well from reading their website it looks like the only difference between the two is the alpha has a better battery life and has a longer duty cycle. I guess thats it? Damn they charge 60 bucks more for that!
The wikipedia article had a simple divergence equation,
Divergence angle = wavelength/Pi/waist size
A beam with a big waist size will have a small divergence, that is all there is to it. [/quote]
But the waist size isn't the same as the beam diameter at aperture , is it? :-/
The way I understood , the waist size was the beam diameter at the smallest point.But it's not necesarily at aperture, it could have an external focal point, so that would make sense if the waist size is bigger it means the laser is better colimated and thus having better divergence.I could be way off here though.I'm having a hard time understanding algebra in english , especially at 2:30 in the morning....
Yeah, the waist is the minimum spot size. Most lasers have the waist either inside the cavity somewhere or just outside of it, but not many 100s of feet or miles outside of it, so you can in general approximate the waist size as the size of the beam coming out of the laser.
If you have a 100mW greenie in a city it could probably span the entire city. Whether or not youll see it or not from your point is different. Cities are very different than the country or desert-or mountains. You have A LOT of light pollution and a lot of well................regular pollution
But the main factor is-if it is a city in the USA its kind of a dumb thing to do to sick a 100mW lgreen laser beam on a building. With th word "terror" being spat out every 5 seconds by politicians and the fact anything over 5mW is ILLEGAL in the USA-they might get the wrong idea that your some kind of harmful criminal. To add to it they have a nice, solid green beam to trace you back to!!!
Bottom line: Refrain from pointing powerful green lasers at city buildings
steelrain hahaha I know. I just find it fascinating how far these things reach. I wonder how powerful my red one was? I got it about 5 years ago from my parents I think it was like 30 bucks from costco or something. Anyways you could see a faint red dot on the mall from our house, which had plenty of light pollution and was approx 200 yards out. Anyways it sounds like you could find yourself in allot of trouble fast if you misuse one of these.
So if these things are illegal how come we can get them so easily? Especially the super high power ones.
your red was probably a 5mW one from the local 7/11 or something. They are cool lasers-some are made semi-nicely. They arent good for much other than annoying your friends cat..........
Green lasers are much brighter than reds. Youve probably seen that in giant bold print if you go search "green lasers" on ebay. Dont buy from their-just laugh at the scams. Most ebay sellers know absolutely nothing about lasers. they see they can see and just sell them.
Anyways, its easy for us to get them mainly because of a few factors.
For one-most of the companies are located in China. New wish.... CNI... Wicked.... are located in china. They make the lasers and chip them to companies that sell them-also usually in china..... (Hence Deal Extreme) In other words-China dosnt care what the hell they sell. It could be radioactive and as long as people bought them they would ship them here.
Another reason is the way they ship it. Wicked used to mark them as "Ballpoint pens" and then changed to "Light-up pens" for a while to get them through customs. Tech Lasers did the same thing to me a while ago. Id bet other companies probably do the same thing.
The third reason is basically there really hasnt been anything REALLY stupid done with it. Sure there are the occasional idiots who shine them at planes and get some huge fines and short jail time, but other than that, laser pointers havent hurt anyone YET. There are still idiots that go and shine them at people and such, but until the media starts freaking out about them and getting people scared (Yes, imagine FOX exaggerating about green laser beams visible from miles that can burn,........)
when that happens you will start to see more crack downs. As it is, most people dont even know lasers come in green.
so you can't simply perfectly focus a laser so it is 2mm diamiter at 1 feet and 2mm diamiter at 50 miles away ???
since that's the kind of laser i want . i don't want a 12 feet dot at 2 miles i want an at most 5 cm dot at 2 miles away