User Panel
Posted: 1/15/2006 6:34:14 PM EDT
This is a 350mW laser.... that's 70 times the strength of the lasers we mount on weapons. (5mW)
Cost is only $3,000. I found this on the net & thought you all might like it... www.laserglow.com/hercules.html THE BUILDING IS 11 MILES AWAY |
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That picture is quite obviously a fake.
Even if it were a completely foggy night, enough to make that beam visible, it wouldn't look anything like, you know, just a green line pasted over in photoshop. |
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It very well could be real seeing as its a 350mW laser. |
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What, you mean the laser wouldn't be the exact same thickness in the picture at the tower as it is at the point of origin? Perspective, what? |
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You must have a variance issued by the CDRH (FDA) to operate a laser greater than a Class IIIa (Visible, <5 mw) in public. From the context of the picture, I doubt that they obtained a variance, and the pic then shows activity in violation of federal regulations on laser safety. I have only used a IIIa green laser outside, and I have used my IIIb (~45mw) green laser in the lab. The photograph looks reasonable considering the power output, possibly using a somewhat long exposure. It doesn't need to be foggy--the normal atmospheric dust and pollution is plenty to show a bright, distinct line when using a high power green laser. Jim |
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Shining one that powerful at a building would be pretty irresponsible too.
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You are quite obviously a moron. www.candlepowerforums.com/vb/showthread.php?t=92396 You have never got to play with powerful lights |
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I guess lasers are immune from the laws of perspective. At 11 miles. |
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Just an observation: Whatever building it is shining on at 11 miles away must be tall. Use photoshop or a similar program to zoom in at the tower. Look at the size of the beam compared to the size of the tower. At that distance, the beam would have to be about 10 or 20 feet around. Maybe bigger (depends on how tall the building is) It spreads out from the size of a speck to 20 feet around, yet retains its concentration and intensity. |
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Have none of you tards seen a green laser at night?
I own a 5mW one. They look exactly like that. |
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"tards"? Can you explain how a beam can be the same width in a picture 11 miles away? But at the same intesity? Or how a beam can be the size of a pencil at the point of origin, but apparently 20 or more feet around 11 miles away, yet still appear to be the same intensity at both points? Perhaps you can enlighten all us 'tards'. |
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If the beam is that bright at 11 miles, it would be dazzling at the closest point. Conversely, if it were that dim at the closest point, it would be invisible at that distance.
Definite fake. |
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Tard. |
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Ablation and attenuation. It’s getting bigger, but you can’t tell because of the gradual change in size and perspective making that size change near imperceptible. By the time the beam is about a foot in radius, it’s so far away it looks like it’s only as big as the original beam. Get a green laser and try it out yourself. |
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I think the person with the laser is inside the tall building. Look at the second picture on their site:
http://www.laserglow.com/images/herc4.jpg |
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Is a regular red laser "dazzling" when you point it at something else? No, it's only bright when pointed directly at you. The same with a green laser. That's kinda the point of a laser, directed energy. If it wasn't it would be called a light bulb... |
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If it's "directed energy", why is it 20+ feet around 11 miles away, instead of being as 'directed' as it is at the point of origin? |
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He is holding it in the 1st pic pointing at the tall building. |
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I already answered that. Ablation and attenuation. Just because it loses energy doesnt mean it's not still directed... |
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Yeah, I see now. |
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I'm not talking about losing energy. I'm talking about a small beam of light being 20+ feet around. Do you have any image editing software? Zoom in on where the light hits the building. If the building is 11 miles away, it must be hundreds of feet high. The beam is a good portion of that building where it hits. And it looks exactly the same as it does at the beginning of the 'beam'. |
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You completely missed my point. Laser light acts, for all intents and purposes, exactly the same way as other light, except that it is not seperated when refracted. White light, when refracted, will split into different colors to some extent, and will not stay in a white beam. The beam that you see next to the laser should be the brightest point. Do you think that if someone were to go several feet from that building and shine the laser at the same angle, that you would be able to see it from 11 miles? If you couldn't in that situation, you couldn't in the picture's situation. My point was that if you are able to see the beam 11 miles away, in VERY CLEAR AIR (you need something in the air to see a beam), the beam close up should be absolutely dazzling. A dim laser would act exactly like any other laser, including this one. I have shined a laser in fog. I cannot see the beam as well far away as I can close up. If the beam of this laser is as easy to see 11 miles away than it is close up, then the beam of my laser should be just as bright 11 miles away as it is close up. But it isn't. |
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As the laser loses energy the cohesion of the beam dissipates and the radius becomes greater. It gets bigger because it's losing energy. But because this is so gradual, when looking at it from the point of origin it appears the same size until it hits the target. With green lasers they are so bright, that along the entire path it’s very visible. That combined with perspective make it look the same size if you’re looking at it from the point of origin. You would need to be perpendicular to the PoO to notice any change in the cross sectional radii. |
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Another point is that if you examine this in in detail, things seem very strange. It's a jpg picture. Which uses lossy compression. Yopu can see it in the clouds and the other parts ofthe picture. But the beam is about the only thing in the picture that is consistant in color and intensity from beginning to end. And it's 11 miles long. No variation in color or compression over the entire length of the beam. Having worked with image editing software for years, I can't see how that is possible. |
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I'm not talking about size, I'm talking about brightness, and I think the others are too. Sure, if the dispersion rate were exactly correct the beam would appear the same size at any distance. But the farther away the beam is, the dimmer it would appear. I also have no idea what you mean by saying that as the laser loses energy the cohesion of the beam dissipates. Losing energy has nothing to do with it. The innards of the laser are not perfect, and it simply spreads a bit. If it were perfectly focused, it would not spread. The only reason a laser would lose energy is if it hit something (i.e. dust or fog), but that would not necessarily cause it to spread out. If the air or particles in the air caused the beam to spread out, it would cause all other light to spread out, which would cause everything you see to look distorted. |
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Have you ever really worked with photoshop? Have any imaging editing software that can zoom and pan? If you do, zoom in at the origin of the beam - say 400% Then pan from left to right. Notice how the beam is exactly the same from beginning to end. I'm sure these guys have a nice, powerful lazer. But the beam doesn't look natural under close examination. Especially the point of termination - look how it ends on the tower. Is there video of this experiment? That would help dispel any doubt. |
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1 more photo posted please........
How about a photo that is 11 miles away.... |
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I know what a laser is. I know how it acts. It acts the exact same way as other light. If you shine a laser through a prism it will bend. However, unlike white light, it will not spread out or separate (since there are no colors to separate). But what do you mean by monodirectional? All light will travel in a straight line unless reflected or refracted. Lasers will not travel in the exact same direction (meaning no beam spread) unless the inner workings of the laser machine are perfect. If they are not, the beam will spread. |
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About damn time.. My head was starting to hurt.... |
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To me the "beam is the same all the way.... Only "bright" point is right at the pointer itself....... |
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Ok, since you know so much about lasers. Do some math for us. According To their website; The beam is < 1.5 mm Beam Divergence is <1.2 mrad Show us the calculation for beam width at 11 miles, starting from < 1.5mm with a divergence of < 1.2 mrad. |
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Just goto: http://www.candlepowerforums.com/vb/forumdisplay.php?f=53
There are hundreds of pictures posted there and they all look exactly like the photos posted earlier. I have no more desire to debate someone that has twice now shown his ignorance of what a laser is.
Thats the difference between a 5mW laser and a 350mW laser. The 350Mw laser wouldn't start dimming till probably 50+ miles. |
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Why would a more powerful laser start dimming farther out? Because it's more powerful and can punch through all the dust and fog in the atmosphere? In the real world, if there's more light, more light will be absorbed by the particles in the air. If you have a dim laser or a powerful laser, the same percentage of light will be refracted/absorbed/reflected in the same atmosphere, meaning you will see the same percentage of the total amount of light. Perhaps you didn't know this, but the only reason you can see the beam is because the air is not perfectly clear. If it was, you would not see anything no matter how bright the laser was. |
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According to the site, their 50mw laser can burn through tape. Does anyone think it would be legal to shine a 350mw laser onto a building?
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As the beam diverges over distance, the beam 'hits' more particles of dust/pollution per unit distance. I suspect that would be part of the explanation of why a beam would appear to be more uniform in brightness over its length than 'common sense' would dictate. By the way, 350 mw is /more/ than enough to burn things, depending on material and color. A common demonstration with 100 mw lasers is to pop a balloon from a distance. Jim |
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I can confirm with firsthand experience that a green laser pushing close to 50 mw (and foucused) will burn through black electrical tape. I do that as a demonstration. Even at 50 mw, there is almost certain instantaneous and permanant damage from direct exposure to the beam, even allowing for the blink reflex. At 350 mw, the damage would be severe, even though it would be mostly restricted to the area of direct exposure on the retina. As I have described it to students, what I show the laser doing to electrical tape, it will also do to your retina. Jim |
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Do you know how to calculate beam size / divergence based on the original size, distance, and listed mrad divergence? I looked online but I couldn't find anything that covers it. |
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That makes no sense. As the beam spreads out, a given area of the beam will get weaker, exactly proportional to its spread. More particles will be hit as the beam disperses, that much is true, but those particles are each being hit by a smaller amount of light. Whether the beam is tiny or huge, it amounts to the same amount of absorption/refraction/reflection, assuming the atmosphere is of uniform particle density. |
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Yes, but would it be legal to shine onto a building? |
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I think maybe he means it gives gives the illusion of uniformity in brightness, if not actual uniformity. |
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I still do not see how that makes sense. The same amount of light will be reflected back no matter how wide or narrow the beam is. Since the intensity of the light that is reflected back to your eyes decreases at the square of the distance, it should get dimmer as it gets farther. I understand that the farther away the beam is the sharper the angle is, and therefore for a given angular size you are seeing more of the length of the beam, so that might explain some of it. I still find it hard to believe that that factor alone could account for the uniformity of brightness at any distance. |
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It would work if you wanted to carry a battery pack around on your back, or a really long extension cord. |
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