with the fusion and protects against damage on the reactor.

The center is obviously the hydrogen being reacted, while heavier gases like nitrogen or argon gas are used to shield the reactor's walls.

You could maybe even use lithium gas in order to further feed tritium into the fusion reaction, since lithium produces tritium hydrogen when under radiation.

What is a page?

Just testing this feature