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FrozenGate by Avery

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nwfreefly said:
:shhh: shhhh Cyp, don't spill the beans man. Once I get into the Oval office I lift the ban on CNI >5mW's so I can finally have the damn PGL 589! You're screwing my master plan up.
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:na::na::na::na::na::na:

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Tonight we had a fairly low cloud deck of only a few hundred feet, I took a photo of the output of my 1 watt 520nm laser pointer shooting through a scary pumpkin head mask which was taped over a 18 inch diameter Fresnel lens. By taking the output a little out of focus, varying the distance the large lens is from the raw output of my laser pointer, I could make the face small or huge, pretty scary looking :p

Sorry for the poor image quality using my cell phone, but it gives you an idea of what it looked like, although far more impressive and brighter in first person.

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Yea, but maybe only 500 feet high, when turning the lens towards one side or the other for an oblique angle to the laser source, the face appears to be looking around :) One cool aspect of having the beam expanded so large and taking it out of infinity focus far enough so you just have a big face in the sky, the beam can't be seen very easily traveling to the cloud base, but you can sure see that face up there.
 
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I'm thinking..., imagine a projector powerful enough to put a picture on a low cloud ceiling at night, so you could play... I dunno like... Super Troopers or something on the sky during a party at your house. Now THAT would be cool!
 
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Alaskan said:
Yea, but maybe only 500 feet high, when turning the lens towards one side or the other for an oblique angle to the laser source, the face appears to be looking around :) One cool aspect of having the beam expanded so large and taking it out of infinity focus far enough so you just have a big face in the sky, the beam can't be seen very easily traveling to the cloud base, but you can sure see that face up there.
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Alaskan thats wicked! You just have to do a Batman signal, if anyone you can:beer:
 
Here are a couple of photo's of my 40 watt 808nm FAP laser driven by 2 VDC at about 40 amps. The photos are of the beam using a camera with the IR filter removed but in color mode. The first photo shows the beam with a collimating lens on it, the second showing the output with that lens removed, just the raw output. I turned the power down for the second photo so the IR intensity would not overcome the camera and allow the individual combined fiber outputs to be more readily visible. The last photo is in black and white camera mode, of course.

ir%20beam1.jpg


The burned spots on the cardboard are from holding the paper from 1/4 to 6 inches away from the output lens. The two smallest spots near my thumb were when 1/4 inch away.

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Even with a camera with the infrared filter removed, you can see IR doesn't produce a very bright beam due to the longer wavelength. What I learned using the IR camera is that the beam output from the IR lens does not converge for cutting, I have several of these lenses and until I could see for myself what is happening with the camera, I had always thought the beam converged to a cutting point and then diverged to make a wider spot, this isn't happening at all, the lens is just collimating the the beam but until I do some more tests, I can't tell if the output is exactly at infinity focus or not. I had measured the divergence to be about 18 mRad with this lens and the specified divergence agrees with this, even when using this lens.
 
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@ Alaskan
I would be interested to know how well that can be focused at a longer distance given it's fiber bundle construction and I wonder how well it could be used to pump a crystal.

Cool pic. :beer:
 
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