How the mW affect to the laser beam range ?

[boboweb]

Thank you all very much for the replies ! But enough theory , it`s time for some practice So my choice generally is between 200mW RED or 50mW GREEN.



Here are the concrete lasers:



DealExtreme: $44.11 Focusable 200mW Red Laser Pointer (1*18650 Included)

DealExtreme: $59.31 HLP18130 Focusable 200mW Red Laser Pointer (2*123A Included)



DealExtreme: $31.90 Focusable 50mW Green Laser Pointer with Safety Key Lock (1*18650 Included)

DealExtreme: $56.89 50mW Flashlight-Style Green Laser - Focusable (18650 Battery Included)



Which to choose ? The "burning" isn`t important for me. I want long and concentrate clear visible beam ! If you know something better that costs about 50$ feel free to recommend it to me. The only requirement is to be focus adjustable !



Thank you in advance !

 

[chipdouglas]

if seeing a beam is what you are about. you will struggle with a 200mw red. green and the new 445nm blue have beautiful beams. red is kinda junky for that. if you are in a smokers house you will see the red beam.

michael

 

[Thengine]

555nm is the highest response of the human eye. The closest color available in lasers is 532nm which is green. Stay with green. You want the lowest divergence possible, beam aperture is moot for "trowing." However you usually get the best divergence from larger apertures, which you don't care about cause you don't want to burn.

That being said there is a nice graph illustrating the HUGE importance of low divergence for a nice bright dot at any reasonable distance:
Laser divergence

(Thank you Jack)

The line approaches a limit of 1.5/1.2 squared, or 156.25% more Irradiance at pretty much any distance of 10M or more (30ft).

Long story short: find a laser with low divergence, power be damned (almost.)

I would suggest the Ledshoppe green, I just bought 3 of them:
http://www.ledshoppe.com/Product/ledp/LP1076.htm
Its a 50mw green with no ir filter but the reviews say it has a really nice divergence, and its CHEAP!

My next laser is going to be an Optotronics once I get a little experience under my belt with some "newbie" Ledshoppe lasers. I fly helicopters with the doors off and I am very excited to try these out at night. Going to give a couple to my co-pilots too.

*Edit* Why focus adjustable? Adjusting the beam doesn't do anything for divergence, and usually you mess it up more then a non-adjustable beam anyways (from what I have read.) The only reason to have focus adjustable is to focus the beam close in and burn things (again from what I have read.)

 

[qumefox]

As far as beam visibility, you have to take rayleigh scattering into account too. The beams on my 24mw 532 and 46mw 405 have about the same apparent brightness, even though the dot of the 532 is a lot brighter than the 405.