Want a light Saber? Super Laser? Here ya go *pic* - Page 2

[ARCHIVED THREAD] - Want a light Saber? Super Laser? Here ya go *pic* (Page 2 of 2)

Posted: 1/15/2006 8:49:14 PM EDT

[#1]

Quoted:
Quoted:
Laser light acts, for all intents and purposes, exactly the same way as other light

wow... just wow. Regular light is not monochromatic, coherent, or monodirectional.

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.

I've been out of college for a while but my business card says 'Laser System Engineer' on it so I'll try. I get ~28.5 meter diameter at 11 miles. I rounded off a bit.

I've been wrong before.

Look, a 532 nm beam @ 350mW rocks pretty hard. Like the curvature of the earth will get you before you cant see it anymore in the right conditions. That said, the picture looks a bit wierd to me too. It could be real but they might have touched it up for the salesmanship effect. When you got in your hands you wouldn't be dissapointed. The airline pilots, the FBI and the CDRH (FDA) would be, though.

J

EDIT

22.8015 m - I used 1.5 mrad ay accident.

Posted: 1/15/2006 8:53:36 PM EDT

[#2]

Quoted:
Quoted:
Quoted:
Laser light acts, for all intents and purposes, exactly the same way as other light

wow... just wow. Regular light is not monochromatic, coherent, or monodirectional.

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.

I've been out of college for a while but my business card says 'Laser System Engineer' on it so I'll try. I get ~28.5 meter diameter at 11 miles. I rounded off a bit.

Well that would explain the beam size @ 11 miles.

Do you have the formula for that handy? I couldn't find anything online.

Posted: 1/15/2006 9:10:56 PM EDT

[#3]

I corrected it I was off a bit.

For the full field divergence you just

multiply the measured length (11 miles=~19000m) by the divergence in mrad (.0012 r)

then add the original beam diameter in. (.0015m)

(19000*.0012)+(.0015)

=Dl

Half field would give you a different number but there are some fractions and a couple more greek letter in the equasion and my 'Fundamentals of Photonics' book is about 2 m away so you get the easy formula.

In short, its a pretty kick ass laser but $3k is a lot- check Ebay weekly.

Here is a picture of 25 W Co2 laser engraver I just bought Friday. I a couple weeks I will be marking knives, receivers, SBRs and other stuff for you guys.

it works like this.

Posted: 1/15/2006 9:16:43 PM EDT

[#4]

Quoted:
I corrected it I was off a bit.

For the full field divergence you just

multiply the measured length (11 miles=~19000m) by the divergence in mrad (.0012m)

then add the original beam diameter in. (.0015m)

(19000*.0012)+(.0015)

=Dl

Thank you.

So I guess what this shows is that powerful green lasers over a distance + low resolution, compressed jpegs = beamshots that look like bad photoshop jobs. (That I was able to approximate myself in photoshop, which is why it seemed hinkey)

Posted: 1/15/2006 9:17:32 PM EDT

[#5]

Quoted:
Quoted:
Does anyone make a mount for this bad-boy

It would work if you wanted to carry a battery pack around on your back, or a really long extension cord.

No Sir. The web site made mention that this thing would run on 3 D batteries.

humm... a mount... well.... it says it is 344mm long by 54mm in diameter.... do they make 54mm rings?

thats around 14.5" long... like a 4D maglite

Posted: 1/15/2006 9:17:51 PM EDT

[#6]

Quoted:
Quoted:
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

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.

I think the original reference was 1.2 mrad divergance with about a 1.5mm original beam size, right?

A small-angle approximation gives a good answer,

(Target diameter) = (distance in meters)*(divergence in radians) + (original diameter)

11 miles is about 18 km, 1.2 mrad = 0.0012 radians, original diameter is 1.5mm = 0.0015 m.

(11 mi dia) = (18,000 m) * (0.0012 rad) + (0.0015 m)
(11 mi dia) = 21 meters.

ETA: Beaten to the punch.

Posted: 1/15/2006 9:22:07 PM EDT

[#7]

Quoted:
Quoted:
Quoted:
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

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.

I think the original reference was 1.2 mrad divergance with about a 1.5mm original beam size, right?

Yes, "sub" 1.2 and 1.5, according to their page.

So the numbers on their site would match up to the perspective of the photo.

If they have photos available at a higher resolution, they should post them and use less jpeg compression - especially at termination it looked really cheesy. The photoshop I did by just drawing a green line, matching the angle, and then saving it at 30% compression looked almost exactly like the original photo.

Posted: 1/15/2006 9:22:36 PM EDT

[#8]

Quoted:
Quoted:
Quoted:
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.
Jim

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

I think maybe he means it gives gives the illusion of uniformity in brightness, if not actual uniformity.

Yes, and combined with the 'blooming' effect of a bright beam on an otherwise dim background, it leads to the kind of photographs you typically see of green laser beams. Photographers often intensify the effect by using long shutter speeds, it saturates the film or digital image in the area of the beam.

Posted: 1/15/2006 9:25:08 PM EDT

[#9]

If you wander around E-bay you'll find green lasers on the far side of 100 mw that cost $55.

They're good for a couple of miles and can light up low flying aircraft (from what I heard at band camp).

Posted: 1/15/2006 9:27:22 PM EDT

[#10]

Quoted:
Quoted:
Quoted:
Quoted:
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.
Jim

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

I think maybe he means it gives gives the illusion of uniformity in brightness, if not actual uniformity.

Yes, and combined with the 'blooming' effect of a bright beam on an otherwise dim background, it leads to the kind of photographs you typically see of green laser beams. Photographers often intensify the effect by using long shutter speeds, it saturates the film or digital image in the area of the beam.

Ok, so that probably explains why along the beam it doesn't suffer from the sort of jpeg artifacts you'd see with other light sources in a normal photo.

Examining the photo I saw compression artifacts all over everything else, but the beam was consistant from beginning to end - like it was drawn on the photo with a pencil brush and then saved as a jpeg.

Posted: 1/15/2006 9:31:23 PM EDT

[#11]

they are way over priced, buy from these guys..

www.wickedlasers.com/

videos on there page as well

Posted: 1/15/2006 9:32:25 PM EDT

[#12]

Hey, I'm not saying it /isn't/ manipulated or otherwise faked, I'm just saying that I dont' see /obvious/ technical reasons why it could not be a genuine photograph.

Posted: 1/15/2006 9:36:35 PM EDT

[#13]

bla...bla...bla...yada...yada...yada...whatever

How you zero the frickin' thing?

Posted: 1/15/2006 9:38:44 PM EDT

[#14]

Quoted:
Quoted:
Quoted:
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

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.

I think the original reference was 1.2 mrad divergance with about a 1.5mm original beam size, right?

A small-angle approximation gives a good answer,

(Target diameter) = (distance in meters)*(divergence in radians) + (original diameter)

11 miles is about 18 km, 1.2 mrad = 0.0012 radians, original diameter is 1.5mm = 0.0015 m.

(11 mi dia) = (18,000 m) * (0.0012 rad) + (0.0015 m)
(11 mi dia) = 21 meters.

ETA: Beaten to the punch.

lol, at least you got closer on the miles to meters conversion. haha. I just feel good that I remember something at all anymore.

Posted: 1/15/2006 9:47:03 PM EDT

[#15]

Neat but I want a Lightsabre.

Posted: 1/15/2006 9:49:15 PM EDT

[#16]

Quoted:

it works like this.

Cool! That video isn't in real-time is it? If it is, your new job will be too easy

Posted: 1/15/2006 9:57:21 PM EDT

[#17]

Quoted:

it works like this.

HOLE-E-SHIT!!! That's fast.

Posted: 1/15/2006 9:58:18 PM EDT

[#18]

"Daddy, where is the planet Mars?"
'Right here son, where the green line is hitting"
"Oops that's not Mars, son. Thats a red dome light from the undercarriage of the 747"

Posted: 1/15/2006 9:58:34 PM EDT

[#19]

Where are the sharks with freakin laser beams attached to their heads?

Is that too much to ask?

Posted: 1/15/2006 10:04:27 PM EDT

[#20]

Green laser pointers are sold for stargazing, meaning you can clearly see the beam all the way to the clouds and beyond if clear skies at night. There is no reason this wouldnt be possible, but I am willing to bet that laser beam is about 6 feet wide on that building.

Posted: 1/15/2006 11:18:26 PM EDT

[#21]

Quoted:

that is the most amazing thing I've ever seen.

[Batman]
You rang?
[/Batman]

Posted: 1/15/2006 11:56:53 PM EDT

[#22]

Blah blah blah !

Damn you friggen smart people

I just want one of those big assed .mil arc spotlights !

That's the coolest fuggen thing I've ever seen !

Posted: 1/16/2006 8:53:53 AM EDT

[#23]

Firstly--the PICTURE on the site may be faked for clarity, but if you are near the laser, you really can see those green beams at night for a long, long, long way.
....
Secondly, $3000 sounds high, I have seen at least one site selling such a (350mW) unit for $1000. It was advertised that it would melt holes in trash bags from 30 feet, and you could actually feel the hot spot on your skin from it. Also I point out that it was an overdriven module of an unspecified rating--but the biggest ones available through any regular civilian channels at that point were only 20 or 30mW. But....
,,,,,
The amateur astronomy guys took to using green "regular" <5mW lasers for sky-pointing out stars and constellations to other people. And among the amateur community, it is now general knowledge that these green laser pointers lose their brightness fairly fast over time (over a couple dozen hours of use) and it isn't a matter of "low batteries". They get dimmer, and stay dimmer. Anybody here using one for anything?
~

Posted: 1/16/2006 9:09:28 AM EDT

[#24]

Quoted:
img.photobucket.com/albums/0603/Dwoog34/Popcorn.gif]

+

Posted: 1/16/2006 9:14:58 AM EDT

[#25]

All light will travel in a straight line unless reflected or refracted.

Actually a black hole will bend it

Bomber

Posted: 1/16/2006 9:15:19 AM EDT

[#26]

Quoted:
All light will travel in a straight line unless reflected or refracted.

Actually a black hole will bend it

Bomber

It is still traveling in a straight line. It only appears to an outside observer that it is bending.

Posted: 1/16/2006 9:15:56 AM EDT

[#27]

Quoted:
Here is a picture of 25 W Co2 laser engraver I just bought Friday. I a couple weeks I will be marking knives, receivers, SBRs and other stuff for you guys.

home.comcast.net/~jasondcrum/Picture_008.jpg

it works like this.

Ooooo, I want one! How much are they running on the used market?

Posted: 1/16/2006 9:24:59 AM EDT

[#28]

Newtonian or inertial?

Bomber

Posted: 1/16/2006 9:37:40 AM EDT

[#29]

Quoted:
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.

It's not a fake. I got to play with a 200mw version and you can see the damn thing as far as it goes. It is very impressive and I want one for no good reason. My wifes grandfather bought one and damn that thing is bright. It has all these damn safeties that you have to manipulate before it will even turn on. Definately cool but not worth the money.

Posted: 1/16/2006 10:24:10 AM EDT

[#30]

Question(s).

Why are the new "high-power" lasers (ie lethal) the military is bringing out, like ZEUS IR?

Other than not being able to back track it, what is the advantage of IR vs Blue-Green?

Doesn't the blue/green wavelengths travel better through water than IR? If you had to shoot through water vapor (rain, cloud) wouldn't Blue/Green be better than IR?

Posted: 1/16/2006 10:32:12 AM EDT

[#31]

I don't feel like reading the whole thread. Has this been posted yet?

See the video!

www.optotronics.com/products.php

Posted: 1/16/2006 10:51:13 AM EDT

[#32]

I could get myself into so much trouble with that thing...

Quoted:
I don't feel like reading the whole thread. Has this been posted yet?

See the video!

www.optotronics.com/products.php

Posted: 1/16/2006 10:57:03 AM EDT

[#33]

Quoted:
I don't feel like reading the whole thread. Has this been posted yet?

See the video!

www.optotronics.com/products.php

That doohickey on the right sure looks like a lightsaber hilt.

Posted: 1/16/2006 3:17:26 PM EDT

[#34]

Quoted:
Quoted:
Here is a picture of 25 W Co2 laser engraver I just bought Friday. I a couple weeks I will be marking knives, receivers, SBRs and other stuff for you guys.

home.comcast.net/~jasondcrum/Picture_008.jpg

it works like this.

Ooooo, I want one! How much are they running on the used market?

About $10-12k. I got a smoking deal on this one because its missing a board- I spent 2 years looking for an affordable one.

Posted: 2/10/2006 10:41:31 AM EDT

[#35]

Good lord. Anyone who has ever had one knows that the beam can be seen pretty clearly even without fog. I had an 10mw HeNe laser and it could be seen for a mile or two on a relatively humid night, no problem. It was the size of a spotlight beam by the time at reached most distant targets. The beam looked exactly as pictured just not nearly as pronounced.

Posted: 2/10/2006 11:14:37 AM EDT

[#36]

The city looks a little like Berlin, Germany. Does anyone know?

Nervermind, it is Toronto. The tall building is the CN tower.

[ARCHIVED THREAD] - Want a light Saber? Super Laser? Here ya go *pic* (Page 2 of 2)

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