Laser Propulsion!! Hercules350 Update

duFontaine

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The other day I was lighting matches with my Hercules350. I had a kitchen match wrapped in 2 layers of red balloon. I lit a few, and stopped to look at the aftermath and noticed some black burned plastic about the size of a grain of rice floating in the air. I took off my goggles and used my little 5mW green pen laser to shoot a piece of debri. I held the pen laser under the piece and it immediately floated straight up! I knew it could not have been the air moving it, because the air was off and the smoke from the matches was just hovering. So, I sat there thinking about what just happened ( thinking I was a total genius and about all the money...). When right at that moment I noticed it coming back down. With the laser in my hand I tried to shoot it again but I was at an angle so instead of it moving straight up, it moved to the side. Now I was excited, I was moving something with my laser at like 5-6 feet. My ceilings are 20 feet and I could "push" it all the way to the top, but as soon as the laser moved off the black soot, it would begin to fall back down.

Ok at this point I thought I was going nuts, this could not be...but it was. I called to my girlfriend to come in and check out my genius. She saw it also and was just as amazed as I was. Can anyone explain? I do remember seeing something on the Discovery Channel about 5 years ago about a man that used a laser to shoot this strange metal disc he had crafted way up into the air. Does anyone have any more info?

One more thing...After having the Hercules350 for over a month now, I've had some time to test it out. It performs better than I ever expected and am still amazed every time I turn it on. Check out the LaserGlow site for a video I sent them popping balloons at over 11ft. It should be up the next time they update their site. My most amazing feat yet was cutting through a tow strap which was thicker than a seatbelt. I'll send a video of this shortly.

Thanks,
duFontaine
 

jkaiser3000

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you stumbled upon a concept discovered several years back (I believe 19th century). This phenomenon is employed in common solar radiometers. I'm not entirely sure how it works, but it has something to do with "thermal transpiration". It's basically a transfer of momentum from the photons of the laser to the speck.

I never thought this could be done in plain atmospheric pressure
:sssh:

Anyway :goodjob:
 

jkaiser3000

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Sorry, forgot to mention. I also saw the program on discovery channel. The guy had a specially shaped, metallic disc placed beneath a laser. I forgot what kind of laser he used, probably IR, but the thing is, the shape of the disc was meant to focus the light to a certain point. As the laser is focused on that point the air surrounding the disc is heated tremendously, and creates an explosion. this explosion is what propelled that thing.

And to think he's planning on using that technique to travel to space. I'm not sure how he plans on doing that, as it will require very high speeds on the order of 17000 to 25000 mph.

Do you think your hercules can help him? :naughty:
 

Lunarmodule

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I recall a TV program like that, Discovery Channel is likely, where they had documented cutting edge alternative propulsion methods specifically for lifting payloads into near Earth orbit and one of them was the laser system as mentioned previously. It consisted of a disc shaped payload carrier with a reflective concave base that focused laser energy into a point just inside the parabola of the reflector, superheating the air and pushing the disc upwards. The bad news: the amount of laser power required was in the order of tens of megawatts and it was extraordinarily inefficient in terms of payload weight tha t could be supported. The biggest difficulty was dynamically maintaining focus and targeting the same area on the bottom of the disc through thousands of feet of atmosphere. From what I recall it worked as a proof of concept on a very small scale, but unlikely to go beyond the prototype stage because of all the complications.

Interesting that you were able to levitate that piece of soot, especially with enough control that high off the ground. Unfortunately, though, I dont think it would work with anything of any significant mass. Out of curiosity, what do you primarily use your Hercules for? Thats a tremendous amount of laser power in a portable package. Congrats on your purchase, I'm green-eyed over here, pun intended.
 

comozo

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duFontaine said:
The other day I was lighting matches with my Hercules350. I had a kitchen match wrapped in 2 layers of red balloon. I lit a few, and stopped to look at the aftermath and noticed some black burned plastic about the size of a grain of rice floating in the air. I took off my goggles and used my little 5mW green pen laser to shoot a piece of debri. I held the pen laser under the piece and it immediately floated straight up! I knew it could not have been the air moving it, because the air was off and the smoke from the matches was just hovering. So, I sat there thinking about what just happened ( thinking I was a total genius and about all the money...). When right at that moment I noticed it coming back down. With the laser in my hand I tried to shoot it again but I was at an angle so instead of it moving straight up, it moved to the side. Now I was excited, I was moving something with my laser at like 5-6 feet. My ceilings are 20 feet and I could "push" it all the way to the top, but as soon as the laser moved off the black soot, it would begin to fall back down.

Ok at this point I thought I was going nuts, this could not be...but it was. I called to my girlfriend to come in and check out my genius. She saw it also and was just as amazed as I was. Can anyone explain? I do remember seeing something on the Discovery Channel about 5 years ago about a man that used a laser to shoot this strange metal disc he had crafted way up into the air. Does anyone have any more info?

One more thing...After having the Hercules350 for over a month now, I've had some time to test it out. It performs better than I ever expected and am still amazed every time I turn it on. Check out the LaserGlow site for a video I sent them popping balloons at over 11ft. It should be up the next time they update their site. My most amazing feat yet was cutting through a tow strap which was thicker than a seatbelt. I'll send a video of this shortly.

Thanks,
duFontaine

Don't get too excited 5mw is to feeble to do what was witnessed by light pressure alone. The only thing that could move the ash was a slight movement of air immediately around the ash cause by the ash being heated. If you held the pointer under the ash then it was most likely the heat from your hand and the laser had nothing to do with it.
 

duFontaine

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jkaiser3000, cool link I always wondered how those worked.

About that show, I only saw it once and never heard of it again, isn't it always like that.

Lunarmodule I use it for advertising purposes. It's a real head turner!!

Comozo, yes I guess it is always possible that the heat from my hand moved the piece of soot. But the closest it ever came to my hand was like 5ft. Hot patches of air could also be a factor, but that still doesn't explain how I was able to direct it's trajectory. It's not like it rode up the beam it just tried to avoid it weather that meant going up or to the side, but it was definitely trying to avoid the beam.

Thanks
duFontaine
 

AJ_Dual

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Even though air is largely "transparent" at 523nm, it's not perfect. The air or micro-contaminants, in the beam would be heated and been constantly expanding and rising. The speck could have been moved by that.

Stuff even smaller than your speck of ash is always in the air; dust, water vapor, etc. The beam is visible from the sides, meaning that the air can't be 100% transparent something is scattering it, which means there has to also be waste heat from whatever's colliding with those photons.

The issue is if it's enough to lift up the ash speck as you observed.
I would love to see what a high powered laser would look like from the side using a thermal imager in still cold air.

To test for thermal lift coming from the beam, you could make a tiny balance beam out of fine wire or balsa sticks, and on one arm, make a horizontal vane or sail out of some really fine tissue. You could then watch for lift by shining the laser underneath it. The other end of the balance could be the indicator needle against a ruler etc.
 
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comozo

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Although you were able to direct the ash it still was not caused by the pressure of light on the ash but was caused by heated air molecules near the surface of the ash.The easiest way to demonstrate this would be to use a radiometer, you know the thing that resembles a light bulb but with black and white squares on the inside that rotate when a source of heat is near.
 
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L.E.D.

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Something that would TRULY use photonic pressure and not heated particles bouncing off a surface would be those "solar sails"... Saw a program (on discovery also) discussing these, gigantic ultra thin metallic sails affixed to a craft for harnessing the propulsion that ONLY the light would give in the airless nearly perfect vacuum of space. Anyone heard of these?
 

Sanny

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Yep, there is even a book by Arthur C. Clarke, "The wind from the sun", which describes a solar regatta where space ships sail in the solar system using the "solar pressure" as thrust.

Photons have a momentum, even if they have zero mass, and by bouncing them off you can gain each time twice their momentum. However the pressures involved are very low and such space vehicles would require huge sails to be effective.
The challenge would be to keep the weight low for such a huge structure, and find an effective way to deploy it once outside the atmosphere.
 

The_LED_Museum

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Star Trek DS9 had an episode called "Explorers" in which Sisko builds a solar spacecraft and he & his son Jake "fly" it, using stellar photon pressure to accelerate it. The spacecraft had large, thin "sails" that enabled it to capture light and use that as an engine. I believe the idea to be scientifically valid; though the part where they fly into a tachyon eddy and are accelerated to warp velocity is probably BS.
 
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shawndoe

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Hi,

Solar sail is the right idea, it's also why comets have tails, that explains the trajectory change. To see if what your doing is really what you think it is would require some generalized math. I don't know how to calculate thrust from photons, but the math is out there. Probably a simple equation using the mass of the object being moved and the photon flux (beam power and wavelength). I'd search it out but I'm at work right now. 350mW is alot of power to dump on something that weighs maybe 5mG tops.

I believe it.
Shawndoe
 

Sanny

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The force exerted by the photons can be calculated by dividing the power of the light source (the total energy of the radiation emitted per unit of time, in Watt) by the speed of light (in meters per second), so 5mW would produce 16.7 picoNewtons of Force, enough to lift 1.7 nanograms.
Even 1kW of light :duck: would only be around 3 microNewtons or 0.34 milligrams.

As in the NASA prototype mentioned in a post above and in radiometers the predominant effect is just the heating of the air.

Can someone confirm my calculations? I need to go to bed :sleepy:
 

comozo

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Speaking of tiny forces exerted...
"Optical traps
An ultraweak force of 25 femtoNewtons, the smallest force ever directly measured, has been experimentally analysed by a scientist in Germany. Alexander Rohrbach from the European Molecular Biology Laboratory in Heidelberg used a 0.53 micron-sized latex bead held in an optical trap to make the measurement. The force was generated by the radiation pressure from a 11 mW blue (488 nm) laser beam that illuminated the bead. According to Rohrbach, such femtoforces are commonly found in nature. Examples include the force exerted by daily sunlight on a small dust particle in the atmosphere, or the friction that that a bacterium has to overcome when travelling through water. (Optics Express 13 9695)"
 

Canuke

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Sanny said:
Yep, there is even a book by Arthur C. Clarke, "The wind from the sun", which describes a solar regatta where space ships sail in the solar system using the "solar pressure" as thrust.


In "Footfall" by Larry Niven and Jerry Pournelle, aliens invading Earth use lasers aimed into the nozzles of craft heading back up to the mother ship.. The laser vaporizes/ignites some kind of material inside the nozzle, and off she goes.
 
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